Discover Magazine 2018-01-02

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January/February 2018

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Evolution’s Timeline Toppled P.10

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Editing Human Embryos Science Under Trump Cosmic Smashup The Great Dinosaur Debate Cassini’s Death Plunge How Cats Conquered the World . . . AND MORE! P.16

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NASA/JPL-CALTECH

NASA’s Cassini space probe spent 13 years gathering information on Saturn and its moons. Read about its highlights on page 20.

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CONTENTS

January/February 2018

1

Enter this code at:

www.DiscoverMagazine.com/code to gain access to exclusive subscriber content.

The solar event that transfixed Americans from sea to shining sea. BY BILL ANDREWS

2

Astronomers See and Hear the Cosmos p.13

A gravitational wave and a flash of light open up a new field of astronomy. BY ERIC BETZ

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The FDA approves a powerful gene therapy to fight a resistant cancer.

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Seven Whole New Worlds p.18

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Hominin Trackways in Greece? p.19

A record-breaking number of Earthsized planets orbit a faint star in a nearby galaxy. BY JOHN WENZ

 

Fossilized footprints may change our family tree. BY GEMMA TARLACH

Science Under Siege But Surviving p.14

We break down the Trump administration’s salty relationship with science. BY GEMMA TARLACH

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‘Living Drug’ Gets Green Light p.17

BY KENNETH MILLER

Human Evolution Timeline Topples p.10

Our ancestors’ origin story is being refined. BY GEMMA TARLACH

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Researchers in a U.S. lab finally test the revolutionary gene-editing tool in human embryos. BY ERIC BETZ

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Cassini Is Dead; Long Live Cassini p.20

The Saturn probe completes its years-long mission in a fiery descent.

Image of the Year Index

p.96

p.98

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Harvey Redesigns Rainfall Maps p.21

The deluge that swamped Houston changes how we measure downpours.

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special issue

ON THE COVER Evolution’s Timeline Toppled p.10 Editing Human Embryos p.16 Science Under Trump p.14 Cosmic Smashup p.13 The Great Dinosaur Debate p.26 Cassini’s Death Plunge p.20 How Cats Conquered the World p.72

ART ERNIE MASTROIANNI Photo Editor ALISON MACKEY Associate Art Director

CARL ENGELKING Web Editor LAUREN SIGFUSSON Associate Editor NATHANIEL SCHARPING Assistant Editor Bloggers

MEREDITH CARPENTER, LILLIAN FRITZ-LAYLIN, JEREMY HSU, ERIK KLEMETTI, REBECCA KRESTON, NEUROSKEPTIC, ELIZABETH PRESTON, SCISTARTER, AMY SHIRA TEITEL, CHRISTIE WILCOX, TOM YULSMAN

ADVERTISING STEVE MENI Advertising Sales Manager 888 558 1544 [email protected]

. . . PLUS 90 more stories that made 2017 a thrilling year in science.

January/February 2018

PLUS

TIM FOLGER, JONATHON KEATS, LINDA MARSA, KENNETH MILLER, STEVE NADIS, ADAM PIORE, COREY S. POWELL, JULIE REHMEYER, STEVE VOLK, PAMELA WEINTRAUB, JEFF WHEELWRIGHT, DARLENE CAVALIER (SPECIAL PROJECTS)

Rummel Media Connections KRISTI RUMMEL Consulting and Media Sales

Discover Editing Human Embryos Science Under Trump Cosmic Smashup The Great Dinosaur Debate Cassini’s Death Plunge How Cats Conquered the World . . . AND MORE!

Contributing Editors

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SCIENCE FOR THE CURIOUS

Evolution’s Timeline Toppled

KATHI KUBE Managing Editor GEMMA TARLACH Senior Editor BILL ANDREWS Senior Associate Editor MARK BARNA Associate Editor ERIC BETZ Associate Editor LACY SCHLEY Assistant Editor DAVE LEE Copy Editor ELISA R. NECKAR Copy Editor AMY KLINKHAMMER Editorial Assistant

BY DEVI SHASTRI

BEST NEW IDE AS & INSIGHTS

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EDITORIAL

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BY SARAH SCOLES

Human Embryo Gets CRISPR Treatment p.16

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BECKY LANG Editor In Chief DAN BISHOP Design Director

VOL. 39, NO. 1

America Looks Up p.7

Discover SCIENCE FOR THE CURIOUS

Editor’s Note Each December, we pause to call out the year’s most interesting discoveries and advances. Yes, it’s a look back, but really it’s a glimpse into our future — each finding is a step on the path to more knowledge. Enjoy your journey as you peruse our picks for the top 100 stories of 2017. We welcome your thoughts, at [email protected].

ON THE COVER: An early-human skull discovered in Morocco is one of several finds in 2017 to shake up the hominin evolutionary timeline. Read more on page 10. NHM IMAGES

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January/February 2018 2017 DISCOVER

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AMERICA LOOKS UP

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TWO THINGS WERE INESCAPABLE THIS SUMMER: the Latin single “Despacito,” and the looming eclipse. The first total solar eclipse in the continental United States since 1979, it was also a uniquely American event, with no other countries getting a peek at totality, and at least a partial eclipse visible in all 50 states. As the moon’s shadow crisscrossed the country on Aug. 21, about 154 million American adults saw the eclipse directly, with another 60 million watching electronically — 88 percent of the adult population. It was the most-observed and most-photographed eclipse in history. In a time of so much bitter division, it’s remarkable that an astronomical event just a few minutes long had the power to bring us together, gazing in joy and wonder at the universe.  BILL ANDREWS

Solar eclipse parties, like this one in Los Angeles, were popular all over the United States on Aug. 21, as millions gathered to watch a partial or total solar eclipse.

January/February 2018 DISCOVER

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Students react as they witness totality in Oregon (left). The sun disappears behind the moon, as seen from Wyoming (below).

The staffs of sister magazines Discover and Astronomy were all over the country during the eclipse. Here, briefly, is what they saw. 1. Thousands of people from all over the world descended on “SolarTown” — a farmer’s field turned eclipse mega-party. Favorable winds kept epic wildfire smoke from ruining the spectacle on eclipse day, when the moon’s shadow was met with hoots and hollers and thunderous applause. An equally epic traffic jam broke out minutes after totality. — Eric Betz, Madras, OR 1

2. What really

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amazed me, and perhaps it was accentuated due to our elevation, was the color: A brief glimpse of the sun’s atmosphere appeared strongly pink, and we saw what appeared to be a bluish tinge with the diamond rings. It was spectacular!

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Eclipse glasses were necessary to safely view all phases of the eclipse (above). Louis Serrano dons his own pair in South Carolina (right). Terrible traffic jams began after totality in Wyoming (below).

3. Not a cloud crossed the powder blue sky, allowing a spectacular view of a surprisingly large sunspot group followed by several ruby red prominences during totality. Shortly after the sun emerged, massive gridlock formed when thousands of vehicles funneled into a handful of exits. — Ernie Mastroianni, Glendo State Park, WY

4. Despite lots of clouds, we saw first and second contacts, the initial diamond ring, the sun’s corona and fourth contact. Hearing 25,000 people screaming at the darkness and the appearance of the corona is something I’ll never forget. — Michael Bakich, St. Joseph, MO

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FROM TOP: PETER DASILVA; ERNIE MASTROIANNI/DISCOVER; JACQUELINE DORMER/THE REPUBLICAN-HERALD VIA AP; LEROY BURNELL/THE POST AND COURIER VIA AP; ERNIE MASTROIANNI/DISCOVER

— David J. Eicher, Jackson Hole, WY

12. It was super cloudy, but we went out anyway and stood around talking until the clouds would get slightly less dense; then everyone would — quick! — put on their glasses and try to catch a glimpse before the clouds filled in again. Those few snatches were cool, but the coolest part was everyone on social media and texting, talking about if they’d seen anything or not. Eclipses: The Great Unifier. — Elisa Neckar, Waukesha, WI

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11. Skies were partly cloudy, but we had a nice shot of the eclipse’s early stages through maximum. With the moon covering only 80 percent of the sun, however, the view was less than breathtaking. — Rich Talcott, Cleveland, OH

10. We watched the eclipse from a steamy city park, which capitalized on its perfect location in the shadow’s path. Amid live music, tall trees and $3 hot dogs, we saw brilliant diamond rings, a diffuse corona and an inky black shadow, accentuated by the shouts and ooh-ing of hundreds. — Bill Andrews, Gallatin, TN

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9. I recall most vividly the jewel-bright ring

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in the sky where the sun had been: science fiction come to life. For just over two minutes, the scale of the cosmos was laid bare. — Nathaniel Scharping, Shawnee National Forest, IL

8. My dad and I traveled together to see our first

Totality is imminent in Columbia, South Carolina (above), as the moon’s shadow slips in front of the sun. Vacationing families in Portland, Maine, (below) safely observe the partial eclipse with homemade solar glasses.

total solar eclipse. We were both blown away — pictures really cannot do it justice, from how the quality of the daylight changes to the reactions of the crowd sharing the experience with us.

FROM TOP: CHRIS MCKAY/WIRE IMAGE/GETTY IMAGES; BEN MCCANNA/PORTLAND PRESS HERALD VIA GETTY IMAGES

— Alison Klesman, Red Bud, IL

5. It was one of the strangest phenomena I’ve ever witnessed. As darkness started to envelop the city, our dogs started barking like crazy. As soon as totality hit, I began jumping up and down, laughing like the Joker. I wasn’t sure 16 hours of driving would be worth two minutes of spectacle, but it most definitely was. — Jake Parks, Columbia, MO

7. It was a sweltering day, but the sky was clear. Excitement filled the air as we sat waiting for that magical moment. As the eclipse began, I heard a kid shout, “It looks like Pac-Man!” Suddenly we were in twilight, the cicadas chirping in confusion, gasps and cheers all around us. I understand why people chase eclipses now. It’s an experience like no other. — Alison Mackey, De Soto, MO

6. That morning, we toyed with battling traffic and crowds to watch from the famed St. Louis Arch, but with a 4-year-old niece in tow, we opted instead for the closest wide-open space — the parking lot of a Schnucks grocery store. Eclipse fever was real: Checkout cashiers were handing out eclipse glasses! — Becky Lang, Crestwood, MO

January/February 2018 DISCOVER

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Human Evolution Timeline Topples

FOR DECADES, SCHOOLCHILDREN ACROSS THE GLOBE were taught our origin story went something like this: An archaic form of Homo sapiens evolved around 200,000 years ago in Africa. By about 100,000 years ago, the population had become anatomically modern humans who, around 50,000 years ago, headed across Eurasia and met up with our distant cousins the Neanderthals (and the closely related Denisovans, not known to science until 2010). Like a game of Jenga, however, researchers have recently been removing bricks and destabilizing that towering timeline. In 2017, a few more bricks came out, and the conventional chronology of our origins finally toppled. What we’re left with: Homo sapiens have been around at least 100,000 years longer than we thought, and left Africa much earlier than we believed. And whenever they ran into other hominin populations, well . . . “Sex happens,” says Erik Trinkaus, a paleoanthropologist at Washington University in St. Louis. “You can draw lines of different lineages on maps, but real populations don’t behave that way.” Trinkaus stresses that revising the timeline for human evolution isn’t the same as starting from scratch: “The differences are of refinement, not in the basic story.”  GEMMA TARLACH

In the mid-20th century, during mining operations at Jebel Irhoud in Morocco, workers turned up some old, possibly human bones. The haphazard find made dating them confidently all but impossible. Paleoanthropologist Jean-Jacques Hublin and colleagues returned to the site recently to excavate an area undisturbed by mining. They hoped to find material that could help them date the earlier discovery. Instead, they found what Hublin calls “a big wow”: the partial remains of at least five humans, plus tools and other artifacts, most of which are about 300,000 years old. The archaic Homo sapiens’ facial features and brain volume are essentially modern, says Hublin, though their skulls’ shape is more primitive. During a June news conference, shortly before the study was published in Nature, Hublin noted it’s unlikely the Jebel Irhoud individuals, the oldest known Homo sapiens fossils by about 100,000 years, are our direct ancestors.

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“We are not claiming that Morocco became the cradle of modern humankind,” Hublin says, “We think early forms of humans were present all over Africa.” And in the journal Science in late September, a separate team offered additional evidence of an earlier start date for our species: By sequencing the ancient DNA of seven individuals from southern Africa, the researchers determined modern Homo sapiens emerged up to 350,000 years ago.

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Reconstruction of an early Homo sapiens skull from the Jebel Irhoud site.

SARAH FREIDLINE/MAX PLANCK INSTITUTE EVA LEIPZIG

1 THE ‘BIG WOW’

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TOP: XIUJIE WU. BOTTOM: TANYA SMITH AND ROKUS AWE DUE

It Takes Two For years, paleogenetic studies have been turning up hints that our species interbred with Neanderthals and Denisovans between 40,000 and 100,000 years ago. A Nature Communications study published in July, however, found evidence the hook-ups began much earlier: roughly 220,000 to 470,000 years ago. Researchers extracted maternally inherited mitochondrial DNA (mtDNA) from a 100,000-year-old Neanderthal bone found in a German cave in the 1930s. The mtDNA is from a Homo sapiens female who evolved in Africa — our homeland — and mated with a Europeanevolved Neanderthal at least 220,000 years ago. But the woman, who passed her mtDNA down through the Neanderthal lineage, was not necessarily an anatomically modern human, notes paleogeneticist Johannes Krause, a co-author of the study. Although he agrees recent evidence pushes back the start date for our species, Krause said the definition of a modern Homo sapiens remains subjective. “The process of humans evolving into anatomically modern humans started 700,000 years ago,” says Krause. That’s when genomic models estimate the last common ancestor of Homo sapiens, Neanderthals and Denisovans existed. “It’s a gradual change. They didn’t pop out of a box.”

