New-Scientist-24-January-2009

EDITORIAL

The future of life, but not as we know it Charles Darwin’s theory of evolution is itself evolving

Michael Rose at the University of California, Irvine, told us: “The complexity of biology is comparable to quantum mechanics.”

Biology has been here before. Although Darwin himself, with the help of Alfred Russel Wallace, triggered a revolution in the mid1800s, there was a second revolution in the 1930s and 1940s when Ronald Fisher, J. B. S. Haldane, Sewall Wright and others incorporated Mendelian genetics and placed evolution on a firm mathematical foundation.

As we celebrate the 200th anniversary of Darwin’s birth, we await a third revolution that will see biology changed and strengthened.

“THERE is nothing new to be discovered in physics.” So said Lord Kelvin in 1900, shortly before the intellectual firestorm ignited by relativity and quantum mechanics proved “It is now accepted that the tree him comprehensively wrong. of life is something we impose on If anyone now thinks that biology is sorted, nature in an attempt to make they are going to be proved wrong too. The more that genomics, bioinformatics and many the task of understanding it more tractable” other newer disciplines reveal about life, the more obvious it becomes that our present understanding is not up to the job. We now None of this should give succour to gaze on a biological world of mind-boggling creationists, whose blinkered universe is complexity that exposes the shortcomings doubtless already buzzing with the news that of familiar, tidy concepts such as species, “New Scientist has announced Darwin was gene and organism. wrong”. Expect to find excerpts ripped out A particularly pertinent example is of context and presented as evidence that provided in this week’s cover story – the biologists are deserting the theory of uprooting of the tree of life which Darwin evolution en masse. They are not. used as an organising principle and which Nor will the new work do anything to has been a central tenet of biology ever since diminish the standing of Darwin himself. (see page 34). Most biologists now accept that When it came to gravitation and the laws of the tree is not a fact of nature – it is something motion, Isaac Newton didn’t see the whole we impose on nature in an attempt to make picture either, but he remains one of science’s the task of understanding it more tractable. giants. In the same way, Darwin’s ideas will Other important bits of biology – notably prove influential for decades to come. development, ageing and sex – are similarly So here’s to the impending revolution in turning out to be much more involved than we biology. Come Darwin’s 300th anniversary ever imagined. As evolutionary biologist there will be even more to celebrate. ■

Limit the fallout from DNA tests DNA testing for paternity can change the course of a life. So to run a test on “stolen” DNA taken from an everyday item, such as a coffee cup or a baby’s dummy, is a gross invasion of privacy – especially when that DNA is an innocent child’s rather than the alleged father’s.

Either way, a child can be harmed if a covert test tears their family apart.

Even if other nations do not follow the UK’s lead in banning stealthy genetic tests (see our investigation, page 8), laws on paternity testing merit review. One option would be to follow practice in France, where DNA tests can only be ordered in the context of a formal hearing to contest paternity. The court can consider the child’s interests and help to cushion life-altering shocks when the test results are disclosed. ■

Doomy thinking WHY on earth would anyone spend energy worrying about something that is really, really unlikely to happen? Better, surely, to save it for more probable events such as losing your job, home or partner. But follow the logic behind assessments of such remote risks and things may look different – leading, for example, to a 10,000-fold rise in the probability that an Earth-guzzling black hole will appear when the LHC restarts (see page 32). It might even take your mind off more mundane worries – until you recalculate the odds, that is. ■

What’s hot on NewScientist.com TECH Intelligence tests for future machines The Turing test has been the benchmark for artificial intelligence for nearly six decades, but there are other ways to test how closely a machine can perform like a human, as our video shows. We explore how a “neural Turing test” changes a person’s brain activity, and how jazz piano can help spot smart computers.

GALLERY Twin rovers celebrate five years on Mars NASA’s plucky rovers have passed a milestone on the Red Planet. Relive their biggest discoveries – and some of their mishaps – in our gallery.

ECONOMICS Lottery win is no guarantee of long-term health

ENVIRONMENT Top 7 alternative energies listed The US could replace

or wealth You probably imagined that a life of financial comfort and good health follows a jackpot payout.

That’s not how it goes, say two studies.

all its cars and trucks with electric vehicles powered by wind turbines that would take up surprisingly little land. So says a detailed study ranking 11 types of non-fossil fuels according to their ecological footprints and their benefits to human health.

COMMENT Why we can’t stop birds downing aircraft Bird strikes put lives at risk and cost aviation $1.3 billion globally by damaging and delaying planes. We explain why last week’s airliner splashdown in New

York’s Hudson River is unlikely to be the last of its kind.

GALLERY Advanced painting in ancient Egypt Wall paintings commissioned by an Egyptian accountant for his tombchapel 3000 years ago reveal new information about archaic painting techniques and the “ancient Michelangelo” who created them.

To read these articles and more, visit www.NewScientist.com

24 January 2009 | NewScientist | 5

LYNN JOHNSON/NGS/GETTY

UPFRONT

Modified imports vex US AFTER a decade of exporting its genetically modified crops all over the world, the US is preparing to block foreign GM foods from entering the country – if they are deemed to threaten its agriculture, environment or citizens’ health, that is.

The warning was given to the US Department of Agriculture, which polices agricultural imports, by its own auditor, the Office of Inspector General (OIG): “Unless international developments in transgenic plants and animals are closely monitored, USDA could be unaware of potential threats that particular new transgenic plants or animals might pose to the nation’s food supply.”

The OIG expects the number of GM crops and traits, and the number of countries producing them, to double

by 2015, raising the risks of imports of GM crops unknown to the USDA. The report urges the USDA to strengthen its links with countries where research is exploding, such as China, India and Brazil. China, for example, is ready to launch the world’s first commercial GM rice, but it has yet to be approved by the USDA. Problems will arise, says the OIG, when new GM products enter the US undeclared – the USDA would be unprepared to test or even identify them.

The OIG cautions against blocks on imports that could be seen as trade barriers, however. In 2006, the World Trade Organization ruled in favour of the US, arguing that the European Union’s stringent regulations on GM crops were anti-free trade.

Science a gogo

to modernise the electricity grid, $8 billion in loans for renewableenergy projects, and $6 billion to improve broadband internet access in rural and other underserved areas.

Education will also get a boost if the stimulus bill passes, with $41 billion going to local school districts and $6 billion for university modernisation.

Health information technology will receive a $20 billion payout, to help prevent medical errors and reduce the unnecessary procedures that make healthcare in the US so inefficient.

–Beware surprises in rice supplies–

Stern carbon call

“Low-carbon technologies could transform society in the way that railways did in the 19th century” technologies could transform 21st-century society in the way that railways and information technologies did in previous centuries, he says.

6 | NewScientist | 24 January 2009

(see also Opinion, page 26) ANDREW MCCONNELL/ROBERT HARDING/ALAMY

NEVER mind the downturn, a green economic revolution must be launched within months, one of the world’s top economists has told New Scientist.

“You do hear voices saying now is not the moment,” says Nicholas Stern, former chief economist of the World Bank and economic adviser to the UK government.

“Now is precisely the moment to make the change.”

Stern believes that low-carbon technologies have the potential to fuel economic growth in a much more sustainable manner than previous booms based on the dot com and housing bubbles. With public money and incentives for private investment, low-carbon

There may be no better time. To reverse the slowdown, politicians have already been discussing some of the biggest cash injections in decades, Stern points out. What’s more, banks are dropping interest rates, which means investors can borrow at a lower cost.

“It has got to be fast,” Stern warns. “The fiscal expansion has got to be put in place, the policy decisions have got to be taken in the next three to four months. They take time to kick in. The urgency of decision-making should be very clear to everybody.”

“SCIENCE, science, science and science.” That was the summary offered by Nancy Pelosi, Speaker of the US House of Representatives, when asked last week in a radio interview about the priorities of a new plan to revive the US economy.

The $825 billion stimulus package now being considered

by Congress – and championed

by President Barack Obama – includes $10 billion for basic scientific research and to upgrade ageing laboratories.

Priorities also include $11 billion

Frog in a hard place PUT aside climate change and habitat destruction for a moment.

Frogs are facing a more mundane threat: our insatiable appetite for them.

David Bickford of the National University of Singapore and his team are calling for greater regulation of the global market for frog meat, in order to avoid species being “eaten to extinction” (Conservation Biology, DOI: –Appetite for destruction– 10.1111/j.1523-1739.2008.01165.x).

For more on these stories go to www.NewScientist.com/section/science-news

60 SECONDS

Stem cell stroke trial

According to UN figures, global trade in frog meat has soared in the past 20 years. France and the US are the two largest importers, with France importing between 2500 and 4000 tonnes each year since 1995. Indonesia exports more than 5000 tonnes annually, mostly to Europe. Frogs’ legs are also very popular in Asian cuisine.

Bickford estimates that about 180 million to a billion frogs are harvested each year worldwide.

“That’s based on both sound data and an estimate of consumption for just Indonesia and China,” he says. “My 180 million minimum is almost laughably conservative.”

and restore connections lost through the stroke.

Working out whether this is happening might be tricky as the stem cells don’t have radioactive or chemical labels to distinguish them from the patients’ own cells,

A PIONEERING trial to test one of the big promises of stem cell science – treating the brain damage caused by stroke – poses technical challenges, but could be of enormous benefit if successful.

“The hope is that the cells On 19 January, the company will differentiate and ReNeuron in Guildford, UK, won restore brain connections approval from the UK regulatory lost through the stroke” authority to inject neural stem cells, originally derived from embryonic stem cells, into the says principal investigator Keith brains of 12 stroke patients. The Muir of the Southern General main aim is to test for safety but Hospital in Glasgow. Instead the the hope is that the stem cells team is relying on brain scans to will differentiate into brain tissue reveal changes in activity.

HIV docs charged

A smarter way for oil firms to pay

PETE OXFORD/MINDEN

THE imprisonment of two GETTING oil and gas companies to contain the harm they do to the prominent Iranian doctors on environment just got a little easier. charges of plotting to overthrow Companies are sometimes asked their government could impede to preserve pristine land to relations between medics in the compensate for the damage their west and Iran, and threatens operations do – both directly and global public health. through the roads, houses and towns The brothers Kamiar and Arash that spring up nearby. This poses Alaei pioneered HIV treatment a problem because the companies and prevention in Iran, and can easily claim credit for protecting helped heroin addicts, working land their activities would never with prostitutes and prisoners have damaged anyway. and distributing methadone, free Now Joe Kiesecker of The Nature syringes and condoms. They won Conservancy in Fort Collins, Colorado, the approval of the World Health and colleagues are applying a Organization and even Iran’s new approach. Using computer hard-line religious authorities. models based on data from the They were imprisoned in June US Department of the Interior, they and have now been charged. Joe predicted changes in land use to Amon of Human Rights Watch in New York suspects the brothers were singled out because of their US connections. Kamiar has a degree from Harvard University and both brothers spoke at US scientific meetings.

If the charges discourage Iranian and western scientists from working together, this could pose difficulties outside Iran, as it has public health problems that require close monitoring, including HIV, drugresistant tuberculosis, H5N1 bird flu and the Ug99 wheat fungus, which threatens global food –Home for antelope, not people– production.

identify locations linked to the Jonah natural gas field in Wyoming that are likely to be developed, even if they are some distance from the gas field itself. By paying to prevent such development, the oil company BP America was able to show that it is protecting endangered habitat.

This has advantages over the traditional approach, in which companies atone for the local environmental damage they cause by improving habitat elsewhere.

These so-called biodiversity offsets are supposed to result in no net loss to ecosystems, but restoring degraded land is expensive and not always successful.

Kiesecker’s approach is now being tried at other sites in the western US.

Illegal loggers cut off The Democratic Republic of the Congo has cancelled logging in about 13 million hectares of forest, its government said on Monday, after it reviewed 156 logging contracts. Only 65 of these were found to conform to minimum legal and environmental standards, and were untainted by corruption.

Atmosphere ahoy!

The glow of an alien planet’s atmosphere has been detected from Earth for the first time. The observations of OGLE-TR056b – a “hot Jupiter” – are good news because space-based telescopes used for the task so far, such as NASA’s Spitzer telescope, are set to lose the capability as they age.

Mainland biolab A centre for research on serious livestock diseases will be built on the US mainland, the Department of Homeland Security announced on 16 January. The National Bio and Agro-Defense Facility in Manhattan, Kansas, will supersede the offshore Plum Island Animal Disease Center in New York, despite misgivings about building such a lab on the mainland, near a large human population.

The hot top 10 Last year was a hot one, ensuring that the 10 warmest years on record have occurred since 1997, the National Climatic Data Center in Asheville, North Carolina, announced last week. Global land and ocean temperatures have increased by 0.05 °C each decade, on average, since 1880, when records began.

No CJD negligence Six French health officials were cleared last week of negligence in causing the deaths of 117 people from Creutzfeldt-Jakob disease. The defendants had injected infants with tainted growth hormone from a cadaver with CJD in the 1980s. But the court ruled that they couldn’t have foreseen any risk at that time.

24 January 2009 | NewScientist | 7

SPECIAL INVESTIGATION / GENETIC PRIVACY

WHO IS TESTING YOUR DNA?

GUILLAUME ZU ILI/AGENCE VU

Stealthy paternity and infidelity tests can destroy privacy and tear familes apart, but the law is struggling to keep up. Peter Aldhous and Michael Reilly investigate

“Even dishonourable behaviour should not automatically strip someone of all privacy”

8 | NewScientist | 24 January 2009

For more on these stories go to www.NewScientist.com/section/science-news

WHEN Ann Chamberlain-Gordon suspected that her husband was cheating, she took his underwear to her place of work – a police forensic lab in Lansing, Michigan.

Her husband, a former professional in the Canadian Football League, denied infidelity, but at a divorce hearing in March 2007, ChamberlainGordon testified that she had found female DNA on his underwear that did not match her own.

The opposing attorney quickly turned the tables on the forensic scientist, however, accusing her of misusing state equipment by running the tests. The Michigan State Police agreed, and Chamberlain-Gordon was fired a few months later.

If she had instead sent the underwear to a DNA testing company, such as Test Infidelity of Chatsworth, California, rather than taking matters into her own hands, Chamberlain-Gordon could have kept her job. “If you suspect your partner is being unfaithful, you can send in a pair of his or her underwear to test for the presence of another person’s genetic material,” Test Infidelity’s website promises.

If Chamberlain-Gordon had suspected a particular woman and obtained her toothbrush, say, the company could also have analysed DNA from that to look for a match.

Test Infidelity is just one of dozens of US companies offering to test DNA taken without the knowledge of the people concerned. Many firms advertise infidelity testing services or

offer “discreet” paternity tests. These allow a man to determine whether he is the father of a child without letting anyone else know what he is up to, or a woman to tell whether a man is the father of her child without involving him in the process.

While the total number of stealthy DNA tests being conducted is unclear, interviews with genetic testing companies indicate that thousands are being run each year in the US alone.

In the UK, such tests are already illegal. But though some US states have passed laws that arguably might outlaw aspects of infidelity or discreet paternity testing, extensive enquiries

by New Scientist have uncovered no evidence that they have been used against firms running these tests.

This regulatory vacuum raises serious privacy issues, say legal experts.

“Even if you are talking about someone engaged in behaviour that you may find dishonourable, this doesn’t mean that person should be automatically stripped of all privacy,” says Gail Javitt, law and policy director with the Genetics and Public Policy Center in Washington DC, part of Johns Hopkins University.

The results of paternity and infidelity tests can tear families apart. So firms that test DNA without consent could cause real harm – especially to vulnerable children. “The emotional consequences are not something that anybody is going to forget,” says Denise Syndercombe-Court, who runs a DNA testing lab at Barts and The London School of Medicine and Dentistry. >

BEWARE THE RESULTS

A coffee can have consequences far beyond a caffeine high

Do stealthy infidelity and paternity DNA tests produce accurate results? You would hope so, given their emotional consequences.

But minimal regulation and oversight mean such tests may be unreliable.

Many of the companies running stealthy tests are accredited for paternity testing through a voluntary scheme run by the American Association of Blood Banks (AABB) in

Bethesda, Maryland. But this accreditation applies only to tests on DNA collected using standard methods such as cheek swabs, and handled with a chain of custody that is robust enough to stand up in court. The AABB gives no guarantee that the firms’ testing of “abandoned” DNA is accurate, nor does it condone the practice.

“Companies cannot affiliate those tests results

with their accreditation,” says Nikki Bass of the AABB. Customers might think some do, though. For instance, Chromosomal Laboratories of Phoenix, Arizona, displays a prominent notice saying “AABB accredited” on a web page that suggests ways to collect abandoned DNA for paternity testing.

Meanwhile, some other firms offering stealthy tests have no AABB accreditation.

24 January 2009 | NewScientist | 9

“Let’s say a man wants to do these tests without the mother knowing. He’s acting for himself; he’s not acting for the child.”

It is not even clear whether all of the firms offering stealthy DNA tests are delivering accurate results – so it is possible that some people’s lives are being turned upside down by scientific errors (see “Beware the results”, page 9).

We all continually shed cells into the environment, leaving our genetic calling card on items that can be picked up by others and analysed. Along with sources like semen stains, DNA can be extracted from such mundane items as coffee cups, chewing gum and even a wellworn hat. Some companies, including Genetic Testing Laboratories (GTL) of Las Cruces, New Mexico, provide a list of the various items they can process, quoting prices and the likelihood of getting a usable DNA sample for each.

DNA can be mined for deeply personal information, such as our susceptibility to various diseases. But companies like GTL and Test Infidelity are not offering to reveal people’s medical secrets. Instead, they test for “CSI has gotten DNA sequences called short tandem the public into repeats (STRs) which vary greatly from doing these person to person and so are ideal for identifying individuals or determining tests. It’s not horribly whether two people are related. expensive” Police scientists also use STRs, and

TV crime dramas may have helped fuel demand for the technology. “CSI has gotten the public into doing these tests,” suggests Barry Lenett of DNA Plus, Test Infidelity’s parent company. “I think they do it because they can, and it’s not that horribly expensive.” To compare your own DNA with a stain from bedding or clothing, Test Infidelity charges $275.

Matching DNA from the stain with that from an item used by a particular suspect costs another $175. Discreet paternity tests cost a similar amount: the DNA Identity Testing Center of Lewisville, Texas, charges $450 for a test involving one “forensic” sample.

With prices within the reach of many people’s wallets, there is a steady demand. Vladimir Bolin, who heads Chromosomal Laboratories in Phoenix, Arizona, says his company processes around 1000 infidelity tests each year.

“It’s remarkably popular,” he says.

Stealthy tests represent a small portion of the total genetic testing business, according to interviews with companies offering the tests. For example, Brandt Cassidy of DNA Solutions in Oklahoma City says that less than 5 per cent of the roughly 500 paternity tests run by his firm each year involve DNA from items such as chewing gum and drinking glasses. But with many firms offering these services, it seems that thousands of tests are run each year on the sly.

CELEBRITY CONCERNS DRIVE PRIVACY LAW The UK’s pioneering “DNA theft” law is in part a response to fears that celebrities’ genetic secrets could be exposed in the tabloid press.

In 2002, reports emerged of an alleged plot to steal hair from Prince Harry to test whether he was the son of James Hewitt, a former lover of Princess Diana.

The danger of an “unscrupulous journalist” analysing DNA from a coffee cup used by a public figure was also among the concerns of the UK Human Genetics

Commission that same year, when it called for the law to be tightened to protect people’s genetic information.

Since September 2006, it has been a crime in the UK to take human bodily material with the intent of analysing DNA without consent. That includes hairs on a brush, saliva on a toothbrush – anything containing enough cells to extract a usable sample of DNA. Nobody has yet been prosecuted, but the penalty is a fine and a prison sentence of up to three years.

10 | NewScientist | 24 January 2009

Australia is considering introducing a similar law, with a maximum penalty of two years in jail, while in Germany legislation to outlaw stealthy DNA testing is in the works following a lengthy legal battle.

The German case concerned a man who contested paternity, basing his claim on a DNA test conducted on chewing gum used by his supposed child. This evidence was initially accepted, sparking a legal dispute that was eventually settled in

the federal supreme and constitutional courts – which ruled the stealthy test inadmissible.

Will it take a highprofile court case or the violation of a celebrity’s genetic privacy to get lawmakers in other countries to grapple with the issue? We may not have to wait long to find out: in April last year, what was claimed to be the remains of Barack Obama’s breakfast was offered for sale on eBay. “His DNA is on the silverware,” the seller wrote.

SCOTT OLSON/GETTY IMAGES

SPECIAL INVESTIGATION / GENETIC PRIVACY

One place this should not be happening is the UK, where a pioneering law outlawing surreptitious testing came into effect more than two years ago (see “Celebrity concerns drive privacy law”). In most other countries, however, stealthy DNA testing has encountered few legal obstacles, despite the harm that could result.

“If everything we do is legal, I believe the people should be entitled to have what they want,” argues Lenett of DNA Plus. “We don’t get into the emotional aspect of it. That’s for Jerry Springer.

We just do the science.”

In the US – the largest market for genetic tests – there is no federal law clarifying people’s right to privacy with regard to “abandoned” DNA. So New Scientist teamed up with the Genetics and Public Policy Center to find out whether any laws in individual states might apply.

The resulting survey identified several states where collecting DNA samples for infidelity or discreet paternity testing, or running the tests themselves, could be judged illegal (see “DNA and the law”). But despite enquiries, including requests for relevant public records, New Scientist could find no sign that these laws had been used to crack down on companies running these tests, or individuals ordering them.

Even in New York, where the state’s Department of Health does police

For more on these stories go to www.NewScientist.com/section/science-news

In 2008, someone put Barack Obama’s breakfast, DNA on the side, on eBay

DNA and the law

These US states have laws* and penalties that could apply to infidelity or paternity testing on the sly Up to 1 year in jail.

Fine of up to $10,000.

