Discover NEUROLOGY
SPACE
Black Holes Get Even Stranger
My Forgotten Language
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SCIENCE FOR THE CURIOUS
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Your Secret Superpower Unlock the hidden clues that shape human relationships
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Countdown to a Massive Eruption Race to Save the Rhino How Stone Tools Shaped Us P.50
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Contents NOVEMBER 2017 VOL. 38, NO. 9
Website access code: DSD1711 Enter this code at: www.DiscoverMagazine.com/code to gain access to exclusive subscriber content.
FEATURES
32 Fields of Fire Near Naples, a sleeping giant is stirring, and according to some scientists, it might soon awaken with a bang. BY RUSS JUSKALIAN
42 Scents and Sensibility Among our five senses, smell receives the least respect. Yet it impacts our relationships and could even save our lives. BY MARTA ZARASKA
50 Last Chance to Be Conservationists are scrambling to save the last five rhino species, limited to ever-shrinking territories in Africa and Asia. BY RUSS JUSKALIAN
58 Our Next Billion Years Many people create a three- or five-year plan for their lives. But what would a billion-year plan to harness the power of the universe for humans look like?
RUSS JUSKALIAN
BY MAX TEGMARK
Rhinos are dwindling as their ranges shrink and poachers hunt some species to near extinction. Can anything be done? See page 50.
November 2017 DISCOVER
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Contents COLUMNS & DEPARTMENTS
6 EDITOR’S NOTE A Sense of Our Own Getting nosy about the hidden powers of a neglected human sense.
7 INBOX Readers weigh in on space travel, brain training and peer-reviewed papers.
THE CRUX
A medical entomologist solves a “tire-some” mystery; exploring the body electric for better human health; digging up Turkey’s rich and varied past; tools of the trade for insect investigation; taking the measure of past Nobel winners; and more.
For a decade, artifacts of human settlements over millennia have been unearthed at a Turkish site. Learn more about the excavations on page 14.
24 VITAL SIGNS
64 ORIGIN STORY
A 37-year-old man shows signs of bipolar disorder and schizophrenia. But what if it’s not all in his head?
Experts are cracking the mystery of how ancient toolmaking evolved — and how it changed our brains.
BY DAMON TWEEDY
BY BRIDGET ALEX
28 MIND OVER MATTER
70 OUT THERE
A Streak of Madness
My Forgotten Language Age isn’t just a number. If you have forgotten your native tongue and want to relearn it, the age you stopped speaking it matters. BY SUSHMA SUBRAMANIAN
Stone Cold Science
Black Holes and Revelations Scientists have discovered a surprising connection between special metals and a well-known celestial phenomenon from which nothing can escape. BY STEVE NADIS
74 20 THINGS YOU DIDN’T KNOW ABOUT …
Color
Learn more on page 28.
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The human eye actually sees only three colors, scientists refer to color in terms of wavelength, and coloring foods goes back at least 3,500 years. BY SYLVIA MORROW
Discover NEUROLOGY
SPACE
Black Holes Get Even Stranger
My Forgotten Language
P.70
P.28
SCIENCE FOR THE CURIOUS
®
Your Secret Superpower Unlock the hidden clues that shape human relationships
P.42
PLUS
Countdown to a Massive Eruption Race to Save the Rhino How Stone Tools Shaped Us
P.32
P.50
P.64
ON THE COVER Black Holes Get Even Stranger p.70 My Forgotten Language p.28 Your Secret Superpower p.42 Countdown to a Massive Eruption p.32 Race to Save the Rhino p.50 How Stone Tools Shaped Us p.64 Cover image: rangizzz/Shutterstock
TOP: HALDUN AYDINGUYN. BOTTOM: JOHN WOODCOCK/DIGITAL VISION VECTORS/GETTY IMAGES
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Discover SCIENCE FOR THE CURIOUS
Editor's Note
®
BECKY LANG Editor In Chief DAN BISHOP Design Director
A Sense of Our Own It’s something most new parents have experienced: You pause while cradling your child to inhale the comforting scent. I remember on many occasions lingering at my infant son’s bedside after checking in on him at night. I felt completely at peace while listening to his soft breathing. Even today, his teenage, shall we say, aroma, is still weirdly comforting. Researchers have found there’s something powerful and grounded in the scent cues we pick up, and read, from others around us. And we often aren’t even aware of it. In our cover story (see page 42), frequent Discover contributor Marta Zaraska mines the work of neuroscientists, olfaction experts and psychologists to unearth this essentially secret superpower we all possess. As one researcher points out, we’ve grown to rely much more on our vision and have lost touch with the power of smell. Yet our noses are big players when it comes to choosing partners, quite likely driven by subtle genetic clues. Our olfaction system can detect fear or anxiety in another person, and some studies have found that these intense emotions are essentially contagious through scent — we respond to that person’s fear in kind. And another study has found that the chemical fingerprint of a criminal is specific enough that sniffers can identify the person from a “scent” lineup with 75 percent accuracy. Much of the nose’s power centers around emotion and memory — both are crucial to the ever-so-subtle information relayed to our brains, a secret sense that’s all our own.
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KNOWING
Surviving Space
THE PROBLEM
Coming Down Is Hard to Do
Settle the final frontier. BY KOREY HAYNES
Floating in space may look fun, but it’s also problematic. Humans, plants and other animals all evolved to survive 1 g of force, the average gravity they feel at Earth’s surface. The body does less work in zero gravity, and returning to normal gravity strains muscles, hearts and the whole cardiovascular system. While the moon and Mars, humanity’s next destinations, do have some gravitational pull, the moon packs about one-sixth Earth’s gravity, and Mars boasts roughly one-third. Scientists think it would be tough to adapt to Earth after living for years on the Red Planet. But what if Martian settlers stay there? And what about space explorers who don’t want to touch the ground at all?
Hundreds of humans have orbited Earth since space exploration began more than half a century ago. In that time, astronauts have walked on the moon and even endured more than a year in microgravity. But becoming a multiplanetary species — whether to flee a dying world or just explore the unknown — means learning to live without easy access to Earth’s resources and conditions. The first space settlers will face some challenges as old as life itself, while other problems will rear their heads for the first time. Humans must solve them all if we want to survive beyond Earth’s warm embrace.
THE SOLUTION
Take Yourself for a Spin THE PROBLEM
Astrogrub While our technology has advanced beyond spears and ceramic jugs, food and water remain an eternal challenge. Astronauts on the International Space Station (ISS) and other nearby outposts can survive on supplies shipped from Earth, but for any human settlement to persist farther out, the thin thread of an Earth-based supply chain will prove dangerously fragile. If there’s a crop failure on Mars — it occasionally happens in Antarctica’s greenhouses, which serve as analogs — colonists can’t live on astronaut ice cream for the two years it would take for emergency supplies to arrive.
THE SOLUTION
Mining and Greenhouses The only sustainable answer is to mine and farm the solar system. Water mining on comets and asteroids should be far more cost-effective than heaving tons of H O out of Earth’s gravitational grip. Greenhouses are also cheaper than shipping. Scientists have already grown small test plots aboard the ISS. Russia’s orbiting Mir station flourished with plants, from wheat to weeds. And perhaps most intriguing, research suggests that Martian and lunar soil could be used to grow crops like wheat and even potatoes. But just in case those crops fail, Red Planet settlers would want enough in storage to make a doomsday prepper seem ill equipped. Space colonizers could even adopt a DIY approach to building materials by baking lunar and Martian regolith — rocks and dirt — into ceramics, rather than transporting heavy supplies like steel and metal.
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Long-term orbiting astronauts could live in a Stanford Torus. The structure, developed by NASA and Stanford University in the 1970s, is a design for a space station: essentially a hollow ring that spins four times per minute. (Picture 2001: A Space Odyssey.) This motion provides “artificial gravity” by means of centrifugal force, like a sock stuck to the drum of a spinning clothes dryer. Astronauts and cosmonauts have spent over a year in zero gravity with few problems, and those mostly arise when reacclimating to Earth. So it’s logical to assume low gravity would be safe, perhaps even pleasant, for short missions. But we have no long-term studies of how humanity would cope with years spent in the gravity of another world. Our best evidence is that between 1969 and 1972, a dozen men walked on the moon’s surface for a few days with no ill effect. Before we discover if we can survive as a species beyond Earth, we should probably take a few more walks out there.
71
I especially enjoyed “Everything Worth Knowing: Surviving Space,” by Korey Haynes (July/August 2017). It is fundamental — and, I’d argue, essential — that we humans continue to slip the bonds of Mother Earth to explore, discover and wonder at the life we will encounter as our brave travelers share our planet’s story and learn of life on a distant world. Loring Olk Phoenix
Spaced Out
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Space travel has been on our minds collectively for some time. We get fired up about it, then our interest wanes when we think of the power it would take to get a ship off the ground to explore planets. I think, to overcome the leave-the-ground bit, the best thing to do is build the ship in space. It can be any size and configuration because there is no friction there. Would it not be easier to upload from Earth than to take off from Earth? I think we are too fascinated with the spectacular launch than with the practicality of it. Clinton Douglas Heber City, Utah
I saw your article on brain training (September 2016) just before I renewed with the training service I had been using. Happily, I can now use that money for something else. Profuse thanks to author Dan Hurley for giving such terrific detail regarding his extensive trials, and congrats on reaping improved cognition after the ordeal was over. Jean Sopko Berlin, N.H.
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Evelyn Haskins Not at this stage! Why not work more on non-vertebrate sources of meat?
In our July/August 2017 issue, we highlighted a recent study that asked 700 people to share their opinions on lab-grown meat. Would they eat it? What kind would they eat? So we asked Discover readers on Facebook the same question, but with a twist: Would you eat lab-grown human meat?
Wayne Snyder I’ll try a big ol’ plate of none of the above.
Eric Plester Yes, absolutely. I’ve always said, if it tastes all right and doesn’t make me sick, why should I care where it comes from or what it is?
David Smith Does anyone remember Soylent Green? This is how it starts. IT’S PEOPLE, SOYLENT GREEN IS PEOPLE!!!!
Martin Schulz Yes! Lab-grown meat has enormous potential to change the world for the better. We could eliminate all the terrible cruelty and bloodshed associated with raising animals for food, as well as eliminate the incredibly massive environmental damage that the meat industry causes.
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THE CRUX T H E L ATEST S C I E N C E N E WS A N D N O T ES
FANCY FOOTWORK Fire ants band together and build temporary shelters by using their own bodies to form towers. To learn how they manage this without crushing each other, Georgia Institute of Technology researchers Craig Tovey and David Hu placed some in a dish with a rod in the center. They found the ants used their sticky feet to cling to each other and form rings that encircled the rod, providing a kind of strong scaffold for the structure. When there was too much weight on any single ant near the bottom, the animal backed off to take a break — and clambered up to the top, rejoining the structure and keeping the overall tower standing.  SYLVIA MORROW; PHOTO BY TIM NOWACK/GEORGIA TECH
November 2017 DISCOVER
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THE CRUX
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As they mature, they gradually lose this ability. But Levin found he could chemically stimulate older tadpoles’ tail stumps and make them regrow their tails. And in related experiments, he made tadpoles grow eyes on their stomachs by changing the electrical Scientists say bioelectricity is the body’s master control. A few aim to properties of cells to mimic those associated with eye formation. harness it to regrow limbs, treat cancer — even unlock immortality. Levin now sees bioelectricity as a sort of master control, one that can turn on a complex cascade of genetic AS A YOUNG BIOLOGIST studying how But those advances only made and biochemical events resulting in wounds heal, Min Zhao found that bioelectricity research more pressing an eye or a tail. His recent cancer he could quicken cellular repairs by by calling attention to what those fields research also supports this hypothesis. exposing an injury to electricity. But couldn’t adequately explain. Zhao, who’s He electrically induced and suppressed tumors in tadpoles, leading the process remained enigmatic until now a professor at the University of him to believe that people’s cancers an experiment by one of his graduate California, Davis, sees bioelectricity as can eventually be reversed by repatstudents failed to achieve the desired an orchestrator of complicated events, terning the abnormal electrical signals result. The more that new tissue drew such as the healing of an injury. transmitted by cancerous cells. toward the current on one side of the Much of Zhao’s recent research has And that’s only the beginning. wound, the more the other side recoiled. focused on diabetics, who are often Enlisting his training in computer What the student had accidentally slow to heal. Studies reveal that wounds science, Levin is now found, according to Zhao, is that on diabetic mice pack abnormally weak electrical currents. determined to crack the current directs the movement of cells, He’s shown that such wounds body’s bioelectric code. and the effect is so powerful it overrides heal faster after applying a He can’t say how long all the physical and chemical signals the corrective charge. that will take, but in his body uses to heal. “When an experiment doesn’t work out as you hoped,” The underlying mechanism, bioelectric future, you’ll Zhao says in retrospect, “maybe it’s Zhao believes, is as old as life “actually get to program trying to tell you something new.” His itself. When a cell membrane at the level of anatomy.” bolt of insight, published in 2006, is punctured, it induces a Animals could be made to invigorated an emerging field known as current between the inside take any conceivable shape. bioelectricity. and outside of the cell. “It’s a Humans could recover lost Encompassing phenomena ranging signal to the cell that there’s limbs and replace failing from tissue regeneration to cancer a hole,” he says. In order to organs. “If you understood metastasis, bioelectricity has been survive, early single-celled how to build all these emerging for a very long time. The organisms could have used structures, you could induce first hint that electricity controls the that signal to direct repair, an them to be constantly body came in the 1780s, when Italian evolutionary advance that he rebuilt,” he claims. physician Luigi Galvani connected thinks survives today. That would put humans — MIN ZHAO severed frogs’ legs to a lightning rod, According to Tufts into the privileged position showing that they twitched whenever University biologist Michael of being like flatworms, lightning struck. In addition to helping Levin, these electric signals are “a gift which can naturally regenerate any inspire Frankenstein, his discovery led from physics,” a natural property of body part, and therefore have an to periodic bursts of experimentation in electricity that evolution was able to indefinitely long life span. the 19th and 20th centuries — revealing, exploit advantageously. “Electricity Levin is now studying flatworms for instance, that wound sites generate is uniquely suited for information as obsessively as tadpoles. “They’ve their own voltage. processing,” he says. Around the same been with us for half a billion years,” However, progress was stymied by time that Zhao started zapping wounds, he says. “It looks to me like regeneration is a solution to aging.” crude electrical instruments and then Levin started researching electricity’s Present at the origin of life, sidetracked by attention-grabbing role in tadpole tail regeneration. In bioelectricity might just be the path breakthroughs in genetics and molecuthe first several days of life, tadpoles lar biology. to our immortality. JONATHON KEATS can replace a severed tail completely. BIG IDEA
The Electric Touch
DAVID PLUNKERT
“When an experiment doesn’t work out as you hoped, maybe it’s trying to tell you something new.”