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EASTERN MASH-UP A pair of partial hominin skulls excavated in Xuchang, China, are unlike any others. Dated to more than 100,000 years old, the crania have a unique blend of features: the internal ear structure and back-of-skull depression seen only in Neanderthals, which have never been found east of Siberia; a low and broad shape consistent with earlier East Asian hominins; and an enlarged braincase similar to other late archaic and modern humans. Trinkaus and colleagues, describing the partial skulls in March in Science, won’t speculate on whether they belonged to Homo sapiens transitioning from archaic to modern, the elusive Denisovans or an as-yet-unidentified hominin species. “People have been thinking in terms of lineages and discrete groups,” Trinkaus says, “These are not separate entities. There’s a unity to humankind now, and there was then.”

A top-down view of a partial skull unearthed in China. The find is more than 100,000 years old and shows a blend of Neanderthal and hominin features.

4 Turning Up Down Under 3

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The conventional timeline placed our species in Australia at no earlier than about 47,000 years ago, despite some archaeological and genomic research hinting at a much earlier arrival date. In July, however, a team reported in Nature that thousands of artifacts from a Northern Australia site were about 65,000 years old. And in August, also in Nature, a separate team reported that they believe teeth found in an Indonesian cave belonged to anatomically modern humans who had occupied the site 63,000 to A scan (bottom) 73,000 years ago. of a tooth (top) That puts modern humans that suggests anatomically far from home tens of modern millennia before the nowhumans were in Australia outdated human evolution many millennia and migration timeline had before we thought. us even leaving Africa.

January/February 2018 DISCOVER

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A museum drawer full of fossils from a Southern California site. The remains hint at the fact humans might have arrived in the Americas more than 100,000 years earlier than we thought.

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A Nature study published in April made a startling claim: Rounded stones found beside fractured mastodon bones near San Diego were evidence of someone processing the animal’s remains 130,000 years ago. The current timeline for humans arriving in the Americas, however, is a mere 15,000 to 20,000 years ago, via Siberia and the now-submerged land bridge Beringia. Many in the field are highly skeptical of the Nature paper. “These are just naturally occurring rocks that, over time, have broken along existing fractures,” says Texas A&M University archaeologist Michael Waters. “The evidence for early human occupation is not there.” Found during highway construction in 1992, the Southern California site yielded the stones and mastodon bones, several of which were fractured or in unusual positions. But the items weren’t interpreted as evidence of hominin activity until recently, when they drew the interest of Steven Holen, lead author of the Nature paper. “My first reaction was, ‘This is not possible,’ ” Holen says. His team took a multidisciplinary approach to analyzing the material, from sophisticated dating techniques to re-creating the kinds of fractures such stones might have made, using fresh elephant bones in Africa. Researchers argue that around Holen argues fluctuating 130,000 years ago, hominins used sea levels exposed Beringia the stones above like a blacksmith uses an anvil. But instead of 130,000 to 160,000 years ago, hammering metal, these archaic when bison crossed the land tool-wielders processed animal bridge into the Americas. It’s remains. possible, he believes, that a population of hominins — Neanderthals, Denisovans or even archaic Homo sapiens — followed the animals. Holen says he knew his paper would ignite controversy, and that he’d be the first to admit “you need to have more than one site if you’re going to have a paradigm shift.” He hopes more researchers will remain open-minded. “The most important thing for a reader to take away from this, and also for young scientists in general, is that we don’t have all the answers,” Holen says. “That’s why we do science."

FROM TOP: KATE JOHNSON/SAN DIEGO NATURAL HISTORY MUSEUM; TOM DÉMÉRE/SDNHM; SDNHM

Stateside Stones and Bones

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ASTRONOMERS SEE AND HEAR THE COSMOS

TOP: ROBERT HURT (CALTECH/IPAC), MANSI KASLIWAL (CALTECH), GREGG HALLINAN (CALTECH), PHIL EVANS (NASA) AND THE GROWTH COLLABORATION; NSF/LIGO/SONOMA STATE UNIVERSITY/A. SIMONNET

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FOR HUNDREDS OF MILLIONS OF YEARS, two city-sized stars — each outweighing our sun — circled one another in a fatal dance. They were neutron stars, the collapsed cores left behind after giant stars explode into supernovas. Then, 130 million years ago, the dance ended. Their collision was fast and violent, likely spawning a black hole. And a shudder — a gravitational wave — rippled across the fabric of space-time. Light from the cataclysm followed seconds later. The space-time distortion and the light reached Earth together on Aug. 17, making astronomical history. Astronomers announced the finding Oct. 16. The gravitational wave first reached Italy’s just-finished detector, Advanced Virgo, before stretching and squeezing the two LIGO observatories in the United States. Orbiting space telescopes and instruments on all seven continents turned to watch the cosmic collision play out in all manner of light: radio, infrared, optical, ultraviolet, X-rays, gamma rays. “It was extremely close to us, and so it was an extremely strong signal,” says LIGO scientist Jolien Creighton of the University of Wisconsin-Milwaukee. In 2016, LIGO (short for Laser Interferometer GravitationalWave Observatory) announced it had detected gravitational waves for the first time, confirming Albert Einstein’s predictions in general relativity. Astronomers compared it to finally hearing the cosmos. But the real breakthroughs would come from hearing and seeing the cosmos simultaneously, or so-called “multi-messenger astronomy.” That’s now happened. This one event produced dozens of research papers boasting thousands of scientists as co-authors. And it uncorked a jug of other scientific feats, like a new direct measurement of the expansion of our universe, and the best evidence yet that gravitons — gravity-carrying particles — have no mass, just like photons (light particles). Astronomers even caught the collision’s chemical fingerprints, revealing the creation of 10 to 100 Earths’ worth of gold and other heavy elements, ending decades of debate on their cosmic origins. “We’ve created a new field of astronomy,” says Ryan Foley of the University of California, Santa Cruz, who led the optical discovery team. “We’ve been walking around for all of humanity being able to see the universe but not being able to hear it. Now we get both.” He adds: “It’s even hard to predict where this field will go, but I can tell you now it’s going to be exceptional.”  ERIC BETZ

Astronomers captured the merging of neutron stars in various types of light, including ultraviolet, infrared and radio waves (above), as well as via gravitational waves — a first.

January/February 2018 DISCOVER

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FOR MANY WHO VALUE SCIENCE, 2017 will be remembered as the dawn of a new era. January saw the inauguration of a U.S. president who has denied climate change and filled his inner circle with anti-science activists. But the year was as much an awakening as an annus horribilis: Researchers and citizens alike, in the United States and beyond, chose to speak out at rallies, on social media and even in the political arena — unprecedented numbers of scientists are considering a run for office. In a year of surprises, setbacks and signs of hope, here are some of the most memorable and consequential moments from the first several months of the new administration.  GEMMA TARLACH

The Paris Exit In 1992, some 150 countries signed the U.N. Framework Convention on Climate Change (UNFCCC) with the goal of flatlining greenhouse gases. At the time, the 1987 Montreal Protocol had already kick-started the healing of the ozone hole, so scientists expected the UNFCCC would succeed, too. However, emissions continued to increase. In late 2016, nations of the world convened again. Their optimistic goal: keep global warming below 1.5 degrees Celsius to avoid doomsday scenarios of rising seas, widespread droughts and

FEBRUARY 17: The Senate confirms Scott Pruitt as head of the EPA, the same agency the former Oklahoma attorney general and committed climate change denier had sued multiple times in attempts to weaken its regulatory reach.

JANUARY 25: In response to a media blackout ordered for the Environmental Protection Agency (EPA), entities such as “TheAltEPA” and “RogueNASA,” ostensibly created by frustrated federal employees, begin posting climate change data and other science-based information on social media.

2017

BEGINS

melting ice. That would mean zero greenhouse emissions by 2050 — an incredible feat. Every country but the United States has since ratified the Paris agreement. By June, reaching that goal seemed questionable after President Donald Trump announced the U.S. would withdraw, though pact rules dictate a four-year wait. European nations, plus China, are moving toward their goals regardless. And energy trends may help: Solar and wind power costs have plummeted, and carbon dioxide emissions in the U.S. have dropped amid shifts from coal to natural gas.  ERIC BETZ

T.J. KIRKPATRICK/BLOOMBERG VIA GETTY IMAGES

4

Science Under Siege But Surviving

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APRIL 22: A crowd of roughly 100,000 gathers to “March for Science” in Washington, D.C. Nearly a million more individuals participate in local events in all 50 states and on every continent.

MARCH 2: The Senate confirms former Texas governor and climate change skeptic Rick Perry as Energy secretary, six years after then-presidential candidate Perry called for the Department of Energy’s elimination.

24: President Trump urges NASA to send a manned mission to Mars despite his proposal to cut the space agency’s budget.

28: The president signs Executive

28: The EPA removes climate change data

Order 13783, which calls for the review and rescinding of many environmental protections.

and other information from its website.

A pro-science rally in Washington, D.C., drew roughly 100,000 participants; many more rallied at sister events across the world.

MAY

OCTOBER

18: Under Ajit Pai — who was

10: The administration announces its

appointed chairman by Trump — the FCC votes to begin dismantling net neutrality safeguards that were put in place in 2015. The decision opens the door to internet service providers controlling which sites consumers access.

intent to kill the Clean Power Plan, an Obama-era initiative to limit carbon dioxide emissions from power plants.

31: EPA head Pruitt says he will bar any scientist who receives agency grants from serving on its advisory boards. The move opens the door for industry-funded researchers to take their place.

SEPTEMBER

FROM TOP: ZACH D ROBERTS/NURPHOTO VIA GETTY IMAGES; LUKE SHARRETT/BLOOMBERG VIA GETTY IMAGES; CHASE DEKKER/WILD-LIFE/GETTY IMAGES

29: The FDA delays required revisions to nutrition labeling by up to three years. The updates, which would have gone into effect in 2018, include more realistic portion sizes and the amount of added sugar in a product.

For a more complete timeline, visit DiscoverMagazine.com/ ScienceUnderSiege

NOVEMBER 3: The White House releases a Climate Science Special Report, part of a congressionally mandated assessment. The conclusion? Human activity is the dominant cause of climate change, contradicting many administration statements.

15: Trump signs an executive order removing requirements for federal properties to withstand increased flooding and other climate change-related challenges.

Kammen quits over the president’s decision to leave the Paris agreement and his response to a white supremacist rally in Virginia. Kammen’s resignation letter includes an acrostic: The first letter of each paragraph spells “IMPEACH.”

24: The DOI announces plans to downsize three national monuments, including Bears Ears in Utah, despite pleas from Native Americans, archaeologists and paleontologists to protect culturally and scientifically significant sites. 31: The DOI limits most environmental impact studies to a year in length and resulting reports to no more than 150 pages. The studies previously lasted for years and could run 1,000 pages or more.

released by the White House slashes funding for both the EPA and FDA by 31 percent. The Centers for Disease Control and Prevention (CDC), Department of Energy and the National Institutes of Health would also see significant cuts.

JUNE 1: The president announces plans to withdraw the U.S. from the Paris agreement. (See opposite page.)

AUGUST

23: State Department science envoy Daniel

23: A proposed budget

JULY 19: Trump nominates Sam Clovis, who has no science background, to be the chief scientist of the U.S. Department of Agriculture. (Clovis’ nomination would be withdrawn Nov. 2 after his name surfaces in an ongoing probe into Russian influence on the Trump campaign.)

8: Following up on President Emmanuel Macron’s June 1 offer to “make our planet great again” by welcoming American scientists, a French government website offers foreign researchers French residency and four-year grants of up to 1.5 million euros (about $1.76 million). 22: The Department of the Interior (DOI) ends endangered species protection for Yellowstone grizzlies despite a two-year decline in the population, paralleling other administration decisions to remove protections for wildlife.

20: Six months into the administration, the president has yet to nominate candidates for a record number of key positions in science-driven government agencies such as the CDC and EPA.

January/February 2018 DISCOVER

15

5 Scientists Urge Caution Researchers should tread lightly when it comes to editing the genes of human embryos, according to guidelines handed down in February. The report — issued by dozens of experts convened by the National Academy of Sciences and the National Academy of Medicine — says so-called germline editing, in which genetic changes are passed to future generations, should happen only when there’s no “reasonable alternative” treatment. Doctors already can remove problematic embryos and implant healthy ones using in vitro fertilization. The panel also said the genes of embryos shouldn’t be edited for reasons other than treating or preventing disease or disability.  E.B.

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Researchers at Oregon Health and Science University captured the development of human embryos in images as part of their work using a gene-editing tool. It’s the first time a U.S. lab successfully repaired a genetic mutation in a human embryo.