Civil right of action for damages

ALASKA

"A person may not collect a DNA sample from a person, perform a DNA analysis on a sample, retain a DNA sample or the results of a DNA analysis, or disclose the results of a DNA analysis unless the person has first obtained the informed and written consent of the person, or the person's legal guardian." This does not apply to paternity testing, however

Up to 1 year in jail.

Fine of up to $1000

FLORIDA

"DNA analysis may be performed only with the informed consent of the person to be tested, and the results of such DNA analysis, whether held by a public or private entity, are the exclusive property of the person tested" Genetic information "may be collected…only with the written consent of the individual…[and] may be used only for purposes for which the individual has given consent"

Not specified

"No genetic testing shall be done in this state on any individual or anywhere on any resident of this state based on bodily materials obtained within this state, without the prior written and informed consent of the individual to be tested...or the legal guardian"

Civil right of action for damages

"No person shall obtain genetic information from an individual, or from an individual's DNA sample, without first obtaining informed consent from the individual or the individual's representative"

6 months in jail.

Fine of $1000

“No person shall obtain genetic information or samples for genetic analysis from a person without first obtaining informed and written consent from the person or the person's authorized representative…

Genetic analysis of a person...without the informed and written consent of the person or the person's authorized representative is prohibited”

Civil right of action for damages

"No person shall perform a genetic test on a biological sample taken from an individual without the prior written informed consent of such individual"

Up to 90 days in jail.

Fine of $5000.

Civil right of action for damages

"A person may not obtain genetic information from an individual, or from an individual’s DNA sample, without first obtaining informed consent of the individual or the individual’s representative"

Up to 1 year in jail.

Fine of up to $6250.

Civil right of action for damages

MINNESOTA

NEW HAMPSHIRE

NEW JERSEY

NEW MEXICO

NEW YORK

OREGON

The UK explicitly outlaws stealthy DNA testing

UK

“A person commits an offence if he has any bodily material intending…that any human DNA in the material be analysed without qualifying consent”

Up to three years in jail and a fine

*Many of these laws have exceptions, including for law enforcement. Other laws have narrower scope, for example, covering health-related tests only, or addressing the disclosure of genetic information but not collection of DNA and testing. For further analysis, see http://www.dnapolicy.org

companies to ensure they abide by regulations on genetic testing in general, there has been little action on stealthy testing.

Since 1996, it has been illegal to perform a genetic test on a resident of New York State, or to disclose its results, without consent. When the law was introduced, few people had heard of DNA testing for infidelity, or discreet paternity tests, and they are not mentioned specifically. But the law was drafted with a broad definition of genetic testing to allow for future developments. “We wanted it to be as encompassing as possible,” says Ron Canestrari, now leader of the Democratic majority in the New York State Assembly, who sponsored the law.

In October 2007, the New York State Department of Health wrote to the paternity testing firm DNA Services of America in Lafayette, Louisiana, reminding it of the law requiring consent for genetic tests. In addition, documents obtained by New Scientist under the state’s Freedom of Information Law show that over the past five years the department has written to more than 20 companies telling them that separate New York regulations demand that paternity or identity tests must be ordered by someone with legal authority, such as a doctor or a court official. This may have helped to prevent some stealthy tests.

Still, the department has issued no specific warnings about paternity or infidelity tests run on DNA taken from everyday items without consent. And the New York’s Office of the Attorney General, which would prosecute breaches of the 1996 law, has taken no action against companies running such tests.

In theory, a resident of New York or any other state with a relevant law who suspects that their DNA has been tested illegally could make an official complaint, prompting an investigation.

Better still, Javitt argues that there should be a public debate on the ethics of stealthy DNA testing as well as legislation at the national level. “There should be clear boundaries on what is off-limits,” she says. ■ See next week’s issue for part 2 of this investigation 24 January 2009 | NewScientist | 11

THIS WEEK

SOUNDBITES

Peruvians walked their prayers into the earth THE ancient, intricate geometric patterns stamped on the surface of a desert in Peru have long been thought of as messages to the gods, or as markers that tracked celestial objects. Now new details about these geoglyphs suggest they may have been made for “prayer walking”.

The Nasca lines are a collection of lines, giant trapezoids, and figures of humans, plants and animals in a desert 400 kilometres south of Lima, Peru. They were created between 400 BC and AD 650 by the removal of reddish oxidised stones from the desert pavement to reveal the lighter sand beneath.

Tomasz Gorka of Munich University in Germany analysed five geoglyph complexes near the city of Palpa, focusing on the large trapezoidal structures which are etched on the plains there.

He measured anomalies in the Earth’s magnetic field caused by changes in soil density at various depths. The team walked the entire site, an area of about 60 hectares, using hand-held sensors.

“We found other lines, in the interior of the trapezoid

structures, which were not visible from the air,” says Gorka, who presented his findings at an archaeological geophysics meeting in London last month.

“The geoglyphs visible today are the most recent stage of a prolonged construction process during which the whole complex of drawings was constantly added

Brain’s blood surge doesn’t match activity

to the brain region where there was blood flow.

Now, Aniruddha Das from Columbia University in New York and colleagues have shown that blood flow can occur without accompanying neural activity. Das used separate techniques to measure blood flow and neural activity in the visual cortex of two macaques trained to carry out a visual task.

Sitting in darkness except for a light that switched on at regular intervals, the monkeys were trained to look away if it was red, and fix their gaze on the light if it shone green.

When the timing of the pauses between the light flashes changed,

CONTRARY to popular belief, a rush of blood to a certain brain region is not always linked to neural activity there, a finding that may guide future brain scan experiments.

Functional MRI scans measure blood flow in the brain.

Neuroscientists interpret this as a sign that neurons are firing, usually as someone performs a task or experiences an emotion.

This enables them to link the emotion 12 | NewScientist | 24 January 2009

“Dogs cannot use condoms, but… they can be ‘fixed’ – painlessly, quickly and permanently.”

to, remodelled, obliterated or changed by use,” adds Gorka.

Some of the lines produced stronger magnetic anomalies than others, prompting Gorka and Karsten Lambers of the University of Konstanz in Germany to suggest that the soil beneath was compacted by people walking back and forth during prayer rituals. “This activity was closely connected to the placing of ceramic vessels along the lines,” perhaps as offerings, says Lambers. Linda Geddes ■

Pamela Anderson in a letter to the municipal commissioner of Mumbai after the city ordered the killing of stray dogs to control their numbers (BBC News Online, 15 January)

“Right now, we very sadly see ideal conditions for outbreaks of disease.”

WHO director Margaret Chan warns that conditions in the densely

Old prayer walks beneath the new?

populated Gaza Strip have become

Magnetic anomalies reveal intricate lines beneath the Nasca geoglyphs in Peru

conducive to infection and disease transmission following Israel’s

AERIAL PHOTO

military offensive (AFP, 19 January)

“We could explain certain mistakes that Galileo made: why he described the planet Saturn as having ‘lateral ears’ rather than having seen it encircled by rings, for example.”

Visible from above Strongest lines detected with magnetometry Weakest lines detected with magnetometry

Paolo Galluzzi of the Institute and Museum of the History of Science

50 m

in Florence, Italy, on seeking Galileo’s

SOURCE: THOMASZ GORKA

DNA to investigate the cause of his

blood flow still increased when the macaque expected a flash, but there was no subsequent increase in electrical activity from firing neurons (Nature, DOI: 10.1038/nature07664).

Das suspects that the brain sent the rush of blood in anticipation of the neurons’ firing.

Christian Keysers from the BCN Neuroimaging Centre in Groningen, the Netherlands, does not believe the result is relevant to the design of previous fMRI experiments and so is unlikely to have an impact on their results. But Das says care needs to be taken in future to ensure that this misinterpretation does not lead to errors. David Robson ■

degenerating eyesight (AFP, 19 January)

“Nothing, nothing in the world is harder than picking yourself up after a cataclysm… and moving forward, and we’ve done it.”

Outgoing NASA chief Michael Griffin speaking at a farewell address about the resumption of shuttle flights after the Columbia shuttle disaster in 2003, which killed seven astronauts (Los Angeles Times, 17 January)

“We have only four years left for Obama to set an example to the rest of the world.”

NASA climate scientist James Hansen urges the incoming president to take urgent action to halt global warming (The Guardian, London, 18 January)

PAUL SOUDERS/CORBIS

For more news go to www.NewScientist.com/section/science-news

DNA tests reveal gorillas in dire straits Linda Geddes

MOUNTAIN gorillas are in more trouble than we thought. Fewer of them are living in Uganda’s Bwindi Impenetrable National Park (BINP) than previous estimates suggest. This is one of only two places worldwide where the gorillas survive in the wild.

Traditionally, conservationists estimate gorilla numbers by counting nests and examining the dung outside each one. “Each individual constructs a nest to sleep in, and before they leave in the morning, they defecate outside it,” says Katerina Guschanski at the Max Planck Institute for Evolutionary Anthropology in Liepzig, Germany.

According to this method, there are 336 gorillas left in the 331-square-kilometre national park. But when Guschanski’s team analysed DNA samples from each pile of dung using a new genetic counting method, the population estimate dropped by 10 per cent to 302. This suggests that some

individuals had been counted twice using the old technique (Biological Conservation, DOI: 10.1016/j.biocon.2008.10.024).

“We assumed that each individual constructs a single nest, but genetic analysis shows that several individuals construct more than one nest,” says Guschanski. This has been observed in studies of lowland gorillas, who construct more than one nest if the original nest starts leaking during a rainstorm, or if a youngster finds the one that it has just built uncomfortable, she adds.

“It is a great confirmation of what new molecular techniques can do for wildlife censusing,” says Marcus Rowcliffe of the Institute of Zoology in London.

It might also mean that the gorilla population in the park is not growing after all – a census in 1997 found 300 gorillas, while one in 2003 found 320 individuals, but these figures may also be inaccurate. “Now we don’t really know what is happening with this population,” says Guschanski.

Stars’ magnetic fossils may come from big bang THE discovery of magnetic “fossils” around young stars in the Milky Way has boosted the case for the existence of magnetic fields right after the big bang.

If primordial magnetic fields existed, they would have influenced how the universe evolved. For instance, they could have skewed its expansion in one direction.

Now, Claude Catala of the Paris Observatory in France and colleagues believe they have found “fossils” of primordial magnetic fields. The team were attempting to answer a puzzle

in astronomy: why a small fraction of so-called main sequence A/B stars have very strong and ordered magnetic fields. These could have formed via two methods: a dynamo mechanism, due to their rotation, or by inheriting fossil fields that existed in the interstellar medium, the gas and dust between stars.

The team focused on the precursors to such stars, known as HAeBe stars, which are in a stage of evolution in which gas and dust is still collapsing into the star due to gravity.

As these stars are very faint and

–Thin on the ground–

“Probably the safest thing is to assume that the population is stable, but we will need to wait for another four to five years to assess how it is changing.”

Although it is bad news that the population is slightly smaller than expected, “it is much better to have an accurate estimation of the population”, says James Burton of the Earthwatch Institute in Oxford, UK. “Knowing

whether it is increasing or decreasing governs the conservation activities.”

The estimate of 380 for the mountain gorillas living in the other main reserve – Virunga National Park in the Democratic Republic of Congo – may be more accurate, as the gorillas are more accustomed to human contact and can therefore be counted directly. ■

scarce in our galaxy, it has been impossible to detect and measure magnetic fields in these stars before, says Catala.

The astronomers used the CanadaHawaii-France Telescope on Mauna Kea in Hawaii to measure the splitting of the HAeBe stars’ spectra by their magnetic fields and found they have fields of a few hundredths of a tesla (www.arxiv.org/abs/0812.3805).

This rules out the dynamo mechanism, as these young stars have not existed long enough to generate their own fields, so they

must have come from elsewhere.

“This is completely in agreement with the fossil field theory,” says Catala.

However, he adds that the team is not entirely sure of their origin, “but it could indeed be primordial”.

Francesco Miniati at the Swiss Federal Institute of Technology, Zurich, says that while the study agrees with the fossil field theory, it does not prove that primordial magnetic fields existed. “It would if we also knew that these stars were primordial first stars, which they are not,” says Miniati. Catala agrees, but says that there is no telescope, existing or planned, that could see the first primordial stars, as they would be billions of light years away. Anil Ananthaswamy ■

“The fossil magnetic fields found around these young stars could indeed be primordial”

24 January 2009 | NewScientist | 13

NASA, ESA, CXC, STSCI, NRAO

THIS WEEK

Spinning black holes are the ultimate batteries YOU wouldn’t want to be nearby when a spinning black hole lets rip. It now seems they can store and unleash the energy of billions of supernovae, with potentially devastating consequences for their host galaxies.

Many of the supermassive black holes that lurk at the centre of galaxies fire out powerful plasma jets that extend for millions of light years. Though the details of how these jets are produced remain murky, there seems to be only two plausible power sources:

one is matter falling onto the black hole, which can’t explain all the cases. The other source is the black hole’s stored rotational energy. Calculations suggest it should be possible for jets to siphon off energy at the expense of the black hole’s rotation as long as magnetic fields are present to connect the black hole to any matter nearby. Persuasive evidence for this has been lacking.

Now a team led by Brian McNamara of the University of Waterloo, Canada, has found what

Did moon’s far side once face the Earth?

Physics in France studied the relative age and distribution of 46 known craters, gouged out by impacts from debris originating in the solar system’s asteroid belt.

According to earlier computer simulations, the moon’s western hemisphere as viewed from Earth should have about 30 per cent more craters than the eastern hemisphere.

That’s because the west always faces in the direction in which the moon orbits, which makes it more likely to be hit by debris, for the same reason that more raindrops strike a moving car’s front windshield than its rear.

However, when Wieczorek and Le Feuvre compared the relative ages of

BILLIONS of years ago, the man in the moon may have performed the ultimate about-face, when an asteroid flipped the moon around.

The far side of the moon never faces us, because the moon rotates once for every orbit it makes of the Earth. Yet an analysis of impact craters shows the far side may once have pointed our way.

Mark Wieczorek and Matthieu Le Feuvre at the Paris Institute of Earth 14 | NewScientist | 24 January 2009

Supermassive black holes are messy eaters, leaving behind many times more matter than they actually consume but there is little sign that this happened.

“It would have had to essentially vacuum all of the matter that was in that galaxy down into the black hole in a period of 100 million years, and we know nature doesn’t work that way,” McNamara says. “Accretion of matter onto a black hole is very inefficient” (www.arxiv.org/ abs/0811.3020).

That leaves black hole spin as the only other energy source.

–Record-breaking galaxy– The black hole could have been set spinning in the first place by may be the strongest evidence yet matter falling onto it much earlier in its lifetime or in the course of a for jets powered by black hole merger with another black hole. rotation. It comes from a galaxy A huge amount of energy can called MS0735.6+7421 (pictured), be stored in black hole spin, and about 2.6 billion light years if it gets released again in the form from Earth. In 2005 data on this of jets, it could have profound galaxy from the Chandra X-ray effects. Black hole jets are Observatory revealed the biggest increasingly suspected of outpouring of energy ever sterilising their host galaxies, identified from black hole jets. heating and blowing away gas Based on cavities the jets have before it can condense to form apparently punched through new stars, for example. the surrounding gas, the team Chris Reynolds of the calculates that in the past 100 University of Maryland in College million years or so jets have Park says this strengthens the case put out 1055 joules, billions of times the energy of a supernova. that some jets are powered by It would have been next to spinning black holes. But he says impossible for matter falling into he is still waiting for “definitive the black hole to power these jets. proof”. David Shiga ■

the craters, using data about the sequence in which ejected material was deposited on the surface, they found the opposite to be true.

Although the youngest impact basins were concentrated in the western hemisphere, as expected, the older craters were mostly congregated in the east. This suggests that the eastern face had once been bombarded more than the western face (Icarus, DOI: 10.1016/ j.icarus.2008.12.017).

“A large asteroid impact may have started the moon turning, more than 3.9 billion years ago”

This could be explained if a large asteroid impact had set the moon turning. Such an impact would have put the satellite’s rotation rate out of whack, so that for tens of thousands of years it would have appeared to slowly turn as viewed from Earth.

Eventually, it would have settled into the current position.

The handful of lunar-rock debris collected from craters formed by a big enough smash suggest that the moon turned to face the other way more than 3.9 billion years ago, says Wieczorek. Asian probes currently circling the moon could reveal additional craters that would support the about-face idea. Richard Fisher ■

For daily news go to www.NewScientist.com/section/science-news

Brain trick makes robot hand feel real Peter Aldhous

A BIZARRE illusion that makes people believe a false hand is part of their own body could be all it takes to imbue prosthetic limbs with a sense of touch.

Although sophisticated robotic prosthetics can now replace amputated hands, they don’t yet provide the brain with the sensory feedback vital to control fine movement. Without feeling pressure from the fingertips, for example, an amputee operating a robotic hand could either break a wine glass by grasping it too tightly, or let it fall to the floor by failing to apply enough grip.

One potential solution is to wire sensors in robotic fingers directly into nerves in the stump, but this poses some technical challenges.

So instead Henrik Ehrsson, a cognitive neuroscientist at the Karolinska Institute in Stockholm, Sweden, decided to see if a trick

ANITA STOCKSELIUS & ANN RAGNÖ

“My first reaction was: they don’t have a hand, so how can the illusion work on amputees?”

known as the “rubber hand illusion” could provide a simpler alternative.

The illusion arises from our brain’s attempts to reconcile conflicting information from different senses. If you place a rubber hand in front of a volunteer and stroke it with a brush while simultaneously brushing one of their own hands, hidden from view, it feels as if the sensations are coming from the rubber hand.

The volunteer also experiences the eerie feeling that the rubber hand is part of their own body.

Ehrsson wondered if he could use the same illusion to “trick” amputees into interpreting strokes applied to their stump as coming from a prosthetic hand.

His team recruited 18 amputees who had lost a hand and stroked their stumps, which were hidden from view, for about two minutes, at the same time as a fleshylooking rubber hand. As the rubber and real hands must normally be stroked in the same place, it wasn’t clear if this would be enough to induce the illusion.

“My first reaction was: they don’t

have a hand. How can it work?” says Ehrsson.

While the illusion was weaker in the amputees than in people with intact hands, tests designed to measure the extent to which people fall for the illusion showed that stroking someone’s stump still works, especially in those who had lost their hands most recently (Brain, DOI: 10.1093/ brain/awn297).

The illusion also had physiological effects: once an amputee started viewing the rubber hand as part of their own body, stabbing it with a needle caused a change to their skin’s electrical conductance as they came out in a cold sweat. “They were expecting it to hurt,” Ehrsson explains.

Greg Clark, whose team at the University of Utah in Salt Lake City is working on ways to provide

sensory feedback from a robotic hand says: “They got effects from very limited training. That encourages me to believe that the effects would grow larger, if the individual had more experience.”

Ehrsson is now working with hand surgeon and neuroscientist Göran Lundborg of Malmö University Hospital in Sweden to apply the illusion to advanced robotic prosthetics. Their goal is to design robotic hands that create the illusory sensations automatically, by connecting sensors in the fingers to actuators that deliver touches to the stump.

Still, Clark suspects that it may be difficult to transmit the full range of sensory information to the brain without some direct electrical stimulation of the nerves. Ehrsson says that the illusion could be combined with electrical nerve stimulation. ■

–The illusion works every time– 24 January 2009 | NewScientist | 15

STEPHEN KAZLOWSKI/SCIENCE FACTION/GETTY

IN BRIEF Breeding crops to keep us cool

Maybe it’s cold outside, but Antarctica is getting warmer IT’S official: all of Antarctica is warming. This overturns previous suggestions that only the Antarctic Peninsula is heating up, while the continent’s interior cooled.

The majority of weather stations on Antarctica sit around the coast, with only two providing an unbroken record from the continent’s interior. This has given a misleading picture of climate trends over the continent.

Eric Steig of the University of Washington, Seattle, and colleagues used satellite data and statistical techniques to fill in the gaps left by the sparse network of weather stations. The revised records show that between 1957

and 2006 temperatures rose by around 0.5 °C, with the strongest warming occurring over western Antarctica and the Antarctic Peninsula (Nature, vol 457, p 459).

“The decline in sea ice cover in the Amundsen Sea appears to be linked to the warming of west Antarctica,” says co-author David Schneider of the National Center for Atmospheric Research in Boulder, Colorado. Regional changes in atmospheric circulation may also play a role.

Previously, scientists believed the apparent cooling of the continent was linked to the depletion of the ozone layer, causing a strengthening of the circumpolar winds and preventing warm air from reaching the interior.

“I don’t question this mechanism, but the underlying warming trend suggests that a lot more is going on,” says Schneider.

Many mates make for superman sperm SPERM that are forced into competing with sperm from other individuals evolve to be faster and fitter in just about every way.

It is known that sperm from promiscuous chimps move faster than those from relatively monogamous gorillas, but no one knew if this was common among animals. Studies in other species have produced conflicting results.

To settle the issue, Sigal 18 | NewScientist | 24 January 2009

Balshine of McMaster University in Hamilton, Ontario, Canada, and colleagues studied 29 species of cichlid fish living in Lake Tanganyika in central Africa.

This is a major family of fish with species employing the full range of mating behaviours from monogamy to “sperm shopping”, in which a female gets several males to fertilise the eggs that she carries in her

mouth (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0809990106).

The team found that sperm of monogamous fish were small and slow. “But [promiscuous] species have more competitive ejaculates, with the most promiscuous producing superman sperm. They were almost twice as fast, larger, there were more of them, and they lived longer,” says team member John Fitzpatrick of the University of Western Australia in Perth.

REPLACING today’s crops with strains that reflect more sunlight could help fight global warming.

Plants reflect some of the incoming solar energy back into space. The proportion a particular plant reflects, known as its albedo, depends on the shape, size and waxiness of its leaves, and can vary within varieties of a species.

Andy Ridgwell’s team at the University of Bristol, UK, studied the effect of a global switch to higher-albedo varieties of all crops. They found that temperate regions would benefit the most.

For example, in North America and Eurasia, where farmland dominates, temperatures could drop by as much as 1 °C during the summer (Current Biology, DOI: 10.1016/j.cub.2008.12.025).