November 2017 DISCOVER
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THE CRUX PERSONAL
They’re Taking Our Tires! An unexpected meeting helps solve an epidemiological mystery. IN THE EARLY 1980S, Aedes albopictus, a mosquito species native to Southeast Asia that spreads dengue fever and yellow fever, turned up deep in the American South. Though there were no reported disease outbreaks, epidemiologists were still worried, especially when huge swarms arrived in Houston. The so-called Asian tiger mosquito had clearly gained a foothold in the U.S., but no one knew how it had gotten there. So medical entomologist Paul Reiter headed to the city, situated near the Gulf of Mexico, to search for larvae (and answers) in containers of standing water — especially inside discarded, used tires. There, a chance encounter along a road on the outskirts of town put Reiter on the trail to solving the mystery. IN HIS OWN WORDS . . .
I found myself in Houston, accompanied by a colleague, kicking tires and gathering information on the character and location of infested sites – the sort of things that medical entomologists like to do. We concentrated our efforts on a profusion of discarded tires on a lonely acre of wasteland not far from the city’s port. Nearly all contained water and were infested with tiny larvae. They were obviously thriving, but the puzzle remained: How had they gotten there? On the second day of my visit, toward sundown, we were packing to leave when a pickup truck drove by and stopped some 150 yards away. Two men got out and started sifting through tires. They would occasionally chuck one into their vehicle.
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Our tires! We had marked them for study! I summoned up courage and approached them. “Good evening, gentlemen. May I ask why you are collecting these tires?” “Our company ships them to Mexico and Guatemala,” they said. “They also ship them in from India.” A moment of bewilderment, then: Eureka! The men looked puzzled that I was so excited. A. albopictus was an Asian mosquito. And they’d said these tires were coming from India. The next morning, I raced to the importing company. The boss was unsmiling and suspicious. Yes, his company imported used tires, he said, but from Japan, not India. Nineteen containers a month. Yes, he
did export to Mexico and to several countries in Central America. Lots of people did, and they imported them from many other countries. I was at the local Department of Commerce by the afternoon, leafing through annual volumes of monthly trade data, import and export. Sure enough,
for every month of every year, there were entries under a series of categories: automobile tires, used; truck tires, used; tractor tires, used; airplane tires, used; and so on. Thus it was that I became the world’s foremost used-tire epidemiologist! AS TOLD TO K.N. SMITH; PHOTO BY GUILLAUME MEGEVAND
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THE CRUX ON SITE
The Secrets Beneath a Suburb Experts are uncovering millennia of history under a Turkish megacity’s outskirts.
V
ANCIENT DRUGSTORE In just a square meter — about the size of a dining table — the team unearthed more than 400 small ceramic or glass bottles alongside mortar and pestles, and another 300 nearby. The finds suggest Bathonea may have been an early pharmacy site. The bottles’ contents chemically resemble the formulas for modern drugs used to treat depression and heart disease.
WHEN ŞENGÜL AYDINGÜN first started surveying the shores of Küçükçekmece Lake in the western suburbs of Istanbul, colleagues doubted she’d find any evidence of ancient human settlement; other researchers had already surveyed the area and hadn’t turned up much. But the area’s geography and water resources looked favorable for early habitation, and her hunch proved correct. “During our initial visual survey in summer 2007, we collected bags and bags of artifacts — Neolithic, Early Bronze Age, Roman, Byzantine — every day for two months,” Aydıngün says. Now, 10 years later, the Kocaeli University associate professor and her team are steadily turning up new evidence — including the exciting finds shown here. These objects are painting vivid pictures of life at the site now known as the Bathonea excavations, from the earliest days of the Lower Paleolithic era to the bustle of a busy trading port during the Byzantine Empire. JENNIFER HATTAM
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V MISSING LINK Experts have long debated how and when agriculture spread from Mesopotamia (see map) into Europe. The discovery of 9,000-year-old flint tools made from local stone — the earliest such tools found in the European part of Turkey — helps fill a gap in the story. Previously, flint tools from this era were discovered elsewhere in Turkey, but never on the European side of the country’s continental divide.
Archaeologists, students and workers digging at the site.
FROM LEFT: HALDUN AYDINGUYN (5). SKULL: ÖMER TURAN. MAP: PINGEBAT/SHUTTERSTOCK
A view of an imperial building from the late Roman period, which lasted roughly A.D. 250 to A.D. 450.
V
11000 B.C.
READING THE BONES Manual labor
10000
specific to two port jobs left its mark on many of the more than 100 Byzantine-era skeletons found at the site: compressed vertebrae typical of a porter carrying heavy loads, and tooth damage that could be from a fisherman’s habit of biting down on net ropes as they were cast.
9000 8000 7000 6000 5000 4000 3000 2000 1000 HITTITE HELLENIC BYZANTINE
A.D. 0 1000 2000
FAST FACTS
SIMPLER STRONGER FASTER!
2007 Site discovered
2009 Excavations began
DATE RANGE OF FINDS Lower Paleolithic to Late Ottoman (roughly 800000 B.C. to the 18th century), including remains from Neolithic, Hittite, Hellenic and Byzantine civilizations
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November 2017 DISCOVER
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98348X © 2017
V RISE AND
THE CRUX INFOART
Nobel by the Numbers A breakdown of past winners. IT’S NOBEL TIME: Committees traditionally announce the recipients throughout the month of October. In honor of this year’s winners, let’s take a look at some stats on laureates of bygone years.* LACY SCHLEY 25
Top Birthplaces of Winners
The Age of the Winner
England and #1 United States: 188 #2 Wales: 67
While middle age is prime time for becoming a laureate, Lawrence Bragg took home the physics prize at age 25 in 1915; Raymond Davis Jr. won a physics prize at 88 in 2002.
20
#3 Germany: 51
CATEGORIES
Total Prizes and Laureates
Medicine/Physiology Chemistry
Laureates
211
Prizes
107
NUMBER OF PRIZES AWARDED
Physics 15
174 108 10
203 110
0
25
30
35
Battle of the Sexes
40
45
50
55 60 AGE OF RECIPIENT
DISCOVERMGAZINE.COM
70
75
80
85
Men: 570 Women: 17
*THIS DATA EXCLUDES INFORMATION RELATED TO PEACE, LITERATURE AND ECONOMIC SCIENCES PRIZES.
16
65
Source: nobelprize.org
MEDAL: © ® THE NOBEL FOUNDATION. CHART: ALISON MACKEY/DISCOVER
5
FAR, FAR AWAY
WHERE THE SUN DON’T SHINE It’s been 2 billion years since sunlight last reached the bottom of these dark craters at the moon’s north pole. That’s because the moon’s axis is nearly straight, so the angle of sunlight varies little. For the same reason, mountains only miles away bask in near-constant sunlight. Researchers created this illustration from thousands of pictures taken by NASA’s Lunar Reconnaissance Orbiter, launched in 2009. This roughly 25-mile-wide swath shows areas that receive the most sunlight (light tones) and those that receive none (black). In the dark areas, temperatures can drop to minus 415 degrees Fahrenheit, among the coldest places in the entire solar system. ERNIE MASTROIANNI; IMAGE BY NASA/GSFC/ARIZONA STATE UNIVERSITY
November 2017 DISCOVER
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THE CRUX
TRENDING BY LACY SCHLEY
Building Blocks
The Truth About Our Trash Humans sure have made a mess of things. Here’s a breakdown of all the plastic waste we’ve dumped on our planet.
8.3 BILLION
metric tons of plastic produced to date
Taking a Shot at Amyloid
TRAPPIST-1 Letdown Many space enthusiasts got their hopes up earlier this year when scientists discovered TRAPPIST-1, a star with a collection of seven Earth-sized planets — three of which were in the star’s habitable zone and could house life-sustaining liquid water. Now, researchers have found these three planets have a very low chance of harboring life. They’re much closer to their sun than we are to ours, so TRAPPIST-1’s ultraviolet radiation would likely strip away most of their atmospheres. While depressing, this knowledge helps us get a better grip on the odds of finding life somewhere beyond our little corner of the universe.
Walking on Printed Glass We started with plastics, progressed to biocompatible inks, and now we can 3-D print glass. German scientists have come up with a way to crank out strong, transparent glass using ink made of powdered glass mixed with a thick liquid compound. Once you print out the design you want, you pop it in a high-temperature oven to evaporate the liquid. And voila! Glass. Although the team isn’t the first to 3-D print glass, their technique is the first to produce strong, clear glass with a standard 3-D printer and less extreme temperatures than previous attempts.
Gene Therapy for Muscular Dystrophy We’re one step closer to treating Duchenne muscular dystrophy, a severe type of the degenerative disorder that breaks down a person’s musculature. The inherited condition, most common in boys, results from a lack of dystrophin, a protein that’s essential for healthy muscles. An international team of experts developed an injection that restored the function of dystophin-expressing genes in 12 golden retrievers. The dogs saw a significant reversal of symptoms that lasted the span of the two-year study, paving the way for human trials.
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9%
What Happened to Our Plastic?
79% Ends up in landfill or environment
Recycled
12% Incinerated
Cumulative Plastic Waste Generation and Disposal in million metric tons Primary waste generated* All waste discarded All waste incinerated All waste recycled
25,000
20,000
15,000
10,000
5,000
0 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 * Plastic created from virgin, non-recylced materials
Building and Construction
12
Consumer and Institutional Products
37 13
Electrical/Electronic
Global Plastics Waste Generation by Industry, 2015 in million metric tons
Industrial Machinery 1 Packaging
141 42
Textiles Transportation
17 38
Other 0
Source: “Production, use, and fate of all plastics ever made,” Science Advances, 2017
30
60
90
120
150
CLOCKWISE FROM BOTTOM LEFT: ANNA BONDSRENKO/SHUTTERSTOCK; NASA/JPL-CALTECH/R. HURT (IPAC); PICSFIVE/SHUTTERSTOCK (2). CHARTS: ALISON MACKEY/DISCOVER
Experts have developed a vaccine that prevents the buildup of amyloid — a protein linked to the neurodegenerative disorder Alzheimer’s disease — in primate brains. The team took DNA from amyloid proteins and integrated it into a vaccine. When injected into the skin of six rhesus macaque monkeys, the vaccine prompted an immune response that blocked the proteins from popping up in the brain. The next step is to plan human trials.
Cosmologists from the U.K., France and Germany have come up with new maps of how dark matter moves throughout the universe. Scientists can’t actually observe dark matter, which makes up about 27 percent of our universe’s total mass, since it doesn’t react to light. So these researchers had to infer its movement by using data from the Sloan Digital Sky Survey
(SDSS), an ongoing project to create a 3-D map of the universe. Here, researchers have layered the location of galaxies (marked with black dots) pulled from the SDSS on top of their dark matter data. Warmer colors represent matter that’s headed our way, while cooler colors indicate matter that’s flying away from us. 180°
210°
15 0
24 0°
°
270°
°
120
TOP: FLORENT LECLERCQ ET AL. 2017. BOTTOM FROM LEFT: STEFANO BENAZZI/UNIVERSITY OF BOLOGNA; THE NATIONAL MUSEUM OF DENTISTRY AFTER ORIGINAL OWNED BY THE GERMAN DENTAL ASSOCIATION; LE CHIRURGIEN DENTISTE/A PARIS CHEZ SERVIERS, 1786; LUCADP/SHUTTERSTOCK
Charting the Unseen Sky
400 ) 300 t-years h g li 62,000 pc = 3,2
v [km/s] 0 -300
-200
-100
0
100
200
200 M 100 rsecs (1 a p a g e in Me Distanc
Source: “The phase-space structure of nearby dark matter as constrained by the SDSS,” Journal of Cosmology and Astroparticle Physics, 2017
300
TIMELINE Dental Doctoring Throughout History A trip to the dentist can be a real pain, even if you’re not among the roughly 1 in 10 people with high anxiety about dental treatments. But a whirring electric drill in your mouth may not seem so bad once you read about these ancient approaches to dentistry. 12000 B.C. Chip off the ol’ chomper: The first known attempt at dental work, as evidenced in a skeleton unearthed in Italy in 1988 with a molar that had been chipped at with a stone tool.
5000 B.C. Legend of the tooth worm: The first documented reference, in a Sumerian text, of a myth popular throughout the ancient world that a worm living in your gums caused dental pain and cavities. 2650 B.C. First dentist: Wooden panels found in ancient Egyptian physician Hesy-Re’s tomb describe him as “Chief of Dentists and Physicians,” the earliest recorded mention of a dentist. A.D. 20 A steamy solution: Roman folk tradition
recommends a minty steam bath to treat toothaches. A.D. 1728 Tooth worm, part II: French dentist Pierre Fauchard publishes work that helps dispel the tooth worm myth, at least among dentists. The myth persists in popular lore, however, until the 20th century. A.D. 1847 Filling the gap: Edwin Truman introduces a natural latex called guttapercha, made from trees found in Southeast Asia, for use in root canal fillings. Previously, dentists had used anything
from silver to lead to asbestos. A.D. 1965 Laser power: Researchers find that treatment with dental lasers makes teeth more resistant to decay. Studies since have suggested laser treatment could, in some procedures, help protect teeth, reduce pain and accelerate healing. Future Print a new one: 3-D printers and digital scanning technology are close to offering easy ways to make and reproduce custom dental products like crowns and veneers. SYLVIA MORROW
November 2017 DISCOVER
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THE CRUX THAT WORD YOU HEARD
Adipocytes IF YOU WANT TO IMPRESS at a cocktail party, bust this term out. It’s just a fancy word for fat cells, which come in two varieties: brown and white. Brown adipose tissue (BAT), which most animals have, is also called “good” fat because it stores energy as small units that burn easily — think of kindling in a campfire. White adipose tissue (WAT), though, is like a log: It’s harder to burn because it stores energy as one big unit. Our bodies can transform WAT to BAT. Unfortunately, it requires intense, prolonged stress, such as sustaining a severe burn. LACY SCHLEY; ILLUSTRATION BY CHAD EDWARDS
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THE CRUX TOOLS OF THE TRADE
Mini Measure The long and short of collecting bug data.
MEET THE MICROSCALE: essentially, a teeny-tiny ruler that’s a must-have for entomologists — researchers who investigate insects. For larger specimens, such as the metallic, wood-boring Chalcophora japonica (or ubatamamushi, as the Japanese call the beetle, pictured at right and below), the device helps measure morphological features, such as genitalia. For smaller species, such as water-dwelling riffle beetles (Optioservus fastiditus, also pictured), the miniature ruler helps measure the bug itself, which comes in at a whopping 2 millimeters long. To use the microscale, researchers take the insect — or, if the bug is dissected, they float the body part in a petri dish of alcohol — and put it under a microscope. Then they line up the specimen with the microscale’s tick marks and record the data. To ensure the critters aren’t damaged or mixed up while experts handle them, they’re affixed to pins and tagged with labels that indicate vital information such as species name, who found the bug and where it was collected. LACY SCHLEY; TOOL AND SAMPLES COURTESY OF
WILLIAM ZUBACK/DISCOVER
ENTOMOLOGIST CRYSTAL MAIER, THE FIELD MUSEUM
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Vital Signs
A Streak of Madness A 37-year-old man’s sudden lapse into mania and paranoia eludes diagnosis until a final clue emerges.