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IN JUST A FEW SHORT YEARS, the gene-editing

tool CRISPR-Cas9 has infiltrated biology labs around the world. This summer, scientists working in a U.S. lab announced they’d used CRISPR to modify viable human embryos, which were kept alive just a few days. The research is a first in the United States, though scientists in China have conducted similar experiments. This latest effort, led by researchers at Oregon Health and Science University, also succeeded in avoiding unintended effects — something that’s plagued other researchers. The team fixed a mutation by removing a diseasecausing gene from an embryo. The repair, reported in August in Nature, corrected an inheritable heart condition, passed down by the embryo’s father, the study’s lone sperm donor. “This embryo gene correction method — if proven safe — can

potentially be used to prevent transmission of genetic disease to future generations,” says study co-author Paula Amato. Once it is proven safe, researchers hope to start clinical trials. That would mean implanting the gene-edited embryo into a woman and studying the genetically engineered child. If clinical trials don’t get FDA approval, study leader Shoukhrat Mitalipov says they would pursue them abroad. Exactly how the mutation was fixed was surprising to Mitalipov’s team. They expected that their use of CRISPR would introduce a “template” to guide the DNA to fix the faulty gene. Instead, the embryo replaced the targeted bad gene with a healthy gene from the mother — a conclusion that’s been criticized by a group of prominent scientists. They questioned the mechanism involved in the repair of the mutation.  ERIC BETZ

LEFT: GUNILLA ELAM/SCIENCE SOURCE. RIGHT: OREGON HEALTH AND SCIENCE UNIVERSITY

In CRISPR-Cas9 gene editing, a guide RNA sequence (green) helps Cas9 protein (purple) cut DNA at the correct spot.

Human Embryo Gets CRISPR Treatment

6 ❯ 

ESSAY

‘LIVING DRUG’ GETS GREEN LIGHT

IMMUNOTHERAPY, THE HOTTEST FIELD IN CANCER RESEARCH, seeks

to supercharge the body’s natural defenses against deadly tumors. Two different approaches are driving the buzz, and one of them got a big boost in August when the Food and Drug Administration approved a “living drug” to treat acute lymphoblastic leukemia (ALL) in children and young adults who’ve stopped responding to chemotherapy. The product, dubbed tisagenlecleucel (pronounced tis-agen-LEK-loo-sell), is the first gene therapy of any kind to be approved in the United States. More specifically, tisagenlecleucel is a type of chimeric antigen receptor T cell (CAR-T) therapy, a technique

pioneered by immunologist Carl June and colleagues at the University of Pennsylvania. First, an inactivated form of HIV, the virus that causes AIDS, is packed with snippets of custom-designed DNA. Next, T cells — the immune system’s foot soldiers — are harvested from the patient’s blood and infected with the virus, which rewrites their genetic code to recognize and destroy cancer cells. Once the engineered T cells have multiplied, they’re infused into the patient, where they go to war. Like the other leading-edge immunotherapy technique — a class of drugs known as checkpoint inhibitors — CAR-T has shown unparalleled potency against cancers that once meant almost certain

HOW TO BUILD BETTER T CELLS ➋ Researchers insert genes that recognize specific cancer cells into the T cells, through an inactive virus.

➊ White

blood cells called T cells are collected from the patient's blood.

➌ The genes

➏ Once inside

reprogram the T cells to produce specific receptors that will target proteins on the surface of a cancer cell.

the patient, the T cells multiply. They hunt cancer cells displaying the target protein and kill them.

➍ The modified

T cells are grown in a lab for about 10 days.

JAY SMITH

➎ The engineered T cells are infused back into the patient.

Source: Novartis

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death. In clinical trials that June’s team initially launched in 2010, over 80 percent of children with recalcitrant ALL went into remission. The therapy was also effective for several other types of blood cancer. “It was really extraordinary,” says David Porter, director of Penn’s blood and bone marrow transplant program. “These were patients for whom nothing else had worked.” The pharma giant Novartis, which agreed to fund further research in exchange for ownership of the results, will bring tisagenlecleucel to market under the trade name Kymriah. In October, the FDA approved a second CAR-T therapy, axicabtagene ciloleucel (developed by Kite Pharma and dubbed Yescarta), for patients with relapsed or refractory non-Hodgkin lymphoma. Rival companies are racing to develop similar products. CAR-T has its hazards. Many patients develop severe whole-body inflammation that can last for days. (Trials of another CAR-T therapy, by Juno Therapeutics, were halted in 2016 after five patients died from brain swelling.) But if the one-time procedure is successful, they’re spared the months or years of side effects that often accompany chemotherapy. The treatment can also eliminate the need for a bone marrow transplant, which carries a far greater risk of death. Researchers are now testing CAR-T therapies against other cancers, including pancreatic and the deadly brain cancer glioblastoma. They’re trying combinations of CAR-T with other treatments, and working to make the technique safe enough to use as an early stage therapy rather than a last resort. “We’re at a tipping point,” says June. “Someday, our current ways of treating cancer will be looked on as barbaric.”  KENNETH MILLER

January/February 2018 DISCOVER

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7

SEVEN WHOLE NEW WORLDS

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ignite into a star. Such stars can have violent eruptions early on, but are extremely stable afterward. So if the planets didn’t cook, life could have later evolved. And research announced in August shows TRAPPIST-1 could be as much as twice our sun’s age. The short distance between worlds also means microbes could planet-hop on space rocks, as described in a June study in the Proceedings of the National Academy of Sciences. “[The] TRAPPIST-1 discovery officially opened a whole new chapter of space exploration,” says Julien de Wit, an MIT researcher who co-discovered the planets.  JOHN WENZ

NASA/JPL-CALTECH

❯ 

IMAGINE LOOKING UP at the night sky and seeing planets looming larger than our moon. It sounds like science fiction, but astronomers discovered it could be reality for the TRAPPIST-1 system, which boasts seven Earth-sized worlds — a record. Some orbit almost as close to each other as the moon is from Earth. In May 2016, members of the Belgian TRAPPIST team announced their small telescope had turned up three potentially habitable planets orbiting a star just 40 light-years away. Then they turned to NASA’s Spitzer Space Telescope to get more detail, and it revealed there were actually a whopping seven. Three orbit in the star’s conservative habitable zone, the region where liquid surface water might exist. The results appeared in Nature in February. TRAPPIST-1 is a cool red dwarf barely bigger than Jupiter in diameter, but about 84 times heavier, giving it just enough mass to

8 ❯ 

Hominin Trackways in Greece? The Game Is Afoot

ABOUT 5.7 MILLION YEARS AGO, on what’s now the

Greek island of Crete, something went for a stroll. Walking on two legs, its clawless feet left impressions. Instead of its first toe sticking out thumblike, as an ape’s would, this creature’s big toe was in line with the other four. This trait and other features preserved in the ancient prints are unique to hominins, primates more closely related to us than to apes or chimps. And in an analysis published in August, researchers concluded — controversially — that these footprints at Trachilos, Crete, appear to belong to a hominin, walking where none was thought to set foot until millions of years later. Other fossilized trackways have provided valuable insight about how our lineage evolved to walk upright, but the oldest currently accepted hominin trackway, at Laetoli in Tanzania, is 3.6 million years old. The Trachilos prints are about 2 million years older. The Greek tracks are also thousands of miles from eastern Africa, where nearly all paleoanthropologists believe

ANDRZEJ BOCZAROWSKI (2)

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hominins — including humans — evolved. Trachilos study co-author Per Ahlberg, a paleontologist at Sweden’s Uppsala University, says critics have accused the team of trying to revive a long-debunked idea that our species evolved in Europe. “Some people have suggested that we are driven by a Eurocentrism claim. We are making no claim whatsoever,” says Ahlberg. “It’s clear modern humans evolved in Africa.” Instead, he says, the Trachilos prints show at least one branch of early hominins was present in Europe, and that members of our family tree were walking efficiently on two legs more than a million years earlier than we thought. “The technical side is well done. The analysis itself is complex and sophisticated — they’ve thought it through,” says William HarcourtSmith, a paleoanthropologist at New York’s Lehman College and the American Museum of Natural History. “[But] the devil is in the details.” For example, Harcourt-Smith notes that bears, whose hind legs do not typically make claw

Trackways on the Greek island of Crete may have been made by a hominin millions of years before most researchers believe possible, challenging our evolution story.

Is this a 5.7 million-year-old hominin footprint? A controversial study says yes.

impressions, were present in this region at the time, but the team compared the prints with only a bear’s forelimb. The lack of claws is one of the traits cited by the authors as evidence a hominin made the prints. “Bears do rear up and move bipedally on occasion,” HarcourtSmith says. “I’m not saying that’s what this is, but it was a major omission not to include hind leg bear prints for comparison. “New things get discovered all the time that challenge old thinking, and that’s wonderful, but this is a big claim. It needs to be properly comparative. It needs to be better,” he adds. In a bizarre twist, in midSeptember some of the impressions were cut from the rock and stolen. Greek authorities quickly arrested a man suspected of trying to sell the prints, which were recovered. The site is now off-limits, under a protective cover of tarps and “a great big heap of rubble,” says co-author Matthew Bennett of Bournemouth University, one of the world’s leading experts on hominin trackways. Bennett says research will continue using the team’s high-resolution digital scans, a permanent record of the trackways: “No scientific data has been lost.”  GEMMA TARLACH

January/February 2018 DISCOVER

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CASSINI IS DEAD; LONG LIVE CASSINI

 SARAH SCOLES

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NASA/JPL-CALTECH//SSI/KEVIN M. GILL/CC BY-SA 2.0; CASSINI: NASA

❯ 

IN OCTOBER 1997, a Titan rocket streaked across the sky and shot a spacecraft called Cassini toward Saturn. The road trip, minus roads, was long, and Cassini didn’t arrive until 2004. But it stayed there till its mission ended on Sept. 15, 2017 — with a bang, and a good deal of whimpering from Earth. Early that morning, engineers at NASA’s Jet Propulsion Laboratory sent Cassini down to meet the planet it had spent 13 years studying. The greeting was fatal for Cassini, which disintegrated as it charged through Saturn’s atmosphere. It was a planned death, a self-sacrifice that meant it wouldn’t crash into Saturn’s moons. Scientists didn’t want to contaminate those satellites — Titan and Enceladus — precisely because of what Cassini had revealed: They weren’t barren balls, but ones with oceans, water, internal energy and nutritious chemicals. The moons demonstrated that planets aren’t the only habitable spots in this solar system, and beyond. Cassini’s gaze at Saturn also revealed more about the formation of giant planets and regular solar systems. “By studying those rings up close and personal, you could draw analogies to how solar systems might form and evolve,” says Scott G. Edgington, Cassini’s deputy project scientist. “There will be generations of scientists who get their Ph.D.s and do research with Cassini data,” he says. “Who knows what they'll find in those 0s and 1s?” That’s why, despite the emotional eulogies, Cassini’s intellectual life will continue long after its physical death.

10 ❯ 

Harvey Redesigns Rainfall Maps

CLOCKWISE FROM TOP: NATIONAL WEATHER SERVICE; NICK OZA/USA TODAY NETWORK/SIPA USA; JOE RAEDLE/GETTY IMAGES

AS HURRICANE HARVEY’S AFTERMATH

dumped rain on the Houston area in August, the staff at the National Weather Service (NWS) knew they were watching history. And as the rain totals were tallied, the agency added not one, but two new colors to its rainfall map: purple for 20 to 30 inches and light pink for over 30 inches. “It’s difficult to predict what has never happened,” says Greg Carbin, who leads the NWS Forecast Operations Branch in College Park, Maryland. “I hope we don’t have to use it again.” The total? Nearly 52 inches in a week in Cedar Bayou, Texas, a record in the continental U.S.  DEVI SHASTRI

Over 30 inches

20-30 inches

Water floods a Houston street (left) after Hurricane Harvey landed in late August. Hospitals and care centers, such as the Gulf Health Care Center in Port Arthur, Texas (above), worked to evacuate patients.

January/February 2018 DISCOVER

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LIFE BENEATH ENCELADUS’ ICE?

Q&A ❯ 

Hunter Waite

Program Director of Space Science and Engineering NASA

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ALIEN MICROBES COULD, IN THEORY, feast beneath the icy surface of Saturn’s moon Enceladus. In April, astronomers reported that the Cassini spacecraft had discovered a chemical brew erupting from Enceladus’ oceans — the same kind that bacteria eat at Earth’s hydrothermal vents. Discover talked with Hunter Waite, Cassini researcher and NASA’s program director of space science and engineering, to take us there.  ERIC BETZ

12 Q A

What did we know about Enceladus before Cassini?

❯ 

Q A

How close did Cassini get?

We went really close. It was about 50 kilometers — the closest flyby over the tiger stripes. We could look at the chemical balance and determine that the [hydrogen] we saw was sufficient to provide food for microbes. The obvious message is let’s go back and try to find life.

Q A

At this point, would you be surprised if we didn't find life on Enceladus?

I would be a bit surprised, yes. But I would be happy to find the answer one way or the other because I think both — whether you find it or not — will lead to a better understanding of how life arose on Earth and what it really means.

FROM LEFT: SOUTHWEST RESEARCH INSTITUTE; MICHAEL BENSON/KINETIKON PICTURES; DEVIBORT VIA WIKIMEDIA COMMONS CC 3.0; ROBERT REISZ

What would it be like flying along with Cassini over Enceladus?

The action happens pretty fast because you’re traveling at 7 or 8 kilometers per second. And [Enceladus] is pretty small — it's like the size of Arizona. You’re getting pummeled by these little ice grains. As you’re flying over, you’ll see these geological features, these scars — little channels, basically — what we call the “tiger stripes.” Within those tiger stripes are the vents, straight from the global ocean. And above the surface of the ocean, a splash comes up — you can imagine a splash from a wave — that will instantly freeze. That’s what creates these grains. These have information about the salt content of the ocean and some of the organics that are present there.

Lufengosaurus

Protein in Dinosaur Rib Is 195 Million Years Old

We knew nothing. We didn’t know anything about the vents. We didn’t know anything about the global ocean. We knew it was a small, icy moon in the Saturn system. But the Saturn system is full of small, icy moons.

