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Dirt is good for you: Curbing our hygiene obsession p61 www.knowledgemagazine.in

Volume 2 Issue 2 February 2012 ` 100

SCIENCE • HISTORY • NATURE • FOR THE CURIOUS MIND

A history of the

world

100 R.N.I. MAHENG/2010/35422

in

natural objects

Surprising objects that illustrate the human journey p24 Plus: How the Homo sapiens beat other hominids to become the only surviving species p66

UP, CLOSE & personal WITH PANAMA BATS p36

DINOSAUR DISCOVERIES LED BY LUCK p46

Q&A: If our body cells are replaced, why do we age? p80

SECRETS OF THE STONEHENGE REVEALED p56

On the cover Portfolio

Nature

FEATURE IN HERE

February 2012

FEATURE PORTFOLIO IN HERE

Panama Bats Panama’s forests are home to a vast array of bats, each uniquely adapted to exploit the habitat.

Photographs by Christian Ziegler

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42

Jan/Feb 2011

February Jan/Feb 2012 2011

XXX

REFLECTED GLORY The skies above Barro Colorado Island teem with thousands of bats. This 1600-hectare rainforest oasis in Lake Gatún in the Panama Canal offers such an abundance and variety of food and roosts that 74 different species of bat live here.

Each species has evolved unique physical adaptations, roost preferences, flight zones and foraging strategies that enable it to avoid competition with its neighbours.

Some, such as this greater bulldog bat (Noctilio leporinus), specialise in hunting fish. Flying low over a pool at night, the bat skillfully plucks its quarry from just beneath the water’s surface. Using echolocation, it can detect tiny ripples as the fish move through the water.

43

36 Portfolio: Panama Bats

SCIENCE

46 Blast from the Past

Digging for dinosaur bones has a lot to do with luck, as Cavan Scott discovers SECRETS OF STONEHENGE

science

The secrets of

STONEHENGE After the recent discovery of a second henge, Robert Matthews investigates how cutting-edge tech looks set to uncover even more archaeological sites

62

this new view are revelations provided by the seemingly miraculous powers of 21st-century science, from groundpenetrating radar and magnetometry to GPS technology.

The power of these techniques was demonstrated in July last year, when an international team of archaeologists made headlines worldwide with an astonishing discovery near Stonehenge. After just nine days of searching, the team uncovered 3 evidence for an entire new structure on Salisbury Plain: a 25-metre wide walled ditch or ‘henge’, containing a circle of pits.

Situated less than a kilometre from

Stonehenge, the structure is believed to be as old, and to have had a similar appearance, its ditches aligned with the more famous structure.

The discovery has been hailed as the fi rst major ceremonial site to be discovered near Stonehenge for half a century.

Yet anyone visiting the site would fail to see anything, as the newly discovered henge lies buried several metres beneath the surface.

Its presence was revealed to the world by the techniques being pioneered during the three-year project that began

last summer.

February 2012

56 The Secrets of Stonehenge Avant-garde technology has made the discovery of the second henge possible

Science

A history of world in

100 Natural Objects A history of the

100 NATURAL OBJECTS

WORLD

05 CHICKEN’S EGG

100 in

02 ARTHROPOD EXOSKELETO N

Arthropods (insects, spiders, crustaceans and their relatives) have become highly successful. Some are very numerous, but none are very big. often depict giant creepy-crawliesYet science-fiction films conquering our world. impossible! Arthropods It’s have an external skeleton and must moult it to grow, so are weak and immobilised until a larger one forms and hardens.

In other words, they cannot get bigger than the maximum survivable size without a skeleton, and, as a result, the largest spiders and insects weigh less than a small rat.

03 BALEEN PLATE

NATURAL OBJECTS

Whales in the suborder Mysticeti have 100 or so of these tough but flexible structures hanging from their upper jaws. They scoop up massive mouthfuls of seawater, then use their tongues to force it out through the baleen plates, trapping plankton. Thus, the world’s largest animals have no need for the teeth so characteristic of most other mammals.

Baleen was highly valued for providing ‘springy’ support in all kinds of goods, from umbrella stays to corsets. It fetched high prices, contributing to the growth of a huge whaling industry.

However, by the early 20th century (due in part to the invention of plastics), it was no longer the most valuable product of the whale harvest, but a waste product instead.

PAT MORRIS selects 100 natural objects that illustrate different aspects of human history in a wider context. They all have a greater than just their immediate appearance.significance

DORLING KINDERSLEY,

PICTORIAL PRESS/ALAMY,

SHUTTERSTOCK, SCIENCE

PHOTO LIBRARY/ALAMY

DIRT IS GOOD FOR YOU

100 objects that illustrate different aspects of human history in a wider context p24

01 HUMAN BRAIN Nothing has had a greater impact on the natural world than the human brain.

It evolved from a simpler primate brain, enabling us to use rational thought to organise our lives, defend ourselves against predators and avoid danger. It meant that we did not need to evolve physical defences such as large claws or teeth.

The human brain has millions of nerve cells, linking sensory organs to our limb and body muscles, and it processes data at high speed to instruct our bodies what to do. The brain is also capable of abstract thought and controls speech and writing, sophisticated forms of communication that make it possible for us to change the world – and even destroy it or visit other planets. No other animal ever did that.

04 AMMONITE FOSSIL Ammonites were once among the most abundant of all marine creatures. They inhabited the last chamber of their coiled shells, the other chambers providing buoyancy as they drifted on the current to catch fish. Today, their fossils are found worldwide, reflecting their great success as a group of animals.

Ammonites survived for tens of millions of years, yet they all died out 65 million years ago.

How could such a widespread group suddenly go extinct? Many scientists think that it was due to a meteor colliding with the Earth.

Maybe we should take the ammonites’ fate more seriously: their intricate fossilised shells are a reminder that it might just happen again.

Domestication of the Indian junglefowl has led to this species becoming the world’s most numerous, useful and abused bird. It can convert grains and debris into valuable eggs and meat, but industrial chicken production has given rise to a major debate about animal welfare standards.

06 ROOT NODULE

Bacteria in the nodules on the roots of clover and other ‘legumes’ take nitrogen from the air and enrich the soil. These plants have long been grown as a simple way to boost crop yields.

07 SCALLOP SHELL

Coastal people have eaten marine molluscs for millennia, but nowadays the scallop shell also stands as a reminder of how easily scallop-dredging fleets can destroy seabed ecosystems.

08 YEAST

Saccharomyces cerevisiae has played a vital part in human history: it reacts with starches and sugars to produce carbon dioxide and alcohol, a process harnessed to make bread and alcoholic drinks.

The many other uses of yeast now extend to the manufacture of biofuels.

09 PEARL

Pearls form when bivalve molluscs deposit shelllining material around an irritant ‘seed’ in their shell. Carl Linnaeus was the first to explain this process, using European freshwater mussels, and in the 1750s he proved that it could be stimulated artificially.

The subsequent history of pearl cultivation reveals our unrivalled ability to tinker with natural processes as we see fit.

10 SEABIRD GUANO

Peru’s mid-19th century golden age, the ‘Guano Era’, was built almost entirely on the profits from dealing in dung. This smelly natural resource consisted of seabird droppings harvested at coastal breeding colonies and then shipped abroad as fertiliser.

February 2012

XXX

W

hen Stonehenge fi rst started to take shape, the Great Pyramids of Egypt still lay 500 years in the future. By the time the Romans arrived, its completion was already as remote in time from them as they are from us.

Over the 5000 years of its existence, Stonehenge has lost none of its power to intrigue. Now archaeologists believe they are on the brink of a revolution, drawing up a whole new concept as to its origin and purpose. The vision of Stonehenge now emerging is one of a site deemed to have miraculous powers, drawing people from far and wide. And underpinning

ALAMY

Photolibrary.com, Science Photo Library/Alamy X2, W Sowry, bon appetit/alamy, dorling kindersley, alaska stock llc/alamy, pictorial press/alamy, winfried wiseniewsky/minden/flpa, wildlife gmbh/alamy, christian ziegler, alamy x2, science photo library

Panama forests are home to bats that uniquely adapt to exploit their habitat

31

Is the modern world’s obsession with hygiene responsible for a global allergy epidemic? Dan Cossins investigates n epidemic is sweeping the world, especially the West. The symptoms vary: sneezing, rashes, swollen eyes and breathlessness. The illness is often debilitating and can be fatal.

But the causes are seemingly harmless things like pollen and peanuts.

This isn’t some fictional doomsday scenario. This is the here and now, where an inexorable rise in allergies is emerging as a serious threat to the health of future generations.

A century ago, no such problems existed. Now, in some parts of the world, allergies affect a third of adults and almost half of children, and they’re becoming more severe. If this continues, allergy experts warn that it could become one of the biggest

A

medical challenges of the next century. So why are our bodies freaking out so much?

It has long been suspected that our hygiene-obsessed modern lifestyle is to blame. But immunologists are now revealing precisely how reduced exposure to bacteria and parasitic worms is damaging the immune system’s ability to regulate itself.

Immune responses that evolved in the presence of certain microbes have been thrown wildly out of kilter in their absence. As a result, the body’s defences have become dangerously over-sensitive to things like dust, pets and foods. And it’s not just allergies. “The same malfunction is also responsible for various other immune-related diseases, including February 2012

61 Dirt is Good For You

Dan Cossins explains how dirt could, in fact, be beneficial for our health

80 Q&A

Does milk chocolate melt more quickly than dark?

67

February 2012

3

Contents

February 2012

Science

FEATURES COVER STORY

26 A History of the World in 100 Natural Objects

Science HISTORY History

dorling kindersley, FLPA, science photo library x2, Ingo arndt, BBC, alamy

science

Nature

science

Nature

Pat Morris compiles 100 natural objects that tell an intriguing tale about the human evolution. Each of them have a greater significance than just their immediate appearance on the cover

38 Portfolio: Panama Bats

Photographer Christian Ziegler joined the throng of scientists who flock to Lake Gatún in Panama to marvel at the hordes of bats that live there on the cover

48 Blast from the Past

Dinosaur bones give scientists big clues about the past, but how are such valuable fossils found?

Cavan Scott tells us more

56 Paws for Thought

Whether equipped with suckers, toes, claws, pads or webbing, feet have adapted to pretty much every environment in which life thrives

26 A History of the World

in 100 Natural Objects

Explore the wider significance of tomatoes, pearls, amongst others

on the cover

58 The Secrets of Stonehenge

Post the recent discovery of the second henge, Robert Mathews investigates how cutting-edge technology is set to reveal more archeological sites On the cover

63 Dirt is Good For You

94

Resource The coolest new books reviewed

11 Update

The rats that aren’t afraid of cats – and much more

Is the world’s obsession with hygiene responsible for a global allergy epidemic? Dan Cossins explains

68 Last Man Standing

Journalist Kate Ravilious reveals how over 50,000 years ago Homo sapiens beat other hominids to become the only surviving species

76 The Big Idea: Out of Africa

92 Gadgets

Charles Darwin was the first to suggest that our similarity to apes pointed to Africa as the home of humankind

82 Subscribe today

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Take your pick from the latest gizmos this month

76 The Big Idea

Out of Africa: Humankind’s origins

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20 Snapshot

The bizarre world of animal feet

UPDATE

Three arresting pictures from the world over to enlighten, tantalise and amaze

Strange Things are Afoot

68 Last Man Standing

Know more about the Homo sapiens’ struggle with other hominids for sole survival

11 The Latest Intelligence

Top research stories from the worlds of science, history and nature

16 Comment & Analysis

Is nuclear power a deadly pursuit or merely an energy source with an image problem?

17 Insights

Actress Poorna Jagannathan traces her journey and inspirations

18 World News in Context

David Keys looks at the changing face of Scottish politics amid increasing calls for independence from the UK

84 Q&A

20 Snapshot

The Morning Glory Pool at the Yellowstone National Park in Wyoming

on the cover

Questions need answers like butter needs bread and cattle needs a shed

92 Gadgets

Need help in finding the right gizmo? This new section gives a heads up on the latest gadgets and applications in the market

Resource 94 Reviews

Recommendations of books, websites and blogs to keep you up-to-date with the world

98 Last Word

Dr T Satyamurthy and J Chandrasekaran of R.E.A.C.H Foundation tell us how modern architecture has a lot to learn from history February 2012

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Welcome

Experts this issue

It’s often stated that in order to prepare for the future one must take stock of the past. So in this fresh bud of an issue, we look back.

In our cover story, the very talented Pat Morris makes an interesting list – of 100 natural objects that illustrate the history of man’s journey on the planet…things that came to be over thousands of years, that define our very existence today.

Did you know that we ( Homo sapiens) were one of the five species roaming the Earth around 80,000 years ago and had to ward off Neanderthals, Homo erectus amongst others to emerge as the dominant specie? In this special issue, that is homage to our rich natural history, do check out fascinating articles on this battle, man’s first journey from Africa, as well as the key behind discovering dinosaur remains.

Continuing with the celebrations of all things past, there is also a Robert Matthews story about the occultish and mysterious Stonehenge.

Do we finally reveal the secrets of its origin? Read on and find out.

So here we are. In 2012. A new beginning. A fresh start. May the new year be the year of inspirations and discoveries for all!

Patrick Morris currently works as a producer-director for BBC Earth and has made many highly acclaimed natural history programmes for over 18 years.

He is the man behind the fascinating Galapagos series in 2006 and the Emmy-winning Life series in 2009 about extreme animal behaviour. See page 26

Cavan Scott is a freelance author, journalist and editor. He has authored many children books and has written for over 50 magazines ranging from lifestyle, consumer titles to business. His latest work is Planet Dinosaur. See page 48

Kate Ravilious is a freelance science writer specialising in physical and environmental sciences. Based in New York, she has published her works in many prestigious newspapers and magazines. She is also the winner of The Daily Telegraph/BASF Young Science Writer of the Year award in 2000. See page 68

Preeti Singh

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Any of numerous extinct terrestrial reptiles from the Mesozoic era (8) The first four legged creatures to develop lungs (10) Around ___ thousand years ago our evolutionary ancestors migrated to Europe and Australia (5) He proposed the theory of Evolution (6) The earliest life appeared on Earth around ____ ______ million years ago (4,8) Human ancestor which existed around 1.8 to 1.3 million years ago (4,7) His book Naturalia Historia is the oldest known Natural History Encyclopedia (5) The early reptiles and mammals lived on _____ (7) The first vertebrates (12) Extinct amphibians widely accepted as the first animals to have recognizable limbs Animal remains from a bygone geological age excavated from the soil (6) Animal order which includes apes and human beings (8) First known creatures to have developed a heart and circulatory system (5,5) Earliest animals to have a brain (9)

H Down 1 2 4 5

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Update

The latest intelligence

P Secret to invisibility cloaks revealed p10 P Wildlife habitats move to combat global warming effects p11 P How did the Moon get its rough side? p12 P Is it a good move to continue to use nuclear power? p14

Toxoplasma gondii parasites (left) appear to have removed rats’ fears of cats – a discovery that could have implications for humans too

Mind control discovery Parasite that hijacks rats’ brains could be playing with our minds xactly how a parasite manipulates the mind of its rodent hosts, making them apparently lose their fear of cats, has been uncovered – laying open the intriguing possibility that something similar could happen inside the human brain.

Rats infected with the single-celled organism Toxoplasma gondii appear to be attracted to their usual foe, making it much easier for cats to catch them. This is good news for the parasite, which can only reproduce sexually in a cat’s small intestine. But how Toxoplasma induces this lifelimiting behaviour in rats has been unknown until now.

Science Photo Library, Thinkstock

E

Neuroscientists at Stanford University, California, found that exposing rats infected with Toxoplasma to cat urine caused neurons to fire in the amygdala – part of the brain associated with emotional response. As expected, there was a response from neural pathways involved with fear, but also from some involved with attraction.

Toxoplasma infects humans as well as cats and rats, through eating undercooked meat and coming into contact with cat faeces. Globally, it’s estimated that 30 per cent of the human population carries the microorganism without obvious symptoms.

There’s some evidence that it could be subtly influencing

Toxoplasma has been linked to neuroticism, reduced attention span and schizophrenia “There was still fear there, but it’s almost as if the attraction pathway had the power of veto,” says Patrick House, the neuroscience PhD candidate who led the research.

behaviour. Czech researchers found the accident rate among military drivers infected with Toxoplasma to be six times higher than normal. It has also been linked with neuroticism

and reduced attention span.

Schizophrenics are more likely to have Toxoplasma.

“Our research opens up the possibility that Toxoplasma could be affecting the human brain, because this is the first evidence that the parasite is directly manipulating the brain of its host,” says House. “We had assumed it was because it manipulates behaviour.

“We have amygdalae too, and from the parasite’s point of view on a molecular and cellular level it’s difficult to tell the difference between the rat brain and the human brain.

It’s a compelling possibility that Toxoplasma is altering something inside the human brain. This is the step before we could say that for definite.

“The next step is to look at the links with Toxoplasma and schizophrenia, and I know some studies are in the works.”

February 2012

9

Update

The latest intelligence

Invisibility cloak Magical material solves mystery n undergraduate student has overcome a major hurdle in the development of a practical invisibility ‘cloak’ that can conceal anything from view.

Invisibility cloaks are materials that bend light around an object so no light hits it, concealing its presence.

A material that can make something else disappear clearly has military potential, but other uses have been suggested ranging from wrinkle creams to transparent cockpit floors that could help pilots when landing aircraft by revealing the runway and landing gear.

The trouble is, the laws of physics mean that the light would have to travel incredibly quickly round the disappearing object for the cloaking material to work – faster than the speed of light. Nothing – matter, energy, light – can travel this fast under most conditions.

A

Getty x2, Esa, NOAA Photo library

12 MARCH 2011

Physicists have found the only solution so far has been to create the conditions where the speed of light can be exceeded – where there is ‘superluminal propagation’. This happens when the background of the object being made invisible does not change and only a limited number of wavelengths of light are sent towards the object rather than a broad spectrum. That works for a stationary object but not for a moving one.

“The way to get rid of these restrictions is to get rid of this requirement for superluminal propagation,” says Janos Perczel, a 22-yearold Hungarian-born physicist studying at the University of St Andrews, UK. Perczel’s solution is to combine an invisibility cloak with another material capable of slowing light down. The result is an ‘invisibility sphere’,

16 MARCH 2011

The newly created icebergs are clearly visible in the right-hand photograph

10

February 2012

Will we one day be able to blend into the background?

inside which any object will vanish – but it will also be invisible itself.

It could be a while before we see – or rather, don’t see – such optical camouflage put to practical use. Perczel’s cloak currently manifests itself as mathematical formulae: it’s a theoretical construct.

The cloak would need to be made from metamaterials – artificial materials made from large molecules that can be combined to produce exactly the required properties. The formulae developed by Perczel,

who was working under the supervision of Ulf Leonhardt, Chair of Theoretical Physics at St Andrews, specify the electrical and magnetic properties of the materials scientists would need to create. “It will take time for the practical side of things to catch up with the theory,” says Perczel.

Even then, Perczel’s invisibility-inducing material would be solid. “It would be quite a challenge to create flexible materials but not impossible,” he says.

Japan’s quake breaks Antarctic ice Huge chunks of ice almost the size of Manhattan broke away from the Sulzenberger Ice Shelf in Antarctica in March as a direct result of the magnitude 9 Tohoku earthquake 13,600km (8,000 miles) away in Japan. The largest icebergs measured 6.5km by 9.5km (4 miles by 6 miles) and were 80m (260ft) thick.

By the time the swell had travelled across the Pacific, it was just 30cm (12in) high.

However, US scientists who have recently released this satellite image say that waves generated by the earthquake caused repeated flexing of the ice shelf and its ultimate fracture.

Before the earthquake, ice had not ‘calved’ from this ice shelf for 46 years.

News in Brief Milestones

Moth species are settling higher up Mount Kinabalu in Borneo each year

Technicians operate the huge Marconi-EMI system at Ally Pally

75 years ago G 2 November 1936: The BBC Television Service is launched – the world’s first regular ‘high definition’ service. Only around 20,000 homes around Alexandra Palace in North London, from where the pictures are transmitted, are able to receive the broadcasts. Sir John Reith, thenDirector General of the BBC, is less than enthusiastic about the new medium. “To Alexandra Palace for the television opening,” he writes in his diary, “I declined to be televised or take part.” He later describes television as “an awful snare”.

100 years ago H 14 December 1911: Norwegian Roald Amundsen becomes the first explorer to reach the South Pole, beating his British rival Robert Scott by 35 days.

Amundsen’s Pole-conquering team includes four other men and 16 dogs. Three days later they leave a tent and a letter stating what they have achieved in case they don’t make it back to their base.

Amundsen’s crew take an observation at the South Pole

Head for the hills Wildlife moves in response to global warming lants and animals around the world are responding to climate change much more quickly than was once thought. New research shows that over the past 40 years, the world’s wildlife has shifted towards cooler climes nearer the poles at the rate of 17km (10.6 miles) per decade and higher altitudes at 12m (39ft) per decade.

Scientists combined data from many studies of species distribution to produce their ‘meta-analysis’. It shows a rate of movement in response to global warming that is three times the previously accepted rate.

“By the time our research had come out I had got over my surprise,” says project leader Chris Thomas, Professor of Conservation Biology at the University of York, UK. “Part of the motivation for doing this research was that back-of-the-envelope calculations using studies coming out indicated that the accepted rates of movement of species were being regularly exceeded.”

Since the 1880s, the average global temperature has risen by 0.8ºC – with two thirds of that taking place in the past 40 years.

Ecologists are sure that the changes in the places where species survive are unambiguously linked to climate change because, they say, the wildlife has moved furthest in regions where the climate has warmed the most.

Some of the study’s specific findings demonstrate the extent of the changes. In just one decade, for instance, moth species have moved on average 67m (220ft) uphill on Mount Kinabalu in Borneo. However, other findings have shown that some species moved more slowly than was expected, some haven’t moved at all and others have even retreated.

Problems arise when an organism runs out of places to move to, such as when it reaches the summit of a mountain. “As the climate continues to warm, some of these restricted species will run out of places to hide,” says Thomas.

The conclusion is cause for concern, he says. “This study is showing that most species are on the move and they are starting to move quite fast. The ecosystem and biodiversity consequences of climate change will be with us sooner rather than later.”

P

Egyptian death solved Medication used by a female Egyptian pharaoh as an eczema treatment may have killed her. A flacon once owned

by Pharaoh Hatshepsut, who lived until 1458BC, now sits in the Egyptian Museum of the University of Bonn. A pharmacologist found that the residue of a liquid inside the vessel contains the hydrocarbon benzo(a)pyrene, one of the most dangerous carcinogenic substances.

Blowing in the wind Computer models have presented the clearest picture yet of the huge distances air-borne microbes can travel between continents, indicating that diseases may be carried thousands of kilometres in the wind. Using models originally designed to predict the movement of dust particles, scientists from the UK and Switzerland released virtual microbes from Mexico and South America and found that some ended up in Australia.

Early animal X-rayed Three-dimensional models of harvestmen (or ‘daddy longlegs’) that lived 300 million years ago show they were similar to their modern-day descendents. An international team of researchers X-rayed harvestmen fossils from France dating from a little over 300 million years ago, in the Carboniferous period. The two species, Macroglyon cronos and Ameticos scolos, indicate that harvestmen were one of the first groups of animals to have modern body plans.

3D model of a 300 million-yearold harvestman

Update

The latest intelligence

EEE ROUND UP The top science, nature and history research from around the world

PLANETARY SCIENCE It has always been a mystery why the side of the Moon nearest Earth is relatively flat while the far side is mountainous with a thicker crust.

A computer model of the Moon’s development suggests it once had a ‘companion’ that slowly collided with the Moon, depositing a thick layer of crust on one side rather than creating a crater. It has been speculated for some time that the Moon formed from the debris of a Mars-sized object that collided with Earth. Its companion could also have formed from this.

Thinkstock x3, NASA SOHO, NAISH / DYKE / CAU / ESCUILLIÉ / GODEFROIT, M JUTZI & E ASPHAUG / Nature

E http://bit.ly/lunarformation Nature

ASTROPHYSICS

Solar flares and coronal mass ejections, phenomena that release charged particles from the Sun’s surface, can now be predicted.