→
Kurt, like many patients brought to the psychiatric emergency room, arrived at the hospital in handcuffs. “We’ve got a streaker,” said the triage nurse. On a cold December evening, something sent this 37-year-old man running naked through the streets. Kurt had argued with the staff at the rental office in his apartment complex. When they threatened to evict him if he didn’t start paying his overdue rent, Kurt called the police. Then, deciding that the voice on the phone was actually a police impersonator, he stripped off his clothes and began sprinting to the nearest station. Two officers picked him up and brought him to our hospital. This wasn’t an unusual tale. In a decade of my training and working as a psychiatrist, each time I’d encountered this kind of bizarre behavior, the cause had turned out to be one of three things: a manic phase of bipolar disorder, a psychotic crisis of schizophrenia or drug intoxication. My task was to figure out which of these applied to Kurt and treat him accordingly. Kurt’s medical record gave little hint where he might fit. He’d received psychiatric care off and on for three years but was never hospitalized. His psychiatrist diagnosed him with major depressive disorder and generalized anxiety disorder — common conditions that wouldn’t explain his recent actions. According to the clinic notes, he drank
24
DISCOVERMAGAZINE.COM
He stared at me for a good 15 seconds before speaking. Then, as had so many patients I’d seen over the years, he told a rambling conspiracy tale that made sense only in his own mind. a few beers most weekends and smoked marijuana once a month, neither of which could account for his recent strange behavior. What had changed?
THE USUAL SUSPECTS My ID badge electronically unlocked the heavy wooden door to the psychiatric wing. Kurt paced in his 10-by-10-foot room. Standing guard outside were a stocky officer and a tall nursing assistant. Kurt was dressed in the standard pocket-free hospital scrubs worn by patients deemed a potential threat to themselves or to others. Confined to a secure space, he was no longer handcuffed. I introduced myself and remained standing with my clipboard in hand. “Can you explain to me what got you so upset and afraid earlier today?” I asked.
Kurt slowed his pacing, then stopped briefly. He stared at me for a good 15 seconds before speaking. Then, as had so many patients I’d seen over the years, he told a rambling conspiracy tale that made sense only in his own mind. Kurt’s paranoid story involved his apartment rental office masterminding an epidemic of global warming, illegal immigration and mass incarceration. The more convoluted his words, the louder he spoke and the faster he paced. “Why did you take off your clothes?” I asked. “They got bugged at the office,” he said. “Somehow they figured out how to sew a wire into them.” After a few more minutes, I realized that I was unlikely to get any useful information. So I asked Kurt if I could speak to someone who knew him. Psychiatry sometimes resembles detective work when the person you’re evaluating can’t or won’t provide the data you need to solve the case. Kurt gave me the OK to contact the apartment rental office and his family. The manager said Kurt had morphed into a different person over the past several months. He had been calm and friendly and on time with his rent, but recently he’d become socially unpredictable and had fallen behind several months on his payments. His brother confirmed that Kurt’s behavior had changed suddenly. Had he started abusing drugs?
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Vital Signs
A SINGLE ABNORMALITY While I was writing my admission note, Kurt’s laboratory tests returned. His urine drug screen had no signs of common street drugs like marijuana, cocaine, crystal meth and heroin. His blood labs showed no alcohol in his system. Outside of alcohol, standard blood tests on patients rarely reveal anything that can account for severe psychiatric symptoms. In Kurt’s case, his various lab results — thyroid, kidney, liver, glucose, sodium and
26
DISCOVERMAGAZINE.COM
Parathyroid glands Thyroid
Posterior view Four parathyroid glands, each about the size of a grain of rice (inset), regulate the amount of the mineral calcium in our bodies.
His various lab results were all normal with one exception: an elevated calcium level in his bloodstream. potassium — were all normal with one exception: an elevated calcium level in his bloodstream. Elevated blood calcium levels, or hypercalcemia, can be induced by a variety of things, including cancer, certain medications and excessive vitamin D intake. But the most common cause is an overactive parathyroid gland in a condition known as hyperparathyroidism. Our bodies have four parathyroid glands, each normally the size of a grain of rice, in the neck. The parathyroids regulate the amount of the mineral calcium in our bodies — vital to the functioning of our nervous system, heart and other muscles, and the health of our bones. Suddenly, I remembered something I’d read about but never seen: Hyperparathyroidism is a rare cause of psychiatric illness. I called the lab to obtain a parathyroid hormone level from the blood sample taken. They told me the results would not come back for several more hours, until after my shift had ended. In the meantime, Kurt was treated with
low-dose antipsychotic and antianxiety medications. The following day during my lunch break, I pulled up Kurt’s computerized medical record. Sure enough, his parathyroid hormone level was elevated, consistent with the most common form of hyperparathyroidism. Once the medications had somewhat calmed Kurt’s acute manic-psychosis, the psychiatric team consulted with the endocrinology specialists, experts on disorders of the thyroid and parathyroid glands among other conditions. During their evaluation, Kurt reported experiencing a variety of symptoms consistent with hyperparathyroidism — joint pain, fatigue and muscle weakness — for several months. An imaging scan showed a hyperactive parathyroid gland. He was referred for surgical removal of the abnormal gland (parathyroidectomy), the definitive treatment for this condition. The day after his procedure, his calcium levels normalized, and he reported feeling better. Weeks later, I looked at his chart and saw a note from his outpatient psychiatrist. Kurt was off the antipsychotic and anti-anxiety medications prescribed in the hospital and back on his antidepressant drug — but at a lower dose, with plans to consider tapering off it in the future. He reported feeling better than he had for many years. “The last several months were a haze,” he told his psychiatrist. “I’m embarrassed to think about what I might have said and done during that time.” Kurt’s story serves as a powerful reminder of an easily forgotten truth: The distinction between mind and body is artificial. Doctors who ignore this reality do so at their patients’ peril. D Damon Tweedy is a psychiatrist at Duke University School of Medicine and author of Black Man in a White Coat: A Doctor’s Reflections on Race and Medicine. The cases described in Vital Signs are real, but names and certain details have been changed.
MONICA SCHROEDER/SCIENCE SOURCE
When Kurt arrived at the hospital, the nurses took a urine sample to test for commonly abused drugs, such as cocaine and methamphetamine. The lab results would come back soon, but I also wanted to know about the newer synthetic drugs that don’t show up on a standard drug screen. “No, nothing like that,” his brother insisted. “Kurt’s always been wary of hard drugs.” Walking back to the psychiatric urgent care office, I thought through possible explanations. Drug intoxication seemed less likely. So did schizophrenia, which usually occurs before age 30. Sometimes depression can become so severe that people lose touch with reality. But Kurt was impulsive and hyperactive, behavior associated with mania, not depression. Could he have bipolar disorder — a mixture of mania and depression — that had been misdiagnosed as a primary depressive disorder all this time? Or maybe the depression medication that Kurt was prescribed had triggered mania and psychosis? I’d read case reports of this happening and seen it once myself, but connecting the two remains controversial in the field. Besides, Kurt had been taking the same drug at the same dose for more than two years. Still in fear about his landlord’s intentions, Kurt agreed to be hospitalized. It would be up to the inpatient psychiatric team of doctors to figure out why his mind had gone astray.
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Mind Over Matter
My Forgotten Language How the brain can lose — and reclaim — an abandoned mother tongue. BY SUSHMA SUBRAMANIAN
I don’t remember my first language anymore, or at least not most of it. When I was 2, I immigrated with my family into the United States from South India, and we all spoke Tamil. I didn’t know any English before I started school, so when my teachers noticed I was behind, my parents decided to stop speaking to me in Tamil. This was a common approach in the 1980s. Now, educators are more aware of the value of bilingualism. I haven’t completely lost my connection to it. I still hear my parents using it all the time. I can watch and get the gist of a Tamil movie or newscast. I can understand my Tamil-speaking relatives and respond to them in English. Talking, though, remains impossible. I know it’s lodged in my brain somewhere, but where? And what would it take to get it back completely?
LISTENING VS. SPEAKING I call Barry Gordon, a neurology professor at Johns Hopkins University, to find out how the brain regions responsible for understanding and speaking might affect my abilities. Is it possible something is amiss in the part of my brain concerned with speaking? That section is called Broca’s area, he explains, and some of the tissue surrounding this spot is
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also involved with speaking. Wernicke’s area is the portion responsible for comprehension. But Gordon was doubtful I was only retaining the language in one area and not the other. That’s because language involves both perception and fine motor skills. Typically we learn a new tongue by listening to the sounds spoken around us and then imitating them. Since I stopped conversing in Tamil, it wasn’t just my speech skills that halted — my comprehension was also stunted. My Tamil remains rather basic, probably lingering around the level it was when I stopped speaking it. I can only understand my relatives because their day-to-day language is pretty simple. So why was I better at understanding than producing? Gordon says people always differ on language skills such as listening, speaking, reading and writing. Monika Schmid, a linguist at the University of Essex and a leading expert on language loss, gives me another explanation: It’s always easier to listen than to produce. The cognitive energy it takes to come up with words is more intense. “Every time
you want to grab a word stored in your brain, you need a certain amount of mental stimulation,” Schmid says. This concept stems from something called the activation threshold hypothesis. Michel Paradis, an expert in neurolinguistics who is associated with McGill University in Montreal, came up with it in 1987, based on years of neuroimaging studies. The idea is that each time someone recognizes a word, the brain needs fewer neural impulses to access it than last time. If a person goes a long time without hearing a word, the activation levels needed to retrieve that word are higher. And producing a word is even more difficult because the excitatory impulse isn’t a response to an external stimulus — it needs to come from within.
AGE MATTERS OK, so it seems I lack the brainpower to go from understanding to speaking. But the limited Tamil I still know could help me to get there, right? According to Arturo Hernandez, a psychologist at the University of Houston and author of The Bilingual Brain, age is critical for learning language. While experts long
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thought there was a single golden age, now the general consensus is that there are several. One occurs around age 3 to 5, precisely when I lost my Tamil. In a 2015 paper, Hernandez and his colleagues studied 66 Spanish-English bilinguals — early learners who started English before age 9 and late learners who started after age 10 — and compared them with 16 people who spoke only English. Their goal was to see what has the biggest impact on how bilingual brains process sounds from their second language: proficiency, socioeducational status or how old they were when they learned their new language. It turns out the bilinguals’ age when they acquired English was most vital. Brain scans using fMRI showed that, when listening to English phonetic sounds, monolinguals, early bilinguals and late bilinguals’ brains lit up in different areas. In particular, young bilingual learners had more activity in prefrontal cortex regions involved with working memory and distinguishing between the sounds of two languages. Familiarity with a language’s sounds can help people learn it more rapidly, even when they, like me, don’t have regular practice, Hernandez says. I explain I can certainly tell when someone passing me on the street is speaking Tamil. But what I need to figure out is whether I can sound out the words myself. He suggests having someone say a sentence to me in Tamil so I can repeat it. Someone never exposed to Tamil would have a near-impossible time performing this exercise. So I try it — sort of. I watch a YouTube clip at home, since I’m selfconscious. Still, I’m happy to find I can easily mimic the video. Another key window for learning language appears to happen around our teen years. Before this time, kids are great at learning words more quickly than the rest of us. But they don’t hold on to long-term memories of many of those words. In this later
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Abandoning your native tongue when you’re young, around the age of these Sri Lankan children, makes it hard to pick it back up as an adult. But with hard work, you can at least relearn the basics.
phase, something solidifies, and we form lasting memories of vocabulary, grammar and language structure. That’s why if someone who knows a language never speaks it again after age 7, there’s a good chance they’ll forget most of it. But if you yank them away around age 12 or older and reintroduce them to it 30 years later, there’s a good chance they won’t miss a beat, Hernandez says. Experts are still debating the exact age when language cements, but they’re getting a better idea. For example, in a study published in 2002, Schmid examined 35 oral testimonies of German Holocaust survivors who fled to England. They generally were given the choice to speak German or English in their interviews. Almost no one who left Germany before age 11 gave the interview in German. But many who left after age 11 did prefer German. Hernandez tells me I’m in a gray area because, though I only used Tamil early in life, I was still exposed to it after I stopped speaking it. My prolonged exposure has likely let me retain a good amount of what little I did learn.
FIRST WORDS So I do have some foundation upon which to rebuild my use of Tamil. How long would it take to become fluent again? Hernandez is hesitant to give me an answer. True fluency would require total immersion, and likely five to 10 years of it to really get there. There are so many variables, such as my level of proficiency when I was little and how much I’ve been exposed to it since. I also have to consider how good I am at learning languages in general and how hard I want to work. Schmid, the language loss expert, agrees, but also points me to a case study in which a Frenchman remembered speaking Mina, the language of the West African country of Togo, when he was a young boy. While born in France, he and his family, native Togolese, spent three and half years living in Togo, where he became fluent in Mina. But after returning to France when he was 6, his family was told not to use Mina with him anymore because it would hinder his French. When he was interviewed as an adult, he had forgotten most of the Mina he used to know. But after several sessions of age-regression hypnosis, he was able to speak full sentences in his childhood language. “I think it will be a case of forcing yourself to say the first sentences,” she says. “Once that has been achieved, I’m not going to promise you anything, and I’m really only going with my gut feeling. But I suspect you will feel the flood gates open.” I hope she’s right. I’ve since joined an online community to find people to converse with and look forward to speaking my first full Tamil sentences in a long, long time. D Sushma Subramanian teaches journalism at the University of Mary Washington. Her favorite Tamil word is upacaram, a form of hospitality that often involves badgering guests to eat more.
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Mind Over Matter
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Fields of Fire A massive volcano beneath Europe is stirring, and millions of lives may be at risk. WORDS AND PHOTOS BY RUSS JUSKALIAN
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Seen from mountaintop monastery Hermitage dei Camaldoli, the suburban sprawl of greater Naples sits atop a massive volcanic caldera that may be poised to erupt. Posillipo Hill, the dark ridge on the left, is part of the wall of the caldera, which stretches 12 kilometers across.
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J Dozens of monitors at the Vesuvius Observatory outside Naples track earthquakes and other regional volcanic activity. The observatory’s director, Francesca Bianco, points out recent tremors around the facility’s namesake, but the bigger threat to the metropolis may be Campi Flegrei, a massive caldera beneath the suburbs, seen in the upper left monitor.