Q A

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RESEARCHERS IN TAIWAN used an innovative technique to find the protein collagen in a dinosaur rib that’s a whopping 195 million years old. Other researchers had previously identified proteins in fossils less than half as old, but those efforts required destroying part of the fossil itself. The new method, described in Nature Communications in January, allows scientists to read chemical signatures present within a specimen to identify (shown as dark spots) proteins and other organic Hematite sealed blood vessels in the fossil, remains non-destructively. helping preserve the collagen. “Most other material is extracted by dissolving the bone,” says co-author and paleontologist Robert Reisz of the University of Toronto Mississauga. “But if you did that with this specimen, you’d see nothing.” The team looked instead at tiny blood vessels, about half the diameter of a human hair, within the rib of an Early Jurassic Lufengosaurus specimen. There they found the specific chemical signal of collagen, which is crucial to connective tissue. The specimen also contained hematite, likely derived from the animal’s blood. The team believes the hematite sealed the blood vessels, protecting the collagen from contamination and degradation. Researchers hope the process of reading the chemical signatures can be refined to reveal details of dinosaur biology — such as thermoregulation — that are difficult to determine from conventional fossils. “The point is that, if you look, you can actually find remains of soft tissues in deep time,” says Reisz. “It opens up our eyes.”  GEMMA TARLACH

January/February 2018 DISCOVER

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14

ESSAY

CLOCK TICKING ON SUPERBUGS

❯ 

13

A Functioning Fake Womb

❯ 

IN A POTENTIAL BREAKTHROUGH for human

babies born prematurely, scientists announced this year they’d successfully removed lamb fetuses from their mother’s wombs and raised them into healthy sheep. Their survival comes thanks to an artificial placenta — called a BioBag — created by researchers at the Children’s Hospital of Philadelphia. The fake womb consists of a clear plastic bag filled with electrolytes. The lamb’s umbilical cord pulls in nutrients, and its heart pumps blood through an external oxygenator. The success caps a decades-long effort toward a working artificial placenta. The BioBag could improve human infant mortality rates and lower the chances of a premature baby developing lung problems or cognitive disorders. But there are still challenges to scaling the device for human babies, which are much smaller than lambs. The scientists are also refining the electrolyte mix and studying how to connect human umbilical cords. They expect human trials in three to five years.  NATHANIEL SCHARPING Illustration source: Children's Hospital of Philadelphia

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watched nervously as drug-resistant superbugs marched around the world, killing hundreds of thousands of people. Then in January, a report from the Centers for Disease Control and Prevention revealed that an elderly Nevada woman had died of a bacterial infection that defied even the biggest guns in the infection-fighting arsenal. That’s when many U.S. experts sounded the alarm: Time is running out to stop these deadly pathogens. “We’re somewhere between total panic and a situation we feel confident we can manage,” says James Johnson, a professor of medicine and infectious diseases at the University of Minnesota. Already, superbugs claim 23,000 American lives every year, and over the past eight years, the number of hospitalized children who are resistant to antibiotics has increased sevenfold. Globally, the situation is much worse: More than 700,000 die annually from drug-resistant infections, particularly in parts of Europe, Asia and South Asia. These regions have inadequate sanitary conditions that create breeding grounds for lethal pathogens — the Nevada woman picked up her fatal bug in India. Some experts warn that new strains of drug-resistant bacteria, caused by years of antibiotic use in humans and livestock, are as concerning as Zika and Ebola. The World Health The superbug CRE, shown in a petri dish, Organization identified a is resistant to almost all antibiotics. dozen groups of bacteria that pose the greatest threat. It could get just as bad in the U.S., warns Johnson. Infected international travelers can accelerate the superbug spread, and domestically there is a large population vulnerable to infection — the frail elderly and people who have compromised immune systems. If antibiotics become less effective, even routine procedures like appendectomies and C-sections could be perilous, and could cause up to 6,300 deaths per year. Still, the U.S. situation has improved, mainly because of more vigilance and better infection control techniques in hospitals where drug-resistant bacteria can be endemic, says John Quale, an infectious disease specialist at SUNY Downstate Medical Center in Brooklyn. “We’re doing a better job because people are scared enough now.” Some promising antibiotics are in development and should be available soon, but none is considered the magic bullet. In the meantime, Johnson says, “we need to find ways to get docs to be better stewards of antibiotics.”  LINDA MARSA

FROM LEFT: JAY SMITH; JAMES GATHANY/CDC

FOR YEARS, UNITED STATES public health officials have

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Pinpointing a Fast Radio Burst

JIUGUANG WANG VIA FLICKR, CC BY-SA 2.0

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ASTRONOMERS ARE FINALLY starting to figure out fast radio bursts (FRBs). The milliseconds-long surges of radiation are rare and sudden — even 10 years after their discovery, we know almost nothing about them. But in January, astronomers announced they’d spotted a repeating FRB and pinpointed its location to a small dwarf galaxy 2.5 billion light-years away. That’s a first for astronomy. The findings appeared in Nature and The Astrophysical Journal. Researchers observed a whopping nine bursts from the same source, dubbed FRB 121102, allowing them to home in on its location. Another team of researchers announced in August they’d detected an additional 14 bursts, and at higher radio frequencies than ever observed before. “The FRB was extremely generous to us,” said study co-author Casey Law of the University of California, Berkeley, during the

The Green Bank Telescope in West Virginia and other radio observatories saw the signal bursts.

announcement. Astronomers also discovered weak, long-lasting radio emissions coming from within 130 light-years of FRB 121102, suggesting the two are related — though we don’t know how, if at all. While the finding confirmed long-standing suspicions that FRBs originated from outside our galaxy, many questions remain, including if any others repeat, and what causes them. Potential origins include highly magnetic neutron stars — the collapsed cores of dead stars — and unusual black holes. “New mysteries in astronomy are somewhat rare,” said co-author Sarah Burke-Spolaor of Western Virginia University, so astronomers are relishing the chase.  BILL ANDREWS

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ESSAY

WHAT IF THE MOST BASIC THING WE KNOW ABOUT DINOSAURS IS WRONG?

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Chilesaurus

FOR THE PAST 130 YEARS, paleontologists divided dinosaurs into two groups, based on a handful of anatomical features — a split they believe occurred early in the animals’ evolution more than 230 million years ago. The “lizard-hipped” saurischians comprised meat-eating theropods such as T. rex and long-necked, herbivorous sauropodomorphs, such as Diplodocus. On the other side of the divide, “birdhipped” ornithischians included beaked plant-eaters such as Triceratops. In March, however, Nature published a proposal that trashes the traditional family tree. Instead, researchers placed theropods with ornithischians, forming a group called Ornithoscelida, and put sauropodomorphs with the early and primitive herrerasaurs. “Our new hypothesis has lots of exciting implications about when and where dinosaurs may have originated, as well as when feathers may have evolved,” says University of Cambridge paleontologist Matthew Baron, lead author of the study. Not all researchers are so enthusiastic: A number of early dinosaur evolution experts have challenged the proposed reorganization. But even some of the critics are open-minded. “I don’t think we can be quite sure whether the new or the traditional arrangement is correct,” says Steve Brusatte of the University of Edinburgh, “but new fossils will hopefully help us untangle it.” Baron and colleagues aren’t waiting for new fossils to be found, however. In August, they published a reanalysis of Chilesaurus in Biology Letters. The dinosaur, first described in 2015 as a bizarre, herbivorous theropod, is actually a primitive ornithischian, according to the study — a placement that would strengthen the authors’ argument for rewriting the entire family tree.  JON TENNANT

SHAKING THE FAMILY TREE

Ornithischia

Sauropoda

Theropoda

Proposed revision

Herrerasauridae

Sauropoda

Theropoda

Saurischia ? Dinosauria

Herrerasauridae Dinosauria

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Ornithischia

TOP: GABRIEL LÍO. BOTTOM: JAY SMITH

Traditional dinosaur evolutionary tree

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17 Fighting Politics With Math Slightly tweaking congressional districts can reveal whether the state in question — Wisconsin here — is gerrymandered.

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IN MARCH, PENNSYLVANIA MATHEMATICIANS proved

a theorem that rigorously demonstrates congressional districts in their home state are gerrymandered, drawn to give one political party an unfair advantage. Their work, which appeared in The Proceedings of the National Academy of Sciences, supports an ongoing lawsuit demanding better boundaries and joins other mathematical efforts to

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analyze districting fairness. The method tests districts by applying small, random changes to their boundaries — say, including that neighborhood instead of this one. Such tweaks shouldn’t consistently change election outcomes, assuming the boundaries started out fair. But if the changes lead to alternate outcomes, the mathematicians proved it meant the district was biased from the beginning — in Pennsylvania’s case, in favor of the Republican Party.

“It’s important to have rigorous ways of demonstrating [gerrymandering], so the decision is not just another partisan debate,” says Wesley Pegden, a mathematician at Carnegie Mellon University in Pittsburgh, who worked on the theorem. The new work may also be useful in other scientific areas that involve random sampling, like how proteins fold and statistical physics.  STEPHEN ORNES

Sea Level Rise: Slow But Inexorable

TOP: WESLEY PEGDEN. BOTTOM: ZAKIR CHOWDHURY/BARCROFT MEDIA VIA GETTY IMAGES

EVEN SHORT-LIVED atmospheric greenhouse

gases, like methane, leave an imprint in the oceans that can last centuries, according to a paper published in the Proceedings of the National Academy of Sciences in January. A hotter atmosphere warms the oceans, which expand, leading to sea level rise. This can be a slow process. Gases can take anywhere from a decade (methane) to 1,000 years (carbon dioxide) to transfer their energy to the oceans. And once gases arrive there, it’s hard to get them out. The takeaway is that if humanity stopped cranking out greenhouse gases immediately, sea levels would still rise for centuries before the heat dissipates through Earth’s atmosphere and into space, says study co-author Susan Solomon, an atmospheric scientist at MIT. The study brings grim news for low-lying islands like Tuvalu in the South Pacific and coastal cities worldwide. “It’s not a tsunami,” Solomon says of the watermark rise. “It’s very, very slow. But it’s inexorable.”  ERIC BETZ

Sea levels could rise for centuries, in part due to greenhouse gases transferring their energy to the oceans. This would contribute to flooding in coastal cities like low-lying Chittagong, Bangladesh.

January/February 2018 DISCOVER

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Portable Detector Shakes Up Neutrino World

Pig Cells That Won’t Go Retro

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NEUTRINOS ARE THE BOO RADLEYS OF PHYSICS. These

tiny, electrically neutral particles are shy to a fault. Sixtyfive billion of them pass through every square centimeter of Earth’s surface each second, and nearly all exit the other side without making their presence known. Juan Collar helped make a Catching them in flight typically neutrino detector requires special detectors weighing portable (top), a far cry from current, thousands of tons. huge detectors (above). “They are harder to detect than anything else we know in particle physics,” says astrophysicist Juan Collar of the University of Chicago. Collar is part of a team called COHERENT that changed the game in August by making the first tabletop neutrino detector. The instrument is 100 times more sensitive than previous technology, Collar says. It works via an interaction between neutrinos and atoms theorized more than 40 years ago: As neutrinos bounce off atoms, they cause atomic nuclei to jiggle. The detector’s first measurements confirmed this predicted effect for the first time. New discoveries could be in store as the device now checks other features of neutrinos, including their electromagnetic properties. And Collar hopes that evensmaller detectors could be useful for monitoring nuclear reactors, which spew out neutrinos.  DEVIN POWELL

FROM LEFT: PHOTOMASTER/SHUTTERSTOCK; JEAN LACHAT/UCHICAGO NEWS; FERMILAB

MORE THAN 100,000 Americans need an organ transplant, and roughly 20 die daily while waiting. Since the early 20th century, scientists have envisioned a workaround in which we could use pig organs, but those so-called xenotransplants have never been humancompatible. This year, bioengineers at Harvard University and technology startup eGenesis reached an important milestone in making that vision reality. Pigs carry retroviruses, which replicate by permanently inserting their genes in the DNA of a host species. And in lab experiments, these porcine endogenous retroviruses (PERVs) tended to leap from pig to human cells. In a paper published in August in Science, scientists addressed this potential biohazard by knocking out the retroviral DNA with the gene editing technology CRISPR-Cas9. After cloning PERV-free embryos, the team implanted them in sows and raised piglets. The little oinkers were completely retrovirus-free. Now, the team is adapting the technique to make other essential genetic modifications, such as knocking out molecules that trigger immune systems to reject organs. “We are working on building a ‘pig 2.0’ with advanced immune compatibility,” says Luhan Yang, eGenesis’ co-founder and chief scientific officer. Humanized with a hand from CRISPR, their organs could match our needs.  JONATHON KEATS

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Q&A ❯ 

Adrian Luckman Glaciologist SWANSEA UNIVERSITY

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AN ICEBERG WEIGHING 1 TRILLION TONS calved from Antarctica’s Larsen C ice shelf around July 10, capturing global headlines. The iceberg, nearly the size of Delaware, is among the largest ever recorded. The calving is not directly linked to climate change, experts say; bergs break away naturally. And the ice was already floating, so it won’t raise sea levels. Of concern, though, is the fate of the remaining 88 percent of Larsen C, which still spans some 17,000 square miles. The event threatens to destabilize Larsen C, recent studies suggest. Since ice shelves act like plugs, removing them lets inland glaciers flow faster into the ocean — and that will raise sea levels. Other massive ice shelves have experienced destabilization after similar calving events. Larsen A, which is C’s Antarctic Peninsula neighbor, crumbled in 1995. Larsen B collapsed seven years later. U.K.-based glaciologist Adrian Luckman of Swansea University leads Project Midas, which tracks Larsen C. He says the recent iceberg caught public attention, but the real science is still to come. — ERIC BETZ

FROM LEFT: COURTESY OF ADRIAN LUCKMAN; NASA EARTH OBSERVATORY

ICY SPLIT-UP COULD DESTABILIZE LARSEN C

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❯  A giant iceberg calved from the Larsen C ice shelf in July.