“Climate change mitigation through plant breeding is a novel idea that merits consideration,” says Eric Kueneman of the UN Food and Agriculture Organization.

Alarm-call chemical to speed healing INJECTIONS of a natural “SOS” chemical have increased the blood supply to damaged muscle in rats.

Damaged mammalian cells produce sialyl Lewisx, a sugar that summons stem cells from the bone marrow in order to build extra blood vessels and feed the tissue. When Erik Suuronen at the University of Ottawa Heart Institute in Ontario, Canada, injected extra sialyl Lewisx into rats with damaged hind limbs, the limbs grew four times as many blood vessels and received twice as much blood flow compared to controls (FASEB Journal, DOI: 10.1096/fj.08-111054).

He now wants to find out whether this accelerates muscle healing, in particular following a heart attack.

For more on these stories go to www.NewScientist.com/section/science-news

JPL/NASA

CONTRARY to a few media reports last week, life has not been found on Mars. But the most sensitive measurements ever made of atmospheric methane – which on Earth is produced mostly by organisms – highlight a few places where life may exist unseen.

Methane was first discovered on Mars in 2003. Since then, some observations have suggested that it is not distributed evenly across the planet, instead hinting at wide areas where the gas is abundant.

Now, a team led by Michael Mumma of the Goddard Space Flight Center in Greenbelt, Maryland, has pinpointed methane plumes in three areas just north of the Martian equator (pictured in red, below).

“This is the very first evidence of local methane sources,” says Mumma (Science, DOI: 10.1126/ science/1165243).

It is unclear what mechanism beneath the surface is producing the methane. Pockets of the gas may have been created through the interaction of water and volcanic rock, but the possibility remains that microbes produced the gas.

“Whatever the source, it indicates the presence of liquid water underground and that there is some type of activity going on, biologic or geologic – and that is exciting,” says Sushil Atreya at the University of Michigan, Ann Arbor.

Cancer drugs could fight antibiotic-resistant “sleeper” bugs CANCER drugs may serve as an unexpected new weapon against some deadly antibioticresistant bacteria.

Antibiotic resistance often emerges when bacteria evolve methods of destroying particular drugs or pumping them out of their cells. But some bacteria take a different approach: in response to an antibiotic they hunker down and simply “sleep” through the onslaught. When the antibiotics are stopped, the dormant bacteria reawaken, which can result in chronic infections.

Previous studies had suggested that such sleeper bacteria overproduce a protein called Hip A. Now Richard Brennan of the M. D. Anderson Cancer Center in Houston, Texas, and colleagues have shown that Hip A gives the bacterium Escherichia coli the ability to sleep through an antibiotic attack. They also found that the protein is a kinase, a type of enzyme that modifies the activity of other proteins and can cause cancer in mammals (Science, DOI: 10.1126/ science.1163806).

Since several cancer drugs work by inhibiting protein kinases, this raises the possibility of using them to treat some forms of antibiotic resistance, something Brennan’s team plans to look into.

They will also investigate whether kinases cause dormancy in other persistent bacteria, such as Mycobacterium tuberculosis and Pseudomonas aeruginosa.

However, the findings will not help combat hospital superbugs MRSA or Clostridium difficile as their resistance does not come from “sleeping” through attacks.

EDWARD PARKER/ALAMY

Methane hints at life on Mars

Cunning crooks con their way out of jail DESPITE the serious nature of their offences, psychopathic criminals get let out of prison sooner than others – in Canada, at least.

Psychopaths tend to be unusually adept at manipulating others, and even the legal system, to their advantage. “In prison, they push administrators to gain better food, resources, or to work outside on road crews,” says Kent Kiehl of the University of New Mexico in Albuquerque.

To find out how effective psychopaths are at duping parole boards, Steve Porter of Dalhousie University in Halifax, Nova Scotia, studied records of 310 male inmates from a Canadian prison.

He found that those termed psychopaths, based on a standard psychological test, were up to 2.5 times as likely as other prisoners to get out of jail early.

They were also “much more likely to then violate their parole than non-psychopaths”, he says.

Bob Hare of the University of British Columbia in Vancouver, who created the psychological tests, says parole boards may need help to tackle the problem. “Many prison officials have told me that they need better training about what a psychopath is,” he says.

Plant cells harnessed to build new drugs STEP aside synthetic chemists. Novel alkaloid molecules that chemists can only dream of synthesising in the lab have been made using the cellular machinery of the periwinkle plant.

Naturally occurring alkaloids such as morphine and the anti-cancer drug vinblastine are already extracted from plants for medical applications.

The chemical complexity of alkaloids makes creating new ones in the lab, or even giving existing ones slightly different properties, very difficult.

So Sarah O’Connor and Weerawat Runguphan at the Massachusetts Institute of Technology turned to the

Madagascar periwinkle Catharanthus roseus (pictured), a plant that naturally makes vinblastine via a complex series of chemical reactions.

They modified the gene for one enzyme involved in an early stage of the process so that it retained its role in making alkaloids, but acted on different starting compounds than it does naturally. When they inserted the gene into periwinkle cells and cultured them in various compounds, the cells made a range of new alkaloids, which could turn out to have medical uses (Nature, DOI: 10.1038/nchembio.141).

24 January 2009 | NewScientist | 19

For daily technology stories, go to www.NewScientist.com/section/tech

NORTHROP GRUMMAN

TECHNOLOGY

US plays ‘I spy a broken sat’ SPY satellites have a new role: as well as watching us they are now spying on each other.

The Pentagon admitted last week that it is using two covert inspection satellites developed for the Defense Advanced Research Projects Agency to assess damage to a failed geostationary satellite – something no one suspected the US could do.

If such satellites can get that close to a target, they could probably attack it.

The Department of Defense says its Mitex micro-satellites, which were launched in 2006, have been jetting around the geostationary ring and have now jointly inspected DSP 23, which was designed to pinpoint clandestine missile launches and nuclear tests, but which stopped working a year after its November 2007 launch. The micro-satellites are trying to nail the problem.

Theresa Hitchens, who becomes director of the UN Institute for Disarmament Research in Geneva this week, is troubled by the secrecy surrounding launch of the Mitex craft. It raises questions about their future use, including potential anti-satellite missions, she says.

“Other nations, notably China, will find this suspicious, and the US behaviour hypocritical” “I am positive other nations, particularly China, will find this development suspicious – and the US behaviour regarding the programme as hypocritical, given that Washington is always chastising Beijing for its lack of transparency regarding its space programmes and intentions,” she says.

–Under surveillance–

Tiny motor could power microbots

My other disc is a hologram

SWIMMING microbots small enough to make their way through arteries are a step closer, thanks to the creation of a tiny mechanical motor.

Developed by engineers at Monash University in Victoria, Australia, the motor uses a piezoelectric material that vibrates in response to an applied electric field to rotate a flagellumlike tail. At just a quarter of a millimetre in diameter, the device is the smallest of its kind (Journal of Micromechanics and Microengineering, DOI: 10.1088/ 09601317/19/2/022001).

The motor could propel a microbot through the bloodstream at up to 6 centimetres per second, the team says. Compared with sensors and microchips, mechanical motors have not shrunk significantly in the last 50 years, they add.

FORGET Blu-ray. Discs which can store 20 times as much data in 3D holograms just moved a step closer, thanks to better materials.

To write the data, two laser beams are aimed at a disc of lightsensitive polymer. One beam has been encoded with patches representing 0s and 1s by shining it through a digital “mask”. At the point in the disc where the beams intersect, they interfere with each other to create islands of bright light and regions of darkness.

Where the lasers’ interference pattern creates bright areas on the disc, small monomer molecules

40bn online music files were shared illegally in 2008, compared with 1.4 billion legal downloads, says the recording industry

link up to form chains with a different refractive index. The data is stored in this pattern, which like a hologram can be read back with another laser.

One initial problem was that the polymers from which the discs are made tend to shrink during this process, creating distortions that make it difficult to read the data back. So Craig Hawker’s team at the University of California, Santa Barbara, have replaced the small monomers with larger ones. Because these take up more space, fewer bonds form between them, reducing this shrinkage and eliminating distortions, Hawker says (Chemical Communications, DOI: 10.1039/b816298k).

“Whopper Sacrifice has been sacrificed” A Burger King message terminating the popular Facebook application, which gave users a free burger in return for dumping 10 “friends”. Facebook was concerned that automatic alerts telling people they had been dumped infringed the dumpers’ privacy (The New York Times, 15 January)

24 January 2009 | NewScientist | 21

TECHNOLOGY

Morphing winglets make for greener aircraft Sleek aerodynamics are crucial for keeping fuel consumption to a minimum, so Boeing and Airbus are racing to produce a dynamic new wing tip Paul Marks

AIRLINE passengers gazing out of their cabin windows could soon be met with an unfamiliar sight – their aircraft’s wing tips changing shape mid-flight.

That is because aircraft makers Boeing and Airbus are developing moveable winglets – the fins at the end of a wing – in a bid to build greener, quieter planes.

The US military has been exploring morphing wings for its uncrewed aircraft for five years. In such planes, a long, high-lift wing useful for loitering can quickly be

“Radical shape-changes are too risky for civil aircraft, so morphing winglets subtly alter the wing shape” transformed into a sharp delta wing to dive towards a target, thanks to the use of composite skins that slide out to alter its shape. Such radical changes would be far too risky on a civil airliner, where any failure of the technology could be fatal, so

research has focused on morphing winglets that alter the shape of the wing more subtly.

Perfected at NASA in the 1970s, conventional, fixed winglets are small, upward extensions to a plane’s wing which disrupt the production of the swirling wake vortices that normally stream from a flat wing tip. This minimises the drag experienced by the wing, making it easier for the plane to cut through the air, which in turn boosts its fuel efficiency. Winglets fixed at an angle of around 25 degrees from the vertical – known as the cant angle – can cut an aircraft’s fuel consumption by 3 to 5 per cent.

By designing these winglets to move during the flight, changing their angle for take-off, climb, cruise and landing approach, for example, Boeing and Airbus hope to improve fuel efficiency even further, while reducing the noise the aircraft makes during landing.

Boeing has filed a patent application on a winglet that moves using shape-memory alloys (SMAs). Engineers working

Shape of wings to come They’ll boost fuel efficiency, cut noise and reduce plane width Wing is straight for take-off and landing, climbing and descent, to maximise lift

The 3-metre tip of the wing can be flexed by either shape-memory alloy rods or hydraulics, allowing the winglet to alter its angle during flight to maximise fuel efficiency

Wing tip is angled to 30 degrees while cruising to minimise drag

30°

Wing tip is angled to 40 degrees while on the ground to minimise wingspan

40°

on an Airbus project are planning to file three patents on their own morphing winglet technology, says Askin Isikveren, chief engineer on the Airbus-funded “Morphlet” project at the University of Bristol in the UK. “The 3 to 5 per cent variation in fuel efficiency today results from using fixed winglets optimised for cruising flight. If we vary the cant angle during flight we can maintain a 5 per cent fuel

reduction all through the flight.”

Allowing the winglet to flatten completely will also give the wing extra lift at low speeds. “That means less thrust from the engines is needed and so we can have a quieter landing approach,” Isikveren says.

The firms have very different ideas about how to build their morphing winglets, however.

Boeing wants to move its winglets using SMA panels that change

Solar-powered plane will gaze down on Mars GREEN technology is not something usually associated with space exploration, but a solar-powered plane that could fly around Mars both day and night may change that.

The Swiss Federal Institute of Technology in Zurich is developing the Sky Sailor, a plane with solar cells on its wings. These would provide power during the day while also 22 | NewScientist | 24 January 2009

charging a battery to keep it aloft at night, says project leader Roland Siegwart. The team believe the Sky Sailor could scour the Martian surface from 1.5 kilometres up for places of interest that a rover might explore, relaying that information back to the lander directing the rover. It could also send images back to Earth.

One advantage of the Sky Sailor

over other proposed flying planetary explorers is that once in the Martian atmosphere it would never need to touch the surface. This removes the hazards and high energy costs associated with take-off and landing, says Siegwart.

The team has flown a prototype plane continuously for 27 hours 800 metres up in the Earth’s atmosphere.

Now it has applied for funding from the European Space Agency so that it can test the Sky Sailor at higher altitudes, where the conditions are more akin to those on Mars.

In the meantime, the plane could prove useful on Earth. Weighing only 2.5 kilograms, it could be launched by hand to monitor forest fires, for example. Jessica Griggs ■

SVENJA-FOTO/ZEFA/CORBIS

For more technology stories go to www.NewScientist.com/section/tech

Wasps have the answer to safer keyhole surgery

structures,” he says.

Simon Waite, a structures specialist with the European Aviation Safety Agency in Cologne, Germany, says another “interesting” challenge will be to ensure morphing winglets cannot interfere with other control surfaces, like the nearby ailerons which produce roll. For instance, if a change to a winglet caused the aircraft to roll to the right, the ailerons would have to compensate. Isikveren is confident that aircraft control systems will cope with this.

With planned airport expansions such as the third runway at London’s Heathrow in the pipeline, the need for greener, quieter aircraft has never been greater. ■

forwards in the same way as the wood wasp’s ovipositor (see diagram).

Preliminary tests have shown that the device can crawl across the surface of brain-like gels and burrow its way into pig muscle tissue. The team will present the probe at the ROBIO conference in Bangkok, Thailand, in February.

Unlike existing rigid surgical probes, the device will be flexible enough to move along the safest possible route, bypassing high-risk

“It will be flexible enough to travel the safest route, bypassing high-risk areas of the brain during surgery” areas of the brain during surgery, for example. It could also reduce the number of incisions needed to deliver cancer therapies to different parts of a tumour, as it can burrow its way to hard-to-reach areas.

Emma Johnson, who works on bio-inspired engineering at the University of Reading, UK, says that the device is likely to be better suited to harder, fibrous tissues like bone and muscle than to soft brain tissue. David Robson ■

Drilling through tissue The probe bores through tissue using a pair of oscillating shafts in the same way that the ovipositor of a wood wasp burrows into wood to lay its eggs As one shaft pushes down, the other is held in place by its teeth...

Wood wasp (Siricidae) ...propelling the whole device downwards

STEVE GSCHMEISSNER/SPL

shape in response to an electric current or heat. The firm also proposes placing a small flap at the trailing edge of the winglet – effectively a mini-rudder – to finetune the winglet’s performance.

Isikveren thinks SMAs are the wrong choice. “The power needed to support an SMA is excessive – it’s a huge drain on the electrical system of the aircraft,” he says.

Instead, his team have stuck with standard, lightweight electric motors to move hydraulic rams.

To ensure the winglet remains streamlined, the team has developed a concertina-like flexible skin made of corrugated Kevlar fabric which surrounds the wing/winglet joint.

Both teams face considerable safety challenges before their technologies can be certified, however. Phil Irving, a damagetolerance expert at Cranfield University near Milton Keynes, UK, cautions that the repeated flexing of the SMA structure in

A BRAIN-boring robot that burrows its way through tissue in the same way a wasp digs through wood could make keyhole surgery safer.

The female wood wasp’s of the Siricidae family use a needle-like ovipositor to deposit eggs inside pine trees. This has two dovetailed shafts, each covered in backwardfacing teeth. To bore into wood, the wasp rapidly oscillates each shaft backwards and forwards. As the shaft is pulled backwards, its sharp teeth catch in the wood’s tissue and prevent it from retreating, so with each oscillation the ovipositor takes a small step forward. The tension created by the gripping teeth braces the shaft and prevents the needle from buckling or breaking. “It can insinuate itself into the tissue with the minimum amount of force,” says Ferdinando Rodriguez y Baena at Imperial College London.

–The Boeing 767 has fixed winglets– Now, a team that includes Rodriguez y Baena is mimicking this Boeing’s design could gradually mechanism to create a medical probe. break down the bonding between The researchers have developed a prototype silicon needle consisting of the winglet and the rest of the two shafts with 50-micrometre-long composite wing. “There are fin-shaped teeth. Motors oscillate difficulties with the long-term the two shafts to propel the device performance of these smart

50 Mm teeth

24 January 2009 | NewScientist | 23

TECHNOLOGY of microwells, and so on. In this important for avoiding false way, the team places nanowires negatives and false positives, and designed to detect certain diseases enables screening for multiple at specific sites on the chip. In disease targets at once,” tests, the team coated nanowires says Keating. between the dielectric properties in DNA sequences that bind to The device will work as a of ethanol and the nanowires nucleic acids from the genomes detector because a nanowire’s creates a force that pushes the of hepatitis B, hepatitis C and resistance changes when nucleic nanowires towards the wells HIV (Science, vol 323, p 352). acids bind to it, and this can (see diagram). “Our DNA-coated By labelling the nanowires rhodium nanowires then snap with fluorescent groups, the team “99 per cent of the wires settled exactly where they into place due to the higher field could see where they ended up. strength there,” says Keating.

They found that 99 per cent of the were meant to, held by The team rinses the chip, nanowires settled precisely where electrostatic forces” then releases another batch they were meant to be, with of nanowires coated with DNA electrostatic forces holding be picked up by circuitry that strands that bind to a different them firmly in place. the group is planing to add. disease marker. This time, “Having many copies of each With nanotechnologists always they electrify a different set type of nanowire in the array is looking for new ways to build on the nanoscale, the Penn State team anticipates that the Nanowire lab on a chip technique will find uses beyond Placing groups of nanowires with disease-detecting coatings in a precise array will biosensors, because it can add enable superfast diagnostics chemical, biological and Rhodium nanowires covered with Nanowires with different optoelectronic components into DNA are attracted into specific coatings can be attracted microwells by an electric field into other microwells traditional silicon electronics.

Geoff Thornton of the London Centre for Nanotechnology at ETHANOL University College London says: “We don’t have a means of positioning a nanowire precisely where we want it right now.”

Indeed, nanowires must often be grown in situ, exactly where ELECTRIC they are needed, which can FIELD present all sorts of thorny design challenges. But perhaps not for SILICON WAFER much longer. Paul Marks ■

Nanowire building kit rewrites the rules of nanotech ONE of the great nanotechnology challenges has been solved by chemists who have worked out how to place individual nanowires onto silicon chips reliably and accurately. The team behind the breakthrough has shown off the technique by building a device that could one day identify diseases from blood samples in a fraction of a second.

Christine Keating and colleagues at Pennsylvania State University in University Park developed their technique using nanowires made of rhodium.

They first took a silicon wafer and carved an array of microwells into it, for the nanowires to sit in.

A pair of electrodes added to each well enables a powerful electric field to form across its length.

The team then divided the rhodium nanowires into groups and coated each group with strands of DNA designed to bind to a specific disease marker.

With the silicon chip immersed in ethanol, they released one group of DNA-coated nanowires into the fluid and switched on the electric fields in some of the microwells. The interplay

Lunar dust buster will keep moon base spotless LUNAR explorers had better be handy with a vacuum cleaner.

A new “lunar dust buster” may be an essential tool for future missions, allowing astronauts to clean up following grubby moonwalks and prevent the dirt penetrating the moon base.

Moon dust is much more of a menace than the terrestrial variety, due to the structure of the particles.

They are covered in tiny spikes that hook into surfaces. This means the dust sticks so tightly to surfaces that 24 | NewScientist | 24 January 2009

brushing alone cannot shift it. “We are talking about abrasive Velcro,” says Pamela Clark of the Catholic University of America, Washington DC, who works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

These spikes also collect electrical charge, which holds them in place on a surface. The dust is so abrasive it can damage machinery, and there are also concerns that it could be dangerous if inhaled.

To solve the problem, Clark’s team is working on SPARCLE, a “lunar dust

buster” that astronauts could utilise in the airlock to a moon base.

The device consists of a positively charged metallic nozzle fitted to an electron gun, similar to those used in electron microscopes, which fires a focused beam of electrons from a hot filament.

Following a moonwalk, astronauts would scan the beam across the surface of their dirty equipment, showering it with electrons until all the dust particles and the surface become negatively charged and

“The dust is so abrasive it can damage machinery, and inhaling it could also be dangerous”

start to repel one another.

This would loosen the particles’ grip, allowing them to fly to the positively charged nozzle where they are captured.

In tests, the dust buster picked up a 2-millimetre-high pile of crushed volcanic rock similar to lunar dust.

The team will present its latest results at the SPESIF conference in Huntsville, Alabama, next month.

Lawrence Taylor, who investigates lunar dust at the University of Tennessee in Knoxville, points out that magnetic attraction might be more effective at removing bigger dust particles. He suggests using a combination of the two techniques. David Robson ■

OPINION

Decision time With the economic case for tackling climate change stronger than ever, the financial crisis provides an opportunity, not an obstacle, says Nicholas Stern AS THE world faces up to the worst global financial crisis since the 1930s, the economic case for tackling the global climate crisis is more compelling than ever.

Fortunately, our ability to respond has also increased as we embark upon a technological revolution that will drive sustainable growth and development of a low-carbon global economy.

Since my colleagues and I published the Stern Review on the economics of climate change in 2006, it has become apparent that the risks and potential costs are even greater than we originally recognised. Global emissions of greenhouse gases are growing more quickly than projected, the ability of the planet to absorb those gases now appears lower than was assumed, the potential increases in temperatures due to rising gas concentrations seem higher, and the physical impacts of a warming planet are appearing at a faster rate than expected.

So, whereas our review recommended that atmospheric concentrations of greenhouse gases should be stabilised within a range of 450 to 550 parts per million of carbon dioxideequivalent, it now seems that our target should not exceed 500 ppm.

That’s if we are to keep down the risks of potentially catastrophic impacts which could result from average global temperatures rising 4 ˚C or more above preindustrial levels. Over the longer term, it is important to limit concentrations more tightly still.