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ust 10 kilometers from the frenetic pulse of central Naples, in stark contrast to the Italian city’s impressive volcanic-stone churches and effortlessly stylish urbanites, sits a boxy, concrete building. Inside this unremarkable government outpost, accessed through a pair of sliding glass doors, is the Vesuvius Observatory monitoring room, lit by the cool glow of 92 flat-panel screens. On each screen, volcanic activity readings, including those from seismic devices sensitive enough to pick up a passing bus, blink and beep in real time. In the middle of the room is a desk. And in the middle of that desk is a single red phone. Twenty-four hours a day, 365 days a year, there are at least two people in the room, ready to pick up the phone and advise the national civilian defense in the event of a volcanic emergency. But Mount Vesuvius, its iconic cone rising conspicuously on the city’s eastern flank, is not the only concern. A potentially even more destructive volcanic giant is tossing fitfully in its sleep, right on Naples’ doorstep: the caldera of the massive volcano system Campi Flegrei, which translates to the fields of fire. If it erupts, an event some researchers feel is increasingly likely, it could be catastrophic
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for Italy’s third-largest municipality and the surrounding countryside. Disruptions could stretch far beyond Italy, too, affecting everything from air travel to agriculture, with ash darkening the skies over Europe and the Mediterranean. The threat comes from the west, in a pockmarked and mountainous landscape abutting Naples just beyond an elongated ridge thick with lovely villas, called Posillipo Hill. The meaning of the hill’s name, “a respite from worry,” belies the story of its formation. Posillipo is at the edge of a volcano caldera so large that to see its full shape requires an elevated vantage point. To stand within it is to be unable to see it. These calderas are born when a volcano system erupts with such force that the resulting crater, instead of merely being flattened, actually slumps downward into the ground afterward. The most powerful eruption believed to be from Campi Flegrei, nearly 40,000 years ago, launched the equivalent of 300 cubic kilometers of ash and pulverized rock skyward. The massive eruption impacted the global climate and may have helped to snuff out the last gasps of the Neanderthals. Now there are signs that Campi Flegrei is stirring once more. At surface level, the caldera is dotted with steam vents, or fumaroles. One of them, the Solfatara di Pozzuoli, has famously lent its name to fumaroles that emit sulfur — such vents
around the world are now known as solfataras. But it was one of Solfatara’s less well-known neighbors, the fumarole Pisciarelli, that attracted attention in 2009. The once-insignificant Pisciarelli started to roar, bubbling mud and spewing steam. It was a hint that something was happening below ground. In 2012, the land within the caldera, which had been rising for nearly a decade, began to rise faster. And in late 2016, a paper in Nature Communications suggested the volcano might be entering a new and potentially much more dangerous phase. There’s just one problem: The dynamics of large calderas are at best a mystery, and reconstructing the steps that led to Campi Flegrei’s past eruptions seems as much Delphic interpretation as science. Experts can’t agree on what the volcano is doing, only that the threat it poses is real.
IN THE AIR Campi Flegrei is unique among volcanoes in that it can be reached by subway. In fact, from the trendy beachfront neighborhood of Chiaia in
Naples, it’s just two stops to the caldera. “Do you smell that?” says my friend Emanuel Scholz, a German geologist who has joined me in the caldera out of professional curiosity on a mild February morning. It smells like sulfur. “This is Campi Flegrei,” says volcanologist Giovanni Chiodini, waiting for us on the subway platform. “Some people think only the Solfatara is the volcano because there is steam coming out. But this is all a volcano.” He moves his arms in a full circle, indicating the entire urban outskirts around us. Then he points down the road toward the Vesuvius Observatory. It’s in the caldera, too, he notes. Chiodini, Scholz and I pile into an underpowered van, and we fight our way through winding streets of molasses-slow traffic. Our destination is the Pisciarelli fumarole, on a small hillside just meters behind an artificial soccer field. (The suburban banality of the setting is surreal. I imagine an irate gym teacher with his hand on his forehead as he loses yet another ball to the volcano.) As we approach the fumarole, white plumes of caustic vapor bite at the insides of my nostrils.
Volcanologist Giovanni Chiodini (in red) shows a visitor around the edges of the Pisciarelli fumarole, an increasingly active volcanic vent within the Campi Flegrei caldera.
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Geologist Emanuel Scholz and an observatory staff member chat beside the Pisciarelli fumarole as it spews gas and boiling mud just a ball’s toss away from a suburban soccer field (above). With a slight shift in wind, a cloud of gas from the fumarole engulfs Chiodini (far right). The volcanologist and his colleagues monitor the fumarole’s every shudder and belch with a variety of instruments (right).
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I hear the guttural roar of what sounds like a redlining motor. “Some years ago,” says Chiodini, “This was a trickle. Not like today.” Dark, gray mud bubbles violently from the fumarole’s center in fist-sized globules and snakes downhill toward the suburb’s homes. The whole thing has a dank and foreboding air. It’s here and at Solfatara that Chiodini believes he’s found the signature of a waking volcano. As the lead author of the 2016 Nature Communications paper, Chiodini documented a change in the molecular makeup of gases spewing from the fumaroles, particularly Solfatara, suggesting that the Campi Flegrei caldera might be approaching the so-called “critical degassing pressure” (CDP), after which an eruption becomes far more likely. His argument hinges on the fact that as magma rises through Earth’s crust, it undergoes a process called decompression, during which it releases a variable mix of volatile compounds. At the CDP, this mix switches over almost fully to water vapor. The massive amounts of water-rich gases then heat hydrothermal systems in the surrounding rocks. The result: at least a tenfold increase in heat transported into the rock layers between the magma and the crust’s surface, weakening them. Up on a small outcrop above the main vent of
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the Pisciarelli fumarole, the observatory has two monitoring systems looking for changes in heat and gas composition emerging from the caldera. One, tucked beside solar panels and under a small shelter, is little more than a coffee-filter sized dome. Every two hours, it measures the gases seeping up from the ground. The other is an infrared camera pointing at an even higher outcrop. The heat moving into the rock there, Chiodini explains, might be a good measure of how active the caldera is. Similar monitoring stations are scattered across the caldera. And what they’ve recorded is concerning: a 25-year decreasing trend in the ratio of certain gases suggests that decompression is occurring and magma may be rising closer to the surface, while an uptick over the last 15 years in heat transfer matches Chiodini’s model of what CDP will look like. The data from the caldera parallels similar trends found before eruptions at smaller volcanoes in Papua New Guinea and the Galapagos. And, according to Chiodini, it suggests that Campi Flegrei’s magma is preparing to let off a dangerous amount of heat. For a while the caldera floor, sitting at ground level, and the rock below it, will act like a plug, holding it all together. But keep adding heat and weakening the rocks, and the plug will eventually fail. Perhaps catastrophically.
Mount Vesuvius
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Posillipo Hill Pisciarelli fumarole Solfatara Roman-era marketplace and temple
THE HEAT IS ON
HYDROTHERMAL NETWORK
On the edge of Naples, the Campi Flegrei caldera, a massive volcano, appears to be stirring. One researcher believes the caldera’s magma may be releasing massive amounts of hot gases, which pump heat into an overlying hydrothermal network of water and rock. This added heat weakens the rocks between the magma chamber and ground level — and may make an eruption much more likely.
HOT GAS
ITALY
DECOMPRESSING MAGMA
JAY SMITH
Naples
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IN THE ROCK Giuseppe De Natale, a physicist by training who monitors the volcanoes at the Vesuvius Observatory, had access to the same data as Chiodini. But his conclusions were very different. Changes in measures such as heat transfer and gas composition are not necessarily red flags; De Natale and colleagues noted in a Nature Communications paper of their own, published in May, that the majority of episodes of such unrest in a large volcano system do not lead to eruption. The real worry, De Natale believes, is not decompressing magma but accumulating stress on Earth’s crust. To find signs of impending danger, look to the ground, De Natale tells me: The caldera’s narrative was written into the land’s deformation over millennia.
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The long record comes courtesy of the nearly 2,000-year-old columns amid ruins of an old Roman marketplace still standing near the waterfront of a nearby town called Pozzuoli. Discovered in 1750, the columns puzzled scientists: They’re dotted with boreholes drilled by a marine mollusk known as Lithodomus lithophagus. It took 200 years to solve the riddle. The so-called “stone-eater” mussels had done their work as the columns moved into and out of the water with the fluctuations of the caldera floor’s elevation. By dating the holes, scientists reconstructed a remarkably consistent record: The ground in the caldera had been sinking at a steady rate of about 1.7 meters per century. That is, except for brief periods when the caldera floor had risen. This happened twice in the past 500 years. The first started about a century before the last minor
Solfatara (opposite), a volcanic vent within Campi Flegrei’s caldera, spews sulfurrich gases that color nearby rocks (above) while a monitoring station (left) keeps close tabs on activity.
eruption in the caldera in 1538, which gave birth to a 134-meter mountain. The second is what volcanologists are worrying about today. In his office, De Natale shows me a simple line graph of the current rise. The most notable features are sharp uplifts of 1.7 meters and 1.8 meters, respectively, from 1969 to 1972 and 1982 to 1984. The latter uplift period was accompanied by numerous small earthquakes — including 600 on the worst day in 1984. On charts tracking the rate of movement of the caldera floor, the uplifts, which occurred in mere geological instants, appear as nearly vertical lines. “But look,” says De Natale excitedly, “the period of uplift from 2005 onward is totally different.” Unlike the previous instances, here the line only gradually bends upward. De Natale’s explanation is that the two uplift periods of the 1970s and ’80s were likely caused
by magma rising from a chamber 8 kilometers underground to form a shallower sill about 4 kilometers beneath the city. As the crust strained to contain the pressure, it fractured, causing the earthquakes. But then the magma stopped moving, and, sometime around 2000, the shallower layer of magma had almost completely cooled. From 1985 until around 2000, the caldera slumped by nearly a meter. Since 2005, the current slow uplift has recouped much of that loss in elevation, but with less seismic activity than in previous periods. One view, says De Natale, is to take the uplift episodes of the 1970s, 1980s and now as independent events. The first two had deformed the ground by more than twice the uplift currently underway, so surely there wasn’t anything yet to worry about. But what if, De Natale says, the three periods are all connected? In that case, the caldera floor is a lot like the proverbial camel’s back: An overweight rider might cause the poor animal’s spine to arch without lasting damage. But load the camel with enough weight, and eventually even the lightest additional cargo — perhaps a single straw — will result in disaster. In a similar way, the breaking point of the caldera floor might not be determined by any single displacement, but by the total net displacement since the process started. If this view holds, the risk for an eruption isn’t determined by the modest uplift since 2005, but by the nearly 4 meters of uplift since 1950. That would
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In the waterfront town of Pozzuoli, located at the heart of the caldera, ruins of a Romanera temple and marketplace (above) attest to past seismic activity. The marine mollusk Lithodomus lithophagus bored holes in the columns (right) during periods when the ground level sank and the ruins were underwater.
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mean the caldera is already under considerable tension. The question is how much more it could take. Even De Natale isn’t ready to say.
A GIANT’S FOOTPRINTS To understand why Campi Flegrei poses such an unpredictable and enigmatic risk requires a removed vantage point and a history lesson. Or, as Antonio Costa, an expert on the formation of calderas tells me, “Without geological history, you cannot know the current situation.” So, after spending a few days with Chiodini and De Natale, Scholz and I join Costa and volcanologist Roberto Isaia at a mountaintop monastery with a view of the caldera and its surroundings. Near the back of the grounds, a stone terrace opens to the stunning vista of a semicircular valley composed of visible craters in its center — remnants of the caldera’s 70 “small” eruptions in the past 15,000 years — and beyond that the deep blue water of the Gulf of Naples. As Costa unrolls a topographical map of what we’re looking at, Isaia becomes animated. His fingers trace the ridge of Posillipo Hill, arcing into the ocean where the island of Ischia sits opposite us. Then he traces a line from the other side of the valley, completing an 13-kilometerwide oval. “That,” he says, “is the volcano.” The sprawling, disorganized, traffic-bound mess
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in the middle is teeming with people. We can see Stadio San Paolo, the third-largest stadium in Italy, with a capacity of 60,000. The observatory is somewhere in there, too. “A new eruption could happen anywhere down there,” says Costa. He produces a timeline of Campi Flegrei’s periods of rest and unrest. “We don’t know if this is the start of a new epoch or not,” says Costa,
noting the irregularity of its past activity. One risk probability map of the area we’re looking at, modeled on eruptions from the past 5,000 years, looks like a rainbow of concentric paint splatters, each larger than the next, with finger-shaped bands extending outward from an epicenter in Pozzuoli. Each color represents the annual probability of being hit by pyroclastic flows, gravity-driven currents of superheated rock and debris that move a lot like an avalanche. The real threat for the greater Naples area, however, is the ash that Campi Flegrei might send skyward. The prevailing wind patterns mean even moderately sized eruptions would drop the bulk of their ejected ash right on the heads of Neapolitans. Drop enough of it, and the flat roofs around the city would start collapsing. It’s a scenario never far from my mind over the last days of my trip. And as we finally prepare to leave Naples, I turn to Scholz and sheepishly admit that, as irrational as it might be, I feel a sense of relief to be going home. “Me, too,” he replies.
POSTSCRIPT OR PROLOGUE? Media coverage of Campi Flegrei’s potential threat erupted around the end of 2016 with the publication of Chiodini’s study. In May, the paper De Natale co-wrote raised alarms again. “Set to Blow?” read one British tabloid. “Italy’s Supervolcano May Be on a Course to Erupt,” warned another. But the caldera itself has been quiet. “The ground level is stable, and the seismicity almost absent,” De Natale writes via email when I ask what the fuss is about. The paper isn’t so circumspect. It postulates that Campi Flegrei’s crust may have as little as a meter left to give before “an eruption can be expected.” The team reached this conclusion by scrutinizing the changing patterns of small earthquakes and uplift at Campi Flegrei and analyzing physical markers of stress from a deep drilling program. They also compared the data against that of other volcanoes, notably two vents in the similarly sized Rabaul caldera in Papua New Guinea that erupted simultaneously in 1994. (Thanks to a local preparedness campaign, the eruption killed only four people.) Their findings offer a model for how rising magma and pockets of hot water or gas stretch the ground beneath a caldera in three distinct phases. In each phase, the ground is less elastic. The final “inelastic” phase is a sign that the crust is stretched to its limits and riddled with small fractures: rigid and ready to erupt. The current uplift, wrote the authors about Campi Flegrei, “suggests that the crust is now
approaching the transition from quasi-elastic to inelastic deformation.” The caldera floor has been pushed upward by about 4 meters since 1950. The bad news is that, if their model is correct, the caldera floor should become inelastic at between 5 and 12.5 meters. The volcano’s unpredictable history and our limited understanding of how caldera volcanoes in general work make it impossible to know whether that limit could be reached in years, decades — or never. That leaves the people of Naples with two models in disagreement over signs of a potential
imminent eruption: one from Chiodini, looking for the CDP and heat-weakened rocks, and one from De Natale, focusing on an accumulation of tension in rocks bent to their limits. To laypeople, that might sound like a reason to trust neither. However, there’s one area where the two models do agree: Campi Flegrei is acting in a way that suggests its first reawakening in 412 years. The long-term life cycle of caldera volcanoes is still largely a mystery, however. Instead of the tossing and turning of a waking giant, both researchers suggest that Campi Flegrei’s movements may simply stop, and the volcano sinks back into a deep sleep. The problem is that nobody will know until it erupts — or doesn’t. That uncertainty reminds me of the unsettled feeling I had walking the streets of Naples, knowing the chance of an eruption is statistically minuscule, but always there. But it also makes me think of what I like most about Naples: its seemingly endless capacity, no matter the conditions, to keep living. It’s a city flanked by volcanoes, with magma beneath its feet. Its cathedrals are literally built of volcanic ash. Almost, I think, like an act of defiance. D
From an overlook at the mountain monastery of Hermitage dei Camaldoli, the suburban sprawl stretching across Campi Flegrei is obvious; the entire densely populated area falls within the red zone on a map showing the area of greatest risk should the caldera erupt.