Q A

15.5 miles

What happens to the iceberg now?

We don't have much information to go on because this is such a large iceberg. The Weddell Sea, which is where all the action is occurring, is choked with sea ice all year round, so it’s not an open ocean that things can float free on. Icebergs have been known to exit this area — quite big icebergs — and head up into the Southern Ocean. How quickly this one will do that is difficult to answer. It might take years and years.

Q A

What’s more scientifically interesting: the iceberg calving or what happens next?

FAR RIGHT: MAX VAN WYK DE VRIES

MUCH OF ANTARCTICA is covered with a thick sheet of ice that obscures what’s below, and it’s tempting to consider the continent as geologically frozen as its landscape. But in the land of snow and ice, there’s a hidden fire. Reporting their findings in May, geology student Max Van Wyk de Vries and his colleagues at the University of Edinburgh used radar surveys to reveal 91 previously unidentified volcanoes in the West Antarctic Rift System, an area where plate tectonics are tearing the continent apart. Some seem to have erupted in the last few millennia. Scientists aren’t sure how, or even if, the volcanoes will affect the overlaying ice sheet. Another pressing question: Will eruptions increase in Antarctica as the ice thins, similar to Iceland after the Ice Age? What’s clear is that no other place on Earth contains as many subglacial volcanoes, and that’s a real wild card for researchers attempting to model the ice sheet’s retreat. — ERIK KLEMETTI

Larsen ice shelf

What can Larsen C’s response to the calving teach us?

There’s a natural experiment going on here. What happens to an ice shelf of this size when you take a large piece out of it?

Q A

Antarctica’s Fiery Underbelly

The thing that doesn’t really interest us is the calving. As soon as we saw this rift starting to cut through, we knew it was going to happen. But the rift itself — how fast that cut through and what held it up — is teaching us a lot about ice shelves. And now we have another very interesting opportunity to study the reaction of the ice shelf.

ANTARCTICA Volcano study area

Elevation (m) 2,000 0 -2,000 -4,000

Confidence factor 2 2.5 3 3.5 4 4.5 5

Researchers used radar to map the landscape underneath Antarctica’s ice sheet and then rated how sure they were that a given feature was a volcano. (A rating of 5 is most confident.)

January/February 2018 DISCOVER

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23

Juno Delivers Jupiter’s Secrets

FROM TOP: NASA; NASA/JPL/SWRI/MSSS/GERALD EICHSTÄDT/ALEXIS TRANCHANDON/SOLARIS; NASA/JPL/SWRI/MSSS/BJÖRN JÓNSSON

Photos from Juno’s orbit of Jupiter reveal amazing vistas. Above, the gas giant’s northern pole area roils with white clouds. Below, the stormy dynamics of the Great Red Spot are visible during a low-altitude pass.

❯ 

NASA’S ONGOING JUNO MISSION, revealing what lies beneath Jupiter’s cloud tops and in its atmosphere, has upended many long-held theories about the king of the planets. “In many ways, it’s a new Jupiter,” says Scott Bolton, Juno’s principal investigator at the Southwest Research Institute in San Antonio. Many scientists had thought that by peering underneath Jupiter’s visibly divided outer layers, they would uncover a uniform, well-mixed planet. But according to a May study in Geophysical Research Letters, Juno has spied strong bands of what appears to be ammonia, indicating the planet is churning up material from its depths and implying a more active and variable world. The probe’s data also show polar regions swarming with unforeseen storms. At the same time, Juno is busy sampling Jupiter’s magnetic field, which is stronger than expected in some places and weaker in others, astronomers announced in the May issue of Science. And the auroras that light up its atmosphere arise not just from charged solar particles slamming into the planet’s atmosphere, as on Earth, but from Jovian moons spewing material toward the planet. So far, Juno’s discoveries raise more questions than answers, and scientists are eager to untangle them. “We’re slowly going to rewrite the book,” Bolton predicts. — KOREY HAYNES

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Age Is Just a Number (of Neural Stem Cells)

CLOCKWISE FROM TOP: CLAUS LUNAU/SCIENCE SOURCE; EADWEARD MUYBRIDGE/LIBRARY OF CONGRESS; SETH SHIPMAN

SCIENTISTS MAY HAVE IDENTIFIED how to slow or even reverse our biological clock. Adult neural stem cells in the hypothalamus — a brain region that regulates hunger, sleep, body temperature and other activities — appear to orchestrate the body’s aging process, they found. Research on lab animals has shown that the number of hypothalamus stem cells diminishes with age. To determine if this cell loss was related to aging, scientists killed off hypothalamic stem cells in middle-aged mice, according to a study that appeared in July in Nature. The mice showed clear signs of aging, such as loss of memory, endurance Hypothalamus and coordination.

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The scientists also discovered that the stem cells released tiny packets of microRNA, bits of genetic material that control how genes function. They injected the mRNA into the middle-aged mice that were missing hypothalamic stem cells and into healthy mice of similar age. In both groups, the treatment slowed aging. The findings could lead to better methods of treating age-related maladies and prolonging life, says lead author Dongsheng Cai of the Albert Einstein College of Medicine. “But it will take some time to translate this into humans,” he says. — LINDA MARSA

CRISPR Goes to the Movies

EADWEARD MUYBRIDGE’S

“The Horse in Motion” was an early demonstration of stop-motion illustration. In keeping with his pioneering spirit, Harvard University researchers have re-created the images by storing data in living bacteria. The results were published in Nature in July. Geneticist Seth Shipman and his team translated the pixels of Muybridge’s moving picture into a code made from the As, Ts, Gs,

and Cs of DNA. Then, using the CRISPR-Cas gene-editing tool, they spliced sequences corresponding to individual video pixels into the genome. The bacteria strung these snippets together in order and stored them in its DNA, letting scientists replay the video. Now that they’ve shown it’s possible to encode and retrieve information sequentially in bacteria, Shipman hopes to create

“molecular recorders” — genetically engineered cells with a time log of their activities. These recorders could someday monitor cellular activities in our bodies — like an airplane’s black box — giving scientists insights into what cells are doing and when. — CARL ENGELKING

Researchers encoded the series “The Horse in Motion” (right) and stored the data in a bacterial genome for later replay (left).

January/February 2018 DISCOVER

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SCIENTISTS HAVE FOUND

ancient human DNA in caves, no bones or teeth required. Instead, an international team located genetic traces of Neanderthals and Denisovans — both distant hominin cousins of ours who died off about 40,000 years ago — just from dirt. Researchers have been able to identify animal and plant DNA from soil samples since 2003, but this is the first time they’ve

extracted hominin DNA. It was no easy feat. The group scooped soil samples from seven European and Russian caves known to have housed prehistoric peoples. Using the latest DNA filtering techniques, researchers sifted through trillions of genetic fragments from plants, other mammals and modern humans to pinpoint the ancient hominin sequences. While they found Neanderthal genetic traces at

Viviane Slon (left), a co-author of the work, prepares a soil sample (such as the one above) for DNA extraction.

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Caves like these in Croatia (top) and Russia (above) housed the soil that researchers used to find genetic traces of our ancient ancestors.

several of the sites, Denisovan DNA turned up only in a Siberian cave. The work, published in Science in April, opens up new possibilities for researchers, says Viviane Slon, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of the study. Now, she says, they could unearth evidence of prehistoric occupation at sites where no human fossils or tools have been found, expanding our knowledge of hominin history. — MARK BARNA

CLOCKWISE FROM TOP: JOHANNES KRAUSE, MAX PLANCK INSTITUTE FOR EVOLUTIONARY ANTHROPOLOGY; RICHARD G. ROBERTS; SYLVIO TÜPKE, MAX PLANCK INSTITUTE FOR EVOLUTIONARY ANTHROPOLOGY; GROUP OF PALEOANTHROPOLOGY MNCN-CSIC

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Sifting Soil for Human Ancestors

B Bu igg tt er on s

ts o N rac

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ROYAL TYRRELL MUSEUM technician Mark Mitchell estimates he spent 7,000 hours chipping away at rock to uncover this 112 million-year-old dinosaur fossil, put on display at the Alberta museum in May. Described formally in August in Current Biology, the animal’s name, Borealopelta markmitchelli, is a nod to Mitchell’s dedication. The plant-eating, tanklike nodosaur is unusually well preserved, including its hefty body armor, large shoulder spikes and even pieces of soft tissue. Only the animal’s front half was found; its partly exposed innards include the fossilized remnants of a last leafy meal. Don Henderson, the Royal Tyrrell’s curator of dinosaurs, believes that soon after death, the nodosaur’s bloated carcass floated down a river out to the ancient Albertan sea where “eventually the body went pop, and he sank like a stone.” Sediment must have then rapidly buried the body, preserving Extremely rare among armored dinosaur fossils, the it with lifelike detail. remains of Borealopelta markmitchelli were preserved with many of its spikes and bony plates in place (above), providing a detailed guide to illustrating what it looked like 112 million years ago (below).

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— SYLVIA MORROW

28

Sperm Counts Plummet

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SPERM COUNTS have

plunged 52.9 percent in the past 39 years in North America, Europe, Australia and New Zealand, according to a July analysis in Human Reproduction Update. This trend is worrisome because, besides affecting male fertility, men with lower sperm counts also have higher rates of heart disease and cancer. They also die at younger ages. The analysis involved 185 studies of 42,935 men conducted between 1973 and 2011. (Men in other parts of the world weren’t included because solid data isn’t available.) Environmental factors are the likely culprits. For example, men with low sperm counts might have been exposed in utero to cigarette smoke or chemicals that disrupt crucial hormone levels. “This is the canary in the coal mine,” says Shanna H. Swan, a study co-author at Icahn School of Medicine at Mount Sinai in New York, “because it has large economic implications about men’s fertility and health.” — LINDA MARSA

CLOCKWISE FROM TOP LEFT: COURTESY OF THE ROYAL TYRRELL MUSEUM OF PALAEONTOLOGY, DRUMHELLER, CANADA; SCIENCE PICTURE CO/SCIENCE SOURCE; DAVIDE BONANDONNA/NATIONAL GEOGRAPHIC CREATIVE

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How to Preserve a Dinosaur

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Psychedelic Drug Tapped for PTSD Therapy

TOP: AUGUSTO ZAMBONATO. BOTTOM: DANIEL DOMINGUEZ/CERN

A GROUP OF RESEARCHERS is one step closer to bringing an unexpected drug into the fray to help treat mental illness: ecstasy. Psychotherapy that incorporates MDMA, the primary ingredient of ecstasy, was designated in August as a Food and Drug Administration “breakthrough therapy” for severe post-traumatic stress disorder. In other words, the therapy is on the fast track toward approval. “If you were to develop a drug to treat PTSD, you’d want it to do exactly what MDMA does,” says Rick Doblin, founder and executive director of the Multidisciplinary Association for Psychedelic Studies (MAPS), which funds and conducts the research. When patients use MDMA, their memories and emotions become more vivid. And in this state, patients experience less fear and anxiety attached to their memories — enough to begin talking about and engaging with their trauma under the supervision of a therapist in a safe environment. MAPS’ phase 2 trial, which ended in 2016, found that 68 percent of patients no longer had PTSD diagnoses. The next clinical trials start in spring 2018. Over 12 weeks, patients will have three daylong MDMA-assisted sessions and a dozen 90-minute therapy sessions with no drugs.

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“It’s known there isn’t a perfect solution for PTSD,” says Doblin. Various styles of therapy and some medications can fail for many patients. Time will tell if MDMA-assisted psychotherapy can change that. — DEVI SHASTRI

A Charming New Particle

PHYSICISTS HAVE FOUND

hundreds of particles made of quarks over the years. Protons and neutrons, for example, are made from “up” and “down” quarks, the two most common and lightest of the six so-called flavors of quarks. But the latest particle discovery, announced at CERN in July, stands out because it’s composed of one ”Up” quark

up quark and two of an uncommon quark flavor called charm. Theories predicted the new particle — dubbed c+c+ (pronounced ka-sighsee-see-plus-plus) — more than 30 years ago, but charm quarks are rare and about five times heavier than up quarks, making “Charm” quarks

Meet the new particle, c+c+.

them unlikely particle ingredients. It took three years of high-energy data collection to find enough c+c+ particles for physicists to be confident in the discovery. The insights into how the two charm quarks interact will lead to a better understanding of how these tiny components of the universe work together, including new predictions of exotic particles. — SYLVIA MORROW

January/February 2018 DISCOVER

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Octopuses Can Stray From Their DNA

IF OUR DNA is a blueprint, then RNA is the messenger, ferrying instructions for biological tasks to our cells. If you’re an octopus, though, that message can change en route. An international research team found that octopuses can edit their RNA, albeit unintentionally. This ability may offer some of the same adaptive benefits as natural selection, but on an individual level. Writing in April in the journal Cell, the scientists said this ability allows octopuses to reinterpret their DNA in a way that could grant them new traits, like better cold adaptation. There were also hints that these RNA changes made the animals smarter. Octopuses are infamously clever, and such RNA editing could help explain why. Adding weight to this

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theory is evidence that nautiluses, a closely related shelled cephalopod known to be less intelligent, don’t possess the same editing capabilities. There is a trade-off, however. To preserve their RNA-editing powers, octopus genomes are much more resistant to mutation, the driving force of natural selection. This means that while individuals can make relatively sweeping changes to their bodies, the species as a whole doesn’t change much from generation to generation.  NATHANIEL SCHARPING

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Mice Born From Space Sperm

LEFT: OCEANBODHI/ISTOCK. RIGHT: TERUHIKO WAKAYAMA/PNAS/JUNE 6, 2017 VOL. 114 NO. 23

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BEFORE THEY WERE BORN, these mice were astronauts. Or rather, the sperm that made them were. Japanese researchers shipped freezedried mouse sperm to the orbiting International Space Station and stored it there for nine months to find out how microgravity and cosmic radiation would affect mice born from the cells. Upon touching back down to Earth, the rehydrated sperm were used to fertilize mouse eggs (which never left the ground). The resulting pups differed little from the purely Earth-based control mice. The sperm did show signs of mutation, which could have harmed the mice, but cells at the beginning of gestation have a supercharged ability to make repairs, compensating for the damage. The findings, reported in June in the Proceedings of the National Academy of Sciences, offer hope to future human space colonists who will not only need to live in space, but create new life there as well.  NATHANIEL SCHARPING

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AMERICAN GEOSCIENTISTS have discovered

2.7 million-year-old ice — the oldest ever by 1.7 million years, researchers announced at the annual Goldschmidt conference in August. The sample was drilled from Antarctica’s Allan Hills “blue ice” area, where unusually old glacial ice is closer to the surface, making it more accessible. Trapped bubbles can offer snapshots of past

Bubbles trapped in ice (above) hold ancient air, giving geoscientists like John Higgins of Princeton University (right) a way to date glacial ice in Antarctica. He and his team drilled at three sites, hauling tents and equipment, such as a drill bit filled with an ice core. The team camped at Allan Hills (below), where old ice is unusually accessible.