This means that annual global emissions must peak within the next 15 years before falling to half 26 | NewScientist | 24 January 2009

Framework Convention on their 1990 level by 2050. Beyond Climate Change, and if they agree that, we will need to limit human to cut their emissions by at least additions to atmospheric 80 per cent by 2050 compared greenhouse gases to under with 1990, this will be an essential 10 gigatonnes of CO2-equivalent per year, compared with the step towards meeting the current 45 gigatonnes. challenge. That agreement Such reductions present a must be effective (on the scale significant challenge, but they required), efficient (keeping costs are affordable and manageable, down), and equitable (recognising costing about 2 per cent of global different resources, skills and GDP each year. Indeed, with good historical responsibilities). policy and increasingly rapid The key to these major technical progress, the costs may reductions in emissions – whilst be considerably lower. The leading maintaining development industrialised nations are due to “The global economic meet in December this year in downturn is an opportunity Copenhagen, Denmark, at the to invest in green tech next annual gathering of the while costs are lower” parties to the United Nations

and growth – is the rapid dissemination and use of lowcarbon technologies. Already, innovation is advancing in many areas at a faster pace than anticipated in our 2006 review.

But such progress needs to be accelerated: we will need a revolution that surpasses the scale and impact of previous worldchanging technologies such as railways and personal computers.

This requires policies and measures that remove barriers and provide incentives for technological development over three timescales.

First, action is needed to further spread existing low-carbon technologies, such as “green” household appliances. This can be done by creating carbon markets in which the price of emitting carbon reflects the potential impact of those emissions, and by introducing energy-efficiency standards to incentivise innovation, for example.

Second, we need more support for the development and scaling-up of technologies that could become commercially viable within the next 15 years, such as second-generation biofuels – which do not directly affect food production – and carbon capture and storage.

CCS is crucial for countries with fast-expanding economies, such as India and China, which currently rely on coal-fired power stations for growth. We need about 30 CCS demonstration projects, on a commercial scale, carried out in developed and developing countries over the next 10 years. This

To comment on these stories go to www.NewScientist.com/section/opinion

technology needs to spread through international and public-private collaborations.

Third, more effort is required to stimulate new breakthrough technologies that will lead to major cuts in emissions beyond 2030. A well-functioning global carbon market would drive these, but public funding for energy research and development should be doubled now from its present global level of about $10 billion per year, with a medium-term target of around 0.1 per cent of world GDP, or about $50 billion per year.

While the global economic downturn could distract us from the bigger task of tackling climate change, it is also an opportunity to bring forward investments in low-carbon technologies while costs are lower. It can provide job opportunities in the short run in key sectors where resources are idle, such as construction.

Investments that improve energy efficiency will also yield benefits when power and heating prices increase again during economic recovery. In the long term, investments in low-carbon technologies could provide sustainable and well-founded economic growth, in contrast to the recent booms, and eventual busts, driven by flaky dotcom ventures or inflated house prices.

Continued unchecked, emissions and high-carbon growth are not sustainable. In 2009, we have a real chance to set a path towards a low-carbon future. It is the only realistic future for growth and for overcoming world poverty. ■ Nicholas Stern is chair of the Grantham Research Institute on Climate Change and the Environment and the ESRC Centre for Climate Change Economics and Policy

MORE ONLINE Watch our exclusive video interview with Nicholas Stern at www. newscientist.com/article/dn16433

World lines Lawrence Krauss

Will Obama see sense about the nuclear threat?

THE possibility that, in an Obama administration, science will drive rational public policy provides an unprecedented opportunity to deal with a gnawing yet persistently neglected threat to the world: nuclear weapons.

No government is likely to declare how many strategic nuclear warheads it has, but the US and Russia are thought to possess at least 5000 apiece. The 2002 Strategic Offensive Reductions Treaty required each nation to have no more than 2200 “operationally deployed” strategic warheads by 2012, yet this represents no real progress towards disarmament, as the target number is essentially identical to that proposed at the 1997 summit on nuclear arms reduction between Bill Clinton and Boris Yeltsin in Helsinki, Finland.

As we object to Iran’s apparent efforts to join the club of nuclear weapons states we should remember that the US, Russia, France, the UK and China have failed to meet their obligations to disarm, some four decades after they all signed the 1970 Nuclear Non-Proliferation Treaty (NPT).

Reducing the size of our nuclear weapons stockpile would not reduce our ability to deter a nuclear attack – a fact acknowledged by politicians such as Henry Kissinger, George Schultz and William Perry. Even 500 active warheads would be sufficient to kill hundreds of millions of people around the world. Reducing the size of the nuclear stockpile would bring one key benefit, though.

Maintaining a huge and complex nuclear infrastructure is not cheap. In a time of increasing budget concerns, this is one area where savings could be achieved with little or no cost to security.

The terrorist attacks in Mumbai underscore the danger of a nuclear confrontation between India and Pakistan. Yet the US has turned a blind eye to an ongoing Pakistani project to build a plutonium reactor that would be capable of making enough fuel each year for up to 50 nuclear weapons. In 2006, Congress approved a nuclear cooperation pact

with India that would help promote that country’s bomb-making capacity. Neither India nor Pakistan has signed the NPT. The new administration needs to defuse the situation by encouraging disarmament in this region, not proliferation.

Aside from the direct sociopolitical and economic consequences of a regional nuclear war, it is now clear that the longer-term impact of even a localised nuclear conflict between Pakistan and India would be more severe than previously estimated. A study published last year shows that global temperatures and growing seasons could decline significantly following as few as 50 15-kiloton explosions, as might result from such a regional war (Physics Today, vol 61, p 37).

Finally, the new administration might bring

“Obama might bring some rationality to the US’s efforts to deploy ballistic missile defence systems” some rationality to the US’s efforts to deploy ballistic missile defence systems here and elsewhere in the world. It has been estimated that over the past 40 years the US has spent upwards of $600 billion on missile defence. Yet despite this, the US is not significantly closer to producing a workable system than it was in 1972 when it signed the Anti-Ballistic Missile Treaty.

Common sense suggests, as the US physics community did in 2003, that we should not use a missile defence system until it is shown to be workable against a realistic threat. Yet the US has nevertheless deployed a currently untested system at a cost of close to $10 billion per year – and the Bush administration complicated relations with Russia by declaring its intent to install it in Poland.

In this new year, as the country and the world look to Barack Obama with hope, he has signalled his intent to address one clear global threat, namely climate change. Leading the world away from the nuclear precipice will require at least as much sound thinking and political courage. ■

Lawrence Krauss is director of the Origins initiative at Arizona State University in Phoenix

24 January 2009 | NewScientist | 27

OPINION LETTERS Contagious mood From Nick Xavier Michael Bond advises seeking out friendships with people of a desirable disposition while distancing oneself from less salubrious acquaintances

(3 January, p 24). If, however, our behaviour and our judgement of others’ behaviour are so reliant on the emotional and intellectual milieu of large friendship networks, is this advice not more obscure than it looks?

The relative importance of certain positive traits may be based on little more than what the group currently holds in vogue. Perhaps a

person with some attributes generally seen as negative may be in possession of other, rarer traits that are currently dismissed by our wider social environment but which may yet prove important.

I would hazard that judging potential friends based on possible future gain could lead to others being wary of your intentions.

Amersham, Buckinghamshire, UK From Graham (full name supplied) Bond’s advice is bad news for those who suffer from clinical depression. Often they isolate themselves, and people avoid them because of their negative disposition. Depressed people need to talk to others – and to see happy people – to effect a mood state change and to alter their negative perceptions of the world.

If everyone followed this advice, the world would quickly polarise into happy, sociable people and lonely, suicidal depressives.

Bracknell, Berkshire, UK From Rachel Findley Hug a depressive today! It helps to remember that when one recovers

Enigma Number 1529

Square corbel ADRIAN SOMERFIELD I invite you to fill in the grid with non-zero digits so that each row is a perfect square with different digits and each row contains all the digits in all rows below it. In no case must a digit be identical with the one below or above it. This can be done in several different ways. (a) Find an example with the number in the top row divisible by 3.

(b) Find an example in which the number in the right-hand column is palindromic.

In each case please send in the number in the top row.

WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 25 February. The Editor’s decision is final.

Please send entries to Enigma 1529, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address).

Answer to 1523 Dicey numbers: 1111111155555556 The winner Tom Marsh of Bourton-on-Dunsmore, Warwickshire, UK

28 | NewScientist | 24 January 2009

from depression, that recovery spreads to all those who have been faithful and loving friends.

If, on the other hand, we all decided to spend less time with our depressed friends, and also to spend less time with friends who have depressed friends, those suffering from depression would become even more socially isolated, and probably more depressed.

There has got to be a better way to spread cheer in a gloomy time.

Practising the body language and the words of cheerfulness is worth a try, too.

Berkeley, California, US

Hydrogen jukebox From Charles Purkess, ITM Power It is unfortunate that David Strahan concluded his article on hydrogen as a fuel by returning to the arguments of the 20th century, focusing on comparing the efficiency of batteries with hydrogen. He completely overlooked the stark reality of the 21st-century global climate challenge and economics, not to mention the acute energy and fuel-supply issues for the UK (29 November 2008, p 40).

Matching energy generation to demand is difficult for many of the renewable energy resources now being installed. The key to effective and economic utilisation of the output from such renewable resources has to be through energy storage.

Much of our present use of hydrocarbons is directed to transport applications, and if the stored energy could be provided in the form of an environmentally neutral chemical fuel suitable for reuse in the existing transport sector it would be of great national importance. The best available answer is hydrogen.

Wendens Ambo, Essex, UK From R. Gammon, Bryte Energy As the world moves towards low-carbon energy systems, an

increasing proportion of primary energy will need to be generated from highly variable wind, solar and other renewable sources, as well as relatively inflexible generators like nuclear and “clean coal” plants.

To provide a buffer during excess electricity production, the electrolysis of water to produce hydrogen will play an important role. It’s a process that generates a fuel as a by-product of grid balancing, rather than presenting an added burden to the energy system.

However, the low “round-trip efficiency” of converting electricity to hydrogen and back again means it is not the preferred option for the storage of grid electricity, which might be better achieved with flow cells such as the vanadium battery (11 October 2008, p 30). Hydrogen’s main role in a low-carbon energy system is in the transfer of energy from the power generation to the transport sector.

Loughborough, Leicestershire, UK

The death of science From Frank Fahy Science is indeed dead if it cannot find a more logical and imaginative apologist than Michael Brooks (20/27 December 2008, p 16). Surely Brooks is aware that most scientific progress is made by means of small incremental steps involving long periods of systematic, undramatic and often tedious investigations, which by their nature cannot be made entertaining.

It is ludicrous to suggest that “the public” should have a greater say in “what science gets funded” because most members are completely unqualified to make a judgement. The public can already influence the resources available to medical science by funding selected charities; but only the stupid or arrogant would claim to be qualified to suggest specific areas

For more letters visit www.NewScientist.com/section/letters ■ Contagious mood ■ Livestock emissions ■ Multiverse/other ■ Science and fun ■ Overselling science ■ Why menopause?

of research to which the funds should be directed.

Brooks’s comparison to a jury in court is flawed. The legal procedure is formally established and rigidly adhered to; speculation is discouraged; and the judge clearly specifies the possible range of verdicts.

Most of the proceedings concern circumstances and actions that a jury understands and are conducted in plain English, not in the specialised terminology and mathematics that are essential for scientific clarity and rigour.

Stockbridge, Hampshire, UK From Chris Grollman A fifth of European Union citizens already put scientific research in their top four areas for desired use of the EU’s budget, ahead of defence and security issues – that is 29 per cent of respondents in Germany and France, though just 7 per cent in the UK – according the Autumn 2008 Eurobarometer survey of EU public opinion (www.tinyurl.com/9ycq4c).

While the tyranny of the

majority should inspire caution, science can be combined well with other public priorities such as public health. Ongoing events also suggest that the science of economic growth – EU citizens’ first spending priority – could do with an overhaul.

London, UK From Jim Grozier, Café Scientifique Brighton There seems to be less public debate nowadays than in the

1960s, when people argued over whether it was justifiable to spend millions on space exploration while there was so much poverty in the world. That debate was flawed – posing a stark choice between research and people’s lives – and ignored far less justifiable public spending, such as that on arms. But at least it was a debate.

Nevertheless, I’m not sure I agree that now is the time to “canvass public opinion… then act on the results”. Science has been marginalised and caricatured – often by the media – for so long that if there were a referendum tomorrow on the level of research funding, I doubt if any of us would be happy with the result. In any case, surely the idea of giving the public any say in government spending would be viewed as dangerously revolutionary by the current regime; consider, for example, the arms-spending issue again.

Probably the most we can hope for is a greatly enhanced outreach programme to make people feel that they have more of a stake in science. Café Scientifique is an effort in that direction.

Brighton, East Sussex, UK From Stephen Wilson For no better reason than the peace of mind of the bourgeoisie, Michael Brooks wants science subjugated to the court of public opinion. Tragically, it already is.

In the US, evolutionary biologists self-censor, spooked by the superior PR of creationists. In Australia, it is impossible to garner support for stem cell research without talking up the prospects of a cure for Parkinson’s disease.

Clinical – and other – breakthroughs tend to arise from the corpus of scientific knowledge. We do science purely because we need to know all we can about all the world. Biasing research according to populist ambitions will only imperil good science, because even the most obscure endeavours

eventually, if unpredictably, yield useful technologies.

Five Dock, New South Wales, Australia

Wikipedians

From Robert Cailliau Wikipedians are disagreeable and closed to new ideas, according to one survey (3 January, p 19).

Could this be because we have to resist continually the agreeableness and new ideas of creationists, revisionists, flatearthers and other quacks?

Prévessin, Ain, France

Multiverse/other From Alex Kasman Amanda Gefter seeks reasonable explanations for the apparent “fine-tuning” of the laws of physics to support life, aside from the multiverse and the intelligent designer (6 December 2008, p 48).

Three alternatives come to mind.

The perception of “fine-tuning” is based on the idea that the parameters of physics – for example the relative strengths of various forces – can be individually tuned. But if some mathematical “theory of everything” were to provide a unified explanation for all of these forces, we might find that they are necessarily related. Their having values less amenable to life would then be as fanciful as having “more sound, but with less fluctuation of air pressure”.

Secondly, it is argued that if these physical parameters were

different, the elementary particles that form matter in our universe would hardly interact and so could not form things like living beings. But it seems possible that there are particles in our universe that we have not noticed because they hardly interact, and that these would interact strongly under a different set of physical laws, and form some sort of matter (and living beings).

Finally, we have been surprised to find life on Earth in places we did not predict it could exist, such as the deep-sea vents. If some sort of life that we cannot presently imagine could arise in many of those hypothetical universes then there is no mystery here at all.

Human ignorance leaves room for simpler and less dramatic explanations than a creator, a multiverse or the power of consciousness… and is something I definitely believe in.

Charleston, South Carolina, US

Wrong heretic From Robert Scopes Memo to Steve Jones: it was Copernicus who finally convinced the world of the real reason why the sun rises every morning, a century before Galileo (20/27 December 2008, p 71).

Koroit, Victoria, Australia

For the record ■ Chris Anderson said that the Bluefin tuna “lays maybe 3 million eggs and three reach adulthood”, and not, as we reported, that “three hatch” (20/27 December 2008, p 52).

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24 January 2009 | NewScientist | 29

OPINION INTERVIEW Photography: Eamonn McCabe

We’re doomed, but it’s not all bad With his 90th birthday in July, a trip into space scheduled for later in the year and a new book out next month, 2009 promises to be an exciting time for James Lovelock. But the originator of the Gaia theory, which describes Earth as a self-regulating planet, has a stark view of the future of humanity. He tells Gaia Vince we have one last chance to save ourselves – and it has nothing to do with nuclear power Your work on atmospheric chlorofluorocarbons led eventually to a global CFC ban that saved us from ozone-layer depletion. Do we have time to do a similar thing with carbon emissions to save ourselves from climate change?

Not a hope in hell. Most of the “green” stuff is verging on a gigantic scam. Carbon trading, with its huge government subsidies, is just what finance and industry wanted. It’s not going to do a damn thing about climate change, but it’ll make a lot of money for a lot of people and postpone the moment of reckoning. I am not against renewable energy, but to spoil all the decent countryside in the UK with wind farms is driving me mad. It’s absolutely unnecessary, and it takes 2500 square kilometres to produce a gigawatt – that’s an awful lot of countryside.

What about work to sequester carbon dioxide?

That is a waste of time. It’s a crazy idea – and dangerous. It would take so long and use so much energy that it will not be done.

Do you still advocate nuclear power as a solution to climate change?

It is a way for the UK to solve its energy problems, but it is not a global cure for climate change. It is too late for emissions reduction measures.

So are we doomed?

There is one way we could save ourselves and that is through the massive burial of charcoal. It would mean farmers turning all 30 | NewScientist | 24 January 2009

their agricultural waste – which contains carbon that the plants have spent the summer sequestering – into non-biodegradable charcoal, and burying it in the soil. Then you can start shifting really hefty quantities of carbon out of the system and pull the CO2 down quite fast.

Would it make enough of a difference?

Yes. The biosphere pumps out 550 gigatonnes of carbon yearly; we put in only 30 gigatonnes.

Ninety-nine per cent of the carbon that is fixed by plants is released back into the atmosphere within a year or so by consumers like bacteria, nematodes and worms. What we can do is cheat those consumers by getting farmers to burn their crop waste at very low oxygen levels to turn it into charcoal, which the farmer then ploughs into the field. A little CO2 is released but the bulk of it gets converted to carbon. You get a few per cent of biofuel as a by-product of the combustion process, which the farmer can sell. This scheme would need no subsidy: the farmer would make a profit. This is the one thing we can do that will make a difference, but I bet they won’t do it.

Do you think we will survive?

I’m an optimistic pessimist. I think it’s wrong to assume we’ll survive 2 °C of warming: there are already too many people on Earth. At 4 °C we could not survive with even one-tenth of our current population. The reason is we would not find enough food, unless we

PROFILE James Lovelock is a British chemist, inventor and environmentalist. He is best known for formulating the controversial Gaia hypothesis in the 1970s, which states that organisms interact with and regulate Earth’s surface and atmosphere. Later this year he will travel to space as Richard Branson’s guest aboard Virgin Galactic’s SpaceShipTwo. His latest book, The Vanishing Face of Gaia, is published by Basic Books in February.

For more Opinion stories, go to www.NewScientist.com/section/opinion

intelligent, communicating species that can consider the whole system and even do things about it. They are not yet bright enough, they have still to evolve quite a way, but they could become a very positive contributor to planetary welfare.

How much biodiversity will be left after this climatic apocalypse?

We have the example of the Palaeocene-Eocene Thermal Maximum event 55 million years ago.

About the same amount of CO2 was put into the atmosphere as we are putting in and temperatures rocketed by about 5 °C over about 20,000 years. The world became largely desert. The polar regions were tropical and most life on the planet had the time to move

“I don’t think we can react fast enough or are clever enough to handle what’s coming up” north and survive. When the planet cooled they moved back again. So there doesn’t have to be a massive extinction. It’s already moving: if you live in the countryside as I do you can see the changes, even in the UK. If you were younger, would you be fearful?

No, I have been through this kind of emotional thing before. It reminds me of when I was 19 and the second world war broke out. We were very frightened but almost everyone was so much happier. We’re much better equipped to deal with that kind of thing than long periods of peace. It’s not all bad when things get rough. I’ll be 90 in July, I’m a lot closer to death than you, but I’m not worried.

I’m looking forward to being 100.

CAMERA PRESS

Are you looking forward to your trip into space this year?

synthesised it. Because of this, the cull during this century is going to be huge, up to 90 per cent. The number of people remaining at the end of the century will probably be a billion or less. It has happened before: between the ice ages there were bottlenecks when there were only 2000 people left. It’s happening again.

I don’t think humans react fast enough or are clever enough to handle what’s coming up. Kyoto was 11 years ago. Virtually nothing’s been done except endless talk and meetings.

It’s a depressing outlook.

Not necessarily. I don’t think 9 billion is better than 1 billion. I see humans as rather like the first photosynthesisers, which when they first appeared on the planet caused enormous damage by releasing oxygen – a nasty, poisonous gas. It took a long time, but it turned out in the end to be of enormous benefit. I look on humans in much the same light. For the first time in its 3.5 billion years of existence, the planet has an

Very much. I’ve got my camera ready!

Do you have to do any special training?

I have to go in the centrifuge to see if I can stand the g-forces. I don’t anticipate a problem because I spent a lot of my scientific life on ships out on rough oceans and I have never been even slightly seasick so I don’t think I’m likely to be space sick. They gave me an expensive thorium-201 heart test and then put me on a bicycle. My heart was performing like an average 20 year old, they said.

I bet your wife is nervous.

No, she’s cheering me on. And it’s not because I’m heavily insured, because I’m not. ■ 24 January 2009 | NewScientist | 31

OPINION ESSAY

They said it could never happen…

When “experts” claim the risk of some catastrophic event is one in a billion – the estimate that the LHC would produce an Earth-eating black hole – how do we know that they’ve got their reasoning straight, asks Mark Buchanan

IF OUR impressive capacity for conscious reasoning is what most clearly sets us humans apart from other species, our capacity for selfdeception over the significance of its conclusions must come a close second.

In the real world, this can be serious. To take a topical example, until recently, people who are supposed to know about such things were utterly confident that serious financial crises were a thing of the past. Financial mathematics of supposedly unprecedented sophistication said so. Just look at us now.

So it’s timely to ask if we might be suffering from similar self-deception about other risks we think we understand. A trenchant new analysis

by Toby Ord and his colleagues at the Future of Humanity Institute at the University of Oxford gives pause for thought. The team’s paper concerns the risks associated with extremely rare but potentially catastrophic events. They cite the start-up of the Large Hadron Collider, which was challenged on the grounds that the high-energy particle collisions it generates might annihilate the Earth by creating a tiny black hole or a deadly shard of strange matter.

In a spectacular (and intentional) understatement, the physicists who first tried to put numbers on such risks – then in the context of the Relativistic Heavy Ion Collider at Brookhaven, New York, a predecessor to the LHC – referred to potentially “profound

PROFILE Mark Buchanan is a consultant for New Scientist, based in France. His books are Nexus, Ubiquity and The Social Atom

32 | NewScientist | 24 January 2009

implications for health and safety”. Invoking quantum chromodynamics, what we know about the gravitational conditions for creating black holes, and our knowledge of near-Earth high-energy collisions due to cosmic rays, they put the chances of a “dangerous event” at around 10-9 per year.