Russ Juskalian is a writer and photographer based in Munich.
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SCENTS SENSIBILITY The nose knows more than you think. BY MARTA ZARASKA
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EVANNOVOSTRO/SHUTTERSTOCK
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magine walking into a meeting room. You shake hands with colleagues, then everyone sits down. Within seconds they all start sniffing their palms, picking up clues about you from the chemical traces left over from the handshakes. Sniffing palms after a handshake, usually within 30 seconds of the interaction, would likely help people learn about someone’s health and genetic compatibility, according to a 2015 study by researchers in Israel. Sniffing can also offer information on people’s emotional state, such as if they are happy, sad or fearful. The smeller gleans these emotions subconsciously, of course. For decades, scientists believed humans were not very good at detecting and identifying odors. Our animal ancestors used their noses way more than we do in modern society, says Jessica Freiherr, a neuroscientist at RWTH Aachen University, in Germany, and the author of several studies on human olfaction. “We are disconnected from our noses,” she says. “We need them much less in everyday life. And our vision overrides the sense of smell in a lot of situations.” But that doesn’t mean we don’t have powerful smell potential. A 2014 study showed that we can distinguish at least 1 trillion different odors — up from previous estimates of a mere 10,000. Awareness of our innate smelling abilities, however, is complicated because the human language doesn’t have words for a trillion smells, and much of smelling happens under the radar of our consciousness. Unlike our other senses, the olfactory nerves do not proceed directly to the brain’s thalamus, the gateway to consciousness. Instead, information feeds from the nose to cortical areas to arouse emotions and memories without our awareness. When it comes to smells, people can be influenced and not realize it.
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Orbitofrontal cortex Decision making and emotional processing Thalamus
t en c S
Olfactory bulb
Instead of proceeding directly to the thalamus like other sensory systems, scent signals first travel to brain regions that process emotions and memory.
Olfactory tract
Amygdala Basic emotions
Entorhinal cortex and hippocampus Memory
A SCENTED FINGERPRINT If you were assaulted by a stranger you didn’t get a good look at, could you identify the person by smell in a police lineup? Would the perpetrator’s body odor be enough? It very well could be, according to a 2015 study by scientists in Portugal and Sweden. Researchers collected body odor samples from 20 male university students. Other students then watched a video of an actual assault by a man on a woman (to stir them emotionally), while sniffing a scent they were told was that of the suspect. In reality, it was the scent of one of the 20 male students. Afterward, the sniffers were given a “lineup” of five odor samples and asked to identify the person whom they had smelled — presumably not a very enjoyable task. Results were quite impressive, though. The “witnesses” were able to pinpoint the would-be suspect 75 percent of the time. Every person has a unique scent. “It’s like a fingerprint,” says Johan Lundström, a neuroscientist at the Karolinska Institute in Sweden. “There is a large genetic component to body odor. Even trained sniffer dogs have a hard time distinguishing between identical twins, unless the twins are on different diets.” Scientists still don’t know how human body odor can act like a scented fingerprint. It could be from the apocrine sweat glands in the armpits, which produce odorless substances made smelly by skin bacteria. In 2015, scientists from the University of Düsseldorf identified unsaturated, or hydroxylated, branched fatty acids as the “olfactorily most dominant,” or stinkiest. Human scent affects our brain differently than other scents. When we catch a whiff, the areas of the brain responsible for social processing light up, according to a study that used positron emission tomography (PET) to measure brain function. “There is much more information in body odor than we can extract from normal odors,” says Lundström, the study’s lead author.
“NOSE-WITNESS” IDENTIFICATION CULPRIT IDENTIFICATION (%)
COUNTERCLOCKWISE FROM TOP LEFT: CORBAC40/SHUTTERSTOCK; DEAN DROBOT/SHUTTERSTOCK; ALISON MACKEY/DISCOVER; EVERETT COLLECTION/SHUTTERSTOCK
We are disconnected from our noses. We need them much less in everyday life. And our vision overrides the sense of smell in a lot of situations.
Hit: correct odor chosen
100 90 80 70 60 50 40 30 20 10 0
False positive: incorrect odor chosen Miss: volunteer thought odor wasn’t in lineup
Chance
Neutral video
Assault video
Research suggests that heightened emotion influences smell sensitivity. In the study using the body odor lineup referenced above, volunteers watched a video of an actual assault by a man of a woman, while sniffing a scent they were told was that of the suspect. They correctly picked that odor 75 percent of the time from a “lineup” of five odor samples. A separate group who watched an “emotionally neutral video” while sniffing chose the correct odor from a lineup just 35 percent of the time. That group also had more false positives. Chance was 20 percent. Source: “Nosewitness Identification: Effects of Negative Emotion,” PLOS One, 2015
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Who Passes the Smell Test?
NOSE TO NOSE: HUMAN VS. ANIMAL Animals more sensitive Spider monkey
Humans more sensitive
18
Mouse
57 35
30
Squirrel monkey
50
11
Pigtail macaque
54
6
Rat
10
31
Short-tailed fruit bat
1
Dog
17
10
5
Common vampire bat
1
14
Common mouse-eared bat
0
13
Pig
2 40
30
20
10
3 0
10
20
30
40
50
60
NUMBER OF ODORANTS In his study to test the olfactory prowess of humans compared with animals, biologist Matthias Laska used a mere fraction of the trillions of smells humans can pick up. Some odors were from fatty acids (mainly body odor), ascetic acids (fruits and flowers) and alcohols (a by-product of microbes). In the end, humans beat out a few notable schnozzes, such as the mouse and pig, and were bested only by dogs. Source: “Human and Animal Olfactory Capabilities Compared,” Springer Handbook of Odor, 2017
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CHART: ALISON MACKEY/DISCOVER. SHUTTERSTOCK IMAGES CLOCKWISE FROM BOTTOM LEFT: HOLGER KIRK. DENNIS VAN DE WATER. RESTYLER. JAROMIR CHALABALA. BELIZAR
An animal schnoz is obviously superior to our own mediocre noses, right? Not so fast. Matthias Laska, a biologist at Linköping University in Sweden, has been comparing senses of smell across species — including humans — for more than two decades. “The more data I collected on different species over the years, the more interesting the picture became,” Laska says. But sizing up how sensitive the snout of, say, a seal is compared with a bat or human isn’t straightforward. People can tell you when a certain scent is no longer detectable. But each animal has to learn to associate a particular odor with a reward and then do something, like press a button, to let researchers know when they smell it. The odors compared between species also have to be the same. That sounds obvious, but while humans have sniffed around 3,300 different scents for science — out of the trillions possible — the highest number for animals is 81, by spider monkeys. Laska only found solid enough data to compare humans with 17 species, all mammals. However, human noses held their own. Humans tested as generally more sensitive sniffers than monkeys and rats on a limited range of odors. In fact, humans detected certain scents at lower concentrations than the notoriously top-notch nostrils of mice and pigs. Humans even beat the indomitable dog for at least a handful of scents. These include aromas produced by plants, a logical evolutionary advantage for our ancestors seeking fruits. The majority of the odors in which dogs bested us were the fatty acids, compounds associated with their own meaty prey. “Odors that are not relevant for you, you are usually not good at [smelling],” Laska says. Bottom line: Humans, Laska says, “are not as hopeless as the classical wisdom will tell us, and dogs are not the super nose of the universe for everything.” ASHLEY BRAUN
TOP: SHPAK ANTON/SHUTTERSTOCK. BOTTOM: MUJICA-PARODI LR, STREY HH, FREDERICK B, SAVOY R, COX D, BOTANOV Y, ET AL. (2009) CHEMOSENSORY CUES TO CONSPECIFIC EMOTIONAL STRESS ACTIVATE AMYGDALA IN HUMANS. PLOS ONE
SMELLING EMOTIONS Another reason you might be able to identify a criminal, or at least someone feeling agitated, is that he or she may simply smell dangerous. In one of Freiherr’s experiments published in 2015 in the journal Chemical Senses, researchers obtained sweat from 16 men. The men took a timed math test and were falsely told they had performed below average. Disgruntled, they then participated in a workout where sweat was collected. As a control, the men took the math test again under no time constraint and were told they got an average score. Again, they followed up with a sweaty workout. Volunteers sniffed the men’s sweat samples while taking a test that measures cognitive performance. When sniffing the sweat of the men told they scored below average, the volunteers were distracted and slower to respond during their own test. When sniffing the sweat from the men’s second workout, the volunteers scored in a manner indicating emotional neutrality. A hefty pile of evidence suggests that emotions have a scent. What’s more, such smelled emotions may be contagious. Say you go out to meet a friend who had been watching funny videos on her mobile phone, making her feel happy. As you approach her, you catch a whiff of her scent and automatically smile. But had your friend just watched a scary movie, her body odor would have likely made you feel apprehensive. Using electrodes, European researchers in 2015 measured the facial movements of volunteers who sniffed sweat samples of people who had watched either pleasant or scary videos — happy-go-lucky scenes from Disney’s The Jungle Book versus hair-raising clips from Stanley Kubrick’s The Shining. After inhaling the scent of The Jungle Book watchers, participants “assumed a genuine happy facial expression,” says Jasper de Groot, a psychologist from Utrecht University in the Netherlands. “It was subtle, yet significant.” Meanwhile, smelling the body odor of stressedout people ups our vigilance, while the odor of people who had just watched something disgusting makes our faces twist in disgust. In fMRI scans, people sniffing the sweat from first-time parachute jumpers lit up the brain’s left amygdala, where basic emotions are processed, suggesting fear is contagious, too. “These chemosignals ring an alarm bell in your brain to attract your attention,” Freiherr says. “Maybe you can smell a dangerous place because somebody was there five minutes ago feeling scared.”
In fMRI scans, people sniffing sweat of first-time parachute jumpers lit up the brain’s left amygdala, suggesting fear is contagious, too.
An fMRI brain scan of a volunteer sniffing the sweat of a parachute jumper shows high activity, in yellow, in the left amygdala.
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Inhaling body odor can offer more information about people than their emotional state. The health and biological compatibility of the opposite sex might also be gleaned, all the better to help pick the perfect mate. In an experiment published in 2014 in the journal Psychological Science, people could tell who showed signs of sickness by their body odor (the researchers injected the sweat donors with a toxin that prompted an immune reaction). From an evolutionary standpoint, smelling sickness or disease has advantages. Choosing an unhealthy partner is not the best way to pass on your genes. Yet of maybe even greater genespreading significance is the ability to tell differences in MHC — the major histocompatibility complex, a gene family linked to the immune system and body scent. Scientists have long known that animals such as mice and rats can tell how genetically related they are to others of their species by smelling one another’s urine. Studies show humans are masters of this skill, too — and thankfully, no urine smelling is necessary. When scientists from the University of Chicago asked a group of women to sniff T-shirts worn for two consecutive nights by different men, the women pinpointed their closest genetic matches — even though there could be millions of unique combinations of MHC genotypes. A study by researchers from McGill University in Canada involving neuroimaging, which creates pictures of the brain’s structure and neural activity, showed that smelling the body odor of someone closely related activates the dorsomedial prefrontal cortex, a part of the brain responsible for recognizing family. “Biologically, it makes sense. We want to protect our own gene pool,” Lundström says. But “it’s not so much picking the best partner, it’s deselecting bad partners.” Research shows that people — and women in particular — prefer potential partners who are somewhat genetically related, but not too related. Having children with someone with an MHC genotype that
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In a study that involved guessing the age of women shown in photos, participants knocked years off of actual ages if they smelled, and enjoyed the smell of, grapefruit.
is too similar, studies show, can lead to spontaneous abortion or low birth weight. Conversely, pursuing someone with a close (or semi-close) genetic makeup means preserving adaptations to an environment — think regional people having immunity to local strains of pathogens. Meanwhile, some scents can make us appear more attractive to potential partners. Take the aroma of grapefruit. In a study that involved guessing the age of women shown in photos, participants knocked off 12 years from actual ages if they smelled, and enjoyed the smell of, grapefruit. If the participants smelled spicy and floral notes, the women appeared four pounds slimmer. And it’s much safer to buy cologne for people within your family rather than outside it. Genetic kinship seems to influence smell preference. In one study, people with similar genotypes chose similar perfume ingredients.
TOP: DEAN DROBOT/SHUTTERSTOCK. BOTTOM: NOMAD_SOUL/SHUTTERSTOCK
SCENT OF A LOVER
SICKOVA TATYANA/SHUTTERSTOCK
THAT NEWBABY SMELL If you’ve ever thought there is something special about the smell of babies, you’re right. In 2013, scientists from Germany, Canada and Sweden took fMRI scans of 30 women while they sniffed the cotton undershirts of newborns. The new moms’ thalamus lit up more than that of women without kids, suggesting the mothers’ increased attention. All the women showed activity in the brain’s neostriate areas, where the reward system lies. The fresh scent of newborns activates the same biological mechanism in women as a baby’s “very round eyes, the round face, the cute voice,” says Lundström, who was involved in the study. It is nature’s way of bonding mother and child. Although only women were tested in that particular study, Lundström suspects that similar results would be found in men. For now, researchers haven’t managed to pinpoint the molecules responsible for that new-baby smell. Lundström and his colleagues have some chemicals under the microscope (figuratively and literally), and are even researching whether the newborn smell could be used to treat depression. The team is also investigating whether women who suffer postpartum depression lack receptors for newborn scent molecules or don’t receive the reward signals from the baby smell. Similar to our ability to winnow out incompatible mates by scent, new moms can distinguish their biological babies by sniffing them. In one classic study, mothers identified the smell of their child from two other newborns six hours after birth, even though mother and child were separated for most of that time. Sixty-one percent of mothers guessed right. (Chance would be 33 percent.) This works the other way, too. Newborns know the scent of Mom by the second day of life. In a 2015 study, breast-fed babies turned their heads toward scent pads of their mothers for nearly twice as long as the pads of lactating strangers. “Mother’s body odor might be learned to some degree, as this odor is related to the chemosensory signature of the amniotic fluid, which the unborn senses,” says Katrin T. Lübke, an olfaction researcher at the University of Düsseldorf in Germany who was not part of the study. Yet simple exposure is not enough for parents to identify the smell of their nonbiological children. In one study, mothers were able to pick the scents of their biological kids in 90 percent of cases, but with stepchildren, they
were only 28 percent accurate. Among families in Wales interviewed for a government-funded study on failed adoptions, several parents mentioned that the distinctive body odor of their child had a negative impact on the relationship. One mom said her adopted daughter “didn’t smell right.” Although our noses can sometimes lead us astray, in general they send us important messages about other people. Be careful, a dangerous person was here and may be lurking nearby. Be cautious, a person is sick and may be contagious. Be alert, your newborn needs your care. Be flirtatious, this person is a potential partner. Being more open to our sense of smell has payoffs, even in modern times. “Listen to your inner voice, because your inner voice might be your nose telling you what to do,” Lundström says. D Marta Zaraska is a freelance science writer based in France and author of Meathooked: The History and Science of Our 2.5-Million-Year Obsession With Meat.