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carbon dioxide and methane levels. This latest sample reveals Earth’s climate history beyond a critical benchmark when, 1 million years ago, glacial cycles shifted from 40,000- to 100,000year periods. Understanding temperature and greenhouse gas shifts through those ice ages could also offer insights into Earth’s future climate.  KATHERINE MAST

CLOCKWISE FROM TOP LEFT: YUZHEN YAN (2); PRESTON COSSLETT KEMENY/PRINCETON UNIVERSITY DEPARTMENT OF GEOSCIENCES

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Ancient Antarctic Ice Is Discovered

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One Magnet to Bind Them All

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A FRENZY FOR TWO-DIMENSIONAL MATERIALS

kicked off in 2004 with the creation of graphene — made from just a single layer, or monolayer, of carbon atoms. Researchers have since made monolayers of metals, semimetals, insulators and more, but magnetism was the final holdout. In June, Xiaodong Xu of the University of Washington published results of the first isolated monolayer magnet in Nature. The new magnet, made of chromium triiodide (CrI3), has some curious properties, just like previous 2-D materials. A single layer of CrI3 crystals was magnetic, but two layers were not. Yet when a third layer was added, the magnetism reappeared. Future applications could use this quirk to switch between magnetic states in computers — difficult using current technology — to improve computer memory. It’s unlikely CrI3 itself will end up in commercial devices. It reacts strongly with water and oxygen,

35

A single layer of chromium triiodide (chromium atoms in gray, iodine in purple)

evaporating within seconds of being exposed to air. But Xu has high hopes the discovery will lead to new fundamental physics. “What we’re really looking for is anything beyond what we can imagine,” he says. “I’m sure it’s there.”  SYLVIA MORROW

Making Blood Cells in the Laboratory

❯  TOP: EFREN NAVARRO-MORATALLA. BOTTOM: DAVID M. PHILLIPS/SCIENCE SOURCE

SCIENTISTS HAVE TAKEN A MAJOR STEP forward

toward making artificial blood by creating blood stem cells in the lab. In two studies reported in Nature in May, teams at Harvard University and Weill Cornell Medicine at Cornell University created hematopoietic stem cells (HSCs). These mature into blood’s essential components: platelets, white blood cells and red blood cells. HSCs also generate a lifetime of blood cells, which must be continually replenished. When the body fails to restock, life-threatening forms of anemia, lethal infections or serious bleeding disorders can emerge. To make the HSCs, the Harvard group used human skin cells to create induced pluripotent stem cells (iPSCs), adult cells researchers

Experts created artificial blood stem cells, the precursors to white and red blood cells (shown here) and platelets.

genetically reprogram to an embryonic-stem-cell state, where they can grow into any kind of cell.

Adding seven transcription factors — proteins that switch on genes — the team then converted the IPSCs into immature HSC-like cells. The Weill Cornell researchers’ process was more direct: Four transcription factors prompted adult mouse endothelial cells, which line the inside of blood vessels, to turn into HSCs. Either approach could produce enough HSCs to transplant and — pending further safety testing — potentially treat leukemia, sickle cell disease and other severe blood disorders. Says George Daley, a stem cell biologist who led the Harvard study: “It’s a real scientific advance and brings us closer to making customized cells we can transplant without worrying about rejection.”  LINDA MARSA

January/February 2018 DISCOVER

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3-D PRINTING is now tackling fertility. A team from Northwestern University showed that mice implanted with 3-D-printed ovaries can birth healthy offspring — a medical first that paves the way to scale up the bioprosthetics for humans. The group printed the organs by overlapping pieces of biocompatible gelatin — think of stacking Lincoln Logs. Then, researchers inserted up to 50 follicles into each ovary. These structures produce hormones and also contain eggs. Next, they implanted two ovaries each in seven sterile mice, and mated them with male mice. After a normal gestation of roughly three weeks, three females gave birth to healthy litters. The study, published in Nature Communications in May, also noted that the new moms lactated, evidence of the follicles’ normal hormone production. Though still a long way off, the team hopes similar methods for humans could allow cancer survivors facing chemotherapy-induced infertility to become mothers.  KATHERINE KORNEI

Researchers implanted 3-D-printed ovaries into sterile female mice that later gave birth. Eggs housed in the ovaries (circled, right) were engineered to glow green under certain light to make the pups (above) easier to spot.

This gelatinous artificial ovary (above) helps mouse eggs (left) develop and survive inside sterile female mice.

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NORTHWESTERN UNIVERSITY (4)

36

Mice Birth Pups From Artificial Ovaries

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German researchers at the University of Tuebingen (above) found a genetic motherlode in ancient Egyptian artifacts, including the sarcophagus (below) of a young girl.

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DESPITE WHAT JURASSIC PARK TOLD YOU, DNA

doesn’t last forever. Even though mummies can preserve human tissues for millennia, most useful DNA doesn’t make it. That’s why it was a pleasant surprise when archaeologists announced in May they’d found three full genomes from Egyptian mummies. Initial analyses are already suggesting that ancient Egyptians had much more Middle Eastern ancestry than Egyptians do today, and more insights likely await. Working with 151 mummies recovered from a large burial site near Cairo, German researchers sampled bones, teeth and soft

tissue to sift out any viable DNA sequences. In all, they recovered 90 mitochondrial sequences — the tiny portion of our genome contained within mitochondria — in addition to the three full genomes, as detailed in a paper in Nature. The mummies were buried between 1400 B.C. and A.D. 400, a span covering ancient Egypt’s New Kingdom and Roman Period. The entire genetic library comprises the most reliable dataset from the area to date, and makes a case for the viability of DNA sequencing in Egyptian archaeology.  NATHANIEL SCHARPING

TOP: JOHANNES KRAUSE/MAX PLANCK INSTITUTE FOR THE SCIENCE OF HUMAN HISTORY. BOTTOM: BPK/ÄGYPTISCHES MUSEUM UND PAPYRUSSAMMLUNG, SMB/SANDRA STEISS

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Unraveling Mummies’ Genetic Secrets

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When Probiotics Really Do Work

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PROBIOTICS SEEM LIKE a good idea: Use products

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The Fastest Fluid

TOP: BROOKHAVEN NATIONAL LABORATORY. BOTTOM: KUNAL PATIL/HINDUSTAN TIMES/GETTY IMAGES

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PROTONS AND NEUTRONS are familiar as tiny solids, but particle accelerators can melt them into what’s called a quark-gluon plasma, or QGP. Studies of the superhot material, first done about a decade ago, have revealed QGP is the hottest, least viscous known liquid and is capable of forming the smallest drop of liquid ever seen. And now, it’s also the fastest known spinning liquid, as reported in August by the STAR collaboration in Nature. In a single second, the authors (an international collaboration working with Brookhaven National Laboratory’s STAR detector) saw the QGP goop rotate a mind-boggling sextillion times — a billion trillions. Getting even small pieces of new information from these experiments is always a challenge, so an experimental measurement of an entirely new feature like rotation speed is huge. QGP production is sometimes referred to as “tiny big bangs” because shortly after the Big Bang, the universe consisted of QGP. These experiments help us understand the fundamental properties of our universe and its origins, and lead the way toward testing emerging theories.  SYLVIA MORROW

that contain beneficial bacteria to fortify our immune systems. But most studies, especially larger ones, had not shown they actually do much good. But now there’s some proof. In a clinical trial in rural India involving more than 4,500 newborns, a U.S.-led team and a team from the Asian Institute of Public Health gave half the babies a specially formulated probiotic concoction, while the remainder got a placebo. The team found the treated infants had a significantly lower risk of developing sepsis, a lifethreatening infection that kills 600,000 newborns globally each year. Only 5.4 percent of babies given the concoction got sepsis, compared with 9 percent who received a placebo, according to the study published in August in Nature. What made this study different is, rather than using off-the-shelf probiotics that can’t gain a foothold in the gut, researchers tested over 280 probiotic strains to find the right one. Their product contained a form of Lactobacillus plantarum, bacteria that can colonize cells in the intestines, preventing the bad bugs from doing the same. “Hopefully, we’ll figure out how the bacteria modulate newborns’ immune system,” says Pinaki Panigrahi, an epidemiologist who led the team. “Because if we can give this to them early enough, it should protect against disease.”  LINDA MARSA

Indian newborns who received a specially concocted probiotic dose were less likely to develop sepsis, a life-threatening infection.

January/February 2018 DISCOVER

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A Titan for the Record Books

THIS PAST SUMMER, paleontologists announced a new contender for largest dinosaur: Patagotitan mayorum. The 100 million-year-old giant was a type of plant-eating, long-necked sauropod called a titanosaur, and is likely the largest creature known to have walked the planet. An international group of researchers described the animal in August in the journal Biological Sciences, after analyzing the partial skeletons of six individuals

unearthed in Argentina in 2014. They estimate the animal grew up to 122 feet long and weighed roughly 69 tons — about the same as 10 fully grown male African elephants, today’s largest land animal. Phil Mannion, a sauropod expert at Imperial College London who was not involved with the study, praises the find. “Whether or not Patagotitan is the largest known dinosaur,” he says, “it fills an important gap in our understanding of these gigantic animals.”  JON TENNANT

TOP: JOSÉ L. CARBALLIDO ET AL./PROC. R. SOC. B 284: 20171219, AUGUST 9, 2017. BOTTOM: CHRISSTOCK PHOTO/ALAMY STOCK PHOTO

16.5 ft.

Patagotitan mayorum, reconstructed below, might be the biggest known dinosaur. This rendering, at left, shows bones from different individuals, with missing bones shown in light blue.

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DISCOVERMAGAZINE.COM

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A 13 MILLION-YEAR-OLD SKULL from Kenya, described in August in Nature, hints at what a common ancestor of all living apes (including humans) looked like. The fossil, from an infant, is the lineage’s most complete skull between 7 million and 17 million years old. The animal had a short snout, similar to that of a gibbon but unlike other apes. Anthropologist and lead author Isaiah Nengo says the fossil offers the best glimpse yet of our distant ancestor: “We now have a face.”  MARK BARNA

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The palm-sized infant skull is a link to our distant primate past.