These events, which can disrupt power grids, often coincide with the appearance of dark patches on the Sun known as sunspots, but forecasting them has proved problematic. Stanford University researchers have now discovered that magnetic fields, the first sign of a sunspot developing, slow down the movement of sound waves.

Measuring these movements can pinpoint an early sunspot.

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February 2012

HEALTH

Fig 1

Fig 2

Fig 3

Fig 4

DEMOGRAPHICS

Between the mid-18th and 20th centuries, the age at which boys physically mature reduced by 2.5 months per decade, according to a statistical phenomenon known as the ‘accident hump’. At the age of reaching sexual maturity, a sharp rise in testosterone levels prompts a surge of violence and risk-taking in boys – and a consequent spike in the death rate. Improvements in nutrition and disease protection are said to be behind the shift in sexual maturity, which is replicated in girls.

However, since the 1950s there’s been no change.

CHEMISTRY

Alligator fat could be powering vehicles in future after it has been identified as a feasible alternative source of biodiesel to soybeans and other food crops. There has been concern that using foods as fuel would drive up their price, but the alligator meat industry currently disposes off millions of kilograms of fat each year. Tests at the University of Louisiana at Lafayette showed that alligator biodiesel is similar in composition to soybean biodiesel and meets nearly all the official safety standards.

The mechanism by which some compounds found in grapes protect the skin from the Sun’s ultraviolet (UV) radiation has been discovered.

UV rays activate ‘reactive oxygen species’ in the skin, compounds that oxidize large molecules such as DNA, which leads to the death of cells. Lab tests have shown that some grape compounds can reduce the formation of reactive oxygen species in skin cells. The Spanish researchers say it could lead to the development of new skin protection treatments.

PALAEONTOLOGY

A fossilised jawbone from Kazakhstan provides new evidence that large birds roamed or flew around the same time as the dinosaurs. Most birds in the Cretaceous period would have been crow-sized, but a fossilised spinal bone found in France in 1995 provided the first indication that there may have also been larger birds. The new fossil would have belonged to a bird that was 2-3m (6.6-9.8ft) tall. It’s impossible to tell whether the newlydiscovered creature, Samrukia nessovi, could have flown.

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Comment & Analysis Paddy Regan wonders whether it’s time to re-think nuclear power

“There’s a clear issue that needs addressing about the perception of nuclear power” A visit to the devastated Fukushima plant two months after meltdown

an nuclear power ever be 100 per cent safe? No, is the short answer. Yet there are currently more than 60 nuclear power reactors under construction around the world and, according to the World Nuclear Association, as of June 2011 28 new reactors had been proposed for the US alone.

The debate surrounding these new nuclear plants has been brought into sharp focus following events in Japan. Reports of core meltdowns and footage of explosions confirmed to many their concerns about the safety of civil nuclear power.

We’re still hearing news about Fukushima. Scientists at the University of California, San Diego, recently released a study showing that sulphur-35 radiation from the stricken power plants could be detected on the west coast of the US. The report does demonstrate the extent of the reactor meltdowns, but it must be said the radiation levels in California could in no way be described as presenting a health risk.

Corbis, PRess association

C

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February 2012

Nuclear reactors work by converting the energy released in nuclear fission, where atoms are split into smaller parts, into heat, which is used to boil water to make steam, which turns turbines, creating electricity.

The danger presented by nuclear reactors is one that will always be there to some degree, regardless of design: exposure to radioactive materials produced in the reactor core. Problems arise if these materials are released into the wider environment. This is what happened partially in Fukushima and much more dramatically at Chernobyl in 1986.

The brutal truth is that no power production method is completely safe.

The failure of the hydroelectric Banqiao Reservoir Dam in Henan Province, China, in 1975 killed more than 20,000 people immediately, with over 150,000 perishing later. Coal, gas and oil power cause thousands of deaths each decade. More than 3000 coal miners died as a result of accidents in China every year between

2001 and 2005. In 2010 in New Zealand, 29 people died in the Pike River coal mine following a methane explosion, and 235 people died in a petrol tanker accident and fire in Sangha in the Congo.

A matter of proportion The mother of all nuclear disasters, the explosion at Chernobyl, resulted in fewer than 50 deaths from acute radiation exposure. Other big nuclear disasters that have become by-words for terrifying events, such as Three-Mile Island and, now, Fukushima, both resulted in zero deaths from acute radiation exposure.

Nuclear safety is improving all the time. Modern pressurized water reactors with two water systems – one that turns to steam and another that keeps the reactor cool – are inherently safer than the 40-year-old boiling water reactors like those at Fukushima, which have one water system that both cools the reactor and generates steam. New so-called ‘Generation IV’ reactors such as thoriumbased molten salt systems, in which the coolant and reactor fuel are combined, hold the promise of even higher safety

Chernobyl was nuclear’s low point, but accidents occur whatever the power production method

COUNT levels. These are the basis of significant research and development in India, among other places.

By over-emphasising the safety issue, the nuclear industry has arguably made an impossible rod for its own back in terms of public perception. That’s not helped by the media coverage.

Radiation figures are quoted in stories without any relative safety margin. The fact is that the typical, healthy human body is ‘loaded’ with radioactivity from carbon-14, produced by cosmic ray interactions in the atmosphere, and potassium-40, which was present when the Earth was formed and is now bound up in human muscle tissue and bones.

Potassium-40 is present in our bodies at much higher levels than the radiation figures reported in most of the news stories on Fukushima.

This is not to make light of the potential radiation dangers. For the technicians fighting to repair a damaged plant, radiation levels need to be carefully monitored. The health effects of radiation are well-understood and can be quantified, in a sad irony, by using data from historic Japanese nuclear weapon attacks. This perhaps leads us to a crucial point: along with media hype of incidents, the psychological link between nuclear power and nuclear weapons could be clouding a more rational view. There’s clearly an issue that needs to be addressed in terms of the perception of nuclear power.

While governments may be open to licensing new nuclear plants, it’s not certain they will be built. Public protests and the economics of nuclear production mean they may not get off the ground. But the alternative to more nuclear plants will be a large gap in the world’s operational power capacity.

Paddy Regan is Professor of Physics at the University of Surrey and a Visiting Researcher at the Wright Nuclear Structure Laboratory at Yale University

What do you think?

Do the benefits of nuclear power outweigh the risks? email: bbcknowledge@wwm.co.in

insights

DOWN

Poorna Jagannathan

3,500,000

“Fear of dying made me a much less cerebral actor, I began feeling much more in my body”

molecules are being screened by computer to see whether they could help convert light to electricity efficiently in next-generation solar cells.

The Clean Energy Project run by Harvard and IBM aims to beat the energy conversion capabilities of today’s cells.

65 species of bacteria, yeasts and fungi, on average, live in the human belly button.

Biologists at North Carolina State University have taken samples from nearly 400 volunteers.

15 degrees centigrade is by how much the body temperatures of King penguins were found to occasionally drop in tests carried out on the Crozet Islands in the Southern Indian Ocean. Such huge drops are thought to help the birds to conserve their energy.

5 times the size of Earth is the proportions of a planet made almost entirely of diamond that’s been spotted by astronomers studying a spinning star, a pulsar, 4000 light years away.

3 is as far as hyenas (Crocuta crocuta) are able to count. Zoologists found they increased their attentiveness based on the number of calls they heard from potential intruders – more calls indicating more intruders.

Your approach to your work is?

I love it when my work feels highly spontaneous and very believable at the same time. A place called The Barrow Group in NYC probably has had the biggest influence on my acting style. Their approach is that acting should seem as effortless as possible.

What challenges do you face?

No matter where I am, I’m always the outsider. In the States, I’m the brown actor who gets pigeonholed for doctors, lawyers and let’s not forget the new emerging genre of ethnically diverse best friend. Lead roles usually end up going to Caucasians. In Bollywood, I’m the “bold” actress from America, not appropriate for the more traditional roles that are doled out to women. So on film, I don’t get to play with the range I get to play in theatre.

Any moment that affected your outlook towards work?

I was swimming with some friends in Bahia, Brazil and the current took us out. I finally did make it back to shore (some eight year old boy dragged my skinny ass back), but there was a dramatic shift in my acting when I got back to it. I think the sheer fear of dying made me a much less cerebral actor and I began feeling much more in my body.

Your views on discipline and study?

I’m a fierce believer in study and training. You have to explore and understand what makes you tick before you understand what makes others tick - and that’s an ongoing process. It’s the reason why therapists have to be in therapy.

Is talent nature or nurture?

I’m a product of my training, more so than my talent.

Training taught me to understand scripts, character arcs, and stakes. It helps me make behaviour repeatable- so if it says “she starts crying” in a script, I can do it every night on stage. I think training makes me feel I can handle almost anything that’s thrown at me.

What is your most marked characteristic?

My inappropriate sense of humour.

What do you daydream most about?

Crank calling. It’s a lost art form.

Poorna Jagannathan is an American actress who made her Bollywood debut with the comedy film Delhi Belly in 2011 for which she won critical acclaim. She has also acted in several television series in Hollywood.

February 2012

15

World News in context Scotland’s political future David Keys examines the events that led to this year’s Scottish nationalist election victory – and the prospect of a referendum on independence For how much longer will Scotland remain a part of the United Kingdom?

ollowing the Scottish nationalist victory in the Scottish elections in May, the Scots are set to hold a referendum on independence within the next three to four years. If passed, such a vote would mean the end of the UK as we know it – and could encourage similar developments elsewhere in Europe, thus helping to change the nature of the European Union itself.

But what caused the recent Scottish electoral sea change? In essence, the transformation has come about through a combination of factors going back many centuries, and developments that have taken place over the past 60 years.

The most important factor is Scotland’s status as a distinct nation – a status that is grounded in its separate political history, its different legal system and its different religious tradition.

REX, Bridgeman art library. illustration BY Sheu-KuEI Ho

F

KEY

Gaelic Kingdom of Dal Riata c. 600AD Land controlled by the Pictish kingdom of Fortriu c. 700AD Early Scottish universities (by 1600)

North Sea

SCOTLAND Aberdeen Atlantic Ocean

St Andrews

Glasgow

Edinburgh

England

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February 2012

In political terms, Scotland was an entirely separate kingdom with its own monarchy and its own parliament for around 700 and 400 years respectively, before the Act of Union in 1707. Scotland owed its medieval and early modern independent statehood to the fact that it simply hadn’t been conquered or settled to the same extent as the rest of the UK by the peoples and powers that determined most of southern Britain’s history – the Romans, the Anglo-Saxons and the Normans.

Instead, the kingdom of Fortriu – Scotland’s own native Pictish tradition of kingship – merged with the western Scottish Gaelic ‘Scots’ royal dynastic system, Dal Riata, to produce a distinctively non-Anglo-Saxon kingdom in northern Britain.

England’s late 13th- and 14th-century attempts to conquer Scotland forced the Scottish state to ally itself to continental powers – especially France – in order to protect itself against English takeover. This fundamentally changed Scottish culture. In terms of education and its legal system, it moved closer to Europe than England.

Before the English invasions of Scotland, many Scots had been educated at Oxford and Cambridge. After the Scots repelled their would-be conquerers, they tended to go to Paris, Orleans and Padua. What’s more, competing ecclesiastical claims over who should control the Scottish church had led to the Pope enforcing a long-lasting compromise by which the Scottish church became neither Scottish nor English-governed but, uniquely, a ‘Special Daughter’ of the Papal See. This too led to greater Europeanisation.

A third development reinforced these trends. Whereas the medieval English state became increasingly centralised – partly courtesy of the late Anglo-Saxons and the Normans – the Scottish state system was relatively decentralised, with local landowners having substantial political and judicial responsibilities.

In order for the system to work, landowners therefore had to be welleducated. This was a factor in the Scottish Parliament’s decision in the late 15th century that the elder sons of all mediumto-large Scottish landowners had to be schooled in the law, Latin and the arts.

This, in turn, contributed to an extraordinary educational expansion in Scotland. By 1600, England had just two universities; Scotland had no fewer than five, albeit smaller ones. The creation of all these universities helped generate a large, highly educated class that wanted political influence and helped produce an extraordinarily vibrant civil society.

The Reformation These trends helped generate another great factor that has historically differentiated Scotland from England – its religious tradition. The Reformation in Scotland occurred in a very different way to that of England, producing very different results.

In England, Protestant supremacy was imposed from the top following Henry VIII’s clash with the Pope in the first half of the 16th century. In Scotland, however, what became the country’s dominant Protestant tradition – Presbyterianism – grew from

A brief history of Scotland 8th/9th century United monarchy evolves 1192 Scottish church becomes a ‘special daughter’ of the Papal See 1296–1338 English invasions

the grass roots up. Consequently Presbyterianism, as opposed to England’s Anglicanism, was relatively democratically organised, with its clergy accountable to popularly elected local church bodies rather than appointed from on high. The result was a distinct and more egalitarian civil society and an enduringly different national identity.

Nevertheless, after the Jacobite rebellions of the early to mid-18th century, by 1760 Scotland had largely evolved into a loyal participatory member of the UK. Forming the union had been an act of political and economic expediency on Scotland’s part. It had just emerged from dire economic problems. The decision to join England in forming the UK, and to therefore scrap its own Scottish Parliament and sovereignty, had been taken by the old Scottish Parliament itself. Although the Scots entered the UK somewhat divided in their enthusiasm, subsequent developments gradually won over the vast majority.

First, Britain’s imperial and mercantile expansion created huge economic, industrial and professional opportunities for the Scots, with many becoming prominent in the British army and imperial administration.

Then, in the 20th century, the experience of the two World Wars seems to have generated a spirit of common destiny and solidarity, which helped reinforce loyalty to the union. Lastly, the post-war UKwide ‘welfare state’ settlement lifted living standards in Scotland, changing key aspects of Scottish society.

But the passing of the Empire, the establishment of relative peace in Europe and the late 20th century perceived erosion of some elements of the welfare state created a new situation in which there were few obvious unifying factors.

The Battle of Culloden put an end to the Jacobite uprising of 1745. Within 20 years, Scotland had largely evolved into a loyal member of the UK

These historical developments formed the background against which more recent factors have come into play. Over the past six decades, the Scottish political landscape has changed beyond recognition. In 1955, half of Scottish voters supported the Conservative Party. In this year’s Scottish parliamentary election the figure was a mere 13.9 per cent.

In the first election for the Scottish Parliament in 1999, almost 40 per cent of voters backed the Labour party. Yet in the Scottish elections earlier this year, that figure was almost 10 per cent down. And while the Scottish Nationalists secured only 14 per cent of votes in 1987, this year their share was 45.4 per cent.

1496 Scottish Parliament orders landowners’ eldest sons to study

Time for change It’s an extraordinary transformation but what lies behind it? Four key factors stand out: the change in the nature of the British Conservative party in the 1980s, especially as perceived in Scotland; resentment over North Sea oil revenues; the idea of Europe as an alternative supra-national umbrella to the UK; and the establishment of a devolved parliament in 1999, which disadvantaged Labour in Scottish parliamentary terms.

Margaret Thatcher’s defeat of Edward Heath’s more traditional brand of Conservative ideology in the late 1970s led to an acceleration in the decline in Scottish support for the Tories. A key turning point was Thatcher’s decision to introduce the widely unpopular poll tax in Scotland in 1989 – a year ahead of England.

But it was the consequences of Thatcher’s economic policies, triggering increased deindustrialisation and unemployment in the 1980s, that perhaps caused most fury in a country that depended even more on heavy industry than did England.

In the late 1980s and the 1990s, as the Scottish Nationalist Party (SNP) and others gained from the Conservative Party’s Scottish decline, Labour decided to counter the SNP’s independence policy with a ‘half-way house’ product: devolution complete with a Scottish Parliament. Labour hoped that devolution would harm the SNP electorally by making its independence policy irrelevant – but, at least in elections to the Scottish Parliament, the SNP’s popularity grew.

The re-establishment of a Scottish Parliament after an absence of almost 300 years confirmed the Scots’ sense of nationhood – and gave the SNP a custombuilt platform from which to operate.

2011 SNP wins Scottish parliamentary election

1560 Scottish church becomes Protestant 1603 James VI of Scotland becomes James I of England 1707 Act of Union creates ‘Great Britain’ 1715, 1745 Jacobite rebellions 1934 SNP formed 1983 Decline of Conservative vote in Scotland 1989 Poll Tax introduced in Scotland 1999 Scottish Parliament re-established 1999–2011 Decline of Labour vote in elections to Scottish Parliament

So why did the UK Labour government create the Scottish Parliament? The answer lies, in part, in the nature and history of the Labour Party itself. Ever since the days of Keir Hardie, a Scot from near Motherwell who was Labour’s first leader (1906), and particularly since the late 1980s, Scottish Labour politicians had been extremely influential in the Labour Party at Westminster. Key leaders, including John Smith, Donald Dewar and Gordon Brown, were sons of Scotland who knew the importance of the Scottish Labour vote in UK electoral arithmetic and feared the SNP’s potential impact on it.

With the creation of the Scottish Parliament, the SNP’s rise quickened, especially when they managed to produce an effective administration despite operating as a minority government between 2007 and early 2011. Now, as a more firmly entrenched majority government, they are committed to holding a referendum on independence. It remains to be seen how the majority of Scots will vote in that ballot.

David Keys has worked on more than a dozen BBC TV history and archaeology documentaries and is a specialist correspondent for The Independent.

find out more E Scotland and the Union, 1707–2007 ed by TM Devine (Edinburgh University Press, 2008) E Understanding Scotland: the sociology of a nation

by David McCrone (Routledge, 2001) www.bbc.co.uk/news/scotland E For the latest developments in the devolution debate February 2012

17

Snapshot

Science

The sun worshipper new caledonia, melanesia

February 2012

Philip Plisson / bluegreenpictures.com

The vessel gliding across the waters of the South Pacific is PlanetSolar, a German-built catamaran that’s attempting to circumnavigate the planet powered purely by solar energy. With 3800 photovoltaic solar cells fixed to its exterior, PlanetSolar boasts a top speed of around 15 knots (28km/h). At its heart is a giant 13-tonne lithium battery capable of storing enough energy for the boat to continue sailing for three whole sunshine-free days. Visiting a number of major cities, the world tour aims to spread the gospel of renewable energy. According to the United Nations, the shipping industry is responsible for 4.5 per cent of the world’s greenhouse gas emissions.

19

Getty

Rush-hour traffic is nothing new.

Shortly after opening 75 years ago in November 1936, the bridge linking Oakland and San Francisco looks to have already reached capacity. Back then, cars used the bridge’s upper deck and a railroad occupied the lower tier. Today, both decks are used by cars, carrying a quarter of a million vehicles every day. The bridge cost $77 metres to build (the equivalent of $1.2bn today). However, after safety concerns were raised following damage caused by the 1989 Loma Preita earthquake, it was decided that a replacement of the eastern span was needed. At a cost of around $6.3bn and taking over 10 years to construct, it is now hoped the replacement will open in 2013.

san francisco, california

Take it to the bridge

Getty

History

February 2012

21

NATURE

Off colour Yellowstone National Park, Wyoming

February 2012

Alamy

The scene here is not an extraordinary natural phenomenon, but an indictment of humankind’s disrespect for the planet. This is the Morning Glory Pool, a hot spring found in Yellowstone National Park. It hasn’t always been this colour. Back in the 1960s, the pool was a stunning electric blue. Since then, because of visitors throwing rocks, coins and litter into its depths, Morning Glory’s crucial heat vents have become blocked, affecting water circulation and reducing its temperature. This has meant the growth of bacteria of different, less vibrant colours. The interlopers are steadily working their way to the pool’s core, diminishing its original effect.

23

A history of the

world

100 Dorling Kindersley, Pictorial Press/Alamy, Shutterstock, Science Photo Library/Alamy

in

natural objects PAT MORRIS selects 100 natural objects that illustrate different aspects of human history in a wider context. They all have a greater significance than just their immediate appearance.

01 human brain Nothing has had a greater impact on the natural world than the human brain. It evolved from a simpler primate brain, enabling us to use rational thought to organise our lives, defend ourselves against predators and avoid danger. It meant that we did not need to evolve physical defences such as large claws or teeth.

The human brain has millions of nerve cells, linking sensory organs to our limb and body muscles, and it processes data at high speed to instruct our bodies what to do. The brain is also capable of abstract thought and controls speech and writing, sophisticated forms of communication that make it possible for us to change the world – and even destroy it or visit other planets. No other animal ever did that.

100 natural objects

05 chicken’s egg

Domestication of the Indian junglefowl has led to this species becoming the world’s most numerous, useful and abused bird. It can convert grains and debris into valuable eggs and meat, but industrial chicken production has given rise to a major debate about animal welfare standards.

Arthropods (insects, spiders, crustaceans and their relatives) have become highly successful. Some are very numerous, but none are very big. Yet science-fiction films often depict giant creepy-crawlies conquering our world. It’s impossible! Arthropods have an external skeleton and must moult it to grow, so are weak and immobilised until a larger one forms and hardens. In other words, they cannot get bigger than the maximum survivable size without a skeleton, and, as a result, the largest spiders and insects weigh less than a small rat.

03 Baleen plate Whales in the suborder Mysticeti have 100 or so of these tough but flexible structures hanging from their upper jaws. They scoop up massive mouthfuls of seawater, then use their tongues to force it out through the baleen plates, trapping plankton. Thus, the world’s largest animals have no need for the teeth so characteristic of most other mammals.

Baleen was highly valued for providing ‘springy’ support in all kinds of goods, from umbrella stays to corsets. It fetched high prices, contributing to the growth of a huge whaling industry. However, by the early 20th century (due in part to the invention of plastics), it was no longer the most valuable product of the whale harvest, but a waste product instead.

04 Ammonite fossil Ammonites were once among the most abundant of all marine creatures. They inhabited the last chamber of their coiled shells, the other chambers providing buoyancy as they drifted on the current to catch fish. Today, their fossils are found worldwide, reflecting their great success as a group of animals.

Ammonites survived for tens of millions of years, yet they all died out 65 million years ago.

How could such a widespread group suddenly go extinct? Many scientists think that it was due to a meteor colliding with the Earth.

Maybe we should take the ammonites’ fate more seriously: their intricate fossilised shells are a reminder that it might just happen again.

06 root nodule

Bacteria in the nodules on the roots of clover and other ‘legumes’ take nitrogen from the air and enrich the soil. These plants have long been grown as a simple way to boost crop yields.

07 scallop shell

Coastal people have eaten marine molluscs for millennia, but nowadays the scallop shell also stands as a reminder of how easily scallop-dredging fleets can destroy seabed ecosystems.

08 Yeast

Saccharomyces cerevisiae has played a vital part in human history: it reacts with starches and sugars to produce carbon dioxide and alcohol, a process harnessed to make bread and alcoholic drinks.

The many other uses of yeast now extend to the manufacture of biofuels.

09 Pearl

Pearls form when bivalve molluscs deposit shelllining material around an irritant ‘seed’ in their shell. Carl Linnaeus was the first to explain this process, using European freshwater mussels, and in the 1750s he proved that it could be stimulated artificially. The subsequent history of pearl cultivation reveals our unrivalled ability to tinker with natural processes as we see fit.

10 seabird guano

Peru’s mid-19th century golden age, the ‘Guano Era’, was built almost entirely on the profits from dealing in dung. This smelly natural resource consisted of seabird droppings harvested at coastal breeding colonies and then shipped abroad as fertiliser.

February 2012

25

xxx

02 arthropod exoskeleton

100 natural objects

Shutterstock, Science Photo Library, J Freund, naturepl.com, The Natural History Museum/Alamy, D Scharf/photolibrary.com, Dorling Kindersley, BSIP/Photoshot, Mary Evans/Alamy

11 loaf of bread

Bread made from wheat, a selectively bred member of the grass family first cultivated up to 10,000 years ago, is one of the most important human foods. To produce it, we have replaced forests and wetlands with enormous wheatfields of little use to wildlife.

12 ice crystal

The unique physical properties of H2O are both creative and destructive.

Water expands as it freezes, and when plant fluids freeze they burst cell walls, which is why frosts kill the majority of plants. Expansion also results in a lower density, so ice floats, enabling fish to survive the winter unscathed.