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Each found beside the body of their poached, dehorned mothers, orphaned rhinos Gertjie and Matimba were taken in at South Africa’s Hoedspruit Endangered Species Centre (HESC). Humans cared for the two around the clock to reduce their physical and emotional trauma. Sheep are sometimes used as surrogate mothers for orphaned rhinos; Gertjie and Matimba eventually formed a herd of three with Lammie the ewe.
LAST CHANCE TO BE Can conservation and anti-poaching efforts save the rhino?
CREDIT
WORDS AND PHOTOS BY RUSS JUSKALIAN
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A helicopter carrying a team of environmental crime scene investigators casts a shadow beside the decomposing body of a poached rhino in South Africa’s Kruger National Park. Poaching sometimes occurs within view of roads that, in daytime, fill with tourists observing the park’s wildlife.
A
mid a decade-long global rhino poaching epidemic, many conservationists wonder how long the animal will survive in the wild. Rhinos are killed for their horns, which are sold illegally in Vietnam and China — at street prices higher than gold — for their purported medicinal qualities. For example, just in South Africa, rhino poaching incidents skyrocketed over 9,000 percent, from 13 in 2007 to 1,215 in 2014. The country responded with dramatically increased funding and the militarization of anti-poaching teams, resulting in a small drop in 2016, to 1,054 poachings. Now, conservationists are scrambling to save the last five rhino species left on Earth, limited to ever-shrinking territories in Africa and Asia. Some governments are even experimenting with the controversial idea of allowing farmers to raise rhinos to harvest their horns (which can be painlessly trimmed and regrown like fingernails). Russ Juskalian traveled to South Africa, Vietnam and Indonesia to document the animals’ last stand. D Russ Juskalian’s reporting was supported by an Alicia Patterson Foundation Fellowship.
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Left: Senior environmental crime scene investigator Frik Rossouw uses a metal detector to search the decaying body of a rhino poached in Kruger National Park. He’s looking for bullet casings and other clues that might help convict the poachers, should they be caught. Rossouw will also collect DNA from the animal to crossreference against a centralized database. Such evidence can help solve individual cases when poached horn is seized, even months or years later, as well as piece together the complex criminal networks responsible for poaching rhinos and transporting their horns to Asia.
Below: Using coordinates phoned in by rangers on the ground, investigators document another poaching incident in Kruger. A standard crime-scene placard beside the lower jaw of the poached rhino provides positioning information in photographs. On the busiest days, there are backlogs of more than a dozen similar cases in the park, and the risks of working in the bush are ever-present. Landing a helicopter in a small break in the trees is dangerous, and the threat of a shootout with poachers is just as real. At this scene, the team’s work ended abruptly when a large animal was heard rustling nearby.
A solitary rhino grazes in Kruger’s southern area, caked in mud after spending time in a wallow — a common rhino strategy for cooling off and protecting their skin from the sun. Many of the rhinos in Kruger have been moved into small, so-called Intensive Protection Zones in order to limit poaching. The zones are monitored by air, remotely and on foot by heavily armed rangers, but shootouts with poachers are common.
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Right, top: On John Hume’s rhino farm northwest of Johannesburg, a veterinary team prepares to cut off a rhino’s horn. The whole process takes just minutes and is painless: It’s akin to clipping one’s toenail, as long as the horn is removed well above the skin. Hume’s farm has over 1,100 rhinos whose regrown horns are removed every one to three years. Hume and others who support the idea say the goal is to create a renewable, legal market for rhino horn to take the pressure off wild rhinos and reduce poaching. But opponents argue that legalizing the trade will reduce the taboo of using rhino horn and encourage so many buyers that farmed horn won’t be able to keep up with demand. Right, below left: A moderately sedated rhino on Hume’s farm rests after a veterinary team cut off its horn. During the process — which involves darting the animal by rifle and then blindfolding it to help keep it calm — the team uses the opportunity to draw a blood sample, vaccinate the animal and conduct a basic physical exam. Right, below right: Calcium and melanin deposits form a dark core in the harvested horn’s cross-section and also strengthen it. Horns typically are made of bone and covered with a thin sheath of keratin. Rhino horns, however, are made primarily of keratin and are chemically almost identical to a human fingernail. The horn has no medicinal value, but users still believe it can help with a range of ailments, from reducing hangovers to increasing energy. With a street price in Asia of $20,000 and up per kilogram, a large rhino horn may be worth upward of half a million dollars by the time it is sold in pieces.
HESC resident Matimba, orphaned by poachers when he was less than a month old, has grown into a mischievous adolescent. After drinking his daily tub of milk from a large saucepan secured in a truck tire, he playfully lifts the tire over his snout.
In the summer of 2013, three rhinos were darted and dehorned by poachers in South Africa. The male died, but the two females survived, despite the poachers’ hacking into their sinuses and nasal cavities to remove their horns. Numerous surgeries, including insertion of Fiberglass nasal casts, saved the animals. About 18 months later, one of them, pictured here at HESC, has started to regrow her still-deformed horn.
LOSING GROUND: RHINOS IN RETREAT Historical Approximate Range Current Range White rhinoceros (Ceratotherium simum) Black rhinoceros (Diceros bicornis) One-horned rhinoceros (Rhinoceros unicornis)
JAY SMITH
Javan rhinoceros (Rhinoceros sondaicus) Sumatran rhinoceros (Dicerorhinus sumatrensis)
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Left: At the border of Indonesia’s Ujung Kulon National Park, the Javan rhino’s last habitat, a ranger on patrol spots a problem: Local men, using a bamboo pole, have pulled apart the border fence’s cables, likely to transport illegally harvested wood, poach small animals and graze their water buffalo herds on the protected land. About 60 Javan rhinos remain on the planet, all of them in this single park, and human encroachment increases the risk of destabilizing their environment. Rhinos can share mud wallowing pits with domestic buffalo, heightening the risk of disease transmission, a particular danger given the small population’s low genetic diversity.
Right: In Vietnam, a woman in her 70s demonstrates how to grind rhino horn in preparation for consumption. Many people use a special dish with a sandpaper-like surface, rubbing the horn in circles in a small pool of water. Others, like the woman in the photo, use a hand file. The woman originally bought the horn to treat her ill husband, but now she uses it when she is dehydrated or feeling low on energy, she says. Paradoxically, she said the killing of rhinos for their horns saddened her, and asked how she could help conserve the species. Below, foreground: The skull of a rhino poached in Sumatra in 2005, on display at the rhino protection unit headquarters just outside Way Kambas National Park, is a testament to the brutality of poaching. A bullet hole is visible above its eye socket, and the snout of the animal has been destroyed, likely when the horn was removed. The last Javan rhino in Vietnam was killed in 2010. And this spring, poachers broke into a zoo in Paris and killed a rhino for its horn.
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A rare Sumatran rhino leaves its fenced enclosure for food and a medical exam, part of its daily routine at the Sumatran Rhino Sanctuary in Way Kambas National Park in Indonesia. The seven rhinos at the facility each live in large, enclosed sections of forest within the park and are closely monitored. The sanctuary’s goal is to develop a breeding population that will protect the genetic diversity of the species and strengthen wild populations. There have been small victories and a few natural births, but a rapidly dwindling natural environment remains the primary threat to the roughly 100 Sumatran rhinos remaining.
Learn more about the plight of rhinos at DiscoverMagazine.com/Rhino
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OUR NEXT BILLION Humanity only just arrived on Earth. But its future is in the cosmos. BY MAX TEGMARK ILLUSTRATIONS BY CHARLES GLAUBITZ
YEARS
THIRTEEN POINT EIGHT BILLION YEARS AFTER ITS BIRTH, OUR UNIVERSE HAS AWOKEN AND BECOME AWARE OF ITSELF. From a small blue planet, tiny conscious parts of our universe have begun gazing out into the cosmos with telescopes, repeatedly discovering that everything they thought existed is merely a small part of something grander: a solar system, a galaxy and a universe with over a hundred billion other galaxies arranged into an elaborate pattern of groups, clusters and superclusters. Although these self-aware stargazers disagree on many things, they tend to agree that these galaxies are beautiful and awe-inspiring. But beauty is in the eye of the beholder, not in the laws of physics. So before our universe awoke, there was no beauty. This makes our cosmic awakening all the more wonderful and worthy of celebrating: It transformed our universe from a mindless zombie with no self-awareness into a living ecosystem harboring self-reflection, beauty and hope — and the pursuit of goals, meaning and purpose. Had our universe never awoken, then it would have been completely pointless — merely a gigantic waste of space. Should our universe permanently go back to sleep due to some cosmic calamity or selfinflicted mishap, it will become meaningless. On the other hand, things could get even better. We don’t yet know whether we are the only stargazers in our cosmos, or even the first. But we’ve already learned enough about our universe to know that it has the potential to wake up much more fully than it has thus far. Perhaps life will spread throughout our cosmos and flourish for billions or trillions of years. And perhaps this will be because of decisions we make here on our little planet during our lifetime. To me, the most inspiring scientific discovery ever is that we’ve dramatically underestimated life’s future potential. Our dreams and aspirations need not be limited to centurylong life spans marred by disease, poverty and confusion. Rather, aided by technology, life has the potential to flourish throughout a cosmos far more grand and inspiring than our ancestors imagined. So if technology can shatter our old perceived limits of life, what are the ultimate limits? How much of our cosmos can come alive? How much energy, information and computation can it extract? These ultimate limits are set not by our understanding, but by the laws of physics. This, ironically, makes it easier in some ways to analyze the long-term future of life than the short-term future. Whereas today’s supermarkets and commodity exchanges sell tens of thousands of items we might call “resources,” future life that’s reached the technological cap needs mainly one fundamental resource: so-called “baryonic matter,” meaning anything made up of atoms or their constituents (quarks and electrons). From a physics perspective, everything that future life may want to create — from habitats and machines to new life-forms — is simply elementary particles arranged in some particular way. Once future life has bumped up against the physical boundaries of what it can do with its matter, there is only one way for it to do more: get more matter. And the only way it can do this is by expanding into our universe. Spaceward ho!
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an amount of mass m would give us an amount of energy E, SURROUND THE SUN When it comes to the future of life, one of the most hopeful where c is the speed of light. Since c is huge, this means a small visionaries is Freeman Dyson. He scoffed at how unambiamount of mass can produce a humongous amount of energy. tious we humans were, pointing out that we could meet all If we had an abundant supply of antimatter (which we don’t), our current global energy needs by harvesting the sunlight then a 100 percent efficient power plant would be easy to make. striking an area smaller than 0.5 percent of the Sahara desert. Simply pouring a teaspoonful of anti-water into regular water But why stop there? Why not simply put all the sun’s energy would unleash the energy equivalent to 200,000 tons of TNT, output to use? the yield of a typical hydrogen bomb — enough to power the Inspired by Olaf Stapledon’s 1937 sci-fi classic novel world’s entire energy needs for about seven minutes. Star Maker, where rings of artificial worlds orbit their parent In contrast, our most common ways of generating energy star, Dyson published a description in 1960 of what became today are woefully inefficient. Digesting a candy bar is merely known as a Dyson sphere. His idea was to rearrange Jupiter 0.00000001 percent efficient, in the sense that it releases a mere into a biosphere in the form of a spherical shell surroundten-trillionth of the energy that it contains. If your stomach ing the sun, where our descendants could flourish, enjoying were even 0.001 percent efficient, then you’d only need to eat 100 billion times more biomass and a trillion times more energy a single meal for the rest of your life. Today’s nuclear reactors than humanity uses today. He argued that this was the natural do dramatically better by splitting uranium atoms through next step: “One should expect that, within a few thousand fission, but they still fail to extract more than 0.08 percent of years of its entering the stage of industrial development, any their energy. Fusion is more efficient than fission, but even if intelligent species should be found occupying an artificial we enclose the sun in a perfect Dyson sphere, we’ll still never biosphere which completely surrounds its parent star.” convert more than about 0.08 percent of the sun’s mass to If you lived inside a Dyson sphere, there would be no nights: energy we can use, because once the sun has consumed about You’d always see the sun straight overhead, and all across the a tenth of its hydrogen fuel, it will end its lifetime as a normal sky, you’d see sunlight reflecting off the rest of the biosphere, star, expand into a red giant, and begin to die. How can we do just as you can nowadays see sunlight reflecting off the moon better? during the day. If you wanted to see BLACK HOLE POWER PLANTS stars, you’d simply go “upstairs” and FOR TODAY’S HUMANS, LIFE his book A Brief History of Time, peer out at the cosmos from the outside IN A DYSON SPHERE WOULD In Stephen Hawking proposed a black of the Dyson sphere. hole power generator, where black A low-tech way to build a partial BE DISORIENTING AT BEST Dyson sphere is to place a ring of habi- AND IMPOSSIBLE AT WORST. holes swallow matter and then convert tats in circular orbit around the sun. To matter into radiation by evaporating, completely surround the sun, you could add rings orbiting it but there are major challenges with making this process fast around different axes at slightly different distances, to avoid enough to be useful. Another interesting strategy is to extract collisions. energy not from the black hole itself, but from matter falling To be long-lived, a Dyson sphere would need to be dynamic into it. Nature has already found a way of doing this all on its and intelligent, constantly fine-tuning its position and shape own: the quasar. As gas swirls even closer to a black hole, forming a pizza-shaped disk whose innermost parts gradually get in response to disturbances and occasionally opening up large gobbled up, it gets extremely hot and gives off copious amounts holes to let annoying asteroids and comets pass through without incident. Alternatively, a detect-and-deflect system could of radiation. As gas falls downward toward the hole, it speeds be used to handle such system intruders, optionally disassemup, converting its gravitational potential energy into motion bling them and putting their matter to better use. energy, just as a skydiver does. The motion gets progressively For today’s humans, life in a Dyson sphere would be disorimessier as complicated turbulence converts the coordinated enting at best and impossible at worst. But that need not stop motion of the gas blob into random motion on ever-smaller future biological or non-biological life-forms from thriving scales. Eventually, individual atoms begin colliding with each there. Certain variants would offer essentially no gravity at all, other at high speeds — having such random motion is precisely and on others you could walk only on the outside (facing away what it means to be hot, and these violent collisions convert from the sun) without falling off, with gravity about 10,000 motion energy into radiation. times weaker than you’re used to. You’d have no magnetic field By building a Dyson sphere around the entire black hole, at (unless you built one) shielding you from dangerous particles a safe distance, this radiation energy can be captured and put from the sun. The silver lining is that a Dyson sphere the size to use. The faster the black hole spins, the more efficient this of Earth’s current orbit would give us about 500 million times process gets, with a maximally spinning black hole delivering more surface area to live on. energy at a whopping 42 percent efficiency.