FRED SPOOR. INSET: ISAIAH NENGO, PHOTO BY CHRISTOPHER KIARIE

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Dawn of the Planet of the Apes

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The Sleepless Seven: First Genes Linked to Insomnia

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Genetic Roots of PTSD

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LEFT: SCOTT PETERSON/GETTY IMAGES. RIGHT: AUGUSTO ZAMBONATO

SPOST-TRAUMATIC STRESS DISORDER (PTSD) affects about

24.4 million Americans annually. Now, researchers have detailed evidence that a person’s risk of developing the disorder — which results from experiencing traumatic events like rape and war — is inherited. The work, published in Molecular Psychiatry in April, pooled results from 11 studies to analyze data from over 20,000 volunteers. Previous research suggested genetics might play a role in developing PTSD. But according to senior author and Harvard epidemiologist Karestan Koenen, those findings only inferred heritability. For this work, Koenen and her team examined the entire genomes of those earlier studies’ participants. They found evidence that not only can PTSD be passed down through generations, but also that some related genes are linked to schizophrenia. They further found that European-American women are about 30 percent more likely than men overall to be genetically susceptible to developing PTSD. Knowing how the condition works on a genetic level could help experts identify those most at risk, and tailor treatment to help them work through their trauma.  LACY SCHLEY

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LACK OF SLEEP hurts people’s concentration, mood

and health. And for those with insomnia — defined as three sleep-deprived nights a week for at least three months — life can become a nightmare. The cause of insomnia, which affects 10 percent of the population, has long been considered psychological. But a June paper in Nature Genetics identified, for the first time, a genetic risk for the condition. A team of international researchers looked for genomic variations between insomniacs and sound sleepers among 113,000 people in the U.K. and found seven genes linked to insomnia. One of the genes had been identified as a risk factor for two sleep disorders: restless leg syndrome and periodic limb movement. Individuals with the insomnialinked genes also appeared predisposed to depression, obesity and cardiovascular diseases. Exploring “what these genes actually do and why they make people vulnerable for insomnia is the next step,” says study co-author Eus Van Someren, head of the Sleep & Cognition Group at the Netherlands Institute for Neuroscience. The research could lead to developing more effective drugs to treat the condition, he says.  MARK BARNA

January/February 2018 DISCOVER

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ke r E H o o d w in CODENAM fi s h ocean sun te ct a NAME M o la ISED Ju ly COMPROM RRITORY KNOWN TE re H e m is p h e S o u th e rn IS R TICS CHARACTE PHYSICAL rr e, to n s; b iz a We ig h s 2 body fl att e n e d ITS KILLS/TRA NOTABLE S h e rs : R e se a rc E VA S IO N f M. h t w in d o fi rs t ca u g th e fi sh 009, but te ct a in 2 th e m fo r e to e va d d e u n ti n co ss ive si z e. it e it s m a sp e d rs a e y

44 Species Exposed!

❯

STEALTH, DISGUISE AND SOME GOOD HIDING SPOTS had

er CODENAME Sk ywalk n bo gib ho olo ck ing NAME Ho olo ck tia nx y ar nu Ja D SE COMPROMI ma r an d an My RY ITO KNOWN TERR so uth we ste rn Ch ina RISTICS PHYSICAL CHARACTE eyeb rows ite wh d ne Down tur ITS NOTABLE SKILLS/TRA cked away in Tu : US AT EL ITE ST kn ow n as iso lat ed mo un tai ns ra re gibbo ns sk y isl an ds, th es e l tra ck ing have taken ca re fu . Bio log ist s to fin d an d ide nt ify th em , bu t fin all y dis cover ed th e brink th ey ’re alr ea dy on of be ing los t.

previously left these agents undetected. The species that scientists exposed and identified in 2017 had been squirreled away in all kinds of places, from the depths of remote oceans to right under our noses.  SYLVIA MORROW

CODENAM E Humbo ld t’s fl y ing s q u ir re l NAME G la u co my s o r eg o n e n s COMPROM is ISED M ay KNOWN TE RRITORY Pa ci fi c N o r th we s t

DEC

IF LASS

IED

PHYSICAL CHARACTE RISTICS W sk in b e tw e bb e d e e n li m b s a n d to rs o u se d fo r , g li d in g d o w n fr o m h e ig h ts NOTABLE S KILLS/TRA ITS CAMOUFL AGE/IMP ERSONAT S in ce th e ION: 1 8 0 0 s, G . o reg o n e re m a in e d n si s h idd e n a m ong p o p u lati o n s o f o th e r fl y in g sq u ir re ls in th e Pa ci fi c N o rt h we st and Cana da. H owe ve r, re ce n t g e n e ti c te st h a s o u te d in g G. o reg o n e n si s a s a se p a rate sp e ci e s.

THIS PAGE FROM TOP: CÉSAR VILLARROEL/EXPLORASUB; PENGFEI FAN; NICK KERHOULAS. OPPOSITE FROM TOP: RYAN RIDENBAUGH AND MILES ZHANG; JANNES LANDSCHO AND RAFAEL LEMAITRE, ZOOKEYS 676: 21–45 (2017) BACKGROUND: SULEYMANKARACESME/SHUTTERSTOCK

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D E I F I S S DECLA

CODENAME Crypt-keeper wasp NAME Euderus set COMPROMISED January KNOWN TERRITORY Southeastern U.S. PHYSICAL CHARACTERISTICS Iridescent exoskeleton

CODENAME Green-eyed hermit crab NAME Paragiopagurus atkinsonae COMPROMISED May KNOWN TERRITORY South African coast

NOTABLE SKILLS/TRAITS STEALTH ASSASSINATION AND IMPERSONATION: It wasn’t until one researcher happened upon this wasp’s home on a casual stroll that its cover was blown. E. set lays its eggs in the new, growing stems of oak trees, in which another wasp, the crypt gall wasp, has also laid its eggs. Just as the new generation of adult gall wasps bores its way out of the tree, newly hatched E. set wasps kill their hosts, eating their way through their victims’ bodies and hiding in the corpse until they reach maturity.

PHYSICAL CHARACTERISTICS Green eyes; living shell composed of anemones held together by sand NOTABLE SKILLS/TRAITS EVASION/CAMOUFLAGE: P. atkinsonae wasn’t spotted until 2012. It could have been just another hermit crab, but a researcher conducting a sea life survey spied P. atkinsonae ’s signature green eyes. Much like M. tecta , it took experts another five years to root out this agent.

January/February 2018 DISCOVER

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45 ❯ 

ESSAY

DIAGNOSING FROM AFAR

IN THE HEAT of the 1964 presidential election

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46

The Equator Could Be Uninhabitable

❯ 

HEAT WAVES CAN KILL PEOPLE,

and by 2100, half of Earth’s population could experience 20 days or more of life-threatening heat every year. And that’s if humans drastically reduce their CO2 footprint. In the worst-case scenario — if greenhouse gas emissions keep growing — some 75 percent of humans could feel that deadly heat, according to a June paper published in Nature Climate Change. The research team, led by University of Hawaii scientists, analyzed future climate trends by looking at studies of past heat waves. They found that combinations of heat and humidity exceeding our ability to cool ourselves with sweat could regularly threaten large swaths of humanity by 2100. What’s more, the analysis indicates that many regions near the tropics in particular — where billions of people live — would experience conditions regularly exceeding that limit, making the areas effectively uninhabitable.  NATHANIEL SCHARPING

FROM TOP: ARIF ALI/AFP/GETTY IMAGES; BOB GOMEL/THE LIFE IMAGES COLLECTION/GETTY IMAGES; FACT MAGAZINE VIA WIKIMEDIA

campaign between Lyndon Johnson and Barry Goldwater, FACT magazine published a fiery headline: “1,189 Psychiatrists Say Goldwater Is Psychologically Unfit to Be President!” Goldwater sued FACT for libel — and won. The American Psychiatric Association (APA), the world’s largest association in the field, reacted to the incident by declaring it “unethical for a psychiatrist to offer a professional opinion unless he or she has conducted an examination and has been granted proper authorization for such a statement.” The 1973 change became known as the Goldwater Rule. The guidelines remained largely uncontroversial for decades, until Donald Trump’s presidential election prompted some mental health professionals to call foul — and go rogue. “After he was elected, people in mental health started getting agitated about the restriction,” says psychiatrist Prudence Gourguechon, an APA member and former president of the American Psychoanalytic Association. A February letter to The New York Times, signed by 33 psychiatrists and psychologists, cited Trump’s inauguration speech as proof of “grave emotional instability” and declared him “incapable of safely serving as president.” Several prominent psychiatrists resigned from the APA to protest what they saw as attempted restriction on their freedom of speech. In response, the APA doubled down, reissuing a reminder to members that the rule remained in effect. Meanwhile, the much smaller American Psychoanalytic Association made headlines when it told members they were free to decide for themselves whether or not to publicly comment on Trump’s behavior. Gourguechon argues the media interest in the ethics rules of otherwise obscure professional associations may be a symptom of something else entirely. “Journalists feel troubled by the demands of their own profession for neutrality,” she says. “I think journalists are displacing their own conflict onto us.”  ANDREW CURRY

47 September 2029

February 2018

Earth orbit

Sun

Jupiter orbit

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Asteroid Hits Reverse

❯ 

IN MARCH, ASTRONOMERS IN CANADA identified an asteroid unlike

any other: It travels the same orbit as Jupiter, but circles the sun in the opposite direction. Only a few other objects in the solar system are known to have such a “wrong way” orbit, and asteroid 2015 BZ509 alone shares its path with a planet. Astronomer Paul Wiegert, from the University of Western Ontario, and colleagues tracked the object during late 2015. They found that its gravitational relationship with the sun and Jupiter keeps it in a safe, stable orbit — and it’s likely been there for around a million years, they reported in Nature. The questions now include figuring out if 2015 BZ509 is more like an icy comet or a rocky asteroid and how it ended up going the wrong way in the first place. Those will help answer what Wiegert calls the big question. “The first asteroid discovered turned out to be one of millions,” he says. “Is BZ509 unique or just the tip of an iceberg?”  STEPHEN ORNES

Asteroid 2015 BZ509 orbit

NASA/JPL-CALTECH; INSET: DAN BISHOP/DISCOVER

This top-down view shows the shifting orbit of asteroid 2015 BZ509 around the sun, and how it overlaps with Jupiter's.

January/February 2018 DISCOVER

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❯ 

BACK IN THE 19TH CENTURY, a French

criminologist named Alphonse Bertillon invented a technique for recognizing repeat offenders by precisely measuring convicts’ facial features. Fingerprinting eventually supplanted his system, but new research done on macaques shows primate brains can naturally keep track of faces thanks to a

kind of bertillonage. The discovery, reported in June in Cell, completely breaks with the standard model of facial recognition, which claims each face you recognize is represented by a single neuron (one cell firing when you see your grandmother, another when you see Jennifer Aniston). Instead, Caltech neuroscientist Doris Tsao showed that individual primate neurons respond to specific facial qualities, such as bone shape and skin color. Inserting electrodes into the brains of two macaques, Tsao worked out which aspects of a face were mapped onto each neuron. Then she validated her findings by showing the macaques additional faces, and accurately reconstructing what they’d seen using only neural recordings. Tsao predicts that, with advances in human brainmonitoring technology, “the ability to decode faces by neuronal activity can be used in forensics, such as reading out a criminal’s face from a witness’ mind.” Are you watching, Monsieur Bertillon?  JONATHON KEATS

Researchers had macaques look at faces (left column), while recording electrical activity from 205 of the monkeys’ neurons. Scientists then used that data to reconstruct those faces (right).

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Actual faces

Predicted faces

LEFT: OLEG SENKOV/SHUTTERSTOCK. RIGHT: COURTESY OF DORIS TSAO

48

I Can See What You’ve Seen

49 ❯ 

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Weighing a White Dwarf

THREE YEARS AGO, ASTRONOMERS put a white dwarf on a scale and watched the needle move. Not literally, says Kailash Sahu, an astronomer at the Space Telescope Science Institute, but their pioneering method of weighing the star really is that straightforward. Their findings appeared in Science in June. When the dwarf, named Stein 2051 B, passed in front of another star from Earth’s perspective, Sahu’s team followed the position of the background star. As general relativity predicts, light from the background star bent around the white dwarf, distorted by its gravitational field. Like the deflection of a scale’s needle, the deflection of the background star’s light let astronomers calculate the white dwarf’s mass (roughly 67.5 percent the mass of our sun). The movement was minute, but the results were stunning. “I almost fell off my chair,” says Sahu. The white dwarf’s mass was exactly in line with predictions made in a theory developed by

Real star position

Observed star position

White dwarf

Astronomers used the Hubble Space Telescope to learn a white dwarf's mass by seeing how much it deflected another star's light.

Subrahmanyan Chandrasekhar in 1930. Previous attempts to confirm the theory had relied on shaky assumptions, but Sahu’s group demonstrated Chandrasekhar’s accuracy while proving their own new method really works.  SYLVIA MORROW

50 Drug Treats Aggressive Form of MS ❯ 

TOP: NASA, ESA, AND K. SAHU (STSCI). BOTTOM: GENENTECH

MORE THAN 400,000 AMERICANS are afflicted

with multiple sclerosis, an autoimmune disease that disrupts the brain’s neural signals to the body. In March, the Food and Drug Administration approved the drug ocrelizumab to treat not only the milder form of MS, but also the primary-progressive form, for which there was no treatment until now. In both types of MS, immune system cells attack and strip away myelin, the fatty protective sheathing that insulates nerve cells. This interferes with nerve signals, causing muscle weakness, lack of coordination, blurry vision, bowel and bladder problems and foggy thinking.

Ocrelizumab is the first FDA-approved treatment for primary-progressive MS.

The new-to-market drug takes a novel approach. Whereas traditional MS medications target the immune system’s T-cells, ocrelizumab focuses on destroying the system’s B-cells, which fuel the brain inflammation that causes the disease to worsen. During clinical trials, MRI scans showed that ocrelizumab reduces new brain inflammation in the milder relapse-remitting form, and slows deterioration in the progressive and most aggressive form. Along the way, the experiments have resulted in important information on how MS attacks the body, says Stephen Hauser, a neurologist at the University of California, San Francisco, whose lab spent decades determining the critical role B-cells play in the disease.  LINDA MARSA

January/February 2018 DISCOVER

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❯ 

CANCER CELLS ARE NOTORIOUSLY ADEPT AT SURVIVAL,

even exploiting vulnerabilities within an individual’s DNA to multiply and spread. In July, researchers at the Broad Institute mapped these cancer-linked genetic mutations, called cancer dependencies, for the first time. “For decades, cancer was a black box, and we didn’t know which genes were important,” says research team leader William Hahn of the Dana-Farber Cancer Institute. “The goal with the dependency map is to identify genes of consequence and reverse engineer what their action is, to devise better therapies.” The team uncovered different kinds of dependencies that cancer cells exploit, such as underactive or overactive genes. The Broad Institute’s visualization of the map, simplified here, illuminates both the complexity and interconnectedness of the genetic pathways that fuel tumor growth. — LINDA MARSA

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Much like biologists classifying living organisms in ever-smaller groups based on shared traits, all the way down to genus and species, the new cancer dependencies map organizes different genetic mutations by how they allow cancer's development and spread. In this visual representation of the map, the inner ring represents all identified cancer-linked mutations.