17 Coconut The coconut palm has one of the largest seeds in the plant kingdom. It is encased in a hard shell, surrounded by a dense, fibrous husk two-three cm thick. These coatings protect the living tissue from damage by seawater, enabling the coconut to be dispersed by ocean currents – it is one of the few seeds to be distributed in this way. Coconuts can be washed ashore almost anywhere, even on British coasts, but they can germinate only on beaches within the tropics.

Historically, the coconut palm has been a major economic resource, especially on low-lying sandy islands where little else grows. It has enabled us to inhabit the remotest tropical islands. Without the coconut, our early colonisation of the tropical oceans would have been much less successful.

13 mahogany

The many tropical tree species loosely referred to as ‘mahogany’ have very hard wood that resists wear and decay, making it ideal for carving and construction work.

Our insatiable demand for tropical hardwoods has been a major cause of rainforest destruction.

18 Foram

14 DNA

The discovery, in the 1950s, of the double helix structure of DNA chains has enabled us to decipher inheritance mechanisms, while offering the prospect of modifying the genetic composition of living things. One day we may even create entirely new organisms.

15 tree ring

Since tree rings are the physical embodiment of patterns of growth, they allow the dating of both living trees and the timber in buildings.

The rings in the trunks of bristlecone pines in California reveal some of these trees to be over 5,000 years old – the oldest plants alive today.

16 the hole in my jumper

This natural object, or rather its absence, is the work of the clothes moth larva, one of the few animals able to digest keratin, the protein from which wool, feathers and fur are made.

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February 2012

19 on The Origin of Species After many years gathering evidence, Charles Darwin finally published his ideas in this seminal work in 1859.

He offered a powerful explanation for the diversity of life, based on natural selection encouraging progressive change among populations of variable individuals. Though Darwin was unaware of the genetic mechanisms that make evolution possible, Origin became one of the key catalysts driving biologists’ thinking.

It might seem misleading to include Origin, a human artefact, in our list of natural objects. But, like all books, it is printed on paper, a product derived from cellulose. It thus reminds us of the important role that this plant fibre has had in shaping human thought.

Foram is the shortened name for a foraminiferan, a tiny protozoan.

Foraminiferans float in the marine plankton and their shells come in many shapes; for example, they may resemble tiny molluscs or bean pods. When the animals die, their perforated shells sink to the seabed. Forams were so abundant about 100 million years ago that their remains built up in thick layers, which later became compressed to form rock (below). England’s chalk hills are made of foraminiferan rock.

Forams are significant for two other reasons. Their distribution and composition give us clues about past climates, and, together with other planktonic deposits, they are a major component of oil.

100 natural objects

20 Malaria mosquito proboscis As it draws blood through its proboscis, the female Anopheles mosquito transmits the malarial parasite Plasmodium, which is one of the biggest killers of humans, responsible for widespread suffering throughout the tropics.

The parasite multiplies inside its human host, causing lethargy and periodic severe fevers. The involvement of mosquitoes in its transmission was suspected even by the ancient Greeks, but the life-cycle of Plasmodium was not unravelled until the 1940s. Though subsequent control of Anopheles mosquitoes has been effective, there is still no cure for malaria.

21 acorn From tiny acorns great oak trees grow, and from them magnificent warships were built. These ‘Wooden Walls of Old England’ helped to repel invading forces for centuries. English naval vessels made from oak also explored and conquered the world, helping to maintain links with the Empire until steel ships replaced them. On land, oak timbers were the main building material for thousands of years.

The wood also made excellent charcoal, fuelling the glass and metal-smelting industries.

24 leech sucker

Leeches secrete an anticoagulant through their sucker-like mouths to keep their hosts’ wounds open while they feed. They were heavily collected for medicinal use in the belief that bloodletting would cure various ailments, and are still deployed in certain specialised surgical procedures.

25 mink coat

Not only does Mustela vison possess a dense layer of soft, fine underfur with exceptional insulating properties, it also has long, lustrous guard hairs, making the American mink the species of choice in the fashion industry.

In addition to the ethical issue of wearing fur, there is also the problem of mink farm escapees, which disrupt ecosystems where they are not native.

26 Sigesbeckia

A ‘founding father’ of ecology and modern taxonomy, Carl Linnaeus, named this genus of insignificant, weedy plants after one of his enemies, Johann Siegesbeck. His system of binomial nomenclature remains in use today.

27 stuffed bird

22 sugarcane Originally a native of tropical Asia, this giant grass reaches 6m tall and is now grown in more than 100 countries.

Crushing the stems yields sugars used in food flavouring and preservation and the manufacture of alcohol; the waste fibre is used to make cardboard and paper and as fuel. Harvesting was formerly by hand – an arduous, labour-intensive task for which slaves were taken from Africa to manage the sugar plantations of the Americas.

2

An elephant’s tusks are enlarged k second incisors in its upper jaw, and those of the adult male African elephant are the biggest teeth of any living mammal. Like all mammalian teeth, they consist mostly of a creamy white substance called dentine. Elephant tusk dentine – ivory – is easily carved and so has been highly prized throughout history. Before the invention of plastics, it was widely used to make relatively utilitarian objects such as knife handles, as well as ornamental items. Trade in this ‘white gold’ went hand in hand with European exploration of the African interior, and the collapse in elephant numbers due to poaching has become one of the great environmental tragedies of recent times.

us t t an h p le e 3

Millions of birds were collected and stuffed to display in Victorian and Edwardian homes. Contrary to popular belief, taxidermy may not in itself have been a threat to the populations of most bird species.

28 garden Peas

By propagating pea plants, Gregor Johann Mendel discovered that the inheritance of particular traits follows predictable patterns. This enabled him to formulate a set of rules that became the basis for the modern science of genetics.

29 Iceberg

Fragments of the polar ice caps, icebergs were once seen purely as a menace to shipping, but today they have morphed into highly visible icons of global warming.

Will melting glaciers and ice caps release huge amounts of trapped water, raising sea levels far enough to obliterate low-lying countries?

We simply don’t know.

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100 natural objects

3o willow tree

W Sowry, Dorling Kindersley, Alaska Stock/Alamy, ICP/Alamy, OSF/Photolibrary.com, ARCO/naturepl.com, W Wisniewski/Minden/FLPA, Nikreates/Alamy; 49. BIOS/SpecialistStock

Wood from English willows, fashioned into cricket bats, is still handled every week by people in former British colonies. It is a symbol of the lasting impact of transferring British culture overseas to the largest empire the world has ever seen.

31 banana

Originally from New Guinea, the banana is cultivated across the tropics.

The fruit we eat nowadays has been bred to contain no viable seeds, so depends on human assistance for dispersal.

32 Tadpole shrimp

This freshwater crustacean is a ‘living fossil’, and has changed little in at least 100 million years.

The adults die when their shallow pools dry up, but their eggs remain viable for many years. The eggs have minimal respiration, challenging our perception of what life is.

37 Egg of the great auk The female great auk laid a single, very large egg. The advantage? A big egg produced a big chick that could go to sea soon after hatching, thereby avoiding land predators. However, this biological benefit was to seal the species’ fate.

Great auks were once widespread across the North Atlantic, but, being flightless, they were restricted to nesting on low ledges, which people found easy to reach. The auk colonies were raided for centuries by mariners and fishermen, and vast numbers of the meaty birds were taken for food and fishing bait.

Unfortunately, the great auk’s single-egg strategy could not compensate for such sustained losses, and the species became extinct when the last individual was shot on the island of Eldey, Iceland, in 1844.

33 Water hyacinth

Thick, choking mats of this South American plant can now be seen floating on lakes and waterways in subtropical regions around the world – a notorious example of the damage the invasive plants can wreak in new areas.

34 platypus beak

When a specimen of this beaked marsupial first reached England in 1799 it was dismissed as a prank.

But the platypus drew attention to the extraordinary species to be found in Australia, and posed questions about how and why they were there. The search for answers helped us to understand evolution, plate tectonics and continental drift.

35 Ayahuasca

This South American vine is the active ingredient in a psychedelic brew taken by Amazonian tribes during spiritual rituals. Like all hallucinogens, it warps our view of the world (apparently).

36 snake hind limb

The presence of ‘pointless’ vestigial structures such as the hind limb bones in snakes is powerful evidence of evolution.

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38 sheep Incisor It was the teeth of sheep as much as the crude tools of Neolithic man that began the deforestation of Britain.

Sheep only have incisors on the lower jaw, which bite against a toothless pad above. This arrangement enables them to crop plants close to the ground, transforming the landscape with every nibble.

Flocks of sheep suppress the growth of trees and have created open habitats, such as the English South Downs, providing ideal conditions for orchids and many other species. But without a foundation of tree roots, grazed land is at risk of erosion.

39 Tomato Originally a New World crop, the tomato reached Europe only in 1530, but Lycopersicon esculentum is now one of the most ubiquitous cultivated plant species. As well as being a hugely versatile food, it is a good candidate for genetic manipulation. One day, a GM strain of tomato may contain the genes for medicines, produced in the fruits as they grow. This could provide an inexpensive alternative to current drug production techniques, though one fraught with pitfalls, too.

100 natural objects

43 fossil hyena tooth

40 GASTROLITH Crocodiles are renowned for their appetite for flesh, but they also swallow stones. Once these have been ingested, they become known as gastroliths.

Gastroliths have been found in the stomachs of dinosaurs, the crocodiles’ long-lost cousins, and are a prominent part of the fossil record. Theories abound as to their purpose: could they be intestinal cleaners, or act as ballast, helping bulky animals to dive underwater? We don’t know, but the most likely role is to grind up food into a digestible paste, in much the same way that birds swallow small stones and grit to help digestion. Like birds, crocodiles can’t chew, so they bolt down chunks of flesh whole. But humans, like many other mammals, swing our jaws from side to side, grinding and slicing food before swallowing. Without our articulated jaws, we, too, might have to serve up stones with dinner.

41 ear of wheat Plant seeds contain a store of carbohydrate to fuel the growing shoot when it germinates, and this compact energy source is equally good at fuelling the metabolic processes of animals, including us. Early humans gathered wild grass seeds to eat before having the idea of planting them to grow what they needed, where it was wanted.

There was a hurdle to overcome: the ears of wild grasses ‘shatter’ when ripe, spilling their seeds. So the first farmers instead selected plants that tended to hold onto their seeds.

This may be a disastrous trait for a wild species, but it has ensured that the descendants of the oldest cultivated wheat plants now grow around the world.

42 termite mound In dry parts of the world, termites are the main consumers of dead plant material, fulfilling a crucial role in the ecosystem. Each colony builds a mound from soil particles cemented together with the insects’ own saliva. A mound may be several metres high and weigh a tonne, and makes an imposing fortress for the termites.

But, inside, they were at risk from overheating.

To compensate, they developed air-conditioning systems of chimneys and cooling chambers long before humans figured out how to ventilate their own dwellings. Today, architects are even looking to their insect counterparts to find new ways of designing self-ventilating buildings.

When fossilised hyena teeth were found in Britain in the 1820s, some people saw them as evidence that Noah’s flood wiped animals from entire regions of the Earth. Later, a more plausible explanation, involving climate change and a much older planet, was to be an important influence on Darwin during his travels.

44 Locust mandibles Swarms of locusts are a force of nature that can devastate crops in minutes. This destruction is powered by a multitude of mouths just a few millimetres wide.

45 dead coral

Coral reefs are the skeletal remains of countless generations of soft, gelatinous polyps, so these tiny animals are, in a sense, ultimately responsible for thousands of wrecked ships and lost lives.

On the other hand, barrier reefs also act as nurseries for fish and protect shores from the fury of the sea.

46 Frog’s leg

Frog’s legs have long been key experimental tools in research into the function of muscles and their associated nerves.

47 Woodworm infestation

The wood-boring larva of the deathwatch beetle, otherwise known as a woodworm, naturally assists the breakdown of dead trees. In building or furniture timbers, however, its activities can be disastrous.

48 fruit fly eye

Studies of the inheritance of eye colour in Drosophila fruit flies have led to major breakthroughs in our understanding of genetics.

49 Elephant molar

The grinding surface on elephant teeth is quite coarse, so food is not shredded finely and entire seeds can pass through their guts unscathed.

Elephant dung thus contains a host of readily recognisable plant material and helps many tree species to disperse.

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100 natural objects

57 cup of tea Tea is an infusion made from the dried and powdered young leaves of Camellia sinensis.

This shrub grows where annual rainfall exceeds 75cm, often at relatively high altitudes in the tropics. In a natural state, it will form small trees, but it is normally pruned to help with the harvesting of the leaves and branch tips.

Tea drinking was considered to be beneficial to health but also became a social activity, and from about 1800, it formed the basis of a major trade between India and Britain.

Enormous areas here and in other parts of the British empire were given over to tea cultivation, creating a distinctive landscape largely devoid of wildlife.

5o honeybee pollen sac

The hind legs of honeybees (and their relatives, such as bumblebees) have a flat, polished area surrounded by spiky hairs for carrying pollen efficiently. Called a pollen sac or corbicula, it is the insect equivalent of a shopping bag and, without it, many crops would go unpollinated.

M Bowler/naturepl.com, We Shoot/Alamy, Mary Evans/Alamy, S D Miller/naturepl.com, Dorling Kindersley, C Keyes/Alamy, 19th era 2/Alamy, K Wheal/Alamy

51 Latex

We have harvested latex from the Hevea brasiliensis tree since prehistoric times. It can be treated by smoke to create rubber, a material that literally makes the modern world go round. In 1876, rubber tree seeds were smuggled out of Brazil to establish rival plantations in south-east Asia – an early example of biotheft.

52 bird’s wing

In cross-section, a bird’s wing has curved surfaces, so that air flows faster over the top than under the bottom, creating lift. This design, known as an aerofoil, has never been bettered, and it continues to keep our aircraft in the skies.

53 dromedary hoof

The broad hooves of camels enable them to walk on soft sand where horses and vehicles cannot go.

These hardy (if bad-tempered) mammals made it possible for us to explore the world’s deserts.

54 Shark tooth

Sharks have no bones, only cartilage, but their teeth are among the hardest substances in the animal kingdom. Added to this, big species have jaw muscles that can deliver a bite force of several tonnes. Small wonder that sharks frighten and fascinate us.

55 Murex shell

This spiky-shelled marine mollusc secretes a milky substance that turns purple on contact with air, forming an intense dye worth more than its weight in silver to the ancient Greeks and Romans. Purple remains the colour of royalty and aristocracy.

56 cotton

One of the most valuable natural fibres in human history, cotton has clothed us for about 8,000 years.

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58 Egret plume In the late 19th century, the long, wispy feathers sported by egrets during the breeding season became highly sought-after for ornamenting fashionable ladies’ hats. Confusingly referred to as ‘osprey’ in the millinery trade, these plumes were imported to the auction houses of London, Paris and New York in huge quantities every season. The wholesale plunder devastated egret colonies, but contributed to a pivotal moment in the history of conservation.

In Britain, campaigns to abolish the trade, initially led by a group of women who pledged not to wear feathers, resulted in the foundation of the Society for the Protection of Birds (now the RSPB) in 1889.

59 Grass tussock Unlike most plants, grasses grow from the base, allowing herbivores (and lawn mowers) to repeatedly remove their above-ground leaves without killing the plants. Grasses can thus thrive where other plants are suppressed or destroyed by grazing pressure.

These areas – grasslands – have been a major wildlife habitat since grasses first evolved, in the Miocene epoch some 20 million years ago. Meanwhile, smaller areas of grass have become one of the most versatile landscaping and sporting surfaces, a status unlikely to be lost any time soon, despite the invention of synthetic turf.

100 natural objects

63 Water flea

This superabundant member of the freshwater zooplankton, also known as daphnia, uses bristles on its legs to trap algae for food. It is the main natural mechanism for removing algae from rivers, lakes and drinking water.

Without it, algal blooms form, and we have to filter water by artificial means.

64 horseshoe crab blood 60 Peacock tail feather The ‘eyed’ feathers of male peacocks are fanned out in an extravagant display to impress females. This conspicuous courtship behaviour, which is often accompanied by cries, has stimulated endless discussion about, and research into, the nature and consequences of sexual selection in animals. The national bird of India, the peafowl was imported to Europe as an ornamental bird and culinary novelty in the Middle Ages, and a peacock logo was adopted by US tv network NBC for its first colour transmissions in 1956.

62 lump of coal

61 Shipworm A shipworm is actually a bivalve mollusc with twin shells that form ‘jaws’ that rasp their way into mangrove roots and ship timbers. Its body is shaped like a long bag, within which the wood paste is digested, and is too big to fit within the paired shells, but the animal is protected by the walls of its tunnel. High densities of these burrows, each up to one cm wide, are disastrous for wooden ships, whose timbers become severely weakened, resulting in leaks or even collapse. This was long a problem in tropical seas, until hulls were protected with paints and copper cladding.

Coal is the compressed and fossilised remains of ancient fern-like plants that lived in the warm swamps of the Carboniferous epoch. These plants trapped the energy of the sun, which can be liberated by combustion; the ancient coal forests thus fuelled the Industrial Revolution 300 million years later. Mining this valuable commodity had major environmental effects, burning it created pollution that killed many people each year as a result of lung disease, and the soot discoloured whole cities and encouraged industrial melanism in peppered moths. Coal is still the main source of energy for generating electricity worldwide.

Little different from their fossils of 400 million years ago, horseshoe crabs have blue, copper-based blood that gels when it comes into contact with bacteria or toxins. The compound responsible is extracted so that medical drugs can be checked for contamination.

65 cetacean ear

The heavy ear bulla (‘hearing chamber’) of cetaceans is part of a specialised auditory system that equips them with underwater echolocation and complex sounds for social communication. Our own version, sonar, is used to navigate, survey the seabed and locate fish.

66 rice

This cereal grain feeds half of the world’s human population.

Its cultivation creates enormous areas of semiaquatic habitat in tropical as well as subtropical countries.

67 Insectdamaged leaf

Many insects eat leaves, harming crops and garden plants. In the 1950s, chlorinated hydrocarbon insecticides were widely deployed to combat this threat, but the chemicals proved to be cumulative and harmful to entire ecosystems, and have now been withdrawn.

68 fish otolith

Otoliths (literally ‘ear stones’) are calcareous lumps in the middle ear of fish that assist underwater hearing. As they develop, they form annual growth lines that can be used to tell the age of a fish. This allows us to understand the age structure of fish populations – vital information that can used to manage fisheries sustainably.

69 snake venom

Snakebite is a major cause of death: 421,000 people a year are envenomed, of which 20,000 die, according to a 2008 survey.

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7o tiger claw

77 horse hoof

Imagebroker/FLPA;, M Schuyl/FLPA, Dorling Kindersley, Bon Appetit/Alamy, Mary Evans Picture Library, S Dalton/NHPA, R Becker/FLPA, Wildlife GmbH/Alamy, Shutterstock

It is easy to forget that tigers were still abundant in relatively recent times (especially in India). Their claws have always been a threat to villagers in forest areas, and though the cats are rarer now, they remain a danger as human settlements encroach further into their habitat.

Horses were among the earliest mammals to be domesticated. Their muscle power made possible physical feats that were beyond us – they could pull heavy loads or carry people for long distances, for instance. Horses were also useful during times of war and down mines. But their hooves were only suitable for walking on grass and soft earth: hard surfaces caused excessive wear and damage to their legs.The fitting of metal shoes ensured that the horse’s talents could be used more widely, particularly on stony ground and city streets.

This enhancement of the hoof meant that horses could travel long distances on roads, either being ridden or pulling stagecoaches and wagons. Fitting and replacing horseshoes is now seen as a specialised craft, but it was a significant industry for centuries.

71 octoPus eye

A prime example of convergent evolution, the octopus eye evolved separately from the human eye, but in many ways is very similar. It also reminds us of the intelligence of these cephalopods: research into their brain function has helped us to understand our own.

72 glow-worm light organ

Female glow-worms emit a bright light to attract males, without wasting energy as heat. The enzymes involved are controlled by genes that can be inserted into other organisms – a useful tool for genetic research.

73 cowrie shell

78 bunch of graPes

A variety of natural objects have been used by humans as a form of currency, and cowrie shells were legal tender in West Africa for centuries. The main species involved was Cypraea moneta.

Vines have been grown for wine making since ancient times – grapes arguably occupy a more significant place in human cultural life than any other fruit. Viniculture originated in the eastern Mediterranean but is now a major global industry, transforming habitats and landscapes, particularly where terracing is needed for drainage.

74 tiktaalik rosaea

So-called ‘missing links’ help us to unlock the mystery of the origins of life. Tiktaalik, dubbed the ‘fishapod’, is one of the most significant: it lived 375 million years ago and is the earliest four-limbed animal known.

75 fungal hyPha

Fungi possess dense masses of these thread-like structures, enabling them to spread, and play a vital role as decomposers.

76 moth antenna

A moth’s feathery antennae can probably detect single scent molecules. Perhaps this extreme sensitivity could be duplicated artificially to create devices able to detect drugs, explosives or food contaminants?

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79 salted cod The Atlantic cod is a hugely fecund fish, with adult females laying millions of eggs each season. Despite the vulnerability of their tiny planktonic larvae, enough survive to continue the species, and it was once said that you could walk across the sea on the backs of the fish.

A valuable cod fishery developed in the 20th century, with much of the catch ending up as salted cod, but overharvesting led to fierce competition for the dwindling stocks, and to economic and political conflicts dubbed ‘Cod Wars’.

100 natural objects

83 VamPire bat tooth

80 Paws of a black rat The black rat is an extremely agile creature and, using its paws to grip ropes, it climbed easily onto countless moored boats and was thus transported around the world, hidden among the cargo. For this reason, it is often called the ship rat. Originally from India, the rodent steadily increased its range, reaching Britain by Roman times. Since the species also thrives in close association with people, it became a serious pest, fouling stored foods and damaging crops. Worse than that, it was a vector of typhus and the plague, periodically causing massive human mortality.

Today, the black rat is rare in Europe, having been displaced by the even more adaptable brown rat.

Vampire bats have fewer teeth than their relatives since they do not need to chew their food. Instead, their sharp incisors inflict a wound from which they lap up blood. This may transmit rabies, a deadly danger in many parts of Central and South America.

84 rhino horn

This horn is used in traditional medicines, but it is made of keratin (the same indestructible protein as hair), so humans cannot digest it. Any health benefits must therefore be imaginary.

some

85 iguanodon 81 cow Pat A cow’s faecal matter is a soft paste lacking recognisable plant remains, which reflects the efficiency of a ruminant’s digestion.

Mammals cannot normally digest cellulose – the main component of plant tissues – but in their enlarged stomach ruminants have a partnership with microbes that are capable of secreting the necessary enzymes. This enables cattle, sheep and goats to feed on grass and coarse vegetation, turning it into useful animal products. Humans have transported domesticated ruminants around the world, often with a severe impact on indigenous wildlife. The dung is normally removed by specialist invertebrates, helping to recycle nutrients back to living plants.

82 Fish swim bladder The swim bladder forms an air-filled bag inside the body of many types of bony fish. It provides buoyancy, which some fish regulate by gulping air into it; others use a special secretory organ to adjust its volume and the degree of buoyancy it provides. Careful control of the swim bladder enables many fish to ‘hover’ in mid-water. The ecological significance of this organ is that it means bony fish can be distributed throughout a three-dimensional environment, without them having to expend energy fighting the effects of gravity. These fish can therefore access more sources of food and be more numerous and widespread than would be possible if they all had to live on the bottom. The swim bladder has an impact on fishing fleets too: they can harvest at all depths.

Dinosaurs from the Jurassic and Cretaceous, such as Iguanodon, the first ‘terrible lizard’ to be named, have come to epitomise extinct species that came to the end of the road. We tend to forget that they were dominant for 100 million years, longer than we may yet manage.

86 cat’s eye

Many nocturnal mammals have a reflective layer in their retina called the tapetum, which greatly enhances night vision. This makes their eyes appear to light up when illuminated.

Copying the principle, roads have lines of artificial cat’s eyes to guide traffic in the dark.

87 electric ray

Electric organs appear to have developed in at least six different evolutionary lines of fish, with the electric ray being the best-known living species to possess them. To our ancestors, this fish must have seemed to have magical powers.

88 nutmeg

Nutmeg is native to the Banda Islands in Indonesia, and was a major driver of the spice trade between the Far East and Europe. It is now grown in many tropical countries.