HARNESS DEAD STARS Although Dyson spheres are energy efficient by today’s engineering standards, they come nowhere near pushing the limits set by the laws of physics. Einstein taught us that if we could convert mass to energy with 100 percent efficiency, E = mc 2 —
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SPHAELERIZERS Future intelligent life might be able to build what I call a “sphaelerizer”: an energy generator acting like a diesel engine on steroids. A traditional diesel engine compresses a mixture of air and diesel oil until the temperature gets high enough for it
to spontaneously ignite and burn. After that, the hot mixture re-expands and does useful work in the process, say pushing a piston. The carbon dioxide and other combustion gases weigh about 0.00000005 percent less than what was in the piston initially, and this mass difference turns into the heat energy driving the engine. A sphaelerizer would compress ordinary matter to a couple of quadrillion degrees, and then let it re-expand and cool once entities known as sphaelerons had converted most quarks into electrons and related particles. We already know the result of this experiment, because our early universe performed it for us about 13.8 billion years ago when it was that hot: Almost 100 percent of the matter got converted into energy, with less than one billionth remaining in the form of quarks and electrons, which make up all the matter we observe in our universe today. So it’s like a diesel engine, except a billion times more efficient!
SUPER-AI If eating dinner is 10 billion times worse than the physical limit on energy efficiency, then how efficient are today’s computers? Even worse than that dinner, as we’ll now see. Seth Lloyd, an MIT quantum computer pioneer, showed that computing speed is limited by energy. This means that a 1-kilogram computer, equivalent to a small laptop, can perform at most 5×10 50 operations per second — that’s a whopping 36 orders of magnitude more than the computer on which I’m typing these words. We’ll get there in a couple of centuries if computational power keeps doubling every couple of years. He also showed that a 1 kg computer can store up to 1031 bits, which is about one billion billion times better than my laptop. Actually attaining these limits may be challenging, even for superintelligent life. However, Lloyd is optimistic that the
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practical limits aren’t that far from the ultimate ones. Indeed, existing quantum computer prototypes have already miniaturized their memory by storing 1 bit per atom. Scaling that up would allow storing about 10 25 bits per kilogram — a trillion times better than my laptop. Moreover, using electromagnetic radiation to communicate between these atoms would permit about 5×10 40 operations per second — 31 orders of magnitude better than my CPU. The potential for future life to compute and figure things out is truly mind-boggling: In terms of orders of magnitude, today’s best supercomputers are much further from the ultimate 1 kg computer than they are from the blinking turn signal on a car, a device that stores merely 1 bit of information, flipping it between on and off about once per second.
STAR-FARERS OF CATAN General relativity says it’s impossible to send rockets through space at the speed of light, because this would require infinite energy. So, in practice, how fast can rockets go? In 1984, physicist Robert Forward pioneered a clever lasersail rocket design. Just as air molecules bouncing off a sailboat sail will push it forward, light particles (photons) bouncing off a mirror will push it forward. By beaming a huge solar-powered laser at a vast ultralight sail attached to a spacecraft, we can use the energy of our own sun to accelerate the rocket to great speeds. Forward calculated that this could let humans make the 4-light-year journey to the Alpha Centauri solar system in merely 40 years. Once there, you could imagine building a new giant laser system and continuing to star-hop throughout the Milky Way Galaxy. But why stop there? Since Forward’s design, there’s been dramatic progress in artificial intelligence. The possibility of computer superintelligence makes the
future look much more promising for those with intergalactic because they had superior technology. In contrast, it’s plausible wanderlust. If you remove the need to transport bulky human that long before two superintelligent civilizations encounter one life-support systems and add AI-invented technology, interanother, their technologies will plateau at the same level, limgalactic settlement suddenly appears rather simple. Forward’s ited merely by the laws of physics. This makes it seem unlikely laser sailing becomes much cheaper when the spacecraft that one superintelligence could easily conquer the other even merely need to be large enough to contain a “seed probe,” a if it wanted to. Moreover, if their goals have evolved to be robot capable of landing on an asteroid or planet in the target relatively aligned, then they may have little reason to desire solar system and building up a new civilization from scratch. conquest or war. For example, if they’re both trying to prove as It doesn’t even have to carry the instructions with it. All it has many beautiful theorems as possible and invent as many clever to do is build a receiving antenna large enough to pick up algorithms as possible, they can simply share their findings and more detailed blueprints and instructions transmitted from its both be better off. After all, information is very different from mother civilization at the speed of light. Then, it uses its newly the resources that humans usually fight over, in that you can constructed lasers to send out new seed probes to continue setsimultaneously give it away and keep it. tling the galaxy one solar system at a time. Some expanding civilizations might have goals that are essentially immutable, such as those of a fundamentalist cult or a Once superintelligent AI has settled another solar system or spreading virus. However, it’s also plausible that some advanced galaxy, bringing humans there is easy — if humans have succeeded in programming the AI with this goal. All the necessary civilizations are more like open-minded humans — willing to information about humans can be transmitted at the speed of adjust their goals when presented with sufficiently compelling light, after which the AI can assemble quarks and electrons arguments. If two of them meet, there will be a clash not of into the desired humans. This could be done either in a lowweapons but of ideas, where the most persuasive one prevails tech way by simply transmitting the 2 gigabytes of information and has its goals spread at the speed of light through the region needed to specify a person’s DNA and then incubating a baby controlled by the other civilization. Assimilating your neighbors is a faster expansion strategy than physical settlement, to be raised by the AI, or the AI could assemble quarks and which inevitably progresses slower electrons into full-grown people who would have all the memories THE POSSIBILITY OF COMPUTER than the speed of light. This assimilation will not be forced, such as that scanned from their originals back SUPERINTELLIGENCE MAKES infamously employed by the Borg in on Earth. This means that if there’s an intel- THE FUTURE LOOK MUCH MORE Star Trek: It will be voluntary, based ligence explosion, the key question PROMISING FOR THOSE WITH on the persuasive superiority of ideas, isn’t if intergalactic settlement is INTERGALACTIC WANDERLUST. leaving the assimilated better off. possible, but simply how fast it can EMBRACING TECHNOLOGY proceed. For example, if it takes 20 years to travel 10 light-years Because sci-fi authors are often dismissed as unrealistic romanto the next star system with a laser-sail system, and then another tic dreamers, I find it ironic that most sci-fi and scientific writing 10 years to settle it and build new lasers and seed probes there, about space settlement now appears too pessimistic in the light the settled region will be a sphere growing in all directions at a of AI. For example, we saw how intergalactic travel becomes third of the speed of light on average. much easier once people and other intelligent entities can be COSMIC SPAM transmitted in digital form, potentially making us masters of Last but not least, there’s the sneaky Hail Mary approach our own destiny not only in our solar system or Milky Way to expanding even faster than any of the above methods will Galaxy, but also in the cosmos. permit: using Hans Moravec’s “cosmic spam” scam. By broadIf we don’t keep improving our technology, the question isn’t casting a message that tricks naive freshly evolved civilizations whether humanity will go extinct, but how? What will get us first into building a superintelligent machine that hijacks them, a — an asteroid, a supervolcano, the burning heat of the aging civilization can expand essentially at the speed at which their sun or some other calamity? If instead of eschewing technology, we embrace it, then we up the ante: We gain the potential seductive siren song spreads through the cosmos. both for life to survive and flourish and for life to go extinct Since this may be the only way for advanced civilizations to even sooner, self-destructing due to poor planning. My vote is reach most of the galaxies within their future light cone and for embracing technology, but proceeding not with blind faith they have little incentive not to try it, we should be highly in what we build, but with caution, foresight and careful plansuspicious of any transmissions from extraterrestrials! In Carl ning. Life’s future potential in our universe is grander than the Sagan’s book Contact, we earthlings used blueprints from aliens wildest dreams of our ancestors, so let’s make the most of it! D to build a machine we didn’t understand — I don’t recommend doing this . . .
WE COME IN PEACE So far, we’ve only discussed scenarios where life expands into our cosmos from a single intelligence explosion. But what happens if two expanding civilizations meet? Europeans were able to conquer Africa and the Americas
From the Book: LIFE 3.0: BEING HUMAN IN THE AGE OF ARTIFICIAL INTELLIGENCE by Max Tegmark. Copyright © 2017 by Max Tegmark. Published by Alfred A. Knopf, an imprint of The Knopf Doubleday Publishing Group, a division of Penguin Random House LLC.
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Origin Story
Stone Cold Science Researchers develop new ways to discover how our oldest tech — and our brains — evolved. BY BRIDGET ALEX
In the Kent State University laboratory for experimental archaeology, the Spot Hogg Hooter Shooter, an automatic bow launcher, fires arrows filmed by high-speed cameras. The arrows are tipped with stone points, which are replicas of ancient artifacts. The replicas are “worthless . . . so we can break them and use them in ways that we can’t with the real artifacts that are priceless,” explains archaeologist Metin I. Eren, who leads the lab. To better understand ancient stone tools, his team creates facsimiles and tests their mechanical properties. It’s just one of the cutting-edge ways archaeologists study humanity’s oldest — and arguably most pivotal — technology. Without stone tools, says Eren, “we wouldn’t be the species we are today.” As early as 3.3 million years ago, human ancestors began bashing rocks into tools — a move that set our lineage on a distinct evolutionary path. For the next 99 percent of our time on this planet, our ancestors depended on stones to survive: for hunting, food preparation, constructing clothes and shelter. While artifacts made of wood and other perishable materials degraded, those made from rock endured. Thus, stone tools provide the richest record of human behavior across time and space. Archaeologists have dug up billions of them. Every one of those artifacts “has a story. It has a history of the people that
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Kent State University archaeologist Metin I. Eren takes aim with the Spot Hogg Hooter Shooter, a modern automatic bow launcher testing an ancient weapon: an arrow tipped with a stone point. Eren’s lab creates replicas of the prehistoric points and other tools to learn how they were used.
Without stone tools, says archaeologist Metin I. Eren, “we wouldn’t be the species we are today.” made it and used it,” says Christian Tryon, an archaeologist at Harvard University. It’s just a matter of learning to read the stones.
Hammerstone
MAKE OR BREAK Flake “Here’s the problem: Stone tools are the leastfamiliar things we excavate,” says archaeologist John Shea of Stony Brook University. “When you find a pot, you can say it looks like a pot. Or you find a temple. It looks like a temple.” Because stone tools are a forgotten technology, the purpose behind different styles is not self-evident. Scholars in the 19th century devised names, like scraper, point and burin, based on shape and assumed function. But they had no evidence that scrapers scraped or points impaled.
Unsure how stone tools were used, archaeologists fared better at determining how they were made. Typically, a rock (the hammerstone) was used to strike another rock (the core) to remove a slender piece (the flake) that was further sculpted into the desired form, such as an arrowhead or knife. To ensure the flake fractured with the right proportions, toolmakers often first shaped the core by knocking off scrap pieces in a Core systematic way. Researchers deduced these steps through feats of reverse engineering. In the 1894 book Man, the Primeval Savage, Worthington G. Smith reported his efforts to reassemble flakes and scraps into their original cores, like 3-D jigsaw puzzles. For three years he studied 2,259 pieces recovered from a site in England, managing to rejoin more than 500 of them (and concluding that shellac dissolved in spirit was the best adhesive for the job). Though tedious, this methodology of refitting has proven essential for understanding stone tool production. Some reassembled cores have dozens of pieces, each a step in a complicated sequence of premeditated maneuvers.
TOP: BOB CHRISTY/KENT STATE UNIVERSITY. BOTTOM: JAY SMITH AFTER L. PATTEN, STONE DAGGER PUBLICATIONS
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Origin Story
Making stone tools requires finesse, as Eren demonstrates (left). His lab produces and tests a variety of tools, including replica Clovis points (above).
THE POINT OF IT ALL Eren started making stone tools in college classes, but to become an expert, he trained at the University of Exeter under Bruce Bradley, as well as with Jacques Pelegrin and Robert J. Patten, all renowned for their toolmaking skills. “It was like a true apprenticeship,” Eren recalls. For two years, Eren practiced the craft about eight hours a day — save one day per week, when he restocked his rock supply by hiking the beaches of South England, loading a backpack with 150 pounds of flint. Now he can create any tool type by hand from the 6,000 pounds of rocks his lab houses, shipped from around the world. When identical copies of tools are required, his team uses lapidary equipment, or rock-cutters, to massproduce them. This unlimited supply of replicas — “as many as we need for statistical validity,” Eren says — enables
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them to conduct destructive experiments, like firing from the Spot Hogg Hooter Shooter. The goal is to test why tools had certain properties: Was a form preferred because it was aerodynamic, durable or just in fashion? Eren recently investigated tools made by early Americans some 13,000 years ago called Clovis points, which have distinctive channel-like divots known as flutes. Based on debris found at archaeological sites, Clovis people broke about 15 to 20 percent of their points while trying to flute them. The risky habit has perplexed scholars, with some speculating that it was an artistic flourish, a way for toolmakers to show off. But in a study this year in the Journal of Archaeological Science, Eren and co-authors found that fluting was practical. Through computer simulations and experiments that included mechanically crushing replicas with controlled force, they showed that flutes
A flint flake replica used to scrape bark will later be residue-tested at Gilliane Monnier’s University of Minnesota lab.
provided shock absorption, preventing points from breaking upon impact.
KNOW YOUR GUNK Replication experiments demonstrate what different types of stone tools could have done, but they do not reveal what any particular artifact did. About a decade ago that question drove Gilliane Monnier, an archaeologist at the University of Minnesota, to put an artifact under an electron beam. “It was clear there was stuff on that tool. I didn’t know what kind of stuff, but there was stuff,” recalls Monnier. She became intrigued by the possibility that artifacts might preserve particles from softer materials they once contacted, such as animal hides and wood. Residue analysis got started in the 1970s, but materials were often identified by their visual appearance under a microscope — a highly subjective method. Other approaches, which measured elemental or molecular composition, were considered reliable but destroyed the residues. Monnier wanted to find an accurate but non-destructive approach. So she began gunking up tools with known substances, the same way our ancestors might have done: whittling wood, slicing roots and grasses, even processing animal parts. “Getting blood wasn’t too difficult in Minnesota,” she adds. “I was able to
TOP: BOB CHRISTY/KENT STATE UNIVERSITY (2). BOTTOM: GILLIANE MONNIER
“Making a stone tool is not a random procedure,” says Tryon. It’s not easy, either. Every year Tryon teaches archaeology undergrads basic toolmaking; the students struggle to produce forms perfected long ago by human ancestors. “Most people think you need to beat the hell out of these things,” says Tryon. “That it requires brute strength. It does not. It’s more finesse. . . . It’s rhythm. It’s gesture.”