That sounds pretty safe, and similarly small or smaller numbers have been cited for the LHC. But as Ord’s team argues, this is not as reassuring as it seems: that’s because this figure represents the chance of a dangerous event only if the physicists’ argument is correct. What if it isn’t?

Finding out requires some careful logic.

Forget the LHC for the moment. Suppose some argument estimates probability X of an event, good or bad, happening. From a probabilistic point of view, Ord and colleagues point out, we cannot just accept this as the best estimate.

The real probability is : (X × PX) + (Y × PY) that is, X multiplied by the probability (PX) that the argument is correct, plus the probability the argument is wrong (PY) multiplied by the chance (Y) that the event will happen if the argument is wrong.

This matters hardly at all if X has some reasonably high value such as 50 per cent, or even 1 per cent. But if X is very small, say 10-20, while the chance the argument is wrong is 10-6, then the first figure becomes as good as meaningless. As the authors put it: “If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect.”

In other words, conclusions about extraordinarily small probabilities require

For more on these stories go to www.NewScientist.com/section/opinion

Estimates of the LHC creating a “dangerous event” included 10-9 per year or much smaller

equally extraordinary care. Any estimate of the likelihood of an event occurring should take into account the chance that the analysis on which that probability has been assigned is flawed or based on error. This is the principle of epistemological uncertainty – that we can’t know anything with total certainty – in action.

Back to the LHC. Many people, me included, find the most convincing argument for the safety of the collider comes from considering the energy densities frequently created by cosmic rays colliding with particles in the Earth’s atmosphere or elsewhere. If the LHC is likely to be dangerous, we should long since have been annihilated. Even so, as convincing as this is, the same problem recurs. The argument has to be more than convincing: we have to be sure there is only the tiniest chance we could be wrong – which is much harder to establish.

Lots of arguments do turn out to be wrong.

To get an idea of how many, Ord and his colleagues looked at the proportion of published scientific papers that are eventually retracted. Using Medline as their source, they found it to be around 1 in 10,000. Given that Medline covers mostly top-ranking journals, they estimate the error rate for all journals to be more like 1 in 1000, which suggests a fairly

CERN/SPL

“It’s easy to be seduced by the nature of logical thinking and its illusion of certainty” high chance of error in any argument. And remember, scientists often don’t publish painful and embarrassing retractions unless forced, so the true rate may be even higher.

Of course, the physicists who considered the LHC risks are capable and cautious people so we might think the chance of their argument being wrong is smaller than 1 in 1000. But even if it were a thousand times smaller, only 10-6, this still seems to undermine the authority of their extremely small estimates.

Of course, it is equally important not to be too pessimistic either. The fact is that we have no knowledge at all about the likelihood of an event happening if one or more of its underlying arguments are wrong. Even if

the argument does not reach the required level of certainty, this does not mean we are in danger – only that we don’t have any guarantee of safety. Not the same thing at all.

Ord and his colleagues rightly stress that further elaboration of the arguments for the safety of the LHC might well reduce the chance of the overall argument for its safety being wrong. But until this kind of work has been done, they suggest, the current safety report cannot be seen as the final word, which seems entirely reasonable to me.

This is an area where it is crucial to focus on the logic, because our intuitions are no help.

Most of us, I suspect, have a gut feeling that certain things “could never happen” and that “people who worry about this are crazy”. Sadly, the fact that we haven’t destroyed ourselves yet is no guarantee that we never will.

It’s easy for any of us to be seduced by the nature of logical thinking and its illusion of certainty. We generally strive to become aware of what former US defence secretary Donald Rumsfeld famously called the “known knowns” and the “known unknowns”, but are perilously ignorant of the “unknown unknowns”, and, worse, blithely unaware of our own ignorance.

This becomes particularly dangerous when it hides flaws in an argument we are relying on for reassurance that potentially catastrophic events are virtually impossible.

It is perhaps an ultimate irony of our human longing for certainty that no amount of effort can definitively prove anything, for we can never discount the possibility that we have made a mistake, and if we enlist others to help us, they too may make mistakes.

Maybe there’s another lesson here: that mathematical certainty isn’t all it’s cracked up to be. We are, after all, biological organisms, and biology never bothers to prove anything. Cell design, for instance, reflects a crazy historical legacy of structures cobbled together to produce workable solutions to thousands of temporary problems. Perhaps we shouldn’t insist that good reasoning conforms to some “pure” proof-making ideal, and accept it is more like those ad hoc biological processes that leave us fallible and vulnerable, but resilient enough to get by in an uncertain world. ■ 24 January 2009 | NewScientist | 33

COVER STORY The tree of life, one of the iconic concepts of evolution, has turned out to be a figment of our imagination, says Graham Lawton

Uprooting Darwin’s tree I

34 | NewScientist | 24 January 2009

one species becomes two. Most branches eventually come to a dead end as species go extinct, but some reach right to the top – these are living species. The tree is thus a record of how every species that ever lived is related to all others right back to the origin of life.

For much of the past 150 years, biology has largely concerned itself with filling in the details of the tree. “For a long time the holy grail was to build a tree of life,” says Eric Bapteste, an evolutionary biologist at the Pierre and Marie Curie University in Paris, France. A few years ago it looked as though the grail was within reach. But today the project lies in Darwin’s first sketch of an evolutionary tree of life

MARIO TAMA/GETTY

N JULY 1837, Charles Darwin had a flash of inspiration. In his study at his house in London, he turned to a new page in his red leather notebook and wrote, “I think”. Then he drew a spindly sketch of a tree.

As far as we know, this was the first time Darwin toyed with the concept of a “tree of life” to explain the evolutionary relationships between different species. It was to prove a fruitful idea: by the time he published On The Origin of Species 22 years later, Darwin’s spindly tree had grown into a mighty oak. The book contains numerous references to the tree and its only diagram is of a branching structure showing how one species can evolve into many.

The tree-of-life concept was absolutely central to Darwin’s thinking, equal in importance to natural selection, according to biologist W. Ford Doolittle of Dalhousie University in Halifax, Nova Scotia, Canada.

Without it the theory of evolution would never have happened. The tree also helped carry the day for evolution. Darwin argued successfully that the tree of life was a fact of nature, plain for all to see though in need of explanation.

The explanation he came up with was evolution by natural selection.

Ever since Darwin the tree has been the unifying principle for understanding the history of life on Earth. At its base is LUCA, the Last Universal Common Ancestor of all living things, and out of LUCA grows a trunk, which splits again and again to create a vast, bifurcating tree. Each branch represents a single species; branching points are where

tatters, torn to pieces by an onslaught of negative evidence. Many biologists now argue that the tree concept is obsolete and needs to be discarded. “We have no evidence at all that the tree of life is a reality,” says Bapteste. That bombshell has even persuaded some that our fundamental view of biology needs to change.

So what happened? In a nutshell, DNA. The discovery of the structure of DNA in 1953 opened up new vistas for evolutionary biology. Here, at last, was the very stuff of inheritance into which was surely written the history of life, if only we knew how to decode it. Thus was born the field of molecular evolution, and as techniques became available to read DNA sequences and those of other biomolecules such as RNA and proteins, its pioneers came to believe that it would provide proof positive of Darwin’s tree of life. The basic idea was simple: the more closely related two species are (or the more recently their branches on the tree split), the more alike their DNA, RNA and protein sequences ought to be.

It started well. The first molecules to be sequenced were RNAs found in ribosomes, the cell’s protein-making machines. In the 1970s, by comparing RNA sequences from various plants, animals and microorganisms, molecular biologists began to sketch the outlines of a tree. This led to, among other successes, the unexpected discovery of a previously unknown major branch of the tree of life, the unicellular archaea, which were previously thought to be bacteria.

By the mid-1980s there was great >

Darwin

YULIA BRODSKAYA/PHOTOGRAPHED BY PIXELEYES PHOTOGRAPHY

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To win the framed original of this 3D artwork, sign by the artist ed see Feedba , ck at the back , of this issue

24 January 2009 | NewScientist | 35

TWO SPECIES BECOME ONE It could be time to ditch the old idea that hybrids are sterile individuals that cannot possibly have played a role in shaping the history of life on Earth. Hybridisation is a significant force in animal evolution, according to retired marine biologist Donald Williamson, formerly of the University of Liverpool, UK. His conclusion comes from a lifetime studying marine animals such as starfish, sea urchins and molluscs, many of which lead a strange double life, starting out as larvae and metamorphosing into adult forms.

The conventional explanation for metamorphosis is that it evolved gradually, with the juvenile form becoming specialised for feeding and

the adult for mating, until they barely resembled each other. Williamson thinks otherwise. He points out that marine larvae have five basic forms and can be organised into a family tree based on shared characteristics.

Yet this tree bears no relationship to the family tree of adults: nearidentical larvae often give rise to adults from different lineages, while some closely related adults have utterly unrelated larvae.

BIOLOGICAL MASH-UP It’s as if each species was randomly assigned one of the larval forms – which is exactly what Williamson argues happened. He believes metamorphosis arose repeatedly

during evolution by the random fusion of two separate species, with one of the partners assuming the role of the larva and the other that of the adult.

If that sounds unlikely, Williamson points out that many marine species breed by casting their eggs and sperm into the sea and hoping for the best, giving ample opportunity for cross-species hybridisation. Normally nothing comes of this, he says, but “once in a million years it works: the sperm of one species fertilises another and two species become one”. The most likely way for this biological mash-up to function is if the resulting chimera expresses its two genomes sequentially, producing a two-stage life history

D P WILSON/FLPA

The starfish Luidia sarsi seems to be two species at once, one forming the larva, the other the adult 36 | NewScientist | 24 January 2009

with metamorphosis in the middle.

This explains many anomalies in marine biology, says Williamson. His star witness is the starfish Luidia sarsi, which starts life as a small larva with a tiny starfish inside. As the larva grows, the starfish migrates to the outside and when the larva settles on the seabed, they separate. This is perfectly normal for starfish, but in Luidia something remarkable then happens. Instead of degenerating, the larva swims off and lives for several months as an independent animal. “I can’t see how one animal with one genome could do that,” says Williamson.

“I think the larval genome and the adult genome are different.”

optimism that molecular techniques would finally reveal the universal tree of life in all its glory. Ironically, the opposite happened.

The problems began in the early 1990s when it became possible to sequence actual bacterial and archaeal genes rather than just RNA. Everybody expected these DNA sequences to confirm the RNA tree, and sometimes they did but, crucially, sometimes they did not. RNA, for example, might suggest that species A was more closely related to species B than species C, but a tree made from DNA would suggest the reverse.

Which was correct? Paradoxically, both – but only if the main premise underpinning Darwin’s tree was incorrect. Darwin assumed that descent was exclusively “vertical”, with organisms passing traits down to their offspring. But what if species also routinely swapped genetic material with other species, or hybridised with them? Then that neat branching pattern would quickly degenerate into an impenetrable thicket of interrelatedness, with species being closely related in some respects but not others.

We now know that this is exactly what happens. As more and more genes were sequenced, it became clear that the patterns of relatedness could only be explained if bacteria and archaea were routinely swapping genetic material with other species – often across huge taxonomic distances – in a process called horizontal gene transfer (HGT).

At first HGT was assumed to be a minor player, transferring only “optional extra”

”The affinities of all the beings of the same class have sometimes been represented by a great tree.

I believe this simile largely speaks the truth…”

Darwin

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Charles Darwin, On the Origin of Species

THE NATIONAL HISTORY MUSEUM, LONDON

Darwin was unaware of DNA, and built the tree of life with only multicellular specimens

functions such as antibiotic resistance. Core biological functions such as DNA replication and protein synthesis were still thought to be passed on vertically. For a while, this allowed evolutionary biologists to accept HGT without jeopardising their precious tree of life; HGT was merely noise blurring its edges.

We now know that view is wrong. “There’s promiscuous exchange of genetic information across diverse groups,” says Michael Rose, an evolutionary biologist at the University of California, Irvine.

From tree to web As it became clear that HGT was a major factor, biologists started to realise the implications for the tree concept. As early as 1993, some were proposing that for bacteria and archaea the tree of life was more like a web. In 1999, Doolittle made the provocative claim that “the history of life cannot properly be represented as a tree” (Science, vol 284, p 2124). “The tree of life is not something that exists in nature, it’s a way that humans classify nature,” he says.

Thus began the final battle over the tree.

Many researchers stuck resolutely to their guns, creating ever more sophisticated computer programs to cut through the noise and recover the One True Tree. Others argued just as forcefully that the quest was quixotic and should be abandoned.

The battle came to a head in 2006. In an ambitious study, a team led by Peer Bork of the European Molecular Biology Laboratory

in Heidelberg, Germany, examined 191 sequenced genomes from all three domains of life – bacteria, archaea and eukaryotes (complex organisms with their genetic material packaged in a nucleus) – and identified 31 genes that all the species possessed and which showed no signs of ever having been horizontally transferred. They then generated a tree by comparing the sequences of these “core” genes in everything from E. coli to elephants. The result was the closest thing yet to the perfect tree, Bork claimed (Science, vol 311, p 1283).

Other researchers begged to differ. Among them were Tal Dagan and William Martin at the Heinrich Heine University in Düsseldorf, Germany, who pointed out that in numerical terms a core of 31 genes is almost insignificant, representing just 1 per cent of a typical bacterial genome and more like 0.1 per cent of an animal’s. That hardly constitutes a mighty oak or even a feeble sapling – more like a tiny twig completely buried by a giant web. Dagan dubbed Bork’s result “the tree of 1 per cent” and argued that the study inadvertently provided some of the best evidence yet that the tree-of-life concept was redundant (Genome Biology, vol 7, p 118).

The debate remains polarised today.

Bork’s group continue to work on the tree of life and he continues to defend the concept.

“Our point of view is that yes, there has been lots of HGT, but the majority of genes contain this tree signal,” Bork says. The real problem is that our techniques are not yet

good enough to tease that signal out, he says.

Meanwhile, those who would chop down the tree of life continue to make progress. The true extent of HGT in bacteria and archaea (collectively known as prokaryotes) has now been firmly established. Last year, Dagan and colleagues examined more than half a million genes from 181 prokaryotes and found that 80 per cent of them showed signs of horizontal transfer (Proceedings of the National Academy of Sciences, vol 105, p 10039).

Surprisingly, HGT also turns out to be the rule rather than the exception in the third great domain of life, the eukaryotes. For a start, it is increasingly accepted that the eukaryotes originated by the fusion of two prokaryotes, one bacterial and the other archaeal, forming this part of the tree into a ring rather than a branch (Nature, vol 41, p 152).

The neat picture of a branching tree is further blurred by a process called endosymbiosis. Early on in their evolution, eukaryotes are thought to have engulfed two free-living prokaryotes. One of these gave rise to the cellular power generators called mitochondria while the other was the precursor of the chloroplasts, in which photosynthesis takes place. These “endosymbionts” later transferred large chunks of their genomes into those of their eukaryote hosts, creating hybrid genomes. As if that weren’t complicated enough, some early eukaryotic lineages apparently swallowed one another and amalgamated their genomes, creating yet another layer of horizontal transfer (Trends > 24 January 2009 | NewScientist | 37

The one true tree?

SOURCE: WELLCOME LIBRARY, LONDON/SCIENCE, VOL 311, P 1283

Eu ry Cr arc en ha e Na arc ot no hae a a Pr rc ot ot h a o a Pl zo eo an a ta A m ts o Fu eba ng e Ne i m In ato se de c Fi ts s sh Bi rd s M ou Ch se/ im rat H p um an

A, B, D- G, E pr - p Ac ote rot id ob eo Cy oba ac bac an ct ter te De ob eri ia ria in ac a Ch oco ter lo cc ia Aq rofl ale u ex s Th ifica i er e Fu mo so to Ch ba gae la cte Ba my ria ct dia Ch ero e lo id Fi rob ete br i s o Ac ba tin ct e Sp ob re iro ac s Pl ch ter an ae ia Fi cto tes rm m ic yce ut t es es

A simplified version of the tree of life, showing relationships between groups that have had their genomes sequenced.

Constructing the tree has been a major aim of biology since Darwin introduced the idea in On The Origin of Species (right) but many now consider the enterprise misconceived in the light of current knowledge

BACTERIA

ARCHAEA

EUKARYOTES Blurring the animal family tree There are many examples of animals acquiring genes “horizontally” from bacteria, viruses and even other animals The cow genome contains a piece of snake DNA that appears to have entered horizontally around 50 million years ago The human gene syncytin, which is vital for placenta formation, originated in a virus Last year, a gene crucial to the function of stinging cells in jellyfish and sea anemones was found to have been transferred from a bacterium

Last universal common ancestor (LUCA)

? in Ecology and Evolution, vol, 23, p 268).

This genetic free-for-all continues to this day. The vast majority of eukaryote species are unicellular – amoebas, algae and the rest of what used to be known as “protists” (Journal of Systematics and Evolution, vol 46, p263).

These microscopic beasties have lifestyles that resemble prokaryotes and, according to Jan Andersson of the University of Uppsala in Sweden, their rates of HGT are often comparable to those in bacteria. The more we learn about microbes, the clearer it becomes that the history of life cannot be adequately represented by a tree.

Hang on, you may be thinking. Microbes might be swapping genes left, right and centre, what does that matter? Surely the stuff we care about – animals and plants – can still be accurately represented by a tree, so what’s the problem?

Well, for a start, biology is the science of life, and to a first approximation life is unicellular.

Microbes have been living on Earth for at least 3.8 billion years; multicellular organisms didn’t appear until about 630 million years ago. Even today bacteria, archaea and unicellular eukaryotes make up at least 90 per cent of all known species, and by sheer weight of numbers almost all of the living things on Earth are microbes. It would be perverse to claim that the evolution of life on Earth resembles a tree just because multicellular life evolved that way. “If there is a tree of life, it’s a small anomalous structure growing out of the web of life,” says John Dupré, a philosopher of 38 | NewScientist | 24 January 2009

biology at the University of Exeter, UK. More fundamentally, recent research suggests that the evolution of animals and plants isn’t exactly tree-like either. “There are problems even in that little corner,” says Dupré. Having uprooted the tree of unicellular life, biologists are now taking their axes to the remaining branches.

For example, hybridisation clearly plays an important role in the evolution of plants.

According to Loren Rieseberg, a botanist at the University of British Columbia in Vancouver, Canada, around 14 per cent of living plant species are the product of the fusion of two separate lineages.

Hybrid humans Some researchers are also convinced that hybridisation has been a major driving force in animal evolution (see “Natural born chimeras”, above right, and “Two into one”, page 32), and that the process is ongoing. “It is really common,” says James Mallet, an evolutionary biologist at University College London. “Ten per cent of all animals regularly hybridise with other species.” This is especially true in rapidly evolving lineages with lots of recently diverged species – including our own. There is evidence that early modern humans hybridised with our extinct relatives, such as Homo erectus and the Neanderthals (Philosophical Transactions of the Royal Society B, vol 363, p 2813).

Hybridisation isn’t the only force undermining the multicellular tree: it is

The entire genome of the bacterium Wolbachia was recently found integrated into the genome of a fruit fly. The fly is, in effect , a fly-bacterium chimera

becoming increasingly apparent that HGT plays an unexpectedly big role in animals too.

As ever more multicellular genomes are sequenced, ever more incongruous bits of DNA are turning up. Last year, for example, a team at the University of Texas at Arlington found a peculiar chunk of DNA in the genomes of eight animals – the mouse, rat, bushbaby, little brown bat, tenrec, opossum, anole lizard and African clawed frog – but not in 25 others, including humans, elephants, chickens and fish. This patchy distribution suggests that the sequence must have entered each genome independently by horizontal transfer (Proceedings of the National Academy of Sciences, vol 105, p 17023).

Other cases of HGT in multicellular organisms are coming in thick and fast. HGT has been documented in insects, fish and plants, and a few years ago a piece of snake DNA was found in cows. The most likely agents of this genetic shuffling are viruses, which constantly cut and paste DNA from one genome into another, often across great taxonomic distances. In fact, by some reckonings, 40 to 50 per cent of the human genome consists of DNA imported horizontally by viruses, some of which has taken on vital biological functions (New Scientist, 27 August 2008, p 38). The same is probably true of the genomes of other big animals. “The number of horizontal transfers in animals is not as high as in microbes, but it can be evolutionarily significant,” says Bapteste.

Nobody is arguing – yet – that the tree

”…The green and budding twigs may represent existing species, and those produced during each former year may represent the long succession of extinct species”

Darwin

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Darwin in his own words

NATURAL BORN CHIMERAS

MITSUHIKO INAMORI/MINDEN

The idea that microbes regularly swap portions of genetic code with individuals from another species doesn’t seem so farfetched (see main story). But could the same process also have shaped the evolution of multicellular animals? In 1985, biologist Michael Syvanen of the University of California, Davis, predicted that it did (Journal of Theoretical Biology, vol 112, p 333). Back then there was no way to test that claim, but there is now.

Syvanen recently compared 2000 genes that are common to humans, frogs, sea squirts, sea urchins, fruit flies and

nematodes. In theory, he should have been able to use the gene sequences to construct an evolutionary tree showing the relationships between the six animals.

He failed. The problem was that different genes told contradictory evolutionary stories. This was especially true of sea-squirt genes.

Conventionally, sea squirts – also known as tunicates – are lumped together with frogs, humans and other vertebrates in the phylum Chordata, but the genes were sending mixed signals. Some genes did indeed cluster within the chordates, but

others indicated that tunicates should be placed with sea urchins, which aren’t chordates. “Roughly 50 per cent of its genes have one evolutionary history and 50 per cent another,” Syvanen says.

The most likely explanation for this, he argues, is that tunicates are chimeras, created by the fusion of an early chordate and an ancestor of the sea urchins around 600 million years ago.