89 ambergris

Sperm whales secrete this waxy substance in their stomachs, possibly to help sharp objects pass through their digestive system. Lumps of it harvested on the coast were used in perfumery.

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100 natural objects

97 bamboo stem

9o Cuttlefish bone

Well-known to millions of caged birds around the world, cuttlefish bone is a chambered, gas-filled shell, made of crystalline calcium carbonate. It allows the cuttlefish to sink or float with little energy expenditure. Discovering how the bones functioned provided insights into the buoyancy mechanisms of other species.

Bamboos are giant grasses that grow rapidly to more than 20m tall. Their light but strong, tubular stems are an important construction material, especially in Asia, where they are used for pipes, poles, furniture and house-building.

Bamboo has also been used as a writing surface since ancient times, which explains why many Asian languages are written in columns rather than rows.

98 Silkworm cocoon

91 elephant bird’s egg

The fine threads that form these cocoons protect the pupa inside while the larva (the ‘silkworm’ – a caterpillar about 10cm long) changes into a moth. The moth uses enzymes to dissolve an escape hole, but must be killed before it does so if the cocoon is to be used by humans.

Silkworms were first kept in China more than 2,000 years ago, and are still the only truly domesticated species of arthropod. They were selectively bred to produce larger cocoons made of a thin, strong single filament that could be unwound and woven into fine cloth. For centuries, the Chinese kept this a secret, but the silk trade stimulated contact with the West, and silkworm eggs were smuggled into Europe in the sixth century AD. Today, artificial fibres are often used instead of natural silk.

Shutterstock, magebroker/FLPA (captive), Mary Evans Picture Library, Wildlife GmbH/Alamy, K Taylor/naturepl.com, Dorling Kindersley

This extinct Madagascan bird laid the world’s largest eggs, which were the size of a bucket! One study has found eggshells in the remains of human fires, suggesting that they provided food for our ancestors. They must have made quite an omelette.

92 Tilted gravestone Constant burrowing by earthworms causes heavy objects such as memorials to sink into the ground, reminding us that worms aerate soil, improve drainage and assist decomposition.

100 Fur seal pelt

93 avian skeleton

Birds have hollow bones, which dramatically reduce their weight.

To compensate, the thin bone walls are supported by bony struts placed where maximum stresses occur in flight. This enables birds to exploit a three-dimensional environment and travel long distances.

94 crab Leg joint

The tubular exoskeletons of arthropods such as crabs offer great strength and protection, but are difficult to articulate at the joints.

Suits of armour were cumbersome in a similar way.

95 hedgehog Spine

The 5,000 spines on an adult hedgehog have evolved to provide protection from most predators, but squashed bodies remind us of the hazards that roads create for wildlife.

96 gecko’s foot

A gecko’s ability to run upside-down across a ceiling would make even Spiderman jealous. The secret is that its soles are covered with microscopic hairs, creating a powerful attractive force.

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99 Dog footprint Dogs were the first mammals to be domesticated. They are social animals that accept leadership by a dominant pack member, and a pup brought up by humans is generally obedient to its ‘master’, though it does depend on the level of training given. Over thousands of years, dogs have become an extension of ourselves, helping farmers to herd their sheep, blind people to stay mobile and hypothermic skiers to return to their chalets.

Pat Morris is a former senior lecturer in zoology at the University of London and an expert on small mammals, especially hedgehogs and dormice.

Fur seals, like sea otters, inhabit the cold waters of the North Pacific, their bodies insulated by a dense layer of underfur with longer ‘guard’ hairs over the top. These valuable pelts enticed Russian entrepreneurs to travel from their own coasts to California.

Captain Cook discovered the lucrative trade in the 18th century, prompting massive exploitation of these mammals, nearly causing their extinction.

In 1911, legal protection was extended to fur seals and sea otters, the first legislation to protect marine mammals.

What do you think?

Did Pat get it right?

What natural objects would you have chosen to symbolise our changing relationship with the world?

Are there any items in your house that you would like to tell us about? Write to us at the address on px, or email bbcknowledge@wwm.co.in

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Panama Bats Panama’s forests are home to a vast array of bats, each uniquely adapted to exploit the habitat.

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Photographs by Christian Ziegler

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Reflected glory The skies above Barro Colorado Island teem with thousands of bats. This 1600-hectare rainforest oasis in Lake GatĂşn in the Panama Canal offers such an abundance and variety of food and roosts that 74 different species of bat live here.

Each species has evolved unique physical adaptations, roost preferences, flight zones and foraging strategies that enable it to avoid competition with its neighbours.

Some, such as this greater bulldog bat (Noctilio leporinus), specialise in hunting fish. Flying low over a pool at night, the bat skillfully plucks its quarry from just beneath the water’s surface. Using echolocation, it can detect tiny ripples as the fish move through the water.

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fang-tastic

G It’s not just specialised hunting techniques that allow so many bats to live in peace. They also avoid competing for roost sites by sheltering in some surprising places.

Spix’s disk-winged bats (Thyroptera tricolor), for instance, roost in rolled-up heliconia leaves. Instead of digits, these tiny animals have small, round suction cups at the bases of their thumbs and under their heels, which enable them to cling onto smooth surfaces. The bats simply lick their pads to improve adhesion.

E Greater spear-nosed bats (Phyllostomus hastatus) prefer to roost in hollow trees, arboreal termite nests and caves. They live communally, with males defending harems of females for the right to mate with them.

With a wingspan of up to 45 centimetres (18 inches), the greater spear-nosed is one of the largest bats in the Americas. Its strong flight enables it to roost up to five kilometres (three miles) from its feeding sites. The fearsome teeth seen here are put to use hunting lizards, frogs, roosting birds and even other bats, though it also eats flowers and pollen.

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So long, suckers

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Serial killer

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G Taken using a long exposure and stroboscopic flash, this photograph captures the hunting technique of the greater bulldog bat (Noctilio leporinus). Flying in a zigzag pattern 20-50 centimetres (eight -20 inches) above the water, the bat chirrups constantly, using echolocation to pinpoint its prey. Once it has detected the telltale ripples of moving fish, it drops almost to the water’s surface and, with impeccable timing, strikes using its feet in a backward sweeping motion as it tries to impale the fish on its long, sharp talons.

When it spears a fish (left), the bat transfers its catch to its mouth, storing the meal in its cheek pouch. This enables it to continue fishing rather than having to stop and feed with each catch.

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Fruit bat G Not all of Panama’s bats are hunters. Fruit-eating bats also play an essential ecological role in the forest, dispersing plant seeds. This great fruiteating bat (Artibeus lituratus) is making off with a juicy fig clamped in its jaws.

It will seek out a safe perch some distance from the parent tree to consume its prize. As it bites off and devours the nutritious outer flesh, it discards the seeds, some of which fall to the ground and germinate.

Tip of the tongue

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E The Pallas’s long-tongued bat (Glossophaga soricina) feeds mainly on nectar. Hovering like an ungainly nocturnal hummingbird, it uses its long tongue to probe deep within large tree flowers and lap up their sweet nectar. It plays an important role as a pollinator for many trees and shrubs in the tropical forests.

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Caught out

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Another specialist hunter, the omnivorous fringe-lipped bat (Trachops cirrhosus) is particularly adept at catching tungara frogs. It tracks them down by homing in on the low-frequency calls emitted by the males to attract mates, and may catch several in an hour.

The frogs respond to the bat’s presence by suddenly falling silent in the hope of evading detection.

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Bat log

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A hollow fallen log provides an ideal roosting site for the common big-eared bat (Micronycteris microtis). Unlike most of its insectivorous relatives, which use echolocation to hunt flying and swimming prey, this species can detect motionless insects and even fruit. It is quite astonishing to watch the bat glean prey, such as caterpillars and perched dragonflies, from leaves, despite so much interfering vegetation cluttering its sonic environment. It’s just one more example of the many extraordinary design innovations that evolution has bestowed on Panama’s bats, giving them the means to flourish in their crowded forest.

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Jan/Feb 2011

Feature Portfolio in here

the location Christian took the majority of these photographs on Barro Colorado Island in Lake Gatún in central Panama. The huge number of bats living here has attracted a host of scientists eager to understand how the many species exploit different ecological niches.

Caribbean Sea

COLON

PANAMA Lake Alajuela

Lake Gatún

Pa n

am

Barro Colorado Island

aC

an PANAMA CITY al

Gulf of Panama

The photographer Christian Ziegler is a German biologistturned-photojournalist who focuses on tropical rainforests and their inhabitants. By introducing some of the charismatic forest animals and their interesting biology to a wider audience, Christian hopes to raise awareness of the problems they face and support for conservation efforts.

find out more

February Jan/Feb 2011 2012

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E www.naturphoto.de Christian Ziegler’s website 45

BLAST This may have been a common sight on Earth around 65 million years ago

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PAST The last two decades have produced some of the most spectacular dinosaur discoveries ever, but many were down to pure luck. Cavan Scott, author of a new book Planet Dinosaur, explains

ALAMY

FROM

palaeontology

February 2012

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palaeontology

hen news breaks of the discovery of a new species of dinosaur, you’d be forgiven for thinking that the scientists who set out in search of the fossils are the ones who made the find. The reality is that many of the greatest discoveries have been down to chance.

Take the 2005 discovery of Gigantoraptor erlianensis. Standing more than three metres (9.8 feet) high at the hip, Gigantoraptor erlianensis is the biggest bird-like dinosaur ever unearthed. Yet its discoverer, Xu Xing of Beijing’s Institute of Vertebrate Palaeontology and Paleoanthropology, wasn’t even looking for it at the time. He was recording a documentary in the Gobi Desert, Inner Mongolia.

“The discovery was a total accident,” says Xu. “The production team were filming me and a

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geologist digging out what we thought were sauropod bones, when I realised the fossils were something else entirely.”

Xu looked more closely at what they’d found and realised this was no sauropod. Sauropods are the long-necked, long-tailed dinosaurs, like Diplodocus. This bone looked more like it might have belonged to a large carnivorous theropod like Tyrannosaurus rex. But that didn’t look exactly right, either.

Gigantoraptor, as it later became known, turned out to be an oviraptorid, a beaked, bird-like theropod. Its size was staggering.

The largest oviraptorid previously discovered had been comparable in size to an emu; most were turkeysized. Here was a creature that was probably about eight metres (26 feet) long. If the bone analysis was anything to go by, it had only been

Corbis, Rex, Getty

Many of the greatest dinosaur discoveries have been down to chance

New discoveries, like these Gigantoraptor erlianensis fossils in China in 2005, always cause a media flurry 48

February 2012

about 11 years old when it died – just out of adolescence. Who knows how big the adult could have been?

Opportunity knocks Sometimes it’s sheer opportunism that plays a part in the discovery of a new species. In 1999, the National Geographic Society announced that the missing link between dinosaurs and modern birds had finally been found. Named Archaeoraptor lianoingensis, the fossil in question appeared to have the head and body of a bird, with the hind legs and tail of a 124 million-year-old dromaeosaur – a family of small theropods that include the birdlike Velociraptor made famous by the Jurassic Park films.

There was a good reason why the fossil looked half-bird, half-dinosaur. CT scans almost immediately proved the specimen was bogus and had been created by an industrious Chinese farmer who had glued two separate fossils together to create a profitable hoax.

But while the palaeontologists behind the announcement were wiping egg off their faces, others, including Xu, were taking note.

The head and body of the fake composite belonged to Yanornis martini, a primitive fish-eating bird from around 120 million years ago.

The dromaeosaur tail and hind legs, however, were covered in what looked like fine proto-feathers.

That fossil turned out to be something special. In 2000, Xu named it Microraptor zhaoianus and

A 1999 Archaeoraptor discovery turned out to be a hoax by a Chinese farmer

palaeontology

Jargon Buster Dinosaur Collective name for the ‘terrible lizard’

terrestrial vertebrates that dominated Earth for 160 million years. Excludes pterosaurs (flying reptiles such as Pterodactyls) and marine reptiles such as Ichthyosaurus. Technically, extinct dinosaurs should be referred to as ‘non-avian dinosaurs’, since birds remain as their living descendents.

Dromaeosaur Family of small to medium-sized birdlike theropods. Includes Velociraptor.

Boasting two sets of feathered wings, Microraptor gui is believed to have glided from tree to tree

Hadrosaur revealed that it had probably lived in the treetops. Although it couldn’t fly, its curved claws provided the first real evidence that dinosaurs could have climbed trees.

Three years later, Xu and his team discovered a closely related species, Microraptor gui, which changed everything. “Microraptor gui had two salient features,” Xu explains. “Long feathers were attached not just to its forearms but to its legs and feet. Then we noticed that these long feathers had asymmetrical vanes, a feature often associated with flight capability.

This meant that we might have found a flying dinosaur.”

The origin of flight has long been a contentious issue. Conventional thinking had it that early birds developed the ability to fly by leaping and running. The idea was that as time passed they started to flap their ‘arms’ in order to stay in the air for longer.

Microraptor’s fossilised feathers suggest that this probably wasn’t the case, at least for this genus. Perhaps flying dinosaurs and early birds threw themselves off tall trees and glided to the ground, like flying squirrels, only later developing the chest muscles they needed to stay aloft. While the jury is still out on which happened first, Xu says that all experts do now agree, “Avian

flight started with four wings rather than two.”

Hitches and hurdles If fate has played a part in recent dinosaur discoveries, it’s also thrown up a few hindrances. Spinosaurus, the largest land-based carnivore ever to walk the Earth, became famous over 10 years ago, thanks to a starring role in Jurassic Park III. This ninetonne killer with the distinctive long snout was actually discovered nearly 100 years ago by German aristocrat and palaeontologist Ernst Stromer, who uncovered the first Spinosaurus remains during an expedition to Egypt in 1912. His finds, including 165 centimetres (65 inches)-long vertebrae that might have supported a sail-like structure on its back, were displayed in Munich three years later. Unfortunately, an RAF air raid in April 1944 razed the museum to the ground and reduced the remains to dust.

Stromer had insisted that Spinosaurus would have been much bigger than T. rex but, for a while, it looked like nobody would know.

“No other Spinosaurus remains were discovered in northern Africa until 1975,” explains Cristiano Dal Sasso, a palaeontologist at the Civic Natural History Museum in Milan.

“A partial skull was [then] found in Morocco, but it remained in a

Duck-billed herbivorous dinosaur family. Includes Edmontosaurus.

KT mass extinction The Cretaceous-Paleogene (formerly known as the Cretaceous-Tertiary) extinction event that ended the Mesozoic era 65.5 Ma and wiped out the non-avian dinosaurs. Now known to researchers as the K–Pg extinction event.

Sauropod Giant, long-necked, long-tailed, herbivorous dinosaurs. Family includes Diplodocus.

Theropod Primarily carnivorous bipedal dinosaurs. Includes T. rex and Spinosaurus.

private collection for 27 years.”

Realising the importance of the specimen, Dal Sasso’s team finally obtained the fossil skull for analysis in 2002 and found Stromer had been right. Even Dal Sasso was surprised at Spinosaurus’s immense size. “The snout alone was a metre [three feet three inches] long, so by comparing it to other spinosaurids we were able to calculate that the owner of this particular skull was about 17 metres [56 feet] in length,” E he says.

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BIG FINDS

The low-down on the species discussed – plus a few old friends

Edmontosaurus First discovered: Alberta, Canada, 1892 (Alaska, 1961) Family: Hadrosaur Length: 13m (43ft) Weight: 4 tonnes Age: 73-65.5m years (late Cretaceous) A herbivore widely distributed across North America, Edmontosaurus was the first dinosaur found in Alaska. It is thought to have been migratory, although younger members of the herd unable to keep up with the adults were left to fend for themselves.

chicxulub crater

Old favourites

The location, on Mexico’s Yucatan Peninsula, of the asteroid hit that wiped out the dinosaurs

• Tyrannosaurus rex (first discovered: 1874)

Argentinosaurus First discovered: Patagonia, Argentina, 1988 Type: Sauropod Length: 30m (98ft) Weight: 73 tonnes Age: 97-94m years (mid-Cretaceous)

Over 30 specimens have been found to date, some almost complete, but scientists still debate the details of its physiology and behaviour.

• Stegosaurus (first discovered: 1877)

Stegosaurus’s brain cavity was no bigger than that of a dog, even though the dinosaur was the size of a bus.

The heaviest known sauropod, Argentinosaurus is the largest dinosaur ever classified. One individual vertebra was 159cm (63in) long. Fernbank Museum of Natural History in Atlanta, Georgia, has a 37m (121ft)-long model on display in its atrium.

• Diplodocus (first discovered: 1877) Victorian scientists assumed Diplodocus lived in water, but subsequent studies show that it would have been unable to breathe.

• triceratops (first discovered: 1888)

Originally mistaken for a gigantic prehistoric bison, over 18 different species of Triceratops were described, although there were actually just two.

Science Photo Library, Dreamstime, Getty x2, Alamy x2, Corbis

Troodon First discovered: 1855 (tooth only), Nebraska Type: Theropod Length: 2.4m (7.9ft) Weight: 50kg (110lb) Age: 75-65m years (late Cretaceous) The small, bird-like Troodon had large eyes, indicating it might have been active at night, and one of the largest brains relative to body mass of any known dinosaur. There is some evidence that it preferred cooler climates and probably predated on Edmontosaurus. Its name means ‘wounding tooth’.

Being alive Where the dinosaurs fit in

(Ma = Millions of years ago)

3500-3400 Ma

2400 Ma

2100 Ma

1200 Ma

550

505 Ma

420 Ma

390 Ma

365 Ma

350 Ma

Life on Earth appears, in the form of singlecelled microbes without a nucleus

Oxygen begins to accumulate in the atmosphere as a by-product of photosynthesis

Probable date of oldest known fossils of eukaryotic cells – cells with a nucleus

Sexual reproduction established, increasing the rate of evolution

Flatworms appear on Earth, the earliest known animals to possess a brain

Appearance of the first vertebrates – jawless fish related to lampreys

Plants colonise the Earth’s landmasses

The first tetrapods – fish that developed legs and moved into swampy land habitats

Early amphibians – the first fourlegged animals to develop lungs

Forests of trees

• Timeline not to scale

palaeontology

Microraptor First discovered: China, 2000 Family: Dromaeosaur Length: 77-90cm long (2.5-3ft) Weight: 1kg (2.2lb) Age: 120m years (early Cretaceous)

Gigantoraptor First discovered: Gobi Desert, Inner Mongolia, 2005 Family: Oviraptorosaur Length: 8m (26ft) Weight: 1360kg (3000lb) Age: 70m years (late Cretaceous)

One of the smallest known dinosaurs, and one of the first discovered with feathers and wings, this dinosaur is unusual in having feathers on its feet as well as arms and hands. It also had plumes on its head and thick feathers on its body.

Although there is no direct evidence that Gigantoraptor had feathers, Chinese palaeontologist Xing Xu thinks it was likely. Most large, bipedal dinosaurs have short, sturdy lower legs, but Gigantoraptor’s limbs are slim, almost chicken-like. Xing believes this could made it the fastest two-legged dinosaur.

EA NY O I LL

Spinosaurus

25 0M I

First discovered: Egypt, 1912 Family: Spinosaurid Length: 12.6-18m (41-59ft) Weight: 7-21 tonnes Age: 112-97m years (mid-Cretaceous)

RS AGO

200 MILLION

Eurasia

YE

Laurasia

A

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LAURASIA

The first ‘spine lizard’ remains were lost during World War Two and it wasn’t until 2002 that more became available for study. Several theories have been put forward concerning the fan of spines on its back, including that it formed a fat-covered hump and that it was used for thermoregulation or display.

O AG

North America Euras

ia

South America

a

South America

str

nta

EQUATOR

Africa

GONDWANA

Au

A

India

ica rct

ali

Gondwana

India

Antarctica

a

trali

Aus

G continental shift

Mesozoic ERA Triassic Period (245 - 208 Ma)

Jurassic Period Cretaceous Period (208 Ma - 145 Ma) (145 Ma - 66 Ma)

These maps suggest how the world would have looked at the time of the dinosaurs. The supercontinent Pangaea (left) split into two landmasses, Laurasia and Gondwana, (right) around 200 Ma. Approximate location of modern continents

300 Ma

251 Ma

230 Ma

220 Ma

195 Ma

141 Ma

65 Ma

2 Ma

Early 19th c

Early reptiles that look similar to modern lizards and feed on early insects and millipedes

Permian-Triassic extinction event (largest of five such events) wipes out 95 per cent of species

Appearance of the first dinosaurs

The first mammals – small, shrewlike creatures that feed on insects

First birds – the only dinosaurs to survive the KT mass extinction to the present day

The first flowering plants emerge

KT mass extinction event.

All non-avian dinosaurs and other species made extinct

Arrival of first modern humans – Homo

First dinosaur fossils were recognised

February 2012

Palaeontologist Sir Richard Owen coins the term ‘dinosaur’ – or ‘terrible lizard’ 51

palaeontology

The skull revealed other secrets. CT scans showed cavities linked to bumps containing bundles of nerve fibres along the snout.

“These pressure receptors are also found on the facial bones of living and extinct crocodilians,” explains Dal Sasso. “They are capable of detecting the slightest movement in water.”

Despite its great size, Spinosaurus is believed to have fed on primitive fish from murky rivers in what is now Morocco’s Kem Kem region. “It’s incredible that such a large animal possessed a sensitive snout that worked with such extreme precision,” says Dal Sasso. “Spinosaurus wouldn’t even have needed to use its eyes.” The dinosaur would have been able to catch fish by vibrations alone.

The Spinosaurus remains aren’t the only extraordinary fossils to have been hidden in a collection and forgotten. For the majority of

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the 20th century, the palaeontology community had ignored the frozen tundra of north Alaska. There was no way, scientists believed, that cold-blooded dinosaurs could survive in such bleak, frigid conditions. But according to Alaskan dinosaur expert Tony Fiorillo, a curator of the Museum of Nature and Science in Dallas, they eventually realised that they were missing a trick.

Lost treasures “The first discovery of dinosaurs in Alaska was actually made by a geologist called Robert Liscomb in 1961,” says Fiorillo. “Unfortunately, Robert was killed in a rockslide the following year, so his discoveries languished in a warehouse for the next two decades.”

In the mid-1980s, managers at the warehouse stumbled upon the box containing Liscomb’s fossils during a spring clean. The

bones were sent to the United States Geological Survey, where they were identified as belonging to Edmontosaurus, a duck-billed hadrosaur. Today, palaeontologists roam this frozen treasure trove searching for remains locked away in the permafrost.

The rewards are worth the effort.

While studying teeth belonging to the relatively intelligent Troodon theropod, Fiorillo discovered the teeth of the Alaskan Troodon were twice the size of those of its southern counterpart. “Even though the morphology of individual teeth resembled that of Troodon, the size was significantly larger than Troodon found in warmer climates.”

Fiorillo says that the reason lies in the Troodon’s large eyes, which allowed it to hunt at dawn and at dusk – times when other dinosaurs would have struggled to see. In the polar conditions of Cretaceous Alaska, where the Sun would all but

End of an era What ended the dinosaurs’ reign – and why did birds survive?

Science Photo Library, Corbis, Getty

After arguing for what seems like a geological age, in March 2010 an international panel of scientists finally agreed that the dinosaurs were wiped out by a 15 kilometres (9.3 mile)-long asteroid that crashed into Chicxulub on Mexico’s Yucatan Peninsula 65.5 million years ago.

The impact – known as the KT mass extinction event – is thought to have been a billion times more powerful than the atomic blast at Hiroshima, triggering earthquakes, fires and tsunamis across the world.

Yet it was the shroud of debris that engulfed Earth after the collision that caused a catastrophic global winter and destroyed half the species on the planet.

“The best evidence for an abrupt extinction event comes from plant fossils,” says Gareth Collins, Senior Lecturer in geophysics at Imperial College, London. “While very diverse

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right up to the KT event, the rapid recovery of opportunist species such as ferns after the event shows that the effects on the climate must have been fast and short-lived.”

Debris found across the planet points to the asteroid falling on Chicxulub. “The global impact debris thickens as you get closer to the 180 kilometres (112 mile)-diameter Chicxulub crater, and has the same chemical signature the world over as the impacted rocks at Chicxulub.”