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Origin Story
TOOLING AROUND THE BRAIN Some researchers think stone tools can answer the big questions in human evolution: How do we differ from other primates and when did our unique human traits emerge? Chimpanzees and some monkeys use tools to a limited extent; they crack open hard-shelled foods with stones as natural hammers and anvils. Pre-human ancestors began breaking rocks to get sharp edges as early as 3.3 million years ago. By 2.6 million years ago, they did so in a standard way, producing what archaeologists call Oldowan tools. But a major innovation transpired around 1.8 million years ago: Homo erectus began sculpting
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Basic Oldowan tool
More advanced Acheulean hand ax In a 2017 study, anthropologist Shelby Putt monitored the brain activity of volunteers trained to make stone tools (left). Neuroimaging showed that creating advanced Acheulean-style tools (above) required engaging many of the same areas of the brain needed to play piano.
When participants made Oldowan tools, brain areas lit up related to vision and movement. Acheulean toolmaking, however, required integration of higher-order regions. rocks into intentional forms, making teardrop-shaped tools known as Acheulean hand axes. According to Shea, these hand axes were “shaped to be carried efficiently. The average length and width are identical to a Samsung Galaxy 7.” Researchers hypothesize that the technological leap was driven by a cognitive leap, an evolution in brain wiring. To test this, Shelby Putt, an anthropologist at the Stone Age Institute and Indiana University, compared the brains of modern people making Oldowan and Acheulean tools in a
study published earlier this year in Nature Human Behavior. As trained volunteers worked stones, they wore caps sprouting wires connected to functional near-infrared spectroscopy (fNIRS). This neuroimaging technique is like MRI, but allows subjects to move freely. When participants made Oldowan tools, brain areas lit up related to vision and movement. Chimps smashing nuts probably engage this level of cognition. Acheulean toolmaking, however, required integration of higher-order regions that are responsible for sensory and motor control, memory and planning. In fact, it was a brain network nearly identical to what’s activated when people play the piano. “We don’t see any chimps playing the piano,” says Putt. She believes that Acheulean tools mark a turning point in our evolution from ape-like to human-like brains. The species that made that turn went extinct long ago, but the stone tools that bore witness to it survive — “the common heritage of all humanity,” says Shea. D Bridget Alex is an anthropologist at Harvard University and a frequent contributor to Discover.
SHELBY PUTT (2)
call my butcher, who knows me pretty well now.” Monnier had colleagues perform traditional residue analysis on the objects and found that most residues cannot be visually distinguished with confidence under a normal microscope: In one study, trained researchers misidentified Monnier’s modern specimens nearly 1 in 4 times. Since then, Monnier and colleagues have experimented using infrared and other forms of radiation to measure residue composition. Results on modern materials as well as artifacts with known residues have been promising. In a 2013 study, for example, researchers removed bits of residue from stone points up to 130,000 years old and used a destructive technique to identify the substance as bitumen. This natural tar likely adhered the points to wooden spears that had long since decomposed. That same year, Monnier analyzed some remaining gunk on the same tools with X-ray and infrared beams and also identified bitumen, proving it was possible to do non-destructively. Having verified her methods, Monnier is eager to analyze unstudied artifacts, “and probably get some surprises.”
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Out There
Black Holes and Revelations Strange metals and black holes have a lot in common, and researchers are exploiting the link to learn more. BY STEVE NADIS
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Black holes, like this one in Centaurus A, have a strange connection to materials in earthly labs.
only in extremely frigid conditions close to absolute zero. High-temperature PHYSICS IS STRANGE superconductors soon The person who became the hot new field, first came across and Sachdev wanted to find this unexpected his own niche within this connection, Harvard booming area. He became University physicist curious about one particularly Subir Sachdev, is a puzzling observation: After Subir Sachdev serious scholar, not these materials are heated above prone to flights of whimsy. the so-called critical temperature, Born in Delhi, India, and with physics they lose their superconductivity and degrees from MIT and Harvard, he assume a different form of matter — was doing postdoctoral work at Bell strange metals. Labs when scientists first created a Strange metals live up to their name. high-temperature superconductor in Perhaps their oddest property relates 1986. Previously, scientists had thought to the peculiar way in which their superconductors — which could carry electrons behave. In ordinary metals, electricity essentially forever without electrons act like individual particles. sustaining any losses — could exist In strange metals, however, quantum
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effects take over, and electrons become “entangled” with each other and can no longer be treated as distinct entities. Electron motions, says Sachdev, “look more like the spread of molasses than pointlike objects traveling in a straight line.” Strange indeed. In 1992, Sachdev and his graduate student Jinwu Ye used that weird quality to build a simplified model of strange metals. They found they could capture the essential features of these complicated materials, containing vast numbers of interacting electrons, with just a single rule: Electrons can move randomly from one atom to another within a given sample, but they can only move in pairs. The model showed that electrical resistance in strange metals should vary with temperature — a reassuring result, given that other
TOP: ESO/WFI/MPIFR/APEX/A. WEISS ET AL. AND NASA/CXC/CFA/R. KRAFT ET AL. BOTTOM: KATHERINE TAYLOR
It sounds crazy. In recent years, scientists have confirmed a remarkable link between two kinds of objects that should, by all rights, have nothing to do with each other: black holes and strange metals. The former are the famous guzzlers of deep space, able to swallow anything — including stars, planets and even light itself — that gets too close. The latter are closer at hand, though less familiar: the stuff left behind when so-called hightemperature superconductors, materials with no electrical resistance, get too hot to superconduct anymore. The exact nature of this relationship remains unknown, but at a basic level, it looks like many of the same rules of physics apply to both black holes and strange metals. And scientists on both sides of the connection have already started using it to learn more about their respective fields. It’s such an astonishing discovery that even the man who made it had a hard time believing it.
JULIEN BOBROFF, FREDERIC BOUQUET AND JEFFREY QUILLIAM/LPS, ORSAY, FRANCE VIA WIKIMEDIA
scientists’ experiments had already verified it. But Sachdev still had no idea how important his humble model would eventually become.
FINDING THE CONNECTIONS A couple of years later, Sachdev and colleagues Antoine Georges and Olivier Parcollet were surprised to find that their model suggested strange metals had a fantastically high entropy — a measure of the number of possible ways particles can arrange themselves. The computed entropy was so high, it almost defied the laws of physics, implying that strange metals were far more complicated than originally supposed. This was an early hint of the mysterious ties between strange metals and black holes, which were also known to have staggeringly high entropies. But it took many more years for Sachdev to recognize those parallels. That journey started in earnest when he heard about the counterintuitive notion that black hole theories might apply to other phenomena in different settings. Theoretical physicists Dam Thanh Son and Andrei Starinets, for example, collaborated on an idea that used black hole math to predict the viscosity of an ultrahot gas, or plasma, that forms in certain particle collider experiments. Perhaps some of those same principles might work for strange metals, Sachdev thought. He soon hit pay dirt. A 2007 Physical Review B paper that Stanford University physicist Sean Hartnoll co-wrote with Sachdev and others noted some uncanny similarities between strange metals and black holes. Besides the aforementioned high entropy, the two objects had the same “characteristic time,” which relates to how long a system takes to reach a resting, or equilibrium, state after being violently disturbed. In 2010, Sachdev discovered an even deeper connection: His model of strange metals also worked for black holes.
After these materials are heated above the so-called critical temperature, they lose their superconductivity and assume a different form of matter — strange metals.
A magnet floats on the magnetic field of a superconductive material, the precursor state of the appropriately named strange metals.
This was shocking. Somehow, the behavior of fleetingly paired-up electrons in the model of an odd material produced on Earth bears some resemblance to the cosmic weirdness of a black hole. The model depicted a strange metal when looked at one way and a black hole when viewed through a different lens. Caltech physicist Alexei Kitaev refined things further in 2014, and the resultant Sachdev-Ye-Kitaev (SYK) model has been mystifying researchers ever since, while affording them new avenues for exploration.
EXPLOITING THE LINK Other physicists started paying attention. Before the SYK model, there wasn’t such an easy and convenient way to study black holes. Researchers suddenly had many more options at their disposal, according to physicist Douglas Stanford of the Institute for
Advanced Study in Princeton, N.J. “You can analyze things about a black hole you couldn’t any other way, like the time evolution of the system,” he says. Stanford is now relying on SYK to learn more about a black hole’s interior, while Kitaev is pursuing the question of what happens to the information carried by objects that fall into a black hole. Insights from black holes, meanwhile, have already given Sachdev and his colleagues some answers. Among other things, they can now better predict the behavior of electrons in graphene, a flat sheet of carbon just a single atom thick, which acts like a strange metal under certain conditions. This superthin, 2-D material — incredibly strong, flexible and light — could have diverse applications in areas that include biomedical devices and consumer tech. Specific predictions were upheld in 2015 experiments at Harvard showing how graphene conducts heat and electricity. The data helped show how graphene and its near-miraculous properties could one day come out of the lab, while further affirming the validity of the SYK model. We could be on the brink of a new era in technology, thanks in part to the model. Sachdev definitely anticipates some practical payoffs down the road. “SYK should advance our understanding of strange metals, which can, in turn, guide the development of hightemperature superconductors and help us pick the best ingredients for these materials,” he says. The crazy link between strange metals and black holes, which even Sachdev didn’t take seriously at first, is finally bearing fruit. So why did it take him so long to exploit the connection he now considers obvious? “I wasn’t smart enough,” he confesses — though the evidence suggests otherwise. D Steve Nadis, a contributing editor to Discover and Astronomy, plays handball in Cambridge, Mass., where he also lives.
November 2017 DISCOVER
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20 Things You Didn’t Know About …
Clockwise from left: Variations in electromagnetic radiation wavelengths give us colors from red to violet and everything in between; the veiled chameleon and Morpho butterfly use different mechanisms to achieve their flashy looks, but if you can’t see the number in the circle, you might be colorblind and unable to enjoy the full show.
BY SYLVIA MORROW
1 For centuries, academics thought colored light was modified white, or “pure,” light. (We’ll get back to how wrong they were in a bit.) 2 And color sometimes is a modifier. For example, coloring foods goes back at least 3,500 years, when ancient Egyptians added wine and other colorants to candy to increase its visual appeal. 3 The history of coloring food is stained with nefarious deeds. Toxic lead- and mercury-based compounds were once pervasive in Asia and Europe to add color to tea and cayenne and curry powders. 4 In the mid-18th century, Americans were so used to yellow milk, tinted with lead chromate to disguise the bluishness of watered-down dairy, that people refused to purchase white milk, thinking it had been colored. 5 They weren’t entirely wrong. In the 1660s, Isaac Newton demonstrated white light is anything but pure: It’s composed of all colors of light combined. 6 Scientists refer to color in terms of wavelength, a characteristic of electromagnetic radiation, but there is no universal match of specific wavelength values to specific color names. Encyclopaedia Britannica, for example, defines blue light as having a wavelength of 450 nanometers, but the average person might call anything between 425 nanometers and 490 nanometers “blue.” 7 And that’s just in English. Other languages, including many tribal African tongues, describe green and blue as different shades of the same color. 8 In Russian, light and dark blue are distinct colors, rather than different shades of the same color. 9 Regardless of language, our biology is the same. Human eyes have evolved trichromatic vision: We only see red, green and blue. Full perception happens in the brain. If your eyes see lots of red and green, but not much blue, your brain decides you’re seeing yellow. 10 Any color where the amount of red, green and blue appear equal will seem gray to humans. 11 This, of course, assumes color vision. Red-green colorblindness occurs when red or green color receptors are missing or mutated, primarily in people with XY chromosomes. 12 In XX-chromosome individuals, however, the same mutated color receptors may provide what’s called four-color vision, though researchers disagree on tetrachromacy’s characteristics and
prevalence. 13 In 2010, 62 years after the first suggestion of human tetrachromacy, a study identified a woman with distinctly enhanced vision. She was picked for the test because two of her three sons had reduced sensitivity to green, suggesting she had the mutation. 14 No matter how many we can see, all colors result from interaction between light and electrons. Figuring out what type of interaction is responsible for each color can be a challenge, however, since there are 15 different mechanisms. 15 Cobalt pigment, for example, makes the rare gemstone blue spinel a deeply saturated blue, while the Maxixe-type beryl gem may appear dark blue after exposure to radiation. 16 And wings of the Morpho butterfly appear as different shades of blue or even violet depending on how the light hits them. This effect is typical with light-scattering structures like the tiny scales that cover the insect’s wings. 17 In 2015, researchers found that the wings of the dragonfly Zenithoptera lanei, though similar in appearance to Morpho wings, get their color from waxy crystals that cover layers of the pigment melanin. 18 This effect, called structural color, has also been found in chameleons that can “tune” nanocrystals in their skin to change color the way tuning a guitar changes its pitch, as reported in 2015 in Nature Communications. The lizards tune up for camouflage as well as mating displays and possibly thermal regulation. 19 Color can also change during chemical reactions. When the hemoglobin in red blood cells loses oxygen, it takes on a bluish tint. But “blue blood” is a myth: Blood flowing through our bodies is dark red due to a mix of hemoglobin with different levels of oxygen. 20 Dark green blood can be a thing, however. In a non-fatal 2005 case, a Canadian man’s blood turned green after he took too much migraine medication. Sulfur atoms had started to bind with his hemoglobin, a process that would typically only occur in putrefying corpses. (Sorry to wrap things up on a dead note. Hope I didn’t give you the blues.) D Physicist Sylvia Morrow is a AAAS Mass Media Fellow.
DISCOVER (ISSN 0274-7529, USPS# 555-190) is published monthly, except for combined issues in January/February and July/August. Vol. 38, no. 9. Published by Kalmbach Publishing Co., 21027 Crossroads Circle, P.O. Box 1612, Waukesha, WI 53187-1612. Periodical postage paid at Waukesha, WI, and at additional mailing offices. POSTMASTER: Send address changes to DISCOVER, P.O. Box 62320, Tampa, FL 33662-2320. Canada Publication Agreement # 40010760. Back issues available. All rights reserved. Nothing herein contained may be reproduced without written permission of Kalmbach Publishing Co., 21027 Crossroads Circle, P.O. Box 1612, Waukesha, WI 53187-1612. Printed in the U.S.A.
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