“We’ve just annihilated the tree of life. It’s not a tree any more, it’s a different topology entirely,” says Syvanen. “What would Darwin have made of that?”

concept has outlived its usefulness in animals and plants. While vertical descent is no longer the only game in town, it is still the best way of explaining how multicellular organisms are related to one another – a tree of 51 per cent, maybe. In that respect, Darwin’s vision has triumphed: he knew nothing of microorganisms and built his theory on the plants and animals he could see around him.

Even so, it is clear that the Darwinian tree is no longer an adequate description of how evolution in general works. “If you don’t have a tree of life, what does it mean for evolutionary biology?” asks Bapteste. “At first it’s very scary… but in the past couple of years people have begun to free their minds.” Both he and Doolittle are at pains to stress that downgrading the tree of life doesn’t mean that the theory of evolution is wrong – just that evolution is not as tidy as we would like to believe. Some evolutionary relationships are tree-like; many others are not. “We should relax a bit on this,” says Doolittle. “We understand evolution pretty well – it’s just that it is more complex than Darwin imagined. The tree isn’t the only pattern.”

Others, however, don’t think it is time to relax. Instead, they see the uprooting of the tree of life as the start of something bigger.

“It’s part of a revolutionary change in biology,” says Dupré. “Our standard model of evolution is under enormous pressure. We’re clearly going to see evolution as much more about mergers and collaboration than change within isolated lineages.”

Rose goes even further. “The tree of life is being politely buried, we all know that,” he says. “What’s less accepted is that our whole fundamental view of biology needs to change.” Biology is vastly more complex than we thought, he says, and facing up to this complexity will be as scary as the conceptual upheavals physicists had to take on board in the early 20th century.

If he is right, the tree concept could become biology’s equivalent of Newtonian mechanics: revolutionary and hugely successful in its time, but ultimately too simplistic to deal with the messy real world. “The tree of life was useful,” says Bapteste. “It helped us to understand that evolution was real. But now we know more about evolution, it’s time to move on.” ■ Graham Lawton is features editor of New Scientist

Is this transition from caterpillar to comet moth the result of fusion of two separate species?

Next week: What are the biggest gaps in evolutionary theory? We ask 16 of the world’s leading evolutionists, including Richard Dawkins and Niles Eldridge, what pieces of the jigsaw they most want to see filled 24 January 2009 | NewScientist | 39

OJO/GETTY

What makes otherwise intelligent people useless at mathematics? Laura Spinney investigates

When numbers don’t add up 40 | NewScientist | 24 January 2009

”Dyscalculics fail to see the connection between a set of objects and the numerical symbol that represents it”

People who struggle with arithmetic may have no problem with more conceptual maths

J

ILL, 19, from Michigan, wants to go to university to read political science. There is just one problem: she keeps failing the mathematics requirement. “I am an exceptional student in all other subjects, so my consistent failure at math made me feel very stupid,” she says. In fact, she stopped going to her college mathematics class after a while because, she says, “I couldn’t take the daily reminder of what an idiot I was.”

Last November, Jill got herself screened for learning disabilities. She found that while her IQ is above average, her numerical ability is equivalent to that of an 11-year-old because she has something called dyscalculia. The diagnosis came partly as a relief, because it explained a lot of difficulties she had in her day-to-day life. She can’t easily read a traditional, analogue clock, for example,

and always arrives 20 minutes early for fear of being late. When it comes to paying in shops or restaurants, she hands her wallet to a friend and asks them to do the calculation, knowing that she is likely to get it wrong.

Welcome to the stressful world of dyscalculia, where numbers rule because inhabitants are continually trying to avoid situations in which they have to perform even basic calculations. Despite affecting about 5 per cent of people – roughly the same proportion as are dyslexic – dyscalculia has long been neglected by science, and people with it incorrectly labelled as stupid. Now, though, researchers are starting to get to the root of the problem, bringing hope that dyscalculic children will start to get specialist help just as youngsters with dyslexia do.

For hundreds of millions of people this really matters. “We know that basic mathematical fluency is an essential prerequisite for success in life, both at the level of employment and in terms of social success,” says Daniel Ansari, a cognitive neuroscientist at the University of Western Ontario in London, Canada. A report published in October 2008 by the British government claimed that dyscalculia cuts a pupil’s chances of obtaining good exam results at age 16 by a factor of 7 or more, and wipes more than £100,000 from their lifetime earnings. Early diagnosis and remedial teaching could help them avoid these pitfalls.

People with dyscalculia, also known as mathematics disorder, can be highly intelligent and articulate. Theirs is not a general learning problem. Instead, they have a selective deficit with numerical sets. Put simply, they fail to see the connection between a set of objects – five walnuts, say – and the numerical symbol that represents it, such as the word “five” or the numeral 5. Neither can they grasp that performing additions or subtractions entails making stepwise changes along a number line.

This concept of “exact number” is known to be unique to humans, but there is long-standing disagreement about where it comes from. One school of thought argues that at least some elements of it are innate, and that babies are born with an exactnumber “module” in their brain. Others

say exact number is learned and that it builds upon an innate and evolutionarily ancient number system which we share with many other species. This “approximate number sense” (ANS) is what you use when you look at two heavily laden apple trees and, without actually counting the apples, make a judgement as to which has more. In this view, as children acquire speech they map numberwords and then numerals onto the ANS, tuning it to respond to increasingly precise numerical symbols.

The debate over exact number is directly relevant to dyscalculics, as tackling their problem will be easier if we know what we are dealing with. If we have an innate exact number module that is somehow faulty in people with dyscalculia, they could be encouraged to put more faith in their ability to compare magnitudes using their ANS, and learn to use calculators for the rest. However, if exact number is learned, then perhaps dyscalculia could be addressed by teaching mathematics in ways that help with the process of mapping numbers onto the ANS. So how do the two models stand up? The innate number module theory makes one obvious prediction: babies should be able to grasp exact numbers. This was explored in the early 1990s. Using dolls, a screen and the fact that babies stare for longer at things that surprise them, developmental psychologist Karen Wynn, then at the University of Arizona in Tucson, showed that five-month-old infants could discriminate between one, two and three. They look for longer if the number of dolls that come out from behind the screen does not match the number that went in.

Some teams have taken a different approach to show that we are born with a sense of exact number. They argue that if exact number is learned, it ought to be influenced by language.

Brian Butterworth from University College London recently did tests of exact number on children aged 4 to 7 who spoke only Warlpiri or Anindilyakwa, two Australian languages that contain very few number words. He found no difference in performance between the indigenous children and a control group from English-speaking Melbourne (Proceedings of the National Academy of Sciences, vol 105, p 13179). This, he says, is evidence that “you’re born with a sense of exact number, and you > 24 January 2009 | NewScientist | 41

KATHY COLLINS/TAXI

map the counting words onto pre-existing concepts of exact numbers”.

Both of these approaches, however, have been criticised. Neuroscientist Stan Dehaene of the Collège de France in Paris points out that Wynn’s finding also fits the rival theory – that babies enter the world with only an intuition about approximate number.

This is because the ANS is concerned with ratios, so is reasonably reliable when the numbers involved are small, but falls off as the proportional size difference shrinks. A size ratio of 1:2 is more easily discernable than 9:10. Wynn tested babies on small numbers and, as Dehaene points out, “one versus two is a large ratio”.

Count on learning What is more, Dehaene has worked with an Amazonian tribe whose language only contains words for numbers up to five, and says it provides good evidence for the idea that exact number is learned (see “One, two, lots”).

Supporters of the idea that exact number is learned also point to research showing how young children actually acquire an understanding of numbers. First they learn what the number word “one” means, then “two” and so on until, around the age of 4, they suddenly grasp the underlying concept of the number line and counting. “There is something very special occurring in development with exact numbers, and with the understanding of number words,” says Dehaene.

For now, the idea that exact number is learned has the upper hand, suggesting that dyscalculia is a learning problem. To complicate things further, however, new research indicates that this may only be part of the story.

It was long thought that the ANS contributes little to performance in mathematics. As it is essential for survival skills such as foraging, it was assumed that everyone would have comparable abilities with approximate number. This myth was exploded in 2008 when Justin Halberda of Johns Hopkins University in Baltimore, Maryland, tested the ANS in 64 14-year-olds and was “blown away” by the variability he found (Nature, vol 455, p 665).

The teenagers, all of whom fell within the normal range for numeracy, watched an array of dots made up of two colours flash onto a computer screen. In each case, they had to say which colour was more numerous. As expected, their judgements became less accurate as the size ratio of the two sets shrank towards 1:1. The surprise was how much faster 42 | NewScientist | 24 January 2009

”First children learn what “one” means, then “two”, and so on until they suddenly grasp the underlying concept” accuracy fell off in some kids than in others, with the poorest performers having difficulty with ratios as large as 3:4.

There was a further surprise in store when the team compared the teenagers’ ANS scores with their mathematics test results from the age of 5 and up. “I literally jumped out of my seat when I saw the correlation going all the way back to kindergarten,” says Halberda. The link remained even after IQ, working memory and other factors had been controlled for, and it only held for mathematics, not for other subjects. A subsequent larger study, including

some children with dyscalculia, confirmed the suspicion that those with the number disorder had markedly lower ANS scores than children with average ability. This implicates a faulty ANS in dyscalculia.

Case closed? Not quite. The problem is that two other groups have come up with conflicting findings. In 2007, Laurence Rousselle and Marie-Pascale Noël of the Catholic University of Louvain (UCL) in Belgium reported that dyscalculic children, when asked to compare the magnitude of collections of sticks – say, five sticks versus

ONE, TWO, LOTS Amazonian hunter-gatherers called the Mundurucú only have words for numbers up to 5.

Does this affect the way they think about mathematical problems? Experts who think that the human concept of exact number is innate would predict not. However, Stan Dehaene of the Collège de France in Paris is among a growing number who believe that exact number is learned and therefore affected by our culture. He decided to test this idea with the Mundurucú.

Working with his colleague in the field, Pierre Pica, and others, Dehaene has found that the Mundurucú can add and subtract with numbers under 5, and do approximate magnitude comparisons as successfully as a control group. But last year the team discovered a big

A game like snakes and ladders can help children develop a sense of exact number

seven – performed no worse than controls.

However, they struggled when asked to circle the larger of two numerals, such as 5 and 7. Ansari’s team has obtained a similar result. Both teams conclude that in dyscalculic children the ANS works normally, and the problem comes in mapping numerical symbols onto it.

How to account for these contradictory findings? Halberda, Ansari and Dehaene believe that there may be different types of dyscalculia, reflecting different underlying brain abnormalities. So in some dyscalculic individuals, the ANS itself is damaged, while in others it is intact but inaccessible so that individuals have problems when it comes to mapping number words and numerals onto the innate number system.

The existence of such subtypes would make

cultural difference. They asked volunteers to look at a horizontal line on a computer screen that had one dot at the far left and 10 dots to the right.

They were then presented with a series of quantities between 1 and 10, in different sensory modalities – a picture of dots, say, or a series of audible tones – and asked to point to the place on the line where they thought that quantity belonged.

English-speakers will typically place 5 about halfway between 1 and 10. But the Mundurucú put 3 in the middle, and 5 nearer to 10 (Science, vol 320, p 1217).

Dehaene reckons this is because they think in terms of ratios – logarithmically – rather than in terms of a number line. By the Mundurucú way of thinking, 10 is only twice as big as 5, but 5 is five times as big as 1,

dyscalculia harder to pin down, and make it difficult to design a screening programme for schoolchildren. At the moment, the condition goes widely unrecognised, and testing is far from routine. But where it is tested for, the tests are relatively crude, relying on the discrepancy between the child’s IQ or general cognitive abilities and their scores in mathematics. Nevertheless, perhaps one day all children entering school will be assessed for various types of dyscalculia. Then teachers may be able to start intervention programmes based on teaching tools that are currently being tested.

One such tool, called The Number Race, in which children compete against a computer for rewards in a series of treasure hunts and other games, has been created by Dehaene and his colleague Anna Wilson. It assumes that the problem lies with the exact number system, so begins with tasks that the ANS is good at, involving numerical comparison, and gradually moves to more difficult tasks such as addition and subtraction. Testing of its effects is ongoing, but early indications are that it may help to bolster dyscalculic children’s concept of number and simple transformations of numerical sets.

Even those researchers who remain convinced that dyscalculia is caused by

so 5 is judged to be closer to 10 than to 1.

The team conclude that “the concept of a linear number line appears to be a cultural invention that fails to develop in the absence of formal education”. With only limited tools for counting, the Mundurucú fall back on the default mode of thinking about number, the so-called “approximate number system” (ANS). This is logarithmic, says Dehaene. When it comes to negotiating the natural world – sizing up an enemy troop or a food haul – ratios or percentages are what count.

“I don’t know of any survival situation where you need to know the difference between 37 and 38,” he says. “What you need to know is 37 plusor-minus 20 per cent.”

a faulty exact number module believe that intervention could help. “After all, genetics isn’t destiny – well, not entirely – and the brain is plastic,” says Butterworth. His team is testing a piece of software that it designed in collaboration with the London Knowledge Lab to strengthen dyscalculic schoolchildren’s basic number concepts. He suspects this will not be enough, however: “It may be the case that the best we can do is teach them strategies for calculation, including intelligent use of calculators, and get them onto doing more accessible branches of mathematics, such as geometry and topology.”

Ansari also points out that children with dyscalculia could be helped immediately by practical measures already in place in schools for pupils with dyslexia, such as extra time in exams. And, of course, simply recognising dyscalculia as a problem on a par with dyslexia would make a huge difference. As Jill says, now that she knows what her problem is, “it’s easier to have the confidence and the perseverance to keep working until I get it”. That, in turn, means the condition becomes less damaging to her self-esteem and perhaps, ultimately, to her chances in life. ■ Laura Spinney is a writer based in Lausanne, Switzerland 24 January 2009 | NewScientist | 43

You’ll want one of these Cast your mind back 30 years, if you are old enough, and you may just remember a rather humdrum, though retrospectively momentous, event. In 1979, the Japanese firm NET launched the first cellular phone network in Tokyo.

For decades the objects remained toys of the super-rich. Who would have thought that today there would be enough cellphones for half the world’s population to have one?

That’s not the only recent technological revolution.

Would you have dreamed that an entire record collection could one day fit in your pocket? How about a system that helps you communicate and share information across the world instantly?

Crystal-ball gazing is a fraught endeavour, but we’ve decided to take the plunge. Over the next six pages we assess the prospects of 10 of the coolest gadgets that in 30 years time may change our lives as much – or maybe more – than cellphones, iPods and the internet.

COMMENT ONLINE To let us know about the things we’ve missed, go to www.newscientist.com/section/tech

44 | NewScientist | 24 January 2009

1 Super-vision Who could ever pass up the chance to try on a pair of real X-ray specs? You may not always like what comes into view, but endowed with Superman-like vision, you would be able to see through solid walls, peer in at your neighbours or keep a watchful eye on your kids upstairs.

Unfortunately, they still don’t exist, despite what those ads at the back of children’s comics suggest. Yet there are some technological tricks that can give you the next best thing.

Unlike visible light, radio waves can pass through solid materials. In 2006, engineers at Cambridge Consultants in the UK announced they had built a briefcase-sized system called the Prism 200 which can detect people through a brick wall by firing off pulses of ultrawide-band radar and listening for returning echoes.

According to the company, these pulses can pass through building materials over 40 centimetres thick, and spot activity over a range of up to 15 metres. The device could

RUSSELL COBB

2

Disappearing act Few dreams have flipped from science fiction to fact as quickly as “invisibility cloaks”.The first, which worked only for microwaves, was unveiled in 2006. Since then the field has been inundated with attempts to make cloaks to rival Harry Potter’s.

Cloaking makes an object disappear by steering electromagnetic waves around it – as if the waves had simply passed through. So far, the only way to do this is with “metamaterials”, which are made of electronic components

designed to interact with light and direct it in a controllable fashion.

The goal is to create a cloak that works for a broad spectrum of visible frequencies. Making these components isn’t easy. They have to be tiny – smaller than the wavelength of light they are designed to interact with.

Last year, a group at the University of California, Berkeley, constructed a material that was able to bend – rather than reflect – visible light backwards for the first time. Ulf Leonhardt at the

be used to track people in hostage situations, the company suggests, but it has a crucial weakness. To avoid being blinded by walls and other fixed structures, it is designed to only register objects that generate rapidly varying echoes. In other words, it can only detect people when they move.

Even human statues would be hard pressed to avoid detection by Erwin Biebl’s radar sensor, however. Biebl’s team at the Technical University of Munich in Germany has built a device that can pick up tiny motions like breathing, or even a beating heart, through a closed door.

His team found that radio waves at between 433 megahertz and 24 gigahertz can pass through skin and bone but are partly reflected by the fatty layer surrounding muscles such as the heart. The team has exploited this by using the Doppler effect to pick up sub-centimetre changes in movement caused by a beating heart or the motion of the lungs. Colin Barras

University of St Andrews, UK, has shown how metamaterials could work over a range of frequencies.

Even more mind-boggling, a team from The Hong Kong University of Science and Technology in China has worked out how to cloak objects at a distance. They suggest using “complementary materials” which have optical properties that cancel each other out. A wave polarised on a single plane passing through one material will become distorted, but this distortion is cancelled out as the wave passes through the complementary material, making it look as if neither material is there. Justin Mullins

24 January 2009 | NewScientist | 45

3

Hands-free healing Modern cellphones may do more than a Star Trek “communicator” can, but Doctor “Bones” McCoy’s portable medical scanner, which revealed internal injuries in an instant, is taking longer to appear in the real world. When it does, it may go a step further: engineers are developing a portable scanner to not only spot internal injuries like torn arteries, but also heal them in a flash.

The secret of this device is highfrequency sound waves. Medics already use these ultrasound beams to examine babies in the womb. But turn up the intensity and focus the beam into a spot and it can generate enough heat to cook tissue.

Lawrence Crum at the University of Washington in Seattle has shown that high-intensity ultrasound can cauterise bleeding arteries. His company, Ultrasound Technology, has developed a hand-held device that allows surgeons to cut through blood-rich organs and cauterise the cut at the same time. Crum hopes to test it in humans this year.

Weak ultrasound beams can also be used to spot the fast flow of blood characteristic of a bleeding artery.

The US government’s Defense Advanced Research Projects Agency (DARPA) is funding a project to combine the two ideas, which will result in the Deep Bleeder Acoustic Coagulation system – a portable device that uses ultrasound to both spot and seal bleeding blood vessels.

The device will consist of an array of ultrasound transceivers built into a cuff that can be wrapped round an injured limb. Transceivers emitting low power ultrasound will scan for reflections from damaged arteries. If they spot a leaking blood vessel, the transceivers zap it. To avoid damage to healthy tissue, several beams are carefully focused to meet inside the body where their combined heat will seal the tear. Ben Crystall

46 | NewScientist | 24 January 2009

4

Spider vs gecko Peter Parker makes it look easy, but replicating his rooftop antics is so difficult it has had researchers climbing the walls for years. The problem is clear: the gloves and shoes of any Spider-Man suit must be able to support the weight of an average person while dangling from the side of a skyscraper. And of course hands and feet must also peel off easily when required – superglue is not an option.

For inspiration, researchers have turned to geckos rather than spiders. In 2003, Andre Geim at the University of Manchester, UK, designed a material with microscopic hairs that mimic those found on geckos’ feet. Intermolecular van der Waals forces, which take effect on tiny scales, encourage each hair to stick to the wall and, because a gecko’s feet are coated with millions of these hairs, the result is a powerful force of attraction. Geim’s material has

5

You power

Your cellphone is a marvel of the modern age. Yet no matter how sophisticated it is, it’s useless the moment it runs out of juice. But what if you could dispense with batteries and simply gather all the energy your gadget needs from the world around you?

For a start, you could plug it into your shirt. In 2008, Zhong Lin Wang at the Georgia Institute of Technology in Atlanta wove a fabric made from zinc-oxide nanowires grown on strands of Kevlar. Each time the material is bent or squeezed, it generates a tiny current.

Wang and his team found they could harvest

hairs made from a substance called kapton, and 1-centimetre-square of it, if pressed hard against a vertical surface, can support 1 kilogram.

But there may be problems scaling the materials up to a useful size. For example, the hairs need to be longer to provide a large enough surface area to support a person, and long hairs tend to tangle.

Nicola Pugno at the Polytechnic University of Turin in Italy might have the answer. In 2007, he came up with a fir tree-like design, with long carbon nanotubes forming a trunk while shorter nanotubes branched off sideways. He has now made gloves that can support around 10 kilograms each.

Nature still has the upper hand, however.

Dirt among the artificial hairs would compromise sticking ability. Geckos feet are self-cleaning, a trick way beyond current designs. Colin Barras

it by coating each fibre with a film of metal.

Gadgets implanted inside your body, such as pacemakers, could be powered by you.

David Tran’s team at Stanford University, California, have devised a heart-powered electricity generator. The gadget produces electricity by forcing a small magnet back and forth through a tiny wire coil. The magnet is housed in a liquid-filled silicone tube with a balloon attached to each end, and the whole device is placed within the heart. As the heart beats, the balloons are squeezed in turn, forcing the liquid – and the magnet – back and forwards through the tube.

Adam Heller at the University of Texas, Austin, has built a fuel cell that can be implanted in an artery and which uses glucose in the blood as fuel. Colin Barras

6 RUSSELL COBB

Jet packs Personal jets occupy a curious position in the world of dream machines because engineers have been building and flying them for decades. Rocket belts, as they are more accurately called, famously featured in the James Bond movie Thunderball in 1965, at the opening ceremony of the 1984 Olympic Games in Los Angeles, California, and in the pages of New Scientist in 2005. It is 40 years since the first rocket belt flew, but all these machines work in the same way – and suffer from the same fatal limitation.

Rocket belts generate thrust by catalysing the breakdown of hydrogen peroxide into rapidly expanding steam and oxygen. The trouble is that each machine can carry only enough propellent for about 30 seconds of flight. Who would want one of those?