If half the species on Earth perished, how did others manage to survive? Many scientists believe small rodents may have avoided the initial blast of thermal heat from the impact by retreating to burrows or into water. When the intense wave of heat had passed, the mammals fed on aquatic plants and insects, both of which were still in abundance even during the global winter.

But how did birds, direct relatives of the dinosaurs, survive the impact?

Angela Milner, Associate Keeper of Palaeontology at the National History Museum, believes it may be down to the size of their brains.

“By looking at birds that lived just after the KT event, we can see that their forebrains – the area that deals with flight and sight co-

ordination – were appreciably larger than the earliest known birds, such as the late Jurassic Archaeopteryx.

We know that the forebrain is larger in modern bird groups that have the most cognitive skills, such as owls and parrots. The fact that birds had bigger brains might have allowed them to adapt to the new conditions of the post-KT world.”

An artist’s impression of the Chicxulub asteroid’s impact

palaeontology

In 1990, Sue Hendrickson discovered the largest and most complete T. rex fossil ever found.

Named after her, ‘Sue’ is on display in The Field Museum, Chicago.

Spinosaurus

For most of the 20th century, Alaska was ignored by palaeontologists disappear for months on end, this proved a useful talent. “Troodon adapted for life in the extraordinary light regimes of the polar world. With this advantage, it took over as Alaska’s dominant theropod,” explains Fiorillo. Finding itself at the top of the food chain, the dinosaur evolved to giant proportions.

Good fortune It’s true that some of the most staggering of recent developments have come from palaeontologists being in the right place at the right time, but this is no reflection on their knowledge or expertise. After all, not everyone knows when they’ve stumbled upon something remarkable.

When Argentine sheep farmer Guillermo Heredia uncovered what he believed was a petrified tree trunk on his Patagonian farm in 1988, he had no way of realising that he’d found a 1.5 metres (4.9 feet)-long tibia of the largest sauropod ever known to walk the Earth.

Argentinosaurus was 24 metres (79 feet) long and weighed 75 tonnes. The titanosaur was brought to the attention of the scientific community in 1993 by Rodolfo Coria and José Bonaparte of the National Museum of Natural Sciences in Buenos Aires. Coria points out that most breakthroughs are not made by scientists, but by ordinary folk.

“Most of the discoveries are made by chance by people not related to research. Even within an exploration project made by professionals, the act of finding fossils depends primarily on luck and a good eye. That part is doable by anybody. But the real scientific discovery is not the finding; it’s what we learn from that finding.”

While any one of us can unearth a fossil, it takes dedicated scientists to see beyond the rock.

Cavan Scott is a freelance journalist and the author of Planet Dinosaur (BBC Books, 2011).

find out more E http://blogs.smithsonianmag.com/dinosaur Dinosaur Tracking blog E The Great Dinosaur Discoveries

by Darren Naish (A&C Black, 2009) E Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages

by Thomas R Holtz Jr (Random House, 2007)

What do you think?

Which is your favourite of all the dinosaurs – and why? email: bbcknowledge@wwm.co.in

How did you discover Sue? The day before we were due to leave the site, we had a flat tyre on the van. While the guys fixed it, I checked out a place I’d been meaning to visit for ages. I got there to see bones sticking out of the hill.

Did you immediately know they were T. rex bones?

I could tell that it was a carnivore as their vertebrae are hollow and a different shape. At that time, the only large carnivore was T. rex. It took me a few minutes to absorb what I’d found.

How long did Sue take to excavate?

Around 17 days. The first five were the worst because we had to work through 30 feet of rock in 130-degree heat. But once we got down to the bones we saw she was still mostly articulated, which meant we wouldn’t have to excavate a huge area.

Her legs were slightly disarticulated but right there and, at first, we couldn’t find the skull. It was the last thing we found.

Do you still visit Sue? I did when she was first unveiled but not so much now. I honestly don’t think I should have been the one to find her. I know people like the fact that a woman found her and we need women role models, but it should have been a 20-yearold female paleontologist who could have made a full career out of her. I was 40 and already doing what I loved. Sue’s not mine and I’m glad she’s at the Field Museum.

She has had a lot of impact on a lot of people. That’s a good thing.

E Read more of this interview on our website at www.knowledgemagazine.com/blog

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Paws for thought Feet are perfectly adapted to lifestyle, whether that’s hanging upside down all day, walking across water, manipulating tools or cleaning out ears

G For digging

G For inching ahead

G For hanging out

European mole

Snail

Two-toed sloth

The powerful, spade-like forepaw of the European mole (Talpa europaea) is well adapted for digging, with its five robust claws and out-turned position.

The mole spends most of its life developing and adapting its network of tunnels.

A snail’s foot is made up of a single, broad muscle that propels the animal forward by sending waves of small contractions from the back of the foot to the front. The sole has a gland near the snail’s head that secrets mucus to smooth its journey.

The two-toed sloth (Choloepus sp.) has two toes on its forefeet and three on its hind feet, with long, hook-like claws to suspend it upside down from branches. Most activity takes place in this state, including eating, sleeping, mating and giving birth.

F For walking on water

G For weight-bearing

Basilisk

Elephant

Basilisks (Basiliscus basiliscus), or Jesus lizards, run on large hind legs which end in long, scalefringed toes and can cross a lake or river at speeds of over 11km/h (6.8mph) without breaking the surface film of the water.

Long, column-shaped legs and feet made of spongy, fatty tissue mean elephants can stand for a long time without tiring. Their feet are sensitive to low-frequency sound and they can communicate over several kilometres by ‘listening’ to vibrations with their feet.

G For travelling slowly

G For ear-cleaning

G For wall climbing

Red-footed tortoise

Slender loris

Tokay gecko

This is the stumpy hind foot of the tropical South American red-footed tortoise (Chelonoidis carbonaria).

The claws wear down to nubs as the animal ages.

Red-foots south of the Amazon have an enlarged spur inside their front legs, to help bend plants over.

The feet and hands of the slender loris are an almost pincer-shaped adaptation that enables the creature to move and sleep easily among tree branches. One digit is shorter than the rest and the nail acts as a claw, which is used for scratching and cleaning the auditory canal.

Tokay geckos can climb even the smoothest vertical surface at a speed of one metre per second (3.3ft/sec) thanks to half a million tiny hairs on each foot. The end of each hair is split many times and covered in discs of keratin that give the foot its adhesive force.

G For tree climbing

G For ducking, not diving

G For catching prey

Chimpanzee

Mallard

Hen harrier

As well as having opposable fingers on their hands chimpanzees (Pan sp.) have opposable toes, which they can close against the other toes to create a precision grip. This provides dexterity for climbing, and holding and manipulating objects such as tools.

This webbed foot belongs to the Mallard (Anas platyrhynchos) – the world’s most common duck.

Unlike some ducks, the Mallard does not dive underwater for its food but feeds by dabbling and ‘upending’ – tail up, neck down – in shallow water.

These sharp talons belong to the hen harrier (Circus cyaneus). Each powerful foot is tipped with sharp claws; the perfect tool for snatching up prey such as mice, rabbits, pheasant chicks and frogs, which the bird hunts on the wing during daylight hours.

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Ingo Arndt x11, thinkstock

Adaptation

The secrets of

STONEHE

ALAMY

After the recent discovery of a second henge, Robert Matthews investigates how cutting-edge tech looks set to uncover even more archaeological sites

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February 2012

Secrets of stonehenge

ENGE hen Stonehenge first started to take shape, the Great Pyramids of Egypt still lay 500 years in the future. By the time the Romans arrived, its completion was already as remote in time from them as they are from us.

Over the 5000 years of its existence, Stonehenge has lost none of its power to intrigue. Now archaeologists believe they are on the brink of a revolution, drawing up a whole new concept as to its origin and purpose. The vision of Stonehenge now emerging is one of a site deemed to have miraculous powers, drawing people from far and wide. And underpinning

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this new view are revelations provided by the seemingly miraculous powers of 21st-century science, from groundpenetrating radar and magnetometry to GPS technology.

The power of these techniques was demonstrated in July last year, when an international team of archaeologists made headlines worldwide with an astonishing discovery near Stonehenge. After just nine days of searching, the team uncovered 3 evidence for an entire new structure on Salisbury Plain: a 25-metre wide walled ditch or ‘henge’, containing a circle of pits.

Situated less than a kilometre from

Stonehenge, the structure is believed to be as old, and to have had a similar appearance, its ditches aligned with the more famous structure.

The discovery has been hailed as the first major ceremonial site to be discovered near Stonehenge for half a century.

Yet anyone visiting the site would fail to see anything, as the newly discovered henge lies buried several metres beneath the surface.

Its presence was revealed to the world by the techniques being pioneered during the three-year project that began E last summer.

Secrets of stonehenge

Winter Solstice Have the hippies got it wrong?

Every midsummer morning, huge crowds gather around Stonehenge to witness the first beams of sunlight enter the heart of the ancient monument. But some researchers now suspect the crowds may be gathering in exactly the wrong place and at the wrong time.

Two other major neolithic structures built around the time of the original Stonehenge – Maeshowe in Orkney and Newgrange in Ireland – have stone chambers clearly constructed to allow the Sun’s light to enter them on just one day of each year: Midwinter’s Day. This has prompted investigations into the idea that the traditional view of Stonehenge may, infact, need to be reversed. In other words, the ancient monument could have been originally designed for a ceremony taking place on Midwinter’s Day – the shortest and darkest day of the year. The geometry of the giant trilithons at the centre of Stonehenge shows that they could have acted as ‘windows’, framing both the Sun and the Moon as they crossed the winter sky. On the shortest day, the setting Sun would have shone through the stones, presaging the longest night of the year.

Its significance remains unclear; according to anthropologist Lionel Sims of the University of East London, it may have been linked to ancestor worship via the myriad stars scattered across the night sky.

Bones at Stonehenge may have belonged to a ruling dynasty

ASTROLAB

press association, robert harding, chris kerns

Was Stonehenge a giant observatory?

E Wales, the original site of the bluestones. The truth of this may soon become clear, with the biochemical analysis of the human remains found around Stonehenge.

In the meantime, the team has put together a new chronology for the creation and evolution of Stonehenge, which it believes best fits the evidence.

The bluestones are also at the centre of the other emerging theory about Stonehenge, which sees it as a centre of healing.

According to Professor Tim Darvill of Bournemouth University, the human remains found at the site have an unusually high level of skeletal trauma – as if something about Stonehenge was of significance for those with serious injury. Intriguingly, there has long been folklore ascribing healing powers to bluestones, and these tales are centred around both Wiltshire, the current site of Stonehenge, and 60

February 2012

One of the most persistent theories about Stonehenge is that it was some kind of giant astronomical observatory. Over 250 years ago, the English antiquarian William Stukeley pointed out that Stonehenge and the outlying ‘Heel Stone’ were oriented roughly towards the point of sunrise on the Summer Solstice – the longest day of the year. In the early 1900s, the English astronomer Sir Norman Lockyer, argued that the slight mis-alignment was due to the known drift in the Earth’s axis. Working backwards, he calculated that Stonehenge must have been built around 1700BC – now thought to be over 500 years later than the true date.

In the early 1960s, the English astronomer Gerald Hawkins of Boston University used computer analysis to reveal what he claimed were a host of alignments within the structure of Stonehenge, which could be used to predict eclipses of the Sun and Moon. Other academics, including the distinguished Cambridge astrophysicist Professor Sir Fred Hoyle, made similar claims.

Subsequent archaeological research supports a link with both the summer and winter solstices, but has cast doubt on the more esoteric theories. Many of the ‘alignments’ have been found to rely on imprecise measurements, and seem to be the result of coincidence or wishful thinking.

Pembrokeshire, the original site of the bluestones. This may explain why two-thirds of the original 50plus bluestones have disappeared: over the intervening millennia, they may have been broken up by those seeking cures.

So which theory is right: Stonehenge as cemetery or a place of healing? According to Professor Geoff Wainwright of the Society of Antiquaries, it’s entirely possible that both are: “There’s no real dispute – it doesn’t have to be one or the other.” He too believes that answers are likely to emerge from further analysis of the human remains found at the site. “The only prediction I would make is that some exciting finds are going to be made there,” he says. “Stonehenge is always producing something new.”

Robert Matthews is a science journalist and Visiting Reader in Science at Aston University, UK. www.robertmatthews.org

find out more E Stonehenge Rosemary Hill (Profile, 2009) E www.bbc.co.uk/history/programmes/ stonehenge BBC Timewatch site on Stonehenge E http://bbc.in/diBMEJ Timelapse animation of the changing appearance of Stonehenge

dirt is good for you

Is the modern world’s obsession with hygiene responsible for a global allergy epidemic? Dan Cossins investigates n epidemic is sweeping the world, especially the West. The symptoms vary: sneezing, rashes, swollen eyes and breathlessness. The illness is often debilitating and can be fatal.

But the causes are seemingly harmless things like pollen and peanuts.

This isn’t some fictional doomsday scenario. This is the here and now, where an inexorable rise in allergies is emerging as a serious threat to the health of future generations.

A century ago, no such problems existed. Now, in some parts of the world, allergies affect a third of adults and almost half of children, and they’re becoming more severe. If this continues, allergy experts warn that it could become one of the biggest

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medical challenges of the next century. So why are our bodies freaking out so much?

It has long been suspected that our hygiene-obsessed modern lifestyle is to blame. But immunologists are now revealing precisely how reduced exposure to bacteria and parasitic worms is damaging the immune system’s ability to regulate itself.

Immune responses that evolved in the presence of certain microbes have been thrown wildly out of kilter in their absence. As a result, the body’s defences have become dangerously over-sensitive to things like dust, pets and foods. And it’s not just allergies. “The same malfunction is also responsible for various other immune-related diseases, including E February 2012

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THE Worst ALLERGIES The everyday substances causing misery

WATER

Water allergy – or aquagenic urticaria – is extremely rare.

When affected individuals come into contact with water, their skin erupts in sores, making the daily shower a painful experience.

Sweat can have the same effect.

It seems that sufferers are hypersensitive to the ions found in non-distilled water.

SUN

We’ve all had sunburn but some folk are allergic to even the slightest exposure to ultraviolet radiation. It’s incredibly rare but those with solar urticaria suffer painful hives all over the skin when they go out in direct sunlight. The agent in the body that causes the reaction is yet to be identified.

LATEX

getty, rex, science photo library x2, photolibrary.com, richardpalmergraphics.com

Natural rubber latex (NRL) – used in thousands of items, including gloves, condoms and balloons – can cause allergic reactions. The most serious form is type 1, which results in anaphylactic reactions. The other form produces a skin rash.

Healthcare professionals are most at risk.

The shiny metal casings of iPods and mobile phones are among the most common causes of allergic-contact dermatitis.

Those affected suffer eczema anywhere that the skin has been touched by a nickel-containing metal surface. Nickel allergy usually develops in response to repeated exposure.

PEANUTS

It affects a tiny percentage of the population, but some of those with a peanut allergy are constantly dining with death as traces are found in so many foods. Symptoms include sneezing, tingling lips and swelling. The most severe cases can result in anaphylactic shock and, if not quickly treated, death.

February 2012

Too clean?

The incidence of these ailments has risen exponentially of late. In 1980, just 10 per cent of the Western population suffered from allergies.

Today, it’s more than three times that. And, according to predictions from the Global Allergy and Asthma Network, by 2015 half of us will suffer from allergies. A group of leading experts recently claimed to The Times that we’re now “in the midst of an allergy epidemic”.

So what’s to blame? Allergies have a strong inherited component, but their rapid rise and peculiar distribution suggest environmental factors. While rare in developing countries, in the West allergies are much more common in cities than rural areas. “All the epidemiological evidence suggests that the rapid modification of the environment in industrialised countries must be in some way responsible for this dramatic rise,” says Delespesse. “The question is how.”

Several explanations have already been proposed, from increased

exposure to allergy triggers in carpeted homes and polluted cities to changes in diet, obesity and breastfeeding patterns. The theory that gained most credence, however, was the ‘hygiene hypothesis’, first proposed in 1989. Observing that allergies were less frequent among people who had serious illnesses during childhood, David Strachan, an epidemiologist at St George’s Hospital Medical School, London, argued that modern immune systems were ill-prepared due to the reduction in serious childhood infection.

The idea was that if you haven’t suffered those infections, you don’t have enough Th1 response cells, one form of immune attack cells, which upsets the required balance and renders another form, the Th2 cells, trigger-happy. In other words, in the confines of our antiseptic modern lifestyle, the immune system falls idle, fails to mature properly and attacks harmless foreign molecules, creating all sorts of self-destructive reactions.

Then, in 1995, the discovery of regulatory T-cells, specialist cells that function exclusively as a brake on the attack cells, revolutionised the way we view the body’s defences. “Instead of doing nothing until provoked, the immune system is constantly having to be restrained and these regulatory T-cells control that,” As we cocoon ourselves with antibacterial products, are we actually creating greater problems?

NICKEL

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E type 1 diabetes, inflammatory bowel disorders and multiple sclerosis,” says Guy Delespesse, director of the Lab for Allergy Research at Montreal University.

“It is a major problem for us.”

dirt is good for you

how allergies work When our eyes swell up and the snot starts flowing from our nostrils, most of us curse the pollen or pooch that caused it. But it’s our malfunctioning immune system that should take the blame. That’s because an allergy – from the Greek meaning ‘altered reactivity’ – is an overreaction by the frontline troops that make up

our body’s defence force to an otherwise innocuous foreign invader. Put simply, when the cells that guard against substances entering the body wrongly identify something as harmful, they set in motion a biological process that leads to the release of chemicals that cause inflammation, sneezing, wheezing and itching.

Lymphocyte cell

First line of defence

Type T

Two different types of lymphocyte cells (B- and T-cells) form the first line of defence in our immune system. Moving freely between tissues and blood vessels, they search for potentially harmful foreign cells entering the body.

Type B Lymphocyte cell

Antigen (pollen in this case)

Type T

Engaging the enemy

Type B

The first time the lymphocytes encounter a foreign cell (or antigen) that they identify as dangerous, they produce an antibody called immunoglobin E (IgE), specifically tailored for that antigen.

B

Immunoglobin E (IgE)

Reinforcements

The IgE molecules then bind to another type of white blood cell, basophils, in the bloodstream and to a similar type of cell, mast cells, found in large numbers in the tissues of the lungs, skin, tongue and linings of the nose and gastrointestinal tract.

M

Basophil Mast cell

Future skirmishes and their cost

M Mast cell Histamine

The next time that antigen turns up, the basophils and mast cells with IgE attached to their surfaces fight the apparent aggressor by releasing chemicals, such as histamine. Those chemicals cause swelling in surrounding tissue. This reaction sets off a cascade of further reactions that continue to harm and irritate the tissues. It’s this irritation that leads to the characteristic allergy symptoms.

explains Dr Graham Rook, Professor of Medical Microbiology at University College London. “What’s actually happening with allergies is a problem of immuno-regulation.”

Several studies have since shown that it’s actually exposure to harmless micro-organisms (or ‘old friends’ as Rook calls them), rather than harmful diseases, that determines how well the immune system regulates its highly aggressive nature. Rook has shown that mice with respiratory allergies get better when treated with dead Mycobacterium vaccae, a harmless bacterium found in mud.

Such studies also suggest that the shift to an antibacterial lifestyle may have caused this disruption of immune development, isolating the body from those friendly microbes.

“The micro-organisms that we evolved with, long before we began this modern lifestyle, became a crucial part of our physiology,” says Rook. “In this state of ‘evolved dependency’, these microbes took the role of switching on the regulatory pathways that allow our immune systems to function as they should.

Without exposure to these microbes, our immune system attacks otherwise harmless foreign molecules.” Rook has labelled this new hypothesis the ‘old friends mechanism’; others call it the ‘microbial exposure theory’.

Whatever it’s called, the next step is to identify which microbes are responsible for this all-important schooling of the immune system.

To that end, immunologists are focusing on the microbes that humans encountered on a daily basis back when we drank from streams and toiled among soil and farm animals. It was in their company that our defence mechanisms evolved, after all.

Microbial secrets A series of studies carried out by Dr Erika von Mutius, head of the Asthma and Allergy department at Munich University, have shown that children who grow up on farms have a far smaller chance of developing allergies than kids growing up in urban areas. “The farm studies show that there February 2012

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Dirt is good for you

unlikely cures The free thinking that’s getting results Let them eat peanuts: how cause might be cure

Is an immunological elixir lurking in these muddy waters?

press association, photolibrary.com

Armed with a growing understanding of the molecular processes that cause inappropriate and self-destructive immune responses, the world’s leading allergists are now exploring some surprising ways to treat and cure long-suffering patients.

The peanut allergy, which affects around four per cent of British school children and accounts for the majority of potentially fatal anaphylactic shock incidents, has come in for particular scrutiny. Now, after a promising pilot study in which 21 of 23 kids were effectively desensitized, researchers at Addenbrooke’s Hospital in Cambridge are confident that a permanent cure is just three years away. The solution: to give them peanuts.

To prove that you can retain the immune system without any damaging side effects, they have launched a major trial. To start with, more than 100 children will be given one milligram of peanut flour – or 1/400th of a peanut – every day. That quantity will then be gradually increased to the equivalent of five peanuts per day, a process designed to familiarize the immune system’s regulatory cells with what is currently viewed as a dangerous invader.

Less palatable, though no less promising, is the growing interest in parasitic worms. Observing that people in Papua New Guinea infected with the Necator americanus hookworm, a parasite that lives in the human gut, did not suffer much from immune-related illnesses, Dr David Pritchard, a biologist at the University of Nottingham, infected a group of allergy sufferers with a small amount of hookworm.

The results were encouraging. After just six weeks the T-cells of worm recipients began to produce lower levels of chemicals associated with inflammatory response, indicating that their immune systems were more suppressed than placebo recipients. Scientists like Pritchard are now looking to isolate the molecular mechanisms that worms use to turn the immune response away from allergies in order to create a new class of drugs.

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February 2012

E must be some combination of factors, some probably microbial – whether from animal faeces, grass dust or unpasteurised milk – that guard against immune regulation problems,” says Rook. “But it’s very difficult to isolate the ones that make the most effective contribution.”

Meanwhile, Dr Bengt Bjorksten, Professor of Paediatrics and Allergy Prevention at Stockholm’s Karolinska Institute, is focusing on the gut, where a vast surface area of intestinal wall plays host to an astonishing diversity of microbial life. Comparing the gut microbes in babies from Sweden, where allergy rates are high, and those from neighbouring Estonia, where living conditions are less sanitised and allergy rates are low, Bjorksten has revealed interesting changes in our gut ecology. Estonian babies were colonised more rapidly and by a greater range of microbes than their Swedish counterparts, suggesting this diversity is a key factor in allergy resistance.

Elusive elixir Many scientists are convinced that effective treatments are not far away. Immuno-biologists both in UK and in America are exploring the effect of helminths – otherwise known as parasitic hookworms – on allergic responses in humans, and the early clinical trials are providing encouraging results. Meanwhile, a recent German study – in which mice exposed to barnyard microbes gave birth to allergy-resistant offspring

– indicates that exposing pregnant women to such microbes may protect their children.

Elsewhere, allergy experts like Guy Delespesse recommend probiotics, in the form of yogurt drinks, as a way of smuggling the good bacteria into the body. And most agree that hygiene needn’t be so absolute. “We’re not saying abandon it altogether,” says Rook, “but obsessive attention to the wrong kinds of hygiene should be curbed. If a kid comes home with muddy hands, it’s unlikely to do any harm. And may well do some good.”

Experts are optimistic about the discovery of the immunological elixir that lurks on the farms and in the guts of allergy-resistant people across the developing world. It should then be possible to find ways to re-educate our frontline troops in the complex art of immunological warfare.

“It’s going to be complicated to isolate the active molecules and transform them into treatments,” concludes Rook. “But I think we’re on the right track. There is hope for future generations.”

Dan Cossins is a freelance journalist based in London and is a regular contributor to BBC Knowledge.

find out more E The Hygiene Hypothesis and Darwinian Medicine Graham Rook (ed) (Birkhauser, 2009) E http://bit.ly/9Gj0vk How farms affect children’s allergies

School in Focus

Christ Church School Byculla, Mumbai

Accolades, prizes and lots of fun, Christ Church School, Byculla knows the perfect mix of academics and extra-curricular activities.

Founded in 1825, Lord Mountstuart Elphinstone, Governor of Bombay laid the foundation stone of the Boys’ school, and Lady Chambers and Lady West of the Girls’ school. It was established in its current form i.e. Christ Church School for day scholars in 1925. Since then, it has established a name for itself as one of the most prominent I.C.S.E. schools in South Mumbai, providing education to students from Junior K.G. to Standard 12.

We are the champions To felicitate the children for their outstanding performances in the inter-school festivals organised this year, Principal Carl Laurie arranged a victory parade for them in open BEST buses around Byculla. He presented each student with a souvenir medal on behalf of the school. A fun-filled party was also organised for the participants.

Children’s Day

14 November was celebrated at the school with a lot of pomp and show.

With varied activities for all age groups, the event was attended by parents as well. A live band added to the festive atmosphere.

We are the World The mega inter-school fest, ‘We are the World’ was organised by the Rotaract Club of H. R. College. Christ Church School represented Brazil and walked away with top honours in the fashion show, dance, choir, culinary presentations and Olympic bidding. The school was declared the champion of the contest.

Annual Atheletic Meet This event, open to the entire school from the playgroup to the junior college, had a host of events for girls and boys.

A marathon from Nariman Point to Chowpatty was also held.

The march-past was a colourful display of school colours .

BBC Knowledge recently organised an event at Christ Church School. If you would like us to visit your school and have it featured on this page, write in to us at bbcknowledge@wwm.co.in

BBC

Ancient humans

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February 2012

Ancient humans

Last man

standing Some 50,000 years ago, Homo sapiens beat out other hominids to become the only surviving species. Kate Ravilious reveals how we did it Additional reporting: Graham Southorn

oday there are nearly seven billion people living on Earth. No other species has exerted as much influence over the planet as us – we’ve inhabited every continent and restructured the Earth’s surface and atmosphere. But our place in the pecking order wasn’t always this high. New scientific evidence sheds more light on our ancestors’ fight for survival against other hominids. So what happened to those other ancient people?

Turn back the clock 80,000 years and we were one of around five species of humans roaming the Earth. Our own species, Homo sapiens (Latin for ‘wise man’) was most successful in Africa. In western Eurasia the Neanderthals dominated, while

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descendents of the Homo erectus may have lived in Indonesia and the Homo floresiensis (the ‘Flores’ or ‘Hobbit’ man) inhabited the Indonesian island of Flores.

Meanwhile, an unusual tooth and finger bone, discovered in Denisova cave in Siberia in 2008, have more recently led scientists to believe that yet another human population – the Denisovans – may also have been widespread across Asia.

Somewhere along the line these other human species died out, leaving the Homo sapiens as the sole survivor.

But what made us the winners in the battle for survival? Was it chance, or did any of our unique skills and attributes have a crucial role to play?

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max planck institute for Evolutionary anthropology, chris hildreth/duke university, science photo library

Ancient humans

E First encounters One of the earliest encounters between human species may have taken place in India, prior to a massive volcanic eruption. Some 74,000 years ago, the Toba ‘supervolcano’ on the Indonesian island of Sumatra blew its top, releasing 2500km3 of magma – nearly twice the volume of Mount Everest. The eruption, which was over 5000 times as large as the 1980 eruption of Mount St Helens in the US, flung ash as far as eastern India, more than 2000km away.

For over two weeks the ash fell like snow, turning day to night, smothering plant life and polluting water supplies. Previously, scientists speculated that the global climate change brought on by the Toba eruption may have nearly wiped out the human race, but archaeological evidence from India shows that this is far from the case.

Unfortunately, no skeletons have ever been found – the moist tropical environment isn’t good for preserving bone – but University of Oxford archaeologist Mike Petraglia and his team have uncovered thousands of stone tools buried underneath the Toba ash.

Amazingly, the same kind of stone tools continue to emerge from the soil layers above the ash, proving that the people who made these tools survived the disaster.

So who were these people? Many of these tools are ‘hand axes’ – simple, efficient cutting blades that Petraglia believes most probably belonged to a species like Homo erectus. But some of the tools,

Neanderthals lived in small groups, as depicted in this museum in Krapina, Croatia

including possible spear tips, of the type used by Homo sapiens, have led Petraglia to speculate that there were two species of human living in eastern India prior to the Toba eruption.

Based on careful analysis of the tools, and dating of the sediment layers where they were found, Petraglia and his team suggest that Homo sapiens arrived in eastern India around 78,000 years ago, migrating out of Africa and across Arabia during a favourable climate period. After their arriva, the simple tools belonging to Homo erectus dwindle and eventually disappear completely. “We think that Homo sapiens had a more efficient hunting technology, which could have given them the edge,” says Petraglia.

“Whether the eruption of Toba also played a role in the extinction of the Homo erectus-like species is unclear.”

Conflict in Europe Some 45,000 years later, another fight for survival was underway. This time the location was Europe and the protagonists were our ancestors and the Neanderthals.

Initially, Homo sapiens and Neanderthals had no reason to compete. But then Europe’s climate swung into a cold and dry phase.

“Neanderthal and Homo sapiens populations had to retreat to refugia [pockets of habitable land] and this heightened competition between the two groups,” explains Chris Stringer, anthropologist at the Natural History

Neanderthals (left) had similar-sized brains to Homo erectus (middle) and Homo sapiens (right) but our ancestors’ brains had more developed temporal lobes 68

February 2012

Ancient humans

Museum in London and author of The Origin Of Our Species.

So how did the two species square up?

Both species were physically strong and stockier than the average human today, but Neanderthals were particularly robust. “Their skeletons show that they had broad shoulders and thick necks,” says Stringer. Our ancestors probably wouldn’t have come off well in a fist fight with a Neanderthal but they may have been skilled with a throwing spear. “Homo

sapiens could use this skill to kill from some distance, with less danger and using relatively little energy,” explains Stringer.

Even if the two species weren’t engaged in direct combat (see ‘Did the early hominids fight each other?’, below), this long-range killing ability may have given Homo sapiens an advantage in hunting.

Both Neanderthal and Homo sapiens skeletons have been found in cold climate regions, living alongside woolly mammoths in Ice Age Britain, for example. The large body size of the Neanderthals helped to keep them warm but it also carried a cost.

“Compared to Homo sapiens living in the same environment, Neanderthals may have needed to consume several hundred more calories every day, which made them much more dependent on game such as deer and horse,” says Stringer.

Chemical analysis of Neanderthal and Homo sapiens bones support this theory, showing that Neanderthals were top-level carnivores, while our ancestors relied on more of a smorgasbord of resources, including small game and fish.

And when it came to keeping warm, Homo sapiens had another adaptive trick up its sleeve: weaving

and sewing. Archaeologists have uncovered simple needles, fashioned from ivory and bone, alongside Homo sapiens dating as far back as 35,000 years ago.

“Using this technology we could use animal skins to make ourselves tents, warm clothes and fur boots,” says Stringer. “Most importantly, we could keep our babies warm, which may have given us the edge over Neanderthals for surviving climate fluctuations.” In contrast, Neanderthals never seemed to master sewing skills, instead relying on tying or pinning skins together (with E thorns, for example).

The DNA of Neanderthals was retrieved from these bone fragments

Did the early hominids fight each other?

Homo sapiens are sometimes shown skirmishing with Neanderthals and Homo erectus. There’s no hard evidence of conflict between the two but it is likely, according to Prof John Shea of Stony Brook University.

“Among the big primates today you can see two strategies for dealing with disputes. Bonobos masturbate and have sex, while chimpanzees fight and annihilate each other.

However, I think the hominids just left each other alone.”

That’s not the only view, however. Back in 1959, the remains of a Neanderthal dubbed Shanidar 3 were found in a cave in Iraq. The skeleton had an unusual injury on its left side – one rib was grazed while the rest were relativity undamaged. Two years ago, evolutionary anthropologist Steven Churchill of Duke University argued that such a wound could only have been caused by a projectile, implying a spear that was thrown rather than thrust. In other words, the Neanderthal named Shanidar 3 might have been killed by one of us – Homo sapiens. Either that or he was simply fatally clumsy.

Paleontologist Steven Churchill (right) and colleagues fire weapons into gelatin to investigate the damage they’re capable of inflicting

February 2012

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Ancient humans

Spears: thrusting vs throwing Neanderthals’ wooden spears were big and heavy, measuring between 1.5m and two metres long and four-five cm thick, and tapered at one end. In the hands of a Neanderthal, this was a deadly weapon. It was mainly used at close quarters, by thrusting into the side of large animals like elephants.

Neanderthals were strong enough to hold a spear steady while an animal writhed, causing huge damage. They could also throw for short distances.

“They could hurl a spear about 10-30m,” explains series consultant Prof John Shea.

Homo sapiens were better throwers, however. Their longer forearms made their entire arms longer, which enabled them to hurl spears over longer distances. Homo erectus is also likely to have used wooden spears. But this species is believed to have palms that faced forwards so, like Neanderthals, they wouldn’t have been able to throw them very far.

Different minds Some of these differences in behaviour and technology may have emerged because the two species thought in different ways. By comparing skull shapes, archaeologists have shown that Neanderthals had similar-sized brains to early Homo sapiens but with a larger occipital lobe (the region at the back of the brain). This part of the brain is associated with visual processing, which may have meant that Neanderthals had keener eyesight and were better able to distinguish things in dimly lit places, like murky forests.

Homo sapiens, however, had a more developed temporal lobe (the regions at the side of the brain, associated with listening, language and long-term memory). “We think that Homo sapiens had a significantly more complex language than Neanderthals and were able to comprehend and discuss concepts such as the distant past and future,” says Stringer.

Furthermore, we may have been able to talk faster. In Homo sapiens the upper respiratory tract is more flexed than that of Neanderthals, making it more efficient at producing a wide variety of sounds quickly.

Penny Spikins, an archaeologist at the University of York, has recently suggested that Homo sapiens may also have had a greater diversity of brain types than

Superstock, science photo library, joao zilhao, el sidron research team

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Our ancestors’ ability to throw spears gave them the edge

Neanderthals. “Our research indicates that part of the reason Homo sapiens were so successful is because they were willing to include people with ‘different’ minds in their society – for example, people with autism or schizophrenia,” she explains.

Recent analysis of the Neanderthal genome support Spikins’s ‘different minds’ theory, Evolutionary anthropologist Svante Pääbo (right) on the hunt for bone fragments in a Spanish cave

revealing that Neanderthals didn’t carry the genes associated with autism or schizophrenia. “It seems reasonable to conclude that Neanderthals were much more similar to each other genetically, and not prepared to accommodate differences in people,” says Spikins. By being tolerant of these seemingly damaging traits, Homo sapiens acquired specialist skills and a diverse population that was better able to adapt to, and exploit, different environments. For example, people with mild forms of autism are often highly skilled at one particular activity.

“It’s not difficult to see how attention to detail, exceptional memory, a thirst for knowledge and narrow obsessive focus can lead to significant achievement in certain realms,” says Spikins. High-precision tools, new hunting technologies and the development of symbolic communication may all have come about by encouraging people to ‘think outside the box’. Meanwhile, people willing to lead an isolated existence may have become explorers, discovering new lands and resources to exploit.

Culture and climate Unusual ways of thinking could also have helped people to come up with new ways of resolving social tensions. “Shamanism, music and dance all helped bind people together,” says Spikins. Meanwhile, skilled artists wowed people with their precise and literal renditions of animals and people, painted onto cave walls.

By around 30,000 years ago, many of these talents and traits were well established in Homo sapiens societies but still lacking from Neanderthal communities. “We see similar kinds of injuries on male and female Neanderthal skeletons, implying that there was no division of labour or specialised roles,” says Spikins.

Tolerance and open-mindedness, combined with a thirst for exploration, provided Homo sapiens with another significant advantage over Neanderthals. Objects such as shell beads and flint tools, discovered many miles from their source, show that our ancestors traded over large distances, exchanging useful materials and sharing ideas and knowledge. By contrast, Neanderthals tended to keep to themselves, living in small groups. They gathered resources from close to where they lived, perhaps failing

Ancient humans

Gorham’s Cave in Gibraltar was one of the Neanderthals’ last known refuges

to discover new materials, technologies or environments outside of their territory.

Nonetheless, Neanderthals were a highly successful species, dominating the European landscape for 300,000 years.Yet within just a few thousand years of the arrival of Homo sapiens, their numbers plummeted. They eventually disappeared from the landscape around 30,000 years ago, with their last known refuge being southern Iberia, including Gibraltar.

Stringer thinks that in many ways the Neanderthals were just unlucky – living in the wrong place at the wrong time. “They had to compete with Homo sapiens during a phase of very unstable climate across Europe. During each rapid climate fluctuation they may have suffered greater losses of people than Homo sapiens, and thus were gradually worn down,” he says. “If the climate had remained stable throughout, they might still be here.”

Last stragglers Once the Neanderthals were out of the picture, only two species of human are believed to have remained: Homo sapiens and Homo floresiensis – the Hobbit people.

As their nickname suggests, these people had

small bodies (only just over one metre tall) and small brains. Nonetheless, they behaved in an intelligent way. They used stone tools, which indicate cooperative hunting, and perhaps also fire for cooking.

Quite possibly they’d still be alive today if it hadn’t been for another mega volcanic eruption 17,000 years ago. It devastated the island, wiping out its vegetation and the Stegodon – a dwarf elephant-like species that may have formed the staple diet of the Hobbit

Painted hunters In Planet Of The Apemen, Homo sapiens were depicted as dark-skinned since they’d only just left Africa. Neanderthals were shown with lighter skins, because they’d made the journey half a million years earlier. According to series consultant Prof John Shea, cloudy European weather could have caused natural selection to favour lighter skins, in order to boost the amount of UV radiation they absorbed. But lighter bodies would be dangerously conspicuous, so they may have painted their faces and bodies before hunting.

“Black manganese – a dark mineral pigment – has been found with Neanderthal remains,” says Shea. “They might have decorated themselves if their skin had lost melanin. The pigment would have acted like camouflage so they could get closer to animals.” There’s even

people. “So far there is no evidence of any competition with Homo sapiens. Perhaps they simply failed to survive the aftermath of the eruption,” says Stringer.

However, it turns out that our fellow human species may not have completely died out after all. Last year, Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues analysed Neanderthal bones and sequenced the Neanderthal genome. They discovered that all humans with ancestry outside Africa share around two and a half per cent of their DNA with Neanderthals. This year, Pääbo and his colleagues carried out the same analysis on the finger bone found in Denisova cave in Siberia. In this case, they showed that the Denisovans share as much as five per cent of their genetic material with present day Melanesians (people living in the islands of South East Asia, such as New Guinea).

“Both Neanderthals and Denisovans have been able to interbreed and have fertile offspring with modern humans,” says Pääbo.

“In some ways, they live on in us today.”

Kate Ravilious is a journalist who has written extensively on ancient civilizations. She specialises in physical and enviornmental sciences.

A Neanderthal make-up container?

Traces of pigments were found on shells

evidence that pigments could have been used for cosmetics, as traces have been found on shells from Spain.

find out more E www.bbc.co.uk/nature/life/homo A site from the BBC Nature team with information on early hominids E The Origin Of Our Species Chris Stringer (Allen Lane, 2011) February 2012

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Buzz

Wader Watch

We have always tried to make BBC Knowledge an interactive read. Here’s just a snippet of what we’ve been upto.

Bird enthusiasts enjoying the Wader Watch

The Bombay Natural History Society (BNHS) and BBC Knowledge had arranged for a Wader Watch programme at Sewri, Mumbai on December 17, 2011.

Eurasian Curlew

Photograph by Asif Khan

Lesser Flamingo

Black-capped Kingfisher

The event was attended by over 50 bird enthusiasts from all walks of life.

Broadly, Waders are all the birds that “wade” in shallow waters – however, the term is used for a specific group of birds mostly belonging to Order Charadriiformes, like plovers, sandpipers and similar birds. The Waders from Central Asia, Siberia and some parts of Europe start landing along the western coast of India and parts of Mumbai in December every year, where they make their home for the next four to five months. The migration of these birds is an annual phenomenon and mainly occurs because of the excessive winter in their respective habitats which

makes it difficult for them to find food.

Participants of the Wader Watch programme learnt about different migratory birds, their habits and habitats. During the visit, birds like Black-tailed Godwit, Lesser and Greater Sand Plover, Little Stint, Western Reef-Egret, Indian Pond-Heron, Black-capped Kingfisher, Eurasian Curlew and Flamingos were spotted.

Conservation issues of Sewri mudflat were also discussed with the participants.

We at BBC Knowledge, ran a special contest on our facebook page and two lucky winners – Ceona Benjamin Salve and Austin – won passes to the event.

The BNHS, along with BBC Knowledge, is planning more such events together in the coming months. Watch this space for more details!

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Announcements n o h c n lau AT S SRM PSLV-C18

SRM University plans to set up a Space Technology Centre at its campus in Kattankolathur with the help of the Indian Space Research Organisation (ISRO). Speaking at a launch of the nano satellite SRMSAT on October 12 on the PSLV-C18, at Sriharikota, Prof Sathyanarayanan spoke about the establishment of the centre in the varsity campus. “Everything is in the planning stage at the moment. The talks in this regard will be carried forward once the launch of SRMSAT is over. It will take another five to six months to get a concrete shape,” he said.

The Group Chancellor for the varsity Mr T R Pachamuthu said that focus, of the centre, would be more on research.

“Once the centre is established, we shall introduce specialised courses on Space Technology to churn out space scientists to meet the growing demands.”

The students of the university, recently adjudged as the number one private varsity in the country, were feted for their efforts of building the satellite SRMSAT. Weighing around 10.4 kg the satellite with a life span of two years, would monitor green house gases, carbon dioxide and water vapour in the atmosphere using a grating spectrometer.

A separate ground station has been set up at the campus, which will start to monitor the satellite after ISRO’s initial one week monitoring of it from its base in Bangalore.

Homo sapiens neanderthalensis walked the Earth between 27,000 and 220,000 years ago

The Big Idea

exploring life’s great mysteries Robert Matthews investigates

Out of Africa Where do we come from? Charles Darwin, the father of evolution, argued that our similarities to apes pointed to Africa as the cradle of modern humans. Now, sophisticated archaeological dating and DNA analysis techniques are confirming and expanding his once-controversial claim – with startling implications for us all. apparently huge diversity of today’s humans, from Scandinavians to Sumatrans, Inuits to Indians, is just an illusion. Ultimately, we are all the descendents of migrants from one place: Africa.

Darwin’s declaration This would come as no surprise to Charles Darwin, the father of evolution. As long ago as 1871, he argued in his book The Descent of Man that all the races of humans were just varieties of a single species, with Africa – the home of the world’s great apes – as the most plausible birthplace of modern humans.

Today, with spectacular discoveries of human fossils routinely being made in sites around Africa, Darwin’s claim

may seem unremarkable. Yet at the time he was writing, all the evidence suggested that the cradle of humankind was much closer to his homeland. The nature of this evidence took a long time to be recognised.

Part of a fossilised humanlike skull had been found in southern Germany around 1700, though its significance was not recognised for over a century. In 1823, the firstever fossilised remains of a human skeleton were found in a cave on the Gower peninsula in South Wales, but again they were misunderstood for years. A similar fate almost befell bones found in 1856 by quarrymen working in the Neander Valley near E Düsseldorf. The workers

Corbis, DPA Photo

o the untrained eye they look like little more than chipped pieces of stone. But according to some, they are the latest clues that could help resolve one of the most vexed questions in science: where do humans come from?

Earlier this year, HansPeter Uerpmann of the University of Tubingen in Germany and his colleagues announced the discovery of fragments of dozens of stone tools up to 125,000 years old at a remote site near the Straits of Hormuz in the United Arab Emirates. That combination of great antiquity and location has sparked huge controversy because, according to Uerpmann and his colleagues, the tools appear to be the work of modern humans – Homo sapiens. And that, in turn, suggests that they can cast light on the mystery of human origins: where did we come from and how did we get where we are today?

It is a detective story that began almost 200 years ago with the discovery of the first human fossil remains. Yet the full picture has only begun to take shape with powerful new techniques of DNA analysis in the last few years.

What it shows is that the

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125,000-year-old stone tools were recently found in the United Arab Emirates February 2012

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The Big Idea

exploring life’s great mysteries

Piltdown Man’s jaw turned out to belong to an orangutan

a matter of proof

Bones of contention

Rex, Thinkstock x2, Wikipedia, alamy, Science photo library, istockphoto, Press association x2

One of the biggest problems in trying to fathom the origins of humans is the dearth of evidence.

Even now, almost 200 years after the first human fossil remains were found, the total number of skeletal remains found so far would fit into the boot of a small car – and that raises the risk of over-interpretation.

In 1922, an American fossil hunter claimed to have identified an entirely new species of human – ‘Hesperopithecus’ – on the basis of a single fossil tooth. It later proved to have come from an extinct pig.

The most embarrassing case was in the 1950s when experts conceded that the skull of the long-sought ‘missing link’ between apes and humans was a medieval human skull combined with an orangutan jaw.

Experts suspect fossil-hunter Charles Dawson constructed the fake to catch out over-excitable academics.

TIMELINE the study of human origins

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E dumped the remains as worthless, and they were only rescued from oblivion by a local teacher. Academics then hailed the remains of an extinct species of human: Homo neanderthalensis – ‘man from the Neanderthal valley’.

Not surprisingly, the bones of Homo neanderthalensis prompted enormous controversy. Some anatomists agreed that they had come from members of a previously unknown species of human, while others pointed to the similarity of skull size with modern humans, insisting the bones merely came from an ancient example of Homo sapiens. As more bones emerged at other sites, some anatomists tried to settle the argument by highlighting supposed differences between Neanderthals and modern humans, such as their ‘knuckle-grazing’ walk. This famous feature of Neanderthals was later shown to be an illusion, based on an overinterpretation of findings from the remains of a single specimen with osteoarthritis.

The dangers of reading too much into too little F have dogged research into human origins ever since.

When the next major piece of the jigsaw of human origins emerged, it too failed to fit Darwin’s ‘Out of Africa’ theory. In 1891, the Dutch physician and fossil-hunter Eugene Dubois found fossilised fragments of a human-like creature in Java. With its much smaller skull, ‘Java Man’ was unlike either modern humans or Neanderthals.

Subsequently renamed Homo erectus (upright man), Dubois’s find was another genuinely new form of human, the first of several found outside of Africa.

1823

1871

H William Buckland of the University of Oxford finds the first human fossils, in South Wales. Named the Red Lady of Paviland, they are actually of a 26,000-yearold male.

H Drawing on the similarities between humans and apes, Charles Darwin predicts in his book The Descent of Man that the origins of modern humans will be found in Africa.

Not until 1904, more than 20 years after Darwin’s death, did the first hard scientific evidence emerge to back his Africa-centred theory. George Nuttall, a bacteriologist at the University of Cambridge, had become intrigued by the newly identified blood groups of humans and carried out tests comparing human blood to that of other creatures. To his astonishment, Nuttall found striking similarities between the blood of humans and that of apes from Africa. The implications were no less astonishing. Despite appearances – and the fossil evidence up to that time – modern humans shared common ancestry with creatures from Africa.

Fossil hunting Unknown to Nuttall, his discovery was the first glimpse of the power of DNA to probe questions of human origins. Years later, scientists would refine his methods to give stunningly precise insight into the events that led to the origins of Homo sapiens. For decades after his pioneering work, however, the focus of attention would switch back to fossil evidence.

The prospect of finding human remains in Africa led fossil-hunters there as early as 1912 but, with few clues about where or what to look for, they came away emptyhanded. Bizarrely, the breakthrough came in the form of a fossilised skull sitting on the mantlepiece of a quarry manager in Taung, South Africa. It was spotted one day in 1924 by a student of Raymond Dart, an Australian professor of anatomy at the University of Witwatersrand in Johannesburg.

Dart quickly identified the skull as that of an extinct baboon and

1891 G Dutch physician Eugene Dubois finds early human remains in Java.

Now known as Homo erectus, the species is thought to have left Africa around 1.8 million years ago.

1904

1924

George Nuttall of the University of Cambridge uses blood groups to uncover the first hints of a link between humans and African apes, presaging the use of sophisticated DNA analysis decades later.

E Raymond Dart identifies the apelike human fossil Australopithecus.