In 1999, a company called Millennium Jet based in Santa Clara, California, built a personal flying machine with two vertically mounted rotors powered by a piston engine. Although promising, the machine crashed during a test flight and the company wound up operations in 2003.

And that might have been that, were it not for the Martin Aircraft Company of Christchurch, New Zealand, which last July launched an entirely different kind of jet pack. Its machine is powered by two turbojet engines, rather than a rocket engine. So it is a bona fide jet pack.

The turbojets turn two vertically mounted rotors that provide lift. The machine runs on standard auto fuel and it can fly for 30 minutes on the single tank, with a range of roughly 50 kilometres. It is fitted with a

parachute in case of emergencies.

The downside is that they cost about $100,000, the same as a high-end car. The company is already taking orders and hopes to deliver the first production machines in the second half of 2009. “I’d imagined it would be a rich boy’s toy but we’ve had interest from the military, searchand-rescue, and all kinds of groups,” says company founder Glenn Martin.

The Martin Jetpack is a little on the large side – it is not so much strap on, as walk into – but if you have always wanted to commute to work with a jet pack, its time to start saving. Justin Mullins

24 January 2009 | NewScientist | 47

7

My other car is a spaceship Fancy feeling the freedom of weightlessness or watching the sun set from orbit in your very own spaceplane? The prospect of zipping into space whenever you choose may not be as ludicrous as it seems.

The biggest hurdle is to find an affordable way to launch a craft into space. The usual approach – essentially stuffing a metal tube full of high-energy fuel and lighting one end – can cost as much as $100 million a shot. One way to reduce this is to add wings: the lift these generate helps a craft climb up through the atmosphere, reducing the amount of fuel needed, and thus the weight of the craft.

This is the strategy adopted by two private companies, Virgin Galactic and XCOR Aerospace, which are developing craft to ferry paying passengers into space.

When it begins operations in 2010, Virgin Galactic’s SpaceShipTwo will be carried to an altitude of 15 kilometres by a launch plane.

At that altitude the spacecraft will detach and its rocket will take over, blasting it into space.

XCOR’s smaller Lynx spacecraft will fly the whole way itself, taking off and landing like

8

Breathe underwater

Even with scuba gear, you can only stay underwater for as long as the meagre air supply on your back allows. Yet the ocean contains oxygen, so why can’t we swim around like fish, extracting the gas from the water as we need it?

In 2002, a diver spent half an hour submerged in a swimming pool doing just this, breathing oxygen extracted from the water by an artificial gill. The device was built by Fuji Systems of Tokyo, Japan, using high-tech silicon membranes. These are permeable to gases but not liquids, so oxygen can diffuse into the breathing air from the water, while carbon dioxide diffuses out – just like the gills of a fish.

But you won’t see divers using artificial gills any time soon,

48 | NewScientist | 24 January 2009

a plane. The company recently announced it will be charging $95,000 per ticket – about half the price of seats on SpaceShipTwo. The Lynx, however, will only travel to an altitude of about 61 kilometres and so will not officially reach space – classed as 100 kilometres and beyond – as SpaceShipTwo is intended to do.

Alternatively, why not dispense with on-board fuel completely? According to Leik Myrabo, an engineer at Lightcraft Technologies, your personal spacecraft could fly into orbit on a beam of microwaves shone upwards from the ground. Myrabo has spent a decade developing small spacecraft that are pushed upwards by a ground-based laser. The beam generates an explosive plasma when it strikes the underside of the craft, creating thrust that pushes it skywards. He has now devised a system that uses microwave beams which he says could carry a crewed “lightcraft” into low Earth orbit by 2025. Myrabo reckons he could power 1000 launches for the cost of a single conventional launch. “I can imagine personal spacecraft taking off within the next 50 to 100 years,” says Patrick Wood from space technology company EADS Astrium, based in Stevenage, UK. David Robson

because simple diffusion gills produce dangerously low levels of oxygen.

Israeli inventor Alan Bodner has tried to get around this problem with a gadget that exploits “the champagne effect”: gases dissolved in water bubble out when the pressure falls. Bodner has shown his method can produce a breathable gas. Problem solved?

Unfortunately not. We need a lot of oxygen and there just isn’t that much dissolved in a litre of seawater. So no matter how efficient the extraction method is, you would have to pump a huge volume of water through it to get enough. And while you do not need to carry air, you do need batteries and the means to make air, which means much more to go wrong.

Artificial gills may have a rosier future for other applications, however. Underwater robots powered by fuel cells could use gills to obtain oxygen. They are also likely to be used to get rid of excess carbon dioxide from submarines and underwater habitats, perhaps boosting the oxygen supply at the same time. Michael Le Page

9

10

RUSSELL COBB

You speak, it translates In The Hitchhiker’s Guide to the Galaxy, Douglas Adams imagined a small yellow fish, called a Babel fish. When popped into one’s ear, it would use brainwave energy, unconscious mental frequencies and something called a “telepathic matrix” to achieve real-time language interpretation, making conversations with aliens effortless.

Well, it’s not yellow, and it doesn’t fit in your ear, but US soldiers in Iraq are using a device that could become a universal interpreter.

The soldiers use a system called IraqComm, developed by SRI International in Menlo Park, California, which consists of a laptop loaded with speech recognition and translation software. Speak into the microphone in Arabic and the software turns the phrases into written Arabic, before translating it into English. After the person has finished talking, a computer voice speaks the translation.

IraqComm’s software, and other programs like it, learned to translate much as a person would – by studying conversations. The software searches for statistical connections between a series of Arabic statements and English translations. For example, when the Arabic word “haar” appears, so does the word “hot” in the English version (the correct translation). If this occurs frequently enough, the program concludes that they mean the same thing. Given enough examples, the software can learn grammar too. A similar system running on a hand-held PDA, called the Speechalator, was developed at Carnegie Mellon University in Pittsburgh, Pennsylvania.

Do not expect these programs to cope with free-flowing language just yet. The IraqComm works well because it focuses on around 50,000 words soldiers need. The broader the subject matter, the harder it becomes for the software to distinguish the alternate meanings required in different contexts. “We’ll get there,” says SRI’s Kristin Precoda. Jim Giles

Smell-o-vision Whether it is the mouthwatering aroma of a roast dinner, the intoxicating perfume of a woman or the sulphurous smell of gunpowder in the heat of a battle, scent is a powerful force. So imagine the impact of TV and video games if scenes were accompanied by their aromas.

That is the idea behind smell-o-vision: giving TVs the ability to produce smells that fit the scenes they are displaying. We still don’t know why we perceive certain molecules to have particular scents and so cannot predict the scent of a novel molecule, nor manufacture a novel molecule to have a particular scent. However, recent advances mean some of these scientific hurdles can be side-stepped, and suggest “smell-o-vision” may become a reality even before we truly understand how olfaction works.

We group scents into about three-dozen categories, such as woody, grassy, faecal, floral and so on, says Avery Gilbert, an olfactory scientist who worked with DigiScents, a now-defunct company that developed smell-o-vision technology in

the late 1990s. DigiScents built a prototype device that could generate most everyday odours. The smells were not perfect replicas but they were recognisable, says Gilbert.

The silver screen is no stranger to smello-vision. It began in crude form in cinemas in the 1950s and has recurred periodically ever since. Most recently, in various scenes in select screenings of the film The New World.

If it was not difficult enough already, emitting aromas for smell-o-vision has further down sides. How do you prevent the scents you release mixing into an unintended cocktail, or lingering longer than the scene requires? Researchers at Sony may have the answer: avoid the nose completely and go straight for the brain (New Scientist, 7 April 2005, p 10). The company’s plans were revealed in a patent application which described the idea of using ultrasound signals to directly stimulate selective parts of the brain to induce scents in a viewer’s or game player’s mind. Unfortunately, to date there has been no whiff of Sony producing the hardware required. Bijal Trivedi ■

24 January 2009 | NewScientist | 49

MATTHEW RICHARDSON

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F

OR most of us the universe is unimaginably vast. But not for cosmologists. They feel decidedly hemmed in. No matter how big they build their telescopes, they can only see so far before hitting a wall. Approximately 45 billion light years away lies the cosmic horizon, the ultimate barrier because light beyond it not has not had time to reach us.

So here we are, stuck inside our patch of universe, wondering what lies beyond and resigned to that fact we may never know. The best we can hope for, through some combination of luck and vigilance, is to spot a crack in the structure of things, a possible window to that hidden place beyond the edge of the universe. Now Sasha Kashlinsky believes he has stumbled upon such a window.

Kashlinsky, a senior staff scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, has been studying how rebellious clusters of galaxies move against the backdrop of expanding space. He and colleagues have clocked galaxy clusters racing at up to 1000 kilometres per second – far faster than our best understanding of cosmology allows.

Stranger still, every cluster seems to be

rushing toward a small patch of sky between the constellations of Centaurus and Vela.

Kashlinsky and his team claim that their observation represents the first clues to what lies beyond the cosmic horizon. Finding out could tell us how the universe looked immediately after the big bang or if our universe is one of many. Others aren’t so sure.

One rival interpretation is that it is nothing to do with alien universes but the result of a flaw in one of the cornerstones of cosmology, the idea that the universe should look the same in all directions. That is, if the observations withstand close scrutiny.

All the same colleagues are sitting up and taking notice. “This discovery adds to our pile of puzzles about cosmology,” says Laura Mersini-Houghton of the University of North Carolina, Chapel Hill. Heaped in that pile is 95 per cent of the universe’s contents, including the invisible dark matter that appears to hold the galaxies together, and the mysterious dark energy that is accelerating the universe’s expansion. Accordingly, Kashlinsky named this new puzzle the “dark flow”.

Kashlinsky measures how fast galaxy clusters up to 5 billion light years away are

travelling by looking for signs of their motion in the cosmic microwave background, the heat left over from the big bang. Photons in the CMB generally stream uninterrupted through billions of light years of interstellar space, but when they pass through a galaxy cluster they encounter hot ionised gas in the spaces between the galaxies. Photons scattered by this gas show up as a tiny distortion in the temperature of the CMB, and if the cluster happens to be moving, the distortion will also register a Doppler shift.

In any individual cluster, this shift is far too small to detect, which is why no one had ever bothered looking for it. However, Kashlinsky realised if he combined measurements from a large enough number of clusters, the signal would be amplified to a measurable level.

Kashlinsky and his team collected a catalogue of close to 800 clusters, using telescopes that captured the X-rays emitted by the ionised gas within them. They then looked at the CMB at those locations, using images snapped by NASA’s WMAP satellite. What they found shocked them. Galaxy clusters are expected to wander randomly through their particular region of space, because matter is >

They call it dark flow, and it could be a signal from beyond the cosmic horizon. Amanda Gefter investigates

Another universe comes calling 24 January 2009 | NewScientist | 51

”The dark flow could be a sign that our bubble universe crashed into another soon after the big bang” distributed in uneven clumps, creating local gravitational fields that tug on them.

Over large scales, however, matter is assumed to be spread evenly, so on these scales the clusters should coast along with space as it expands. What’s more, everything in the standard model of cosmology suggests that the universe should look pretty much the same in all directions.

Out of bounds So what is behind the dark flow? It can’t be caused by dark matter, Kashlinsky says, because all the dark matter in the universe wouldn’t produce enough gravity. It can’t be dark energy, either, because dark energy is spread evenly throughout space. That, leaves only one possible explanation, he concludes: something lurking beyond the cosmic horizon is to blame.

Before the findings were published in October in The Astrophysical Journal Letters (vol 686, p L49), Kashlinsky knew how heretical his idea would seem . “We sat on this for over a year checking everything,” he says.

“It’s not what we expected or even wanted to find, so we were sceptical for a long time. But ultimately it’s what’s in the data.”

No one knows exactly what might lurk over the horizon or indeed how large the cosmos is (see “Just how big is the universe?”, page 53) But Kashlinsky suspects it is a remnant of the chaotic state that existed just a fraction of a second after the beginning of time, before a phenomenon known as inflation took hold.

It is generally thought that our universe began as a tiny patch in some pre-existing space-time forming a bubble which then underwent a burst of exponential expansion.

This period of inflation stretched and smoothed our universe, leaving an even distribution of matter and energy. Outside this bubble, far beyond our cosmic horizon, things might look very different. Without inflation’s ironing skills, space-time could be highly irregular: smooth in one neighbourhood and with massive structures or giant black holes in another. “It could be as bizarre as one can imagine, or something 52 | NewScientist | 24 January 2009

rather dull,” says Kashlinsky. Either way, he suggests that something outside our bubble is tugging on our galaxy clusters, causing the dark flow.

Other, more radical, explanations for dark flow have also been floated. It is possible – even likely, some say – that ours wasn’t the only bubble to inflate out of primordial space-time. In this “eternal inflation” scenario, bubbles pop up all all over the place, each defining its own universe within a larger multiverse.

Many cosmologists are happy to relegate those other universes to that dusty corner of theory where unobservable by-products are stored. Mersini-Houghton is not one of them.

She argues that the dark flow is caused by other universes exerting a gravitational pull on galaxy clusters in our universe. She and her colleagues calculated how other universes, scattered at random around our bubble, would alter the gravity within it (www.arxiv. org/abs/0810.5388). “When we estimated how much force is exerted on the clusters in our universe, I was surprised that the number matched amazingly well with what Kashlinsky has observed,” she says.

“I firmly believe that this is the effect of something outside of our universe.”

Others believe dark flow could be a sign that our bubble universe crashed into another bubble just after the big bang. In eternal inflation each bubble universe can pop into existence with its own unique set of particles and forces of nature, so collisions between bubbles can have dramatic consequences.

If two universes with the same physics collide, they will generate a burst of energy, then merge. However, if two very different universes collide, a cosmic battle ensues. At the site of the crash, a wall of energy called a domain wall will form, holding the two incompatible worlds apart. The bubble with lower energy then expands, sending the domain wall sweeping through its rival, obliterating everything in its path.

If our universe underwent such a collision, any lingering evidence of the cosmic wreckage should appear in the part of the sky facing the impact site. The collision’s impact should distort space, and that would in turn affect how light rays, including the CMB, travel through it and how large-scale structures, including galaxies and clusters, evolve.

Looking out across the sky today, we would expect to see the universe exhibiting strange properties in the direction of the collision.

The collision might have imprinted a special direction onto the CMB, says physicist Anthony Aguirre of the University of California, Santa Cruz. “As you move away from the special direction, the temperature [of the CMB] would change.” Physicists are now combing the data looking for the hallmarks of such a shift. Whenever there are weird things happening on a large scale within the galaxy, the remnants of a collision are a candidate for explaining it, Aguirre says.

A completely different take on dark flow

Edge of the universe The “dark flow” of wayward galaxy clusters that appear to be pulled in one direction could give us our first hint of something beyond the cosmic horizon, which normally marks the limit of the observable universe Dark flow of galaxy clusters OBSERVABLE UNIVERSE COSMIC HORIZON (45 billion light years from observer) OBSERVER

Expansion of space-time

Dense patch of space-time attracts galaxy clusters inside the cosmic horizon

JUST HOW BIG IS THE UNIVERSE?

MATTHEW RICHARDSON

It is 13.7 billion years since the big bang, so light now reaching us cannot have started its journey longer ago than that. Yet the most distant object we could conceivably see today lies further away than 13.7 billion light years. That’s because throughout the life of the universe, space has been expanding. Taking this into account, cosmologists calculate that the edge of our observable universe is now approximately 45 billion light years away.

Beyond that, who knows? The inflation theory of cosmology predicts that the universe grew from a bubble.

Just how big that bubble has now become depends on how long inflation lasted. If it continued for a very long time – in this context “very long” is still only a fraction of a second – then the edge of our universe might lie far beyond the 45-billion-light-year limit of our vision. That could also rule out the possibility of observing the influence of other universes on our own. As physicist Matthew Kleban of New York University puts it: “It’s totally possible that we live in a multiverse and we’ll never know because there’s been so much inflation.”

comes from Luciano Pietronero and Francesco Sylos Labini of La Sapienza University in Rome, Italy. They say the standard cosmological model is wrong, and that a different model might explain the motion of galaxy clusters that Kashlinsky found. “This is just another element pointing toward the fact that the standard picture of galaxy formation is not correctly describing what is going on in the real universe,” Pietronero says.

Predictions of the motion of galaxy clusters based on the conventional model assume matter is evenly distributed throughout space on very large scales. Pietronero and Sylos Labini claim analysis of the distributions of galaxies and galaxy clusters throughout the sky shows that this is not true, and that at large scales matter is like a fractal. If that is the case, the gravitational field throughout the universe would also be irregular and could lead to the effects Kashlinsky observed. New results from the Sloan Digital Sky Survey, which has already mapped about a million galaxies, will help give Pietronero and Sylos Labini a more precise picture of the spread of matter, which they hope will confirm their ideas. “I think we will have interesting news very soon,” says Sylos Labini.

A fractal universe would, however,

raise big problems of its own. For one thing, a fractal distribution of matter is incompatible with cosmic inflation, so theorists would be left to figure out how it arose in the first place (New Scientist, 10 March 2007, p 30) .

Probing the multiverse Physicist Douglas Scott of the University of British Columbia in Vancouver, Canada, is also sceptical that dark flow is evidence of anything outside our observable universe.

“There is no reason at all to expect it to come from structures beyond the horizon,” he says. Scott notes that so far dark flow has only been observed out to distances that are only a few per cent of the total distance to the horizon. “If the effect is real,” he says, “then the likely explanation would be some very large-scale structure, but still within the horizon.” Such a structure, though, would still present a major challenge to cosmology’s standard model.

The most important thing now is to confirm that dark flow is real and that it continues all the way out to the cosmic horizon. Two other teams have made measurements consistent with Kashlinsky’s results, but only on scales less than 200 million light years – just a short step

compared to the distance out to the horizon.

To confirm their finding, Kashlinsky’s team will be analysing more recent WMAP data and working with researchers at the University of Hawaii on data from an all-sky X-ray catalogue. The tiny Doppler effect that Kashlinsky uses to measure the clusters’ velocities is only observable in bulk, which means the more galaxy clusters he can look at the better. “If confirmed, this will be an exciting way of probing the ultimate structure of the universe and perhaps even the multiverse,” Kashlinsky says. “But you have to check and recheck.”

“If this thing is confirmed and it is real, it will be incredibly important,” says Aguirre, “on the same order of discovery as the realisation that those little smudges on the sky are other galaxies. The most important thing it would tell us is that the standard picture is broken in some way. And the most exciting thing it could tell us is that there are other universes.” If it does, space and time will open up to reveal a reality that is so much bigger than we know. When that happens, those claustrophobia-stricken cosmologists will finally be able to breathe easy. ■ Amanda Gefter is an editor at New Scientist 24 January 2009 | NewScientist | 53

HISTORIES

One hundred years ago in a lab at Harvard University, a young zoology student was busily overseeing the breeding of pair after pair of brother and sister mice. The “Mouse Man”, as he was known on campus, was trying to create the first inbred lab animal – a strain of mouse whose genes would be stable and identical. Such a mouse would allow biologists to reliably replicate their experiments for the first time. His professor said it couldn’t be done, but the Mouse Man proved him wrong. We are all indebted to those inbred mice and their descendants, which have helped researchers develop treatments for a wide range of human diseases.

WELLCOME LIBRARY, LONDON

The Mouse Man of Maine IT BEGAN with one small mouse and a simple, if tedious, instruction. Clarence Cook Little was a Harvard undergraduate when his zoology professor thrust a live mouse across the lab bench and told him to learn everything he could about it. Little went one better. In the third year of his degree, in 1909, he created the first inbred strain of mouse, providing researchers with a homogeneous genetic background on which to experiment. Before that, they could never be certain whether the results of their research were genuinely the result of an experiment or stemmed from genetic inconsistencies in their test animals.

Little, the great-grandson of America’s most famous patriot, the Revolutionary Paul Revere, would remain a champion of the laboratory mouse all his life. He was particularly interested in cancer and was convinced that the key to understanding the disease lay in the study of genetics and that the best way to study genetics was by using inbred mice.

In 1929, the student who had once sketched mice in the margins of his zoology notes founded the Jackson Laboratory, a centre for research into mouse genetics, in Bar Harbor, Maine. But even he could not have foreseen the enormous power of inbred strains, says Steve Brown, director of the Mammalian Genetics Unit at MRC Harwell in Oxfordshire, UK. 54 | NewScientist | 24 January 2009

“The concept of creating inbred strains is fundamental to genetic studies,” says Brown.

Today, Little’s original lab mouse has been joined by thousands of strains. About 25 million mice are used in labs around the world each year, making it the most common animal research model. Tiny Mus musculus has helped clarify the nature of a raft of human illnesses, from cancer and diabetes to Alzheimer’s disease and obesity. Crucially, the lab mouse has been a stand-in for humans, testing treatments which have led to the development of drugs for rheumatoid arthritis, leukaemia and osteoporosis to name but a few.

While Little is indisputably the man behind modern lab mice, he was not the first to experiment with them. Researchers of yore recognised that mice share many physiological systems with humans. They are also easy to feed and house, have a three-week gestation, produce large litters and reach maturity in just 10 weeks. They have one other big advantage, says Karen Rader, a historian at Virginia Commonwealth University in Richmond, who has written the definitive book on lab mice, Making Mice. “The mouse is enough like us that results can apply to us, but not so much like us that people get upset about conducting experiments on them.”

In fact, the lab mouse might have got off to a much earlier start if Gregor Mendel – the father of genetics – hadn’t been thwarted by his bishop. In the 1850s, Mendel began his investigation of inheritance by studying coatcolour traits in mice. But he was a monk and his bishop decreed that a monastery was no place to experiment with copulating mice.

Mendel switched to a study of peas.

Nor were biologists the only people to experiment with mice. Breeders of fancy mice had tinkered with mouse genes for centuries.

Seventeenth-century illustrations show how people in Japan bred and collected unique strains, creating albinos and mice with spotted coats. They also bred “waltzing mice” that seemed to dance, a peculiarity later discovered to be the result of an inner-ear defect.

By the 20th century, such breeders had established clubs and exhibited their prize specimens at mouse shows. As a student, Little often judged these shows at the behest of his professor William Castle, who saw it as way to

For our histories archive, visit www.NewScientist.com/topic/histories

THE JACKSON LABORATORY

Clarence Cook Little shows off his creations at the Jackson Lab

“Judging fancy mouse shows was a way to scout for interesting mutants” scout for genetic mutants of interest to science. It was this link to mouse fanciers that ultimately led to Little’s lab mouse.

More specifically, it led to one mouse fancier, retired schoolteacher Abbie Lathrop. After a failed attempt at raising poultry, Lathrop hoped to make a living from the fancy mouse craze and began to breed popular strains on her farm in Granby, Massachusetts. She soon attracted scientific customers. “I know it sounds bizarre, in terms of genetics, that people would seek out this mouse breeder on a farm in Granby,” says Rader. “But she always had the best mice. She was a local celebrity.”

Lathrop was also a scientist in her own right.

When she noticed some of her mice suffered from skin lesions, she sent samples to her scientific clients, including Leo Loeb, a

pathologist at the University of Pennsylvania.

He confirmed Lathrop’s suspicions that the lesions were cancerous and the pair spent the next five years publishing joint research on tumour transmission in mice.

Little, meanwhile, had recognised the potential in Lathrop’s stock. Lathrop had bred many generations of brother and sister mice to create unique strains, and such relative genetic similarity would make an excellent starting point for his work. Little began his project largely because he needed to do some independent research to qualify for Harvard’s doctoral programme, but he was also eager to prove one of Castle’s hypotheses wrong, says Rader. Castle believed interbreeding could never create a stable and pure genetic strain.

He also doubted that the mice would remain fertile after generations of inbreeding.

Indeed, Little soon found he had taken on something of a challenge. As fancy mouse breeders had already discovered, few progeny of brother-sister matings survive. Litters are

small and the young sometimes sterile.

But Little eventually found a strain that flourished. He named it dilute brown nonagouti (DBA) – dilute because it had less pigment than its wild cousins, brown as opposed to the more common black, and non-agouti because it didn’t have the grizzled-looking fur of other mice.

By 1947, scientists understood the value of inbred mice. That year, the Jackson Laboratory was destroyed in a fire that consumed the town of Bar Harbor, killing 14 people and 90,000 mice. The following day, research institutes and individual geneticists who had acquired mice from the lab began sending back breeding pairs so that Little could re-establish his colonies, says Rader.

Little claimed to have received just one angry letter from an anti-vivisectionist women’s club, which suggested it might have been better if he and his scientists had burned instead of the mice. Anti-vivisectionists of the time were largely concerned with cats and dogs. The public’s sympathy rarely extended to rodents, which were regarded as vermin and carriers of disease.

The return of the mice paved the way for two important discoveries. George Snell’s studies of tumour transplantation and rejection in mice in the late 1940s laid the foundation for modern immunology.

Without it, human organ transplants would be impossible. Another of the rebuilt lab’s scientists, Leroy Stevens, also made great strides with his own studies of tumour transplantation, which eventually led to the discovery of embryonic stem cells.

The decoding of the mouse genome in 2002 opened up still greater possibilities.

We now know that 99 per cent of human genes have a comparable version in mice and many of them are located in the same place on the chromosome. That means scientists can work out the role of any human gene by creating mice lacking the equivalent gene. When the mice exhibit a defect, scientists can pinpoint the gene’s function and test treatments.

“Little wouldn’t have dreamed about this, but he would have been thrilled,” says Rader.

Indeed, on his 80th birthday in 1968, Little drew a cartoon of a lab mouse on a pedestal.

The drawing shows him looking up at the mouse which says: “You’re not so damn smart.

You’ve had 80 years. Look what my family has done in 39 years.” Sharon Oosthoek ■ Further reading: Making Mice: Standardizing Animals for American Biomedical Research, 1900–1955, by Karen Rader, Princeton University Press (2004) 24 January 2009 | NewScientist | 55

BOOKS & ARTS

Fighting over the underdog Neil deGrasse Tyson made some unlikely enemies when he supported Pluto’s planetary demotion

Reviewed by David Shiga

IN LATE 2006, Neil deGrasse Tyson received an angry letter: “Dear Mr Tyson… Why do you think Pluto is no longer a planet?

I do not like your anser[sic]!!! … Pluto is a planet !!!!!!!” signed, “your friend Emerson York”. It was one of a stack of cute hate mail from thirdgrade students in Pennsylvania.

The letters were prompted by the controversial new definition adopted by the International Astronomical Union that year, which required a planet to have “cleared the neighbourhood around its orbit” in addition to orbiting the sun and being round.

This led to an embarrassing downgrade to “dwarf planet” for Pluto, which resides in the Kuiper belt, a zone populated by countless small, icy objects.

Though Tyson was not directly responsible for the definition, he had been considered “a public enemy of Pluto lovers the world over” since 2001, he says. That’s when a New York Times article drew attention to a provocative solar system display Tyson had installed at New York’s Hayden Planetarium, where he is director.

The display showed only eight planets, Mercury through Neptune. Pluto was placed with other diminutive, frozen denizens of the solar system’s fringes, with the apparent implication that it was nothing but a glorified chunk of distant debris.

56 | NewScientist | 24 January 2009

favorite planet,” adding, “Please Now, in The Pluto Files, Tyson write back, but not in cursive offers a highly entertaining history of Pluto with an emphasis because I can’t read in cursive.”

Most fascinating about the on its place in culture, especially book is what it reveals about in the US, where affection is the public’s relationship with strong for an object jokingly astronomy. While scientists described by one NASA scientist seeking funding tend to as a “true-blue American planet”. emphasise the potential practical We learn that the name Pluto, benefits of their work for fear that however, was suggested by an 11-year-old English girl, and would “There is intense public have been an unlikely pick from interest in what’s out an American. At the time of there in the solar system, Pluto’s discovery in 1930 by no matter how distant” US astronomer Clyde Tombaugh, its name was associated in the people will not otherwise support US with Pluto Water, a laxative promoted with the slogan: “When it, the planet controversy shows that there is intense public nature won’t, Pluto will.” interest in what’s out there in Equally enjoyable are letters the solar system. No matter how from school kids taking Tyson to distant or disconnected from task. “Dear Scientest [sic]… some daily life, planets are personal. people like Pluto… If it doesn’t Last year I attended a debate exist then they don’t have a DARREN PHILLIPS/AP/PA

The Pluto Files: The rise and fall of America’s favorite planet

by Neil deGrasse Tyson W. W. Norton & Co, $23.95

over the planet question between Tyson and Mark Sykes, director of the Planetary Science Institute in Tucson, Arizona. Sykes argued that when objects are massive enough for gravity to shape them into spheres, their gravity also radically transforms their interiors. This triggers geological activity – such as volcanic eruptions soon after the object’s formation – that shapes its surface in ways that less massive bodies, like small asteroids, never experience.

For the purpose of understanding the detailed properties of individual objects, then, there is a case to be made for distinguishing between those that are massive enough to become round, which we might call planets, and those that are not – a point I wish Tyson had made in The Pluto Files. There is little space in the breezy book to delve deeply into planetary science, but this distinction deserved a sentence or two.

While Tyson emphasises the things that set Pluto apart from the eight official planets, like its cluttered and elongated orbit, he does not argue against calling it a planet. We should spend less time classifying objects as planet or non-planet, he says, and more time thinking about the myriad ways to group them, from size and composition to formation history and weather. He makes a good case for moving beyond the definition debate, but it is unlikely to sway the hordes of devoted Plutophiles – especially the angry correspondent who told Tyson: “Pluto is a planet because I say so.” ■ David Shiga is a physical sciences reporter for New Scientist

For more reviews go to www.NewScientist.com/topic/books-art

Full metal warriors

NORTHROP GRUMMAN

The new world of remote warfare is eerily fascinating, and more than a little chilling

Wired for War: The robotics revolution and conflict in the 21st century by P. W. Singer, Penguin Press, $27.95 Reviewed by Jeff Hecht

ANYONE who thinks robot warfare is science fiction should talk to my plumber.

His cousin got into the US Air Force Academy, but isn’t aiming to be a top gun. Instead, the cadet is training to fly remotely controlled robotic aircraft from the safety of a chair, far from enemy fire. The plumber considers that a smart move; fighter pilots can get killed.

If you want the whole story of remote warfare, pick up a copy of Wired for War, in which Peter Singer, a fellow of the non-profit Brookings Institution in Washington DC, exhaustively documents the Pentagon’s penchant for robotics. Think of it as the next step in the

mechanisation of war: swords and arrows, guns, artillery, rockets, bombers, robots. In fact, robotics is not a new passion. In the 1980s, President Ronald Reagan talked of building a fleet of robotic battle satellites that could automatically destroy Soviet nuclear missiles before they reached US targets.

Now, robotic systems are being used for real. Unmanned aerial vehicles such as the aptly named Predator fly reconnaissance missions in the Middle East. If they spot “bad guys”, they can mark them with laser bullseyes that “smart” bombs can target.

On the ground, wheeled robots go places too dangerous for soldiers, checking for hidden insurgents and defusing the improvised explosive devices (IEDs) which have taken a heavy toll in Iraq.

Field troops are enthusiastic, too, reporting that robots save lives. And the US navy sports autonomous undersea vehicles that can be programmed to spend hours searching underwater.

So what’s not to like about turning war over to the robots?

For starters, people are sure to get in the way, and robots sometimes pick the wrong targets. Singer cites a chilling example from 1988, when the high-tech radar on the USS Vincennes mistook an Iranian airliner for an F-14 Tomcat fighter jet coming in for an attack. The ship’s crew shot it down, killing 290 civilians. Even soldiers can have a hard time sorting the insurgents from the civilians; spread autonomous robots around and deadly encounters on a smaller scale could become daily tragedies.

But the greatest danger is that turning battles over to the robots could give the illusion that wars can be won with little human cost, encouraging high-tech powers to launch wars on whims.

Singer’s book examines robotic warfare, its origins and consequences. Its 436 pages are rich with food for thought, such as a section on the role of sci-fi in inspiring military planners, but it is also overflowing with details – a few of them questionable – which blunt Singer’s points and make the book drag. Military robotics are important, but bloat hurts an otherwise good book.

Jeff Hecht is a consultant for New Scientist in Boston, Massachusetts

Life as we know it Every Living Thing: Man’s obsessive quest to catalog life, from nanobacteria to new monkeys by Rob Dunn, HarperCollins, £15.99/$26.99 Reviewed by John Whitfield

IF YOU think that cataloguing life is largely a matter of butterfly nets and flower presses, you might be surprised by the range of science covered in Every Living Thing. The usual suspects are here, such as Linnaeus and those who have devoted their lives to ferreting

out an inordinate variety of beetles from tropical forests. But the life we can see is just the start: microscopes and DNA sequencing have revealed whole new realms living in extreme environments such as undersea hot springs. Rob Dunn even looks at the search for life elsewhere in the universe, weaving scientists’ stories cleverly with those of their science.

While species-counting is important, cataloguing life is about more than accountancy. It is about understanding what life is, where it came from, and what it is capable of. The harder we look, he shows, the stranger and more spectacular the answers become.

Special teens Teenagers: A natural history by David Bainbridge, Portobello Books, £14.99 Reviewed by Kate Douglas

AT A time when youth culture is feared and demonised, here is a welcome antidote. As well as providing a highly readable account of the physical, emotional and mental changes that occur in the second decade of life, David Bainbridge argues that teenagers are the most impressive creatures on the planet. The evolution of adolescence, he contends, is what allowed the human brain to make its “great leap forward”.

Bainbridge’s thesis is thoughtprovoking, if not entirely convincing. Recent research leaves no doubt that the teenage years are special, but was the emergence of adolescence, between 800,000 and 300,000 years ago, necessary for us to become fully human?

Surely the adult brain could be rewired without all that teenage angst? Perhaps, instead, the evolution of rebellious, creative teenagers who see the world afresh each generation is what allows our species to be so adaptable to whatever life should throw at us.

24 January 2009 | NewScientist | 57

BOOKS & ARTS

Photography: Peter Wasilewski

Painting with ice This is a “frizion”, and it was created by NASA scientist and artist Peter Wasilewski. Rather than painting on canvas like most artists, he creates his images with polarised light and ice.

To do this, Wasilewski takes a Petri dish of ice in the process of freezing, sandwiches it between two polarising filters and passes white light through. The first filter polarises the light, causing all the rays to vibrate in the same plane.

Ice crystals split polarised light

58 | NewScientist | 24 January 2009

into two rays which travel at different velocities through the ice, so when the rays are recombined at the second polarising filter there is a phase difference between them.

This causes interference, creating the startling colours in the image.

The colours are determined not only by the lattice structure of the ice, but also by its thickness. By controlling the thickness, for example by varying the temperature of the surrounding water, Wasilewski produces a wide variety of different patterns.

Wasilewski’s day job is studying the magnetic properties of meteorites and rocks from the moon and Earth. He learned about this peculiar property of ice crystals while studying samples he had collected from the pale blue ice near the Transantarctic mountains that divide east and west Antarctica. Water ice can also be found in the frozen oceans of Jupiter’s moon Europa, near the Martian poles, in the tails of passing comets and even in the dense clouds of matter from

which stars form. The lattice structures of these ice crystals vary because of the different temperatures and pressures present when they form. Only the ice found on Earth is known to have the correct structure to produce a frizion. Lucy Dodwell ■ A selection of frizions is currently on display at the Alaska State Museum in Juneau. To see more frizions visit: www.newscientist.com/topic/ books-art

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FEEDBACK

they were sure they were hearing real left and right stereo. But Sony then merged with BMG and laid off the people planning to release CDs of “Stokie in stereo”.

Refusing to let the matter rest there, the Leopold Stokowski Society managed, after a long battle, to get clearance to release those recordings of Wagner’s Ride of the Valkyries and Mendelssohn’s Midsummer Night’s Dream in “stereo”. Edward Johnson writes in the latest issue of the society’s journal: “Nay-saying listeners can now explain how such vivid instrumental separation can be obtained from one mono source.”

Let fresh battle commence.

THIS week, as we approach the 200th anniversary of Darwin’s birth, Feedback invites readers to provide 50 words on the thoughtprovoking theme of: “Things you would never have heard Charles Darwin say about evolution.”

The editors will reward what we judge the wittiest non-Darwinism with the framed original of the beautiful artwork in “Uprooting Darwin’s tree” on page 31 of this issue, signed by the artist Yulia Brodskaya.

You may enter the competition by email – with the subject line “Darwin Competition”, please – or by fax or post or by going to www.newscientist.com/article/ dn16399. The competition closes on Monday 16 February. The winning entry and the best runners up will be published in the 7 March issue of New Scientist.

THE recording world, Feedback reported three years ago, has been split over “accidental stereo”

(18 March 2006). In the old vinyl days, it was standard practice to cut two blank wax discs at the same time, in case one was a dud. Usually the two discs were fed from the same microphone, but if two microphones were used, the two discs would have accidentally captured stereo – or so some engineers claimed.

Others disagreed vigorously, so much so that EMI’s planned 1992 UK release of an accidental stereo recording of Elgar’s The Kingdom: Prelude was abandoned. A later “stereo” release by UK independent record label Naxos of the same composer’s Cockaigne Overture failed to resolve the issue, as professionals who listened to it clashed over whether it really was in stereo.

Now the argument has started all over again. A few years ago in the US, Sony Music found a stash of originals by Leopold Stokowski and his All-American Youth Orchestra that had been recorded in 1941. The discs were in pairs marked L and R rather than the usual A and B, and when the Sony engineers listened,

Arms full, Andy Thomson approached the sliding doors in a London store. When they didn’t open, he noticed a sign beside them saying: “Customers should use push buttons to open automatic doors” 84 | NewScientist | 24 January 2009

SEATED and with a few moments to spare, Dan Barrett tells us, he found himself reading the packaging of some Andrex toilet paper, as one does. He learned that it contained eight rolls of 2-ply tissue. Fair enough, he thought – but it went on to tell him that there was an average of 360 sheets per roll, that average sheet size was 124 × 110 millimetres and that average roll length was 44.64 metres. This, he thought, was getting a bit silly – but the clincher, which applied to the entire pack, was: “Average total area 39.28 square metres.”

“Are others finding a use for the product that I don’t know about, such as wallpapering?” he wonders. “And why are they not using a more standard unit of measurement, such as the football field?”

WITH the recent holiday period still fresh in his mind, Daniel Livingstone calls our attention to a UK broadcast in the run-up to Christmas on BBC Radio 1’s Newsbeat. In it, Rachel Vreeman and Aaron Carroll of the Indiana University School of Medicine, Indianapolis, debunked some “Festive Medical Myths”, after which Newsbeat promptly proceeded to drift into mythological territory of its own.

One of the debunked myths was the popular belief that “most body

heat is lost through the head”.

This, it transpires, is simply not true, but Newsbeat inadvisedly went on to “prove” it by suggesting that wearing a woolly hat in winter has no effect. The programme sent two subjects to stand in the cold, one wearing a Santa hat and one with a bare head. After a while, thermometers were used to measure their body temperatures. The reporter announced with satisfaction that both temperatures were the same, in the apparent belief that this proved no heat had been lost by the person with the bare head.

In fact, of course, losing heat from any part of your body won’t usually affect your core temperature – but the more heat you lose, whether from your head or anywhere else, the more energy your body has to use to keep its thermostat up. Livingstone hopes that no Antarctic explorers were listening to this broadcast.

FINALLY, Ian Dearing tells us that just before Christmas he received a message with the subject line: “Important Message from Santa.”

Imagine his disappointment when he opened the message to find it was from a bank and its full title was: “Important Message from Santander Group.”

You can send stories to Feedback by email at feedback@newscientist.com.

Please include your home address.

This week’s and past Feedbacks can be seen on our website.

Last words past and present, plus questions, at www.last-word.com

THE LAST WORD Altered images Driving along in the car the other day, my four-year-old son asked why things that were closer to us were moving faster than those further away. What should I tell him?

even though he could put his hands together to confirm they were the same size.

Secondly, I showed him that it takes more objects to fill the same amount of visual space if they are further away. For example, if the hand further away is half the apparent width of the one closer, it takes two hands to fill the same width.

Finally, I got him to think about something moving, such as an index finger traced slowly from one side of his palm to the other. If it moved at the same speed when it was further away, it travelled the same actual distance (a palm’s width), but seemed to have travelled only half as far. So

Thanks for a vast number of answers to this question, many of which were probably more suited to undergraduate level than to a four-year-old. However, one notable group of wags insisted on sidestepping the answer at all costs. Among these was the inevitable “Ask you mother”, from Tony Turner of Tuross Head, New South Wales, Australia. Stephen McIntosh of Hull, UK, suggested: “You are far too intelligent for a four-year-old… have a lolly.” More “It takes more objects encouraging was the answer from to fill the same amount of visual space if they Dave Oldham of Northampton, are further away” UK, who offered: “If you can ask a question like that at four years of age it won’t be many more years it would take twice as long for it to before you can explain it to me.” look like it had travelled the same And congratulations to Peter distance. I then summed up by Gosling of Farnham, Surrey, UK, explaining that the distant things for his unashamedly literal view were not actually moving slower, of the world. His advice was: they just looked as if they were.

“I think you should tell your son I also had to explain why it that it is illegal for him to be looked as if the trees and houses driving at four years old.” – Ed were moving when my son was sure that they weren’t really. First, ■ When my son (now nearly 10) I got him to move his hand in was a similar age, I tried to explain front of his face, and then to hold this phenomenon during a train his hand still but move his head journey. First I pointed out that from side to side. In each case he objects further away look smaller. could see that the hand seemed I used his hands to show this: if he to move across his vision in the held one hand close to his face and same way. I told him that the two the other at arm’s length, the one movements were equivalent and at arm’s length appeared smaller, he seemed to accept that.

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The other passengers on the train thought I was a little strange, but it kept my son quiet.

Keri Harthoorn Stoke-on-Trent, Staffordshire, UK ■ The answer is that the type of optical system that is used by our eyes causes us to perceive a particular object as “smaller” the more distant it is – a phenomenon called foreshortening. As our vision system converts the angles subtended by the things we are looking at into apparent distances on our retina, this causes nearby objects to sweep through our field of vision much more rapidly than distant ones. So while distant and nearby objects are within the same field of vision, those further away take longer to pass across it, as they have a low angular velocity, than those that are closer.

You can demonstrate this by placing your hand on a newspaper. Make a “V” with your index and middle fingers and sweep it along the text. Your hand is the car, and the V is your field of view. You can see that the text near your fingernails takes a long time to move from one finger to the next, while the text closer to your hand moves more rapidly.

Gregg Favalora Arlington, Massachusetts, US ■ One way to demonstrate this process is to put a toy car on a path representing the road, with an object placed 30 centimetres ahead and 30 centimetres to the side of it. Show your son how the

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object goes from being diagonally ahead to diagonally behind the toy car when you move it forward 60 centimetres. Then do the same thing, but with the object 3 metres ahead and 3 metres to the side.

This time the car has to travel 6 metres to cause the same change in the angle at which someone in the car would view it. Also point out that it takes much longer for the car to travel 6 metres as for it to travel only 60 centimetres.

Eric Kvaalen Cambridge, Massachusetts, US

THIS WEEK’S QUESTIONS SPICE ATTACK

The Last Word has told us why garlic makes your breath and body smell, but I want to know why the spice methi, or fresh fenugreek, has a similar, possibly stronger, effect.

Nikki Bedi BBC Radio Asian Network, UK ON A HIGH

A number of athletics and cycling world records have been set at high-altitude venues, for example during the 1968 Olympic games in Mexico City. Presumably the air is thinner so there is less resistance, enabling them to run or cycle faster. But surely oxygen uptake at altitude is more difficult, so there must be a point at which altitude no longer favours athletes. What is this point and why? And which tracks or velodromes come nearest to it?

Carlos Loeb Madrid, Spain