Initially rejected as implausible, his claims are backed by later finds, resurrecting Darwin’s Out of Africa theory for human origins.

migration patterns

We were not the first out of Africa While there is now a growing consensus that modern humans migrated out of Africa, it’s also clear that we were not the only human-like creature to make the trek – or even the first. Radioactive dating suggests that Homo erectus left Africa around 1.8 million years earlier. But recent analysis of bones found in Asia points to another exodus some time after Homo erectus but before modern humans.

DNA extracted from a fragment of female finger bone found in Denisova Cave in Siberia’s Altai Mountains in 2008 shows that the woman was genetically different from both modern humans and Neanderthals. Calculations suggest all three had a common ancestor around a million years ago, pointing to a departure date from Africa around that time.

Dating methods suggest this first example of a ‘Denisovan’ lived around 30,000 to 48,000 years

began wondering what else had been found at the quarry.

Shortly afterwards, Dart received two boxes of material dug up by the quarry workers. The first contained nothing of value, but in the second he found fragments of a skull-shaped fossil. Their small size suggested an ape-like creature,

Scientists gather at Denisova Cave, where a distant human ancestor’s remains were found

ago. Researchers have already found Neanderthal remains in the same area from around the same period, showing that the Denisovan woman and her kind co-existed with both modern humans and Neanderthals. This in turn raises the possibility of interbreeding between all three types. Experts think this might help explain otherwise perplexing fossils found elsewhere in China and Mongolia, which have so far defied simple classification.

DNA studies have also revealed that around five per cent of the genetic

blueprint of modern humans from Papua New Guinea and its surroundings appears to derive from Denisovans – again supporting the interbreeding hypothesis.

With so few fragments to work with, researchers are wary of pushing their theories too far. Even so, there is considerable excitement that this finger bone may represent a hitherto unknown species of human that walked out of Africa like Homo erectus and modern humans.

but the jaws, teeth and other anatomical details were unlike those possessed even by chimpanzees, our closest living relatives.

Dart recalled Darwin’s old Out of Africa theory and wondered if he was looking at the remains of the creature from which both humans and chimpanzees had evolved – the fabled ‘Missing Link’.

Within a few months, Dart’s discovery was making headlines worldwide. He named the creature Australopithecus africanus – ‘Southern African ape’ – and immediately ran into a barrage of criticism. Leading scientists insisted he was pushing the evidence much too far and that the skull was simply a fossilised ape’s head. Others rejected the implication of an African origin for humans on essentially racist grounds: to them, it was inconceivable that modern humans could have emerged from the homeland of slaves.

1987

1992

2008

2011

Allan Wilson of the University of California and colleagues use the ‘Mitochondrial Eve’ concept and DNA to argue that humans came from Africa less than 290,000 years ago.

H University of Utah researchers claim DNA suggests all modern humans are descended from just 10,000 people who left Africa 50100,000 years ago.

An international team finds the first evidence for a new form of ‘Denisovan’ human that left Africa around one million years ago in the Denisova Cave in Siberia.

H Researchers at the University of Cambridge reveal evidence that modern humans from Africa overwhelmed the Neanderthals and pushed them into extinction around 35,000 years ago by sheer weight of numbers.

Focus on Africa The significance of Dart’s discovery was rejected until the 1940s, by which time many more specimens of Australopithecus had emerged to support his view of them as a distant ancestor of humans. Africa now became the focus of the quest for human origins. Ever more specimens of humanlike creatures began to emerge, with names like Australopithecus afarensis, Australopithecus boisei and Homo habilis. Yet the emerging picture of human origins was becoming E February 2012

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exploring life’s great mysteries

E less clear. Arguments broke out between rival teams of scientists over the relationship between all these different creatures. Which were direct descendants of modern humans? Which were just evolutionary dead ends? And how could the African origins of modern humans ever be proved?

A key part of the puzzle fell into place in 1960. While working in the Olduvai Gorge of Tanzania, the Kenyan fossil-hunters Louis and Mary Leakey found part of a skull belonging to Homo erectus – the same human species Dubois had found thousands of miles away in Java. The discovery formed a crucial link between early humans in Africa and those found elsewhere in the world. Radioactive dating later showed that the African Homo erectus fossils were up to 1.8 million years old – far older than most of the specimens found elsewhere. This

suggested Homo erectus had begun to leave Africa by around two million years ago.

The obvious implication was that they had then evolved into Neanderthals – and even Homo sapiens in many different locations. Yet while appealingly simple, this so-called ‘multi-regional’ view of human evolution was hardly compelling.

Modern humans may actually have evolved from the Homo erectus that remained in Africa, leaving the continent in a second exodus long after the first. Over a century after Darwin’s original proposal, this became a central claim in the Out of Africa theory: that modern humans had first emerged in Africa, and left the continent long after Homo erectus, ultimately replacing all other species across the globe.

New evidence Proving it was a different matter, however.

There was always the possibility that fossilhunters had simply missed a vital clue.

Some other source of evidence was needed and, during the 1960s, it began to take shape in the laboratory of biochemist Allan Wilson and colleagues at the University of California.

They resurrected the basic idea behind George Nuttall’s blood tests: that today’s humans carry clues to their origins in their cells. As ever, their early findings provoked enormous controversy. By studying the blood proteins of humans and apes, they claimed the two had parted company around five million years ago – far more recently that the fossil evidence had otherwise suggested. Despite a storm of protest, later fossil evidence backed Wilson’s chronology.

Encouraged by this success, the team went on to devise another technique, based

the story of extinction

Whatever happened to the Neanderthals?

Alamy, science photo library

Ever since their bones were first discovered around 150 years ago, the fate of the Neanderthals has intrigued researchers. Explanations for why their 300,000-year domination of Europe suddenly ended around 35,000 years ago range from an inability to cope with

Did Neanderthals die outdue to Homo sapiens outcompeting them?

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February 2012

climate change to clashes with invading Homo sapiens.

Earlier this year, a team led by Sir Paul Mellars of the University of Cambridge unveiled evidence that Neanderthals were overwhelmed by sheer numbers of Homo sapiens who arrived from Africa

around 40,000 years ago.

Analysis of sites in southwestern France suggests that the Neanderthals found themselves outnumbered by at least ten to one – pushing them into an unequal contest for resources.

The migrants possessed better hunting equipment,

such as well-crafted spears, while cave paintings suggest they also had more sophisticated brains and social structures. In the face of such abilities, the Neanderthals would have found themselves in a losing battle for survival – in some cases, quite literally.

.

Question Time British anthropologist Chris Stringer is a research leader in human origins at the Natural History Museum in London

What first led you to take the Out of Africa theory seriously?

It was my own research showing that the Neanderthals in both Europe and western Asia were unlikely ancestors for modern humans, coupled with the growing fossil, dating, archaeological and genetic evidence that Africa was the most likely region for our origins.

What are the theory’s key features?

Fossil-hunters Mary and Louis Leakey found teeth and skull fragments from Homo erectus in Tanzania

on ‘mitochondrial DNA’ (mtDNA) found in living human cells. By comparing the mtDNA of modern humans from different parts of the world, Wilson hoped to gauge just how recently we all shared a common ancestor – the so-called ‘Mitochondrial Eve’. The team found relatively little difference between the mtDNA of modern humans, consistent with Homo sapiens having emerged fewer than 290,000 years ago. They also found that the biggest differences were among Africans – just as expected if they are the oldest members of Homo sapiens.

The triumph of DNA Wilson’s findings made headlines around the world and spurred DNA-based research by many others. The results of all these studies provided the first glimpses of the complex story of modern humans. First, they point to Africa being the birthplace of Homo sapiens who emerged around 120-220,000 years ago. They also suggest that around 55,000 to 70,000 years ago, perhaps as few as 3,000 members of the species walked out of Africa and fanned out across the world.

On the way, they met the descendants of Homo erectus, who had left Africa around 1.8 million earlier, and also the Denisovans of Asia, whose ancestors had also made the journey around a million years ago.

Many intriguing questions remain.

For example, how did these pioneering Homo sapiens interact with those they met on their odyssey? Dating of remains

shows that there was a brief period of coexistence with the Neanderthals but, by around 35,000 years ago, Homo sapiens had become dominant – but how? Did they outbreed and outwit the Neanderthals, or push them into extinction by violence? F Questions also surround the route taken by the migrants as they left their continent of origin. Hans-Peter Uerpmann’s recent discovery of tools at the site in the United Arab Emirates suggests Homo sapiens may have chosen a path taking them across the Red Sea and into the Arabian peninsula, which was a much less forbidding region at the time. Where did they go after that?

Researchers are now hoping to find evidence further north, in Iran and beyond. But while their quest for answers continues, it now seems all but certain that, as Darwin first suggested over a century ago, ultimately we are all Africans.

Robert Matthews is a science journalist and holds the position of Visiting Reader in Science at Aston University, UK. www.robertmatthews.org

find out more E Born in Africa: the quest for the origins of human life

by Martin Meredith (Simon & Schuster/PublicAffairs, 2011) E Out of Eden: the peopling of the world

by Stephen Oppenheimer (Robinson, 2004) E www.humanorigins.si.edu The Smithsonian Institute’s human evolution resources

Firstly, that Africa was the place of origin for most of the distinctive anatomical and behavioural traits of modern humans – with the caveat from recent research that these traits did not originate in a single region of the African continent. Secondly, that regional (or ‘racial’) differences were superimposed on the original shared features of modern humans at a later date, as modern humans spread and diversified around the world.

What do you think prompted the migration?

I think that demographic changes – increases in population size, density and social networks – fuelled the expansion of modern humans, first in Africa and then, from about 60,000 years ago, outside of Africa. These changes were probably partly driven by favourable climatic conditions in eastern Africa 50-70,000 years ago, and partly by behavioural changes.

What recent discovery about the theory has most impressed you?

I’m very excited by the genomic evidence that Neanderthals and a newly identified type of human known as the Denisovans contributed DNA to recent human populations living outside of Africa. Until recently, the strongest version of the Out of Africa theory had Homo sapiens replacing other forms of humans with negligible interbreeding. We now know this was not so.

And there is growing evidence that interbreeding with archaic humans happened in Africa too.

What mystery would you most like to see answered about the theory?

Are there significant differences in the brains of modern humans compared with archaic humans? And, if so, what do the differences signify?

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P Do hummingbirds mate in mid-air? p81 P Do other animals have identical twins? p84 P Do viruses die? p84 P Is carbonated water as hydrating as still? p85 P How can the moon exactly eclipse the sun? p87

EXPERT PANEL Susan Blackmore

A visiting professor at the University of Plymouth, UK, Susan is an expert on psychology and evolution.

Dave Brian Butvill

Based in Costa Rica, Dave studied zoology before becoming a freelance writer specialising in the natural world.

Eugene Byrne

A journalist and author, Eugene has written several books of popular history and contributes to BBC History Magazine.

Robert Matthews

Robert is a writer and researcher. He is a Visiting Reader in Science at Aston University, UK.

Gareth Mitchell carnegie mellon university, Illustration by Jonty clark, thinkstock x2

As well as lecturing at Imperial College London, Gareth is presenter of Digital Planet on the BBC World Service.

Luis Villazon

Luis has an MSc in zoology from the University of Oxford.

He is a freelance science journalist based in the UK.

This snake-like robot is among the world’s most sophisticated robots

Q KNOW SPOT VY Canis Majoris is the largest star on record. Estimates give it a diameter of 2.5-3 billion km (1.55-1.87 billion miles), which makes it 1800-2100 times larger than the Sun.

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February 2012

What is the world’s most advanced robot?

The Honda Motor Corporation’s Asimo, with its humanoid appearance and ability to walk and climb stairs, has been dubbed the world’s most advanced robot.

Yet, during the crisis at the Fukushima nuclear power plant, this triumph of Japanese robotic

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engineering was not deployed in the reconnaissance and cleanup operation. Instead, US-made military robots were drafted in.

Perhaps that’s because Asimo is primarily a PR device whose ultimate function is in domestic settings or helping the elderly. Elsewhere, researchers at Carnegie Mellon University in Pittsburgh have created one of the world’s most sophisticated snake-

umber erage n The av es that a of tim g blinks bein human ingle day in a s

like robots (above), while a team at the University of California at Berkeley is working on robots the size of insects. While Asimo’s walking is impressive, robotic snakes and bugs can reach parts that Asimo can’t. So, a robot’s sophistication should really be measured against the tasks it’s been designed to perform. GM

w

QuicKFIRE

Did you know?

Cycling champ revealed as easy rider Never mind the latter-day blood doping controversies that dog the Tour de France – the winner of the 1904 event was disqualified for taking his bike on a train for part of the route.

Maurice Garin had won the inaugural Tour the previous year and he led the second competition from start to finish. However, the race was plagued by scandals and accusations of cheating. Cyclists were said to have been pulled along by cars and motorcycles – and to have hired thugs to beat up

Q

Why do some trees have smooth bark and others rough?

Tree bark is a defence against herbivores, insects and parasitic plants. The smooth bark of a beech tree makes it hard for insects and ivy to gain a foothold, but to keep the surface smooth, the tree must grow its bark quite slowly. This makes it slow to seal injury sites, where branches have snapped off, and also limits the overall growth rate of the tree.

Oak trees have bark that grows four times faster than that of beech, which allows for speedy repair. It also helps the tree to retain moisture, so oaks can survive in dry Mediterranean environments. But the rapid growth causes the bark to wrinkle and crack – and this harbours insects. To counter this, the oak must spend a greater proportion of its metabolic resources producing tannins in order to

A

How does radiation escape from a black hole?

Black holes are renowned for having gravitational fields so strong that not even light can escape from inside them. Yet in 1974, Stephen Hawking claimed that black holes emit radiation. In fact, the radiation is generated by the intense gravity fields acting on the region of space just outside the black hole, and thus remains just beyond its clutches. RM

Do hummingbirds mate in mid-air? rivals. Four months after the end of the Tour, an enquiry found that Garin was one of those who had cheated,

allegedly by jumping on a train and travelling in comfort between two stages.

He was stripped of the title.

make the bark unpalatable.

Trees in very damp environments, such as birch, often have very thin bark that they shed regularly. This is because they’re prone to lichen and moss infestation and exfoliating like this lets them get rid of these parasites. LV

the case of most brain cells. But while most cells are regenerated, the processes involved become progressively unreliable over time.

In particular, the DNA carrying the instructions for cell processes becomes damaged, eventually preventing any more cell division.

The result is the increasing level of decrepitude we call ageing. RM

If our body cells are replaced, why do we age?

Q

The cells in our bodies live for anything from a few hours, in the case of certain types of white blood cells, to a few weeks, for skin cells, to many decades, in

A

Hummingbirds have very weak legs and can barely walk.

Consequently, they do almost everything on the wing. This means courtship involves an elaborate aerobatic display, both to impress the female and to drive away rival males. The actual mating is one of the few behaviours they land for, but it’s very brief. After just four seconds they’re done and the male and female go their separate ways, never to meet again. LV

Does milk chocolate melt more quickly than dark?

No. The melting point of chocolate is an important property that is precisely controlled at the manufacturing stage. Chocolate needs to melt between 34-36ºC (93-97ºF) so that it’s solid at room temperature but still melts in the mouth. Milk fat lowers the melting point so manufacturers add other vegetable fats to compensate. LV

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What is the Antikythera Mechanism?

Found on the seabed in 1901 near the island of Antikythera, halfway between Greece and Crete, the mechanism is one of the most astonishing archaeological discoveries ever made. Displayed at the National Archaeological Museum in Athens, it looks like a badly corroded chunk of car engine. But X-ray analysis has shown a concealed system of bronze gears and dials covered with inscriptions and scales. Most astonishing of all, it dates from around 120BC and was made with a precision not seen again for at least another millennium.

Studies by archaeologists suggest the mechanism was a sophisticated astronomical computer, its dials displaying information about the positions of stars and planets as well as solar and lunar eclipses. In 2008, Antikythera Mechanism Research Project researchers announced that one of the dials displayed the dates of the ancient Olympic Games, an event of huge cultural importance to the Ancient Greeks.

The team also uncovered important clues as to where the mechanism may have been made.

Faint inscriptions around one of the dials give the names of the months according to the calendar of Corinth, an ancient city-state

The Antikythera Mechanism is a fascinating piece of engineering from 120BC

Alamy, Thinkstock, Dreamstime, Getty. Illustration by Jonty clark

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roughly halfway between Athens and Sparta. RM

Q

When can a plant be pronounced dead?

Plants don’t have localised organs as animals do.

‘Pronouncing’ death implies a host of anthropocentric assumptions.

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You could take a leaf cutting from an otherwise dead plant and grow a whole new plant from it. Is that the same plant or not? Irreversible death probably can’t be said to have occurred until the whole plant has withered or rotted. LV How do rabbits communicate with each other?

Q A

Rabbits are specialists at non-verbal communication

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By many different means.

In a large warren, rabbits

often have lookouts who thump loudly on the ground with their feet if they sense danger.

These vibrations carry through the ground to other rabbits on the surface as well as those in burrows underground.

Then there’s grooming. Like many other social species, rabbits groom each other, not just to keep their fur clean, but also to maintain friendships and control their hierarchy. Rabbits lower down in the hierarchy groom those above, with the top rabbit not doing much, if any, grooming of others. Rabbits also mark their territory using special scent glands on their chins; the scent of their urine and faeces can also be used to communicate. They have mating displays involving special movements, and they emit oinking and humming noises.

There are many other movements that convey

QuicKFIRE

Did you know?

What is the weak nuclear force?

The bribe is high A British parliamentary candidate once arranged for a boatload of opposition voters to be shipped to Norway. In 1754, John Wilkes, a notorious rake and member of the legendary Hellfire Club, stood for election as MP for Berwickupon-Tweed, the northernmost town in England. Some of those entitled to vote were staying in London at the time but, eager to keep the devilish Wilkes from winning, they organised a trip back to their hometown by sea. Wilkes got word of this and bribed the captain of the ship, who landed them not on the border of England and

information to other rabbits even if they’re not primarily for that purpose. These include pricking up the ears, standing in lively or sluggish positions and even leaping about with pleasure. SB

Q

Known to physicists as the ‘weak interaction’, this is one of the four fundamental forces at work in today’s Universe. As its name suggests, it is pretty feeble and short-range, but it has the power to turn the constituents of the nucleus – protons and neutrons – into each other. This makes it the driving force behind some forms of radioactivity and also the nuclear reactions that power the Sun and stars. RM

Does cheese give you nightmares?

Scotland but close to the Norwegian town of Christiania, now Oslo. Although a potentially ingenius plot, it proved a pointless exercise in corruption

– Wilkes lost the election anyway. He did take a seat in the House of Commons three years later though, as MP for landlocked Aylesbury.

What keeps the Earth’s core from cooling? o 0C

550

Why do men start going grey at the temples?

Men’s hair (and, indeed, women’s too) goes grey when the follicles stop producing enough of the pigment melanin to provide the colour. Also, every hair makes some hydrogen peroxide, which is a bleach, and this builds up over time, especially if you’re stressed. So hair bleaches itself from the inside out. But just why greying usually starts around the temples remains unknown. SB

Why is the Earth’s interior still so hot?

You’d have thought that Earth, originally a molten ball, would have completely cooled billions of years ago. The fact that the interior is still hot bears witness to the presence of radioactive uranium, thorium and potassium, trapped since the planet’s formation. These disintegrating atoms warm up their surroundings to temperatures as high as 5500ºC (9900ºF) at the Earth’s core. RM

There is nothing particular about cheese, but if you go to bed with a full stomach, you may spend more of the night in REM (rapid eye movement) sleep, which is when your most vivid dreams occur. Whether those dreams are good or bad will depend on your underlying anxiety level – and whether you get tangled up in the blankets. LV

A

KNOW SPOT Jimpa, a Labrador/Boxer cross, holds the record for the longest journey home by a lost pet dog. The homsesick hound turned up at his owner’s old house in Victoria, Australia, after walking 3200km (2000 miles) from Nyabing in Western Australia.

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KNOW SPOT In May 2008, Finnish computer programmer Jerry Jalava lost part of his finger in a motorcycle accident. However, he then decided he needed information at his fingertips and so replaced it with a USB device.

Instead of a regular fingertip prosthetic, he has a 2GB USB memory stick.

Spot the difference: can pups be identical?

Q

Do other animals have identical twins?

Yes, but rarely. Puppies and kittens in one litter are usually fraternal twins, developing from eggs and sperm from the same mother and father.

Sometimes, if the mother mates with more than one male, they may be half-siblings. Even more rarely, as in humans, a single zygote (fertilised egg) splits in two to create two kittens, puppies, lambs or calves with identical genetic make-up. SB thinkstock x2, Science photo library X2

A

Which is less environmentally friendly: soap or shower gel?

Q

There are arguments for both. The detergent in shower gel is a petrochemical product, so it uses up fossil fuel reserves and it doesn’t biodegrade well. It also tends to be packaged in plastic containers that don’t

A

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biodegrade either. Soap is made by reacting plant or animal oil with sodium hydroxide. This is an efficient process that requires very little energy and the only by-product is glycerine, which is also useful, so there aren’t lots of chemicals dumped into drains or landfill. On the other hand, most soap is made using palm oil, nearly all of which is harvested unsustainably and contributes to rainforest deforestation in Indonesia and Malaysia. Soap usually contains some detergent as well. The greenest option is probably to use natural soap that isn’t made from palm oil. LV

Q

viruses can’t thrive independently.

Instead, they must invade a host organism and hijack its genetic instructions.

That said, it makes sense to talk of how long viruses can remain

VITAL STATS

461ºC

of Venus, mperature Surface te est planet in the ºF) the hott tem (862 Solar Sys

Do viruses die?

Strictly speaking, viruses can’t die, for the simple reason that they aren’t alive in the first place. Although they contain genetic instructions in the form of DNA or the related molecule, RNA,

viable and capable of infection.

Some, such as influenza virus and HIV, can’t survive for more than a few hours outside a host organism unless kept under carefully controlled conditions. But others, notably the deadly smallpox virus, can easily remain infectious for years. Historians now believe that dormant smallpox viruses brought to Australia by British doctors in 1787 could have caused a mass outbreak of smallpox among Aborigines two years later.

RM

A

A smallpox virus can stay infectious for years

Strange but true Master morphers Just morph – that’s the ticket if you’re a water flea (Daphnia spp.). This tiny creature isn’t a real flea, but a freshwater crustacean that gets around threats to its survival by mutating.

If big-mouthed predators such as fish or water bugs frequent its vicinity, the water flea’s head may elongate up to twice its size in just a few days, making it more difficult to fit in the mouth of a potential predator. If smaller foes show up it turns prickly, sprouting ‘neck teeth’ or a spiky crown for protection.

It also grows a spear-like tail, which is more than just a weapon. A water flea swims in short bursts, ‘hopping’ forward, sinking, then hopping again – hence the name. Its new tail slows its rate of sinking so it needn’t beat its oar-like antennae so much when travelling. Since many of its pursuers hunt via vibration, this makes the Daphnia harder to find.

In addition, the population morphs as a whole: when among enemies that prefer large prey, over time individuals shrink,

Q

Is carbonated water as hydrating as still?

A

Hydration is just a fancy word for absorbing water.

Since your digestive tract is a continuous unbroken tube that

The water flea is the ultimate in shape-shifters

and vice versa. Daphnia can reproduce every week or thereabouts, so the effect is almost immediate. If there are too many ambush predators around, a generation of sluggish swimmers is born. Slow travellers are less likely to cross paths with a hunter that is hiding and waiting to strike.

runs from your mouth to your anus, anything you swallow must either be absorbed or come out at the other end. If you don’t fully absorb the water in a drink, the inevitable consequence is diarrhoea. Carbonated water might

But the water flea saves its best trick for times of crisis. If, for example, its pond habitat starts drying up, females produce ‘resting’ embryos in thick eggs that resist years or even centuries of drought. The embryonic Daphnia wake up to a predatorfree world once the water is back. DBB

make you burp, but it doesn’t give you diarrhoea, so it must hydrate you just as well.

Sugary drinks have a lower net hydration benefit because after the water has been absorbed, some of it must be used to

digest the carbohydrate. Drinks containing alcohol or caffeine will be absorbed perfectly well, but they suppress the effect of antidiuretic hormone (ADH) and so cause you to produce more urine.

The most important factor in

The choice of ‘Still or sparkling?’ is something of a luxury in the desert

February 2012

85

QA &

Your questions answered

bbcknowledge@wwm.co.in

architecture, permitting defenders to drop things onto the heads of attackers. They were also essential for throwing water of whatever temperature on any fires the enemy may have started. EB

hydrating your body, though, is how much you drink. Most people get satiated on water much more quickly than with drinks that have something to make them more interesting – like flavour or sugar or fizz. So if you prefer carbonated water, you’re likely to drink more of it and it will therefore hydrate you better. LV

Q

Q A

Does the Moon have a molten core?

This was one of the questions the Apollo missions were tasked with Is the use of boiling oil as a weapon in medieval warfare historical fact or Hollywood fiction? resolving over 40 years ago, but only now is the answer becoming clear. The astronauts placed Oil was expensive, but the seismometers on the lunar surface History provides some accounts conventions of medieval warfare of its use. The Jewish defenders to detect ‘moonquakes’ in the of Yodfat (Jotapata in modern-day held that the inhabitants of a hope that analysis of how the town resisting attack could be Lower Galilee) are said to have shockwaves travelled through the put to the sword – so defenders’ used it against Vespasian’s troops Moon would reveal what lay at financial priorities would change in AD 47. Other mentions include its core. The seismometers were dramatically. It’s likely that the real during the Hundred Years’ War finally switched off in 1977 – and reason that oil was used rarely is siege of Orléans (1428-29), the scientists have been trying to simply that few places possessed make sense of the data ever since. Great Siege of Malta (1565) and enough of it. the siege of Sommières in the One major problem has Reports of boiling water and French Wars of Religion (1573). been finding the signals of deep heated sand being poured on Some authorities claim that moonquakes among the ‘noise’ attackers are far more common oil would have been hot, of other events, including in ancient and medieval warfare. rather than boiling, meteor impacts. Using (Hot sand getting into your armour and that it would computers to clean is, by all accounts, a rather have had the up the data, a team VITAL STATS nasty experience.) added advantage led by Renee By the Middle Ages, openings of making the Weber of NASA’s of the s re in the floor and battlements were attackers’ footing Marshall Space et m in Depth ed oil well, essential elements of castle more slippery.

Flight Center longest drill coast of the situated off in Huntsville, 8ft) 31 0, (4 r ta Qa Alabama, has now found evidence that the KNOW SPOT Moon has a core very similar to that of the Earth, with a solid On 23 June 2009, innermost region and a molten New Yorkers Erin outer core. RM Finnegan and Noah

A

thinkstock, Alamy x2, dreamstime x2, thinkstock

12,289

Is it true that, in a medieval siege, beleaguered defenders would pour boiling oil on their assailants?

Q

Boiling oil is a favourite with Hollywood – and nowadays with computer war games, too.

A

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February 2012

Why is yawning contagious?

Fulmor took getting married to new heights when they exchanged vows in zero gravity. The plane they were on, a modified Boeing 727-200, flew 15 ‘parabolic arc’ dives from 10,970m to 7315m (35,992ft to 24,000ft), allowing the couple to experience weightlessness as they pledged their troths.

It’s only humans, dogs and chimpanzees that have been observed to yawn contagiously. They yawn when someone else yawns first. This contagion is not imitation, but an automatic response to yawn when you see, hear or even think about someone else yawning.

Among the theories is the suggestion that contagious yawning keeps groups of people in the same state and ready to work together. So if one person is sleepy, others will feel sleepy too and thus the whole group can coordinate their routines.

Others suggest that it maintains group vigilance, keeping groups alert together.

Yawning can also occur in response to anxiety, so another theory is that contagious yawning is used to warn others of danger.

These group theories gain some support from evidence of a brain connection between empathy and contagious yawning, but really there is no generally accepted theory to explain it. SB Are you yawning yet?

KNOW SPOT

Does a light beam shine into eternity?

The largest object in the Kuiper Belt (the cloud of gases and debris lying at the farthest reaches of the Solar System) is an object called 50,000 Quaoar. Measuring 1300km (800 miles) across, it orbits the Sun at a distance of six billon km (four billion miles). It was discovered by Chad Trujillo and Mike Brown of the California Institute of Technology on 4 June 2002.

Q

A giraffe’s high blood pressure saves it from a life of dizziness

Do light beams travel forever?

In the absence of anything to absorb them, light beams would seem able to travel forever.

But in 1929, astronomer Fritz Zwicky at the California Institute of Technology suggested that the redshift effect observed in the light of distant galaxies may actually be the result of light running out of puff.

The standard view is that the redshift is due to light rays getting stretched by the cosmic expansion of space and time, shifting them to longer wavelengths closer to the red end of the spectrum. Zwicky suggested that perhaps the light from distant galaxies was simply losing energy as it travelled vast distances. Such ‘tired light’ would appear to increase in wavelength as it slows, and thus mimic the redshift effect.

It’s an intriguing idea, but observations of distant supernovae have shown that these colossal

A

explosions appear to take longer to fade away the more distant they are – exactly as expected if the redshift is due to the stretching of space and time rather than light getting tired. RM

Q

Do giraffes get dizzy?

Not too dizzy. Fortunately for them, giraffes have hearts that weigh more than 11kg and that can generate twice as much blood pressure as a human heart. The vessels in the giraffe’s neck divert blood from the tongue and ears to the brain when the animal lifts its neck.

The jugular vein also constricts to prevent the blood draining away too fast. LV

A

Ask the Experts?

Ever wondered… well, anything? Email bbcknowledge@wwm.co.in and our team of experts will consider your question for our next available issue.

We’re sorry, but we cannot reply to questions individually.

12.38

QuicKFIRE How can the Moon exactly eclipse the Sun? It’s pure coincidence. The average angular diameter, or width of the Sun as seen from Earth, is 32.5 arcminutes (where 60 arcminutes is equal to 1º and 180º equal to the whole of the sky). The angular diameter of the Moon is 31.7 arcminutes. Since this is smaller, it will only create an annular eclipse, where the Sun is still visible in a thin ring. But the distance to the Moon varies slightly through the course of a month, and the distance to the Sun varies through the year, so when the Moon is closer to Earth and the Sun is further away, a total eclipse is possible. LV

How are particles put into the LHC? The particles that are smashed together in the Large Hadron Collider (LHC) come from nothing more glamorous than a bottle of hydrogen gas. Consisting of single electrons orbiting protons, these atoms are heated up until their electrons are stripped off and the protons that remain are then directed through a series of accelerators to increase their speed. They are squirted into the LHC under the control of gigantic magnets, accelerated to near-light speeds – and then smashed together. RM

Is lightning hotter than the Sun? A lightning bolt heats the air immediately surrounding it to about 20,000ºC (36,000ºF). The shockwave caused by the thermal expansion is what we hear as thunder. This is more than three times the temperature at the surface of the Sun, but it’s still a lot cooler than the Sun’s core, which is around 13.6 million degrees C (24.5 million degrees F). LV

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Gadgets New Tech

What the market has to offer in the coming few months  Canon Legria Camcorder FS405

 Mouse Scanner LSM- 100 The LG LSM-100 Mouse Scanner is the world’s first mouse with an embedded scanner function that offers convenience, mobility and simplicity to the users. It is equipped with LG’s Optical Character Recognition technology that converts scanned text into a Microsoft Word or Excel document that can be edited and manipulated. The results can also be shared in real time through Facebook, Twitter etc.

Price: `3,500 approx • www.lg.com/ae

 iPhone Lens Dial

www.canon.co.in, www.lg.com/ae, www.photojojo.com, apple store x5

The latest camcorder from Canon, a 2.7 inch model with a 5.4 megapixels resolution and an optical zoom lens of 37x, delivers on its promise of brilliant video recording time. Suited for everyday use, this user-friendly camera features a pre-REC function button to ensure moments are captured even if the record button is pressed three seconds late. With this lightweight model (220g), you can consider shaky videos as one of the past things, since its high resolution captures clear and steady images.

The iPhone Lens Dial, with its three rotating lens, is turning heads with its compact design, style and innovation. It allows users to take photos with either of three lenses – telephoto, fish eye and wide-angle, all with their mobile lens. The difference in the quality of image comes from the lens, which alters the photo captured before it hits the iPhone’s processor rather than post-processing software; a process that occurs in case of an image-altering app.

This difference gives the user a variety of effects to choose from.

Price: `14,995 • www.canon.co.in Price: `13,000 approx • photojojo.com

5 apps to conserve, discover, explore and survive the wildlife

Instant Wild App

Survival

Carnivores

Project Noah

Bees

Chance upon a new species or rediscover an extinct wild one with this app developed

by London’s Zoological Society. Receive images taken by motion-sensitive cameras placed in remote locations around the world.

This fast-paced game tests your motor skills as also your grey cells. Pinch, swipe and double-tap to unlock facts and photos of the wild, beat other competitors to be crowned the ‘Top Survivor’.

Fight for your survival as you struggle to capture the dinosaurs in six distinct wild environments, equipped with ten weapons and hunting accessories; a tranquilizer or radar, battling it through six survival levels.

Tracking the migratory patterns of a myna or take a picture of an insect resting on your window-sill. You can also upload images onto the Project Noah community for your fellow explorers to help you identify any animal.

Spring is in the air and as the bees head off to collect honey for your hive, sort the honey collected in different jars and help them avoid the onslaught of dragon-flies as you race against the sun to finish your task.

Users: iPhone/iPod/iPad

Users: Apple and Android

Users: iPhone/iPod/iPad

Users: iPhone/iPod/iPad

Users: iPhone/iPod/iPad and Android

Have suggestions for any gadget/application? Share with other readers, please email bbcknowledge@wwm.co.in

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Resource

A feast for the mind

All ears: in the Arctic, the great grey owl can hear its prey under the snow

Adélie penguins cling on in the Antarctic

The chilling truth Documenting the polar world – while it’s still there Frozen Planet: a world beyond imagination

FLPA, naturepl.com

By Alastair Fothergill and Vanessa Berlowitz BBC Books, 312 pages, `1425

K Published to accompany the seven-part BBC TV series of the same name, Frozen Planet tracks Earth’s polar regions throughout one calendar year, from sunlight-shy winters to comparatively mild summers that almost make them hospitable places.

Fothergill and Berlowitz, respectively Frozen Planet’s executive producer and series 90

February 2012

producer, escort us to the last wildernesses on the globe – the Arctic and the Antarctic. These places are markedly different.

The North Pole is located on the frozen Arctic Ocean, whose constantly moving ice sheets dictate that the Pole’s only permanent marker is a rust-proof titanium Russian flag planted in the seabed, 4km (2.5 miles) below the surface. By contrast, the snowbound South Pole occupies the centre of a mammoth area of land. Buildings are even constructed there.

Of course, their inhabitants are notably different too – but the book isn’t all polar bears and

penguins. Other hardy creatures get well-deserved exposure.

Creatures like the great grey owl that can hear its prey – the vole – moving around under the snow, or ‘spyhopping’ killer whales that, in breaks in the ice, lift their noses out of the water to assess when they’ll next be able to take a breath. The authors also highlight the surprising amount of flora both above and below the oceans, as well as devoting plenty of pages to these ice lands’ truly humbling landscapes. Whatever the subject, the book’s extraordinary photography does it complete justice.

The fascinating stories and tremendous images are, though, underscored by a long-resonating note of pessimism. The ice caps are shrinking, these wildernesses are retreating. In his foreword, Frozen Planet’s presenter Sir David Attenborough explains why documenting these regions is crucial; “for this may well prove to be our last chance to record, in their full splendour, these astonishing wonderlands that have existed for hundreds of thousands of years before humans reached them and which now, within a century, may change beyond recognition”.

Nige Tassell is a journalist who writes for The Guardian and The Sunday Times

Across the Universe Making the big ideas accessible Knocking On Heaven’s Door: how physics and scientific thinking illuminate the Universe and the modern world

By Lisa Randall Bodley Head/Eco, 464 pages, `1251

K In recent years, the scientist who makes a breakthrough in his or her field and then writes a popular book about it has become something of a publishing phenomenon. Lisa Randall is famous for her innovative work in particle physics, investigating whether there are more dimensions in reality than just those of which we’re currently aware. Part of the motivation behind the Large Hadron Collider (LHC) at CERN is to test this. Randall’s first book, Warped Passages, described these ideas for the general public and brought her to wide attention. But then comes the challenge: can she do an encore?

Her second book, Knocking On Heaven’s Door, shows how hard it is to improve on a winner. Randall covers several different themes – the relation between science and religion, the origins of particle physics, aspects of cosmology – each of which could be a book in its own right. By covering so much, the result is a thinly spread fast-food menu, much like a multi-course Chinese takeaway compared to the haute cuisine served up by writers of the quality of Richard Dawkins, Bill Bryson and Steven Weinberg, who have already written eloquently and at length on these ideas.

The latter half of the book moves towards the LHC, and gives some feeling for the Higgs boson, though how much will be understood by first-timers is uncertain. It will be another year or two before major insights are expected from the LHC and, when the new paradigm is revealed, Lisa Randall may be well placed to describe its meaning with authority. But that time is not yet here.

Frank Close is a particle physicist and author of The Infinity Puzzle (OUP, 2011)

Knocking On Heaven’s Door author Lisa Randall (centre) visits the LHC

A fossilised leaf of the ginkgo tree, still resilient and wild in parts of China

Live forever?

Hunting down extinction-defying species Survivors: the animals and plants that time has left behind

By Richard Fortey HarperPress, 400 pages, `1760

K The phrase ‘survival of the fittest’ implies that evolution is a march ever onwards, ushering in the new and expunging the old. Not so, says Richard Fortey in his engaging new book. If it weren’t for the oddities that extinction missed, we’d know much less about evolution than we do, and we’d fail to appreciate its richness.

Fortey, a man described by Bill Bryson as being “without peer amongst science writers”, tours the world to see his survivors in their natural habitats. In Delaware, he watches the frenzied spawning of horseshoe crabs, practically unchanged since the Jurassic; in New Zealand, he explores isolated islets where the tuatara – the last vestige of a kind of reptile that inhabited Earth before dinosaurs – still roams; in the hinterlands of China, he finds the last wild-growing ginkgo trees; and in Queensland, Australia, he encounters the lungfish, testament to what fish might have been like before they sprouted legs and walked ashore.

Survivors is rather like an enormous cake – rather rich for consumption in one go – but some of the writing is exceptional.

My favourite is Fortey’s description of the multi-coloured bacterial colonies in the hot springs of Yellowstone, in tune with an ever-changing landscape and yet memorialising the earliest days of life on Earth.

Henry Gee is a senior editor of the journal Nature February 2012

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Resource

A feast for the mind

Get your clicks Our pick of internet highlights to explore

In profile SOUTIK BISWAS India Correspondent

Troops charge ashore on D-Day, arguably the most significant single day for Britain during World War II

Fighting on the beaches Britain’s version of World War II Britain at War: from the invasion of Poland to the surrender of Japan, 1939-1945

Bridgeman art library, Thinkstock

By Richard Overy Imperial War Museum/Carlton, 142 pages, `2112

K Britain at War comes with impeccable credentials. It is written by Richard Overy, a World War II specialist at the University of Exeter, and published in association with one of the UK’s leading military history institutions, the Imperial War Museum.

Overy’s narrative combines headline events such as the Battle of Britain, Dunkirk and D-Day, with lesser-known campaigns in the seas, the Middle East and Africa. He writes with clarity and authority, providing succinct synopses of the moments and personalities that mattered.

Throughout, the text is enlivened with maps and copious images.

What differentiates Britain at War from its competitors is the incorporation of a selection of removeable facsimile documents.

Readers can peruse Montgomery’s handwritten notes for D-Day, a letter from a Dunkirk evacuee and newspaper headlines from the day the war ended. One of the most fascinating replicas is a French intelligence map from April 1940 – just before the German invasion – where the large number of question marks reveals how little the Allies actually knew about their opponents’ intentions.

On the downside, the preponderance of military information means that the human dimension of the war is not explored in much depth. Also, as the title makes clear, this is very much Britain’s story, so the crucial conflict between Germany and USSR is only mentioned in passing. Nevertheless, the beautifully produced Britain at War has much to offer the military history enthusiast.

Rob Attar is Deputy Editor of BBC History Magazine 92

February 2012

Current location: New Delhi Blog: www.bbc.co.uk/news/correspondents/soutikbiswas

Soutik has reported on Indian politics and culture for the BBC since becoming India Correspondent in 2003 What is it about India?

It’s the most fascinating country in the world for a journalist – vast, complex, maddeningly diverse. It is rich and poor, tolerant and intolerant. You never know enough about India – the place surprises you all the time.

Do you follow any bloggers yourself?

I don’t follow any blogger consistently. Where is the time?

I do follow a lot of columnists like Paul Krugman, Maureen Dowd and Robert Fisk. I also like the range of subjects and opinion the Freakonomics blog offers.

Why do you blog?

It’s a welcome release from the unrelenting grind of the 24/7 news operation of which I am a part. I worry that it’s often written in the middle of my busy day job when I’m already tired. But I try to keep my head clear and do it justice.

Which blog was most difficult to write and why?

It must have been the one I wrote on the contentious issue of whether India should pursue its nuclear energy drive. I had to consult a number of scientists who, I believe, are fair and reasoned on the subject.

Which story has been your personal favourite?

I did a couple of stories on India’s private micro-finance meltdown and the attacks on the right to information activists, which came out reasonably well.

How big a problem is corruption in modern Indian society?

Corruption is India’s existential problem. Its deeply ingrained caste system and hierarchy makes it an intrinsically ‘unfair’ society, allowing corruption to thrive. Corruption hurts the poor most and the middle class happily acquiesces to it.

Much of your blogging seems to be about problems faced by village youth and women in the region. Why? The young and women are driving the changes in India. If you ignore them, you’re putting the future of India in peril. Thanks to migration, many families live with one foot in the village and one foot in the city. It is this migration that is going to determine the future of India.

H PODCAST

H BLOG

H WEBSITE

Psychological small talk

Musings on nature

Spiritual centres

www.bit.ly/psychobabble

http://bbc.in/wondermonkey

www.sacredsites.com

Psychobabble is a fortnightly 40-minute podcast that grabs hold of everyday happenings and subjects them to the vigorous methodology of experimental psychology. Hosted by a team of knowledgeable, enthusiastic PhD students and describing itself as a combination of “life, psych-science and blue-sky musings”, Psychobabble’s remit is wide-ranging.

Past episodes have been dedicated to selfdeception, the sublimity of advertising and, most crucially, how facial hair defines you in the minds of others.

The Wonder Monkey blog is an informed and perceptive blog by BBC Nature online editor Matt Walker. He’s an amiable guide on this exploration of the natural world, his words both concise and precise on a variety of subjects – the moth’s self-destructively attraction to a flame; the myth that a swan sings beautifully just before its demise; the shocking cannibalistic tendencies of primates.

It’s not all about death, though. True to the blog’s name, Walker also muses on whether a monkey can indeed wonder.

One hundred years ago this year, Machu Picchu, the Inca lost city located high on a mountain ridge in southern Peru, was brought to the world’s attention through its ‘discovery’ by the American historian Hiram Bingham. It’s just one of a multitude of spiritually significant locations from across the world celebrated by the Sacred Sites website that offers in-depth histories of places both world-famous (Stonehenge, Uluru/Ayers Rock in Australia) and less familiar, such as the curious mountain-top shrine of Nemrut Dagi in Turkey.

H WEBSITE

H WEBSITE

H WEBSITE

The natural world

The letters of Darwin

History of space travel

www.eol.org

www.darwinproject.ac.uk

http://bbc.in/spacemissions

The free Encyclopedia of Life portal is an excellent resource for those curious about the natural world.

Boasting information on nearly 700,000 species gathered from more than 160 trusted sources, it celebrates the planet’s extraordinary biodiversity.

Valued by the public, teachers and professional biologists alike, it’s recently undergone a facelift that allows a more user-friendly and interactive experience. No more excuses for not knowing your arsenic bean from your elbow crab.

The Darwin Correspondence Project is an endeavour of mindboggling dedication. Contained within are details of all the known letters written by or to Charles Darwin – more than 15,000 of them.

But that’s not all. Every letter written or received by 1868 (14 years before Darwin’s death) has been transcribed and is fully searchable. Not only do they offer a fascinating character study of the great man, they also provide a vivid snapshot of Victorian social life and the 19th-century academic world.

Courtesy of the BBC, discover the full stories behind many of those pioneering, often dramatic voyages into the final frontier. There’s the 1957 Sputnik mission, the first Earth-orbiting satellite; the oxygen tank explosion experienced by the Apollo 13 crew in 1970; and the probe Messenger that’s currently collecting data from Mercury. As well as a multitude of pictures and videos, there are also respected explanations from such figures of authority as Patrick Moore and Brian Cox.

If you have a favourite website, blog or podcast that you’d like to share with other readers, please email bbcknowledge@wwm.co.in

February 2012

93

The

last word

Modern architecture has much to learn from heritage temples

“Archeological remains herald many untold truths about our ancestors” he theory and practice of ancient Indian architecture is recorded in various texts like the Vedas and vernacular literature. These documents reflect various logical approaches to problems faced during the course of progress of mankind.

The wonder that was India can be understood if one had access to the archaeological remains through these texts.

In fact, these remains herald many untold and unwritten technical knowledge of our ancestors. One such study is presented below.

Rajarajeswaram, the Brahadisvara temple at Thanjavur stands testimony to many events of the past millennium and is a landmark monument in providing materials for understanding the social, religious, literary and administrative set up of the great Chola Empire. It is viewed as a lighthouse, which guided many activities of the great empire. The king, who visualised that all such missions should continue permanently as long as the humanity endures, wanted an everlasting building where spirituality and human care could co-exist.

The architects’ planning started with the selection of site and preparation of drawings, selection of materials, and stone genesis of different varieties for different

Dr. T. Satyamurthy

T

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February 2012

Karnakuta

(corner block)

Construction of the Rajarajeswaram temple at Thanjavur

purposes. All precautionary measures were taken to maintain the stability of the Vimana (the pyramid-shaped roof tower) under any external gravitational forces.

It is fascinating that the temple has withstood natural calamities including seismic shocks for the past thousand years. In the past two hundred years itself, more than 10 seismic disturbances have been recorded by various agencies like the Meteorological department and Geological Survey of India in this area around present Tamil Nadu.

For protection during earthquakes, the three principles applied by architects and seismic science experts of that time were: • If the earthquake stress of seismic shocks exceeds the

permissible stress of the masonry, it may endanger the building • The danger is due to the weak masonry joints, which departs even in minor shocks • The wall should also be well-footed to bear the shocks in a tangible way as a single-knitted structure.

Derived from the above, the three measures required for making the building seismicfree are: • Making the load-bearing walls as an interlinked masonry to bear extra stress • To well-knit the corners, offsets so that it will not slide away during shocks • The roof should be retrofitted or stiffened enough to form a single unit so that during external shocks the thrust will be transferred to the walls and the roof will not collapse.

The amazing fact is that most of the Dravidian style of architecture followed these rules. The techniques adapted here became a model for all later temples and forts and structures in southern parts of the peninsula.

The mystery of taking up the stone blocks to create the Sikhara (mountain peak) of the Vimana is also an engineering feat that was well-planned and executed. Elephants were made to drag the blocks up and down from the other side of sand dunes created on either

side of the super structure.

Again, to avoid collapse during the build, sand was also filled inside the core of the structure to give it an internal resistance from within.

Rajarajeswaram has been protected from external gravitational forces for over 100 decades. Modern architects, civil and structural engineers can learn several scientific approaches and solutions by closely studying these, which lie within every three kms in Tamil Nadu.

The big question is – are all the heritage structures identified and documented, in India?

The sad part is most of them lie in ruins. Government agencies should create a database of all the heritage structures in the country, with fund allocation and manpower.

With stringent rules to protect, common people should be made aware on the dos and don’ts through all forms of media to preserve the heritage structures in India.

Dr T Satyamurthy is the founder trustee of the R.E.A.C.H Foundation and has served at the Archaeological Survey of India in various capacities for up to 36 years.

J.Chandrasekaran is PRO & Secretary of R.E.A.C.H Foundation, looking after its restoration and antiquity preservation team coordination.