The inner ring's different segments each contain those genetic mutations that facilitate cancer through a similar mechanism, such as errors in making proteins.

KNOW THINE ENEMY: Mapping genetic mutations based on similarities in how they enable cancer can help researchers identify potential targets for new therapies.

Radiating from the inner ring, mutations are grouped by more specific shared traits, such as those that cause errors in making the same kind of proteins.

THE BROAD INSTITUTE OF MIT AND HARVARD

51

Mapping the Monsters

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52 Amber Preserves Tick’s Last Supper ❯ 

AN AMBER-TRAPPED TICK found in

the Dominican Republic contains the oldest mammalian red blood cells ever discovered. According to a study in the Journal of Medical Entomology in March, a grooming primate likely punctured the tick’s shell — releasing blood and betraying its presence to scientists millions of years later — and then flicked the critter into tree sap, where it was preserved for some 15 million to 45 million years. The cells contain a parasite related to a modern species commonly carried by ticks, shedding light on the entwined history of our ancestors and the organisms that preyed on them. — NATHANIEL SCHARPING

53 ❯ 

A Quick Start to Long-Lasting Memories

NEUROSCIENTISTS THOUGHT long-term

TOP: GEORGE POINAR JR./OREGON STATE UNIVERSITY (2). BOTTOM: LIGHTSPRING/SHUTTERSTOCK

Close-up of fossilized blood cells.

memories took weeks to form. But MIT researchers have discovered those memories can take hold in the brain much sooner. The team used a technique called optogenetics, in which light-responsive proteins are genetically inserted into brain cells, allowing researchers to activate them with lasers to find out what they do. The group trained mice with these engineered neurons to fear an electric shock and, with a blast of laser light, could spot

the brain cells involved in that painful memory. The team identified memory cells in the neocortex — the brain’s

outer layers, which house longterm memories — within just a day of the shock. When the scientists stimulated those cells with light, the critters cowered in fear, showing that the long-term memories were already there. Along with furthering our understanding of memory, the results, published in April in Science, also may help explain what happens during dementia. “We are nothing but memory,” says senior author Susumu Tonegawa. “So we want to understand how it works, and we want to understand why it goes wrong.” — JESSICA MCDONALD

January/February 2018 DISCOVER

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❯ 

TO STUDY GLOBAL WARMING, one group

of Antarctic researchers ditched fancy models in favor of a more hands-on approach: They heated the ocean themselves. British Antarctic Survey scientists placed panels equipped with heating elements on the seabed in Antarctica and warmed the devices by either 1 or 2 degrees Celsius. When the researchers checked back a few months later, the effects were starkly apparent.

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A group of small filter-feeding invertebrates had taken over on top of the heated panels, completely shifting the balance of the tiny test ecosystem. The scientists’ work, published in September in Current Biology, reveals the impact of the warming predicted to occur over the next 50 years. With such a loss of diversity comes increased sensitivity to disease and other potential threats, likely robbing ecosystems of their resilience. — NATHANIEL SCHARPING

Divers (top) from the Rothera Research Station in Antarctica monitor heated panels (above), designed to mimic ocean warming, on the seabed near Adelaide Island.

TOP: GAIL ASHTON. BOTTOM: SABRINA HEISER

54

Ocean Test Plots Reveal Effects of Warming

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55

Stuck on You

❯ 

TO PROTECT THEMSELVES

Bioengineers inspired by slug secretions (top) have created an adhesive that sticks to even wet biological tissues (above).

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Mathematicians See Within

❯ 

JULES VERNE MIGHT BE

disappointed to learn that we still can’t journey to the center of the Earth. But those curious about what’s down there — metal or monsters? — can take heart from a mathematical proof nearly four decades in the making. The proof, posted online in February, demonstrates that an object’s insides can be mapped exactly without cutting it open. All you need to know is how quickly waves travel between every possible pair of points on the object’s surface. Strictly speaking, the proof applies only to certain mathematically perfect objects. “The Earth is far from mathematical idealization,” says Stanford University’s András Vasy, one of three mathematicians behind the proof. Still, he hopes their work will lead to better tools for geology, which already investigates Earth’s interior by studying seismic waves, and medical imaging, which infers the internal details of bodies from electromagnetic waves like X-rays. — DEVIN POWELL

CLOCKWISE FROM TOP LEFT: NIGEL CATTLIN/ALAMY STOCK PHOTO; MIKKEL JUUL JENSEN/SCIENCE SOURCE; WYSS INSTITUTE AT HARVARD UNIVERSITY

against predatory birds, some slugs have evolved to produce a defensive mucus that secures them to virtually any surface. Strong, stretchy and effective even in wet environments, the adhesive could be useful for surgeons struggling to plug and patch patients’ slippery organs — if only the substance could be efficiently manufactured. Harvard University bioengineer Jianyu Li has now mimicked this slug mucus in the lab, making synthetic glues using extracts from shrimp shell and algae. “Our adhesives are engineered to copy the essential biochemical and microstructural characteristics of the mucus,” he says. Like defensive mucus, Li’s concoctions can bond surfaces chemically, physically and electrostatically. Initial tests, reported July in Science, have demonstrated effective adhesion to animal hearts and livers, as well as cartilage and arteries. The slime that saves slugs’ lives could do the same for humans. — JONATHON KEATS

Our Neighbor, Homo naledi

❯ 

THE 2013 DISCOVERY OF HOMO NALEDI in South Africa’s Rising Star cave system added a new member to our family tree, but researchers initially were unable to date the small-brained hominin. In papers published in the journal eLife in May, anthropologist Lee Berger and his team finally placed the remains between 236,000 and 335,000 years old, younger than many expected based on the hominin’s primitive features. The relatively recent date suggests H. naledi might have overlapped with archaic Homo sapiens in the region. Berger’s team also announced more H. naledi specimens — including “Neo” (below), the most complete individual found so far — from an entirely new chamber in the cave system. The story of H. naledi is far from over. — NATHANIEL SCHARPING

WITS UNIVERSITY/JOHN HAWKS

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January/February 2018 DISCOVER

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58 ❯ 

The Pitter-Patter of Cosmic Dust

THOUSANDS OF POUNDS OF COSMIC DUST — known

often collected from rooftops, to Imperial College London’s Matthew Genge, Larsen found his first micrometeorite. The pair has since identified hundreds more. Research based on their catalog appeared in Geology in February. — SYLVIA MORROW

JAN BRALY KIHLE AND JON LARSEN

as micrometeorites — arrive on Earth daily. Scientists have long ignored the common space stuff that surrounds us, however, since cities abound with similar-looking particles. Instead,

researchers seek micrometeorites in remote places like Antarctica. But Jon Larsen, a Norwegian jazz musician turned micrometeorite photographer, managed to strike space dirt among the diaspora of human-made dust. After years of sending photos of urban dust,

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59 Go West, Young Tree ❯ 

AMERICAN TREES are marching west,

and that’s a surprise to ecologists. As the climate warms, researchers expected many plant species would move farther north — and to higher elevations — as they chase cooler climes. But more trees have actually expanded west over recent decades, according to a May study in Science Advances. A team led by scientists at Purdue University examined about 30 years of U.S. Forest Service data covering 86 types of trees in the eastern United States. In addition to the general westward migration, their study showed the trees aren’t moving in unison. While leafy deciduous trees, such as oak and maple, were more likely to go west, evergreen trees more often pushed north. The researchers say their findings indicate that moisture currently plays a more important role than temperature for many species. The trees are simply following the rain. — ERIC BETZ

60 ❯ 

A Flu-Fighter’s Fall From Grace

TOP: AUGUSTO ZAMBONATO. BOTTOM: MATTHEW BAKER/PRESS ASSOCIATION VIA AP IMAGES

WHEN TAMIFLU came on the

market in 1999, it promised to curtail severe influenza symptoms and even save lives, especially among the frail elderly and the chronically ill. In 2010, in the midst of the H1N1 swine flu pandemic, the World Health Organization (WHO) designated Tamiflu as an “essential medication,” encouraging governments to stockpile it. As a result, the drug has generated over $9 billion in sales worldwide just from government purchases. But Roche, Tamiflu’s maker, had buried the results of several clinical trials. Independent reviews of this

unpublished research, in 2012 and 2014, found no evidence that Tamiflu reduced hospitalizations or deaths; it also caused adverse effects. That should have been the end of Tamiflu. But it was not until June that WHO finally

downgraded the drug on its list of core medications. Critics blasted both WHO’s delay and Roche’s failure to release all of the clinical trial data, including some of the largest studies. University of Georgia epidemiologist Mark Ebell, who analyzed some of the unpublished data, echoed an editorial in The British Medical Journal when he called the situation a “multisystem failure” that diverted public health dollars into buying a marginally effective drug instead of using them for research into better treatments or more pressing health care concerns. — LINDA MARSA

January/February 2018 DISCOVER

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61 ❯ 

Spotting Autism Sooner

DIFFICULTY COMMUNICATING,

Communication and Symbolic Behavior Scales (CSBS) Social communication

Mullen Scales of Early Learning (MSEL) Cognitive ability

Repetitive Behavior Scale-Revised (RBS-R) Repetitive behaviors Each of the images above shows connectivity levels during different behavioral tests in brains of infants who would eventually be diagnosed with autism spectrum disorder (ASD). Blue lines signify more connectivity than non-ASD infants while red lines signify less connectivity. These behavioral tests and the corresponding connectivity levels were likely contributing factors to how a computer algorithm was able to go back through these infants’ brain scans and accurately predict nine out of 11 babies who would go on to be diagnosed with ASD by age 2.

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LEFT: OLGA LISTOPAD/SHUTTERSTOCK. RIGHT: R.W. EMERSON ET AL., SCIENCE TRANSLATIONAL MEDICINE (2017)

repetitive behaviors, sensory overload — all suggest autism spectrum disorder (ASD). These hallmarks generally appear by the time kids are 2 years old, and doctors can’t start treating the neurodevelopmental disorder until these symptoms show up. But now, a June paper in Science Translational Medicine describes a computer model that predicted which 6-month-old infants would display symptoms at the 2-year mark. U.S. researchers scanned the brains of 59 high-risk infants and waited 18 months to see which babies were diagnosed with ASD. The team then compared neural connectivity between the two groups and developed a model that correctly identified — using only the infant scans — nine of the 11 children who ended up with symptoms. If you can start therapy before these symptoms show up, you have a chance of improving many of the issues that lead to autism, says neuroscientist Robert Emerson of the University of North Carolina at Chapel Hill and a co-author of the paper. — MARK BARNA

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Ice Storms on Mars

CLOCKWISE FROM BOTTOM LEFT: ISRO/ISSDC/KEVIN M. GILL/CC BY 2.0; MAX PLANCK INSTITUTE FOR NUCLEAR PHYSICS (2)

A NEW WEATHER SIMULATION predicts nighttime snow flurries on arid Mars, shedding light on how the Red Planet’s scarce water supplies move through the atmosphere. In 2008, the Phoenix lander observed snowfall in Mars’ sky. But scientists believed the snow, falling under its own slight weight, would take hours to drift down, and would probably evaporate before hitting the ground. The new research, published in August in Nature Geoscience, shows nighttime air currents are turbulent, with convection strong enough to churn the snow down in a matter of minutes, resulting in more reaching the ground. While the amount of snow is minimal, that precipitation would be a crucial step in Mars’ water cycle, both present and past. Lead author and planetary scientist Aymeric Spiga at the Université Pierre et Marie Curie in Paris says that the snow in his model is more like an ice storm of tiny particles than Earth’s intricate, fluffy flakes. Standing on Mars early in the morning, “you would see it as a very thin and sparse frost,” he says. — KOREY HAYNES

While astronomers knew Mars was home to the occasional light snowfall, they recently learned the Red Planet may also host more intense precipitation.

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Positive Proton Loses Weight

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THE PROTON GOT a little lighter this year, thanks to measurements of its mass that are three times more precise than the best previous effort. This tweak to one of the building blocks of matter, good to 32 parts per trillion, should help refine measurements of other phenomena and test fundamental symmetries in nature. To reweigh the proton, scientists in Germany trapped the particle within magnetic and electric fields. Using phenomenally sensitive detectors from Japan, they compared the particle’s vibrations, which are related to its mass, with the vibrations of a carbon atom (the mass standard-bearer for atoms). Students everywhere hope they don’t have to memorize the mass calculated by the researchers and published in July in Physical Review Letters: 1.007276466583 atomic mass units. — DEVIN POWELL

Physicists set up a Penning Trap, which manipulates electric and magnetic fields, to study a single proton in isolation. They found its mass was actually a little lower than was previously estimated.

January/February 2018 DISCOVER

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OUR TRASHY LEGACY

❯ 

8.3 BILLION METRIC TONS. That’s how much plastic humanity

has produced thus far, according to a study published in July in Science Advances. Of that, nearly 80 percent has been thrown out (as opposed to recycled or burned), which means over 6 billion tons of plastic waste is strewn about our planet. A portion of it ends up in the ocean, where it can float for years or wash ashore on pristine islands. One remote South Pacific island had accumulated an estimated 38 million pieces of plastic trash as of 2015. Here’s a breakdown of how we use plastics and where they end up. — NATHANIEL SCHARPING

HOW HEAVY IS 8.3 BILLION METRIC TONS?

MILLION METRIC TONS

CUMULATIVE PLASTIC WASTE GENERATION AND DISPOSAL

296,000,000,000,000

—

New plastic waste generated*

— — —

Discarded Incinerated Recycled

25,000

20,000

15,000

20 OZ. SODA BOTTLES

10,000

1,660,000,000,000,000 CREDIT CARDS

5,000

0 YEAR

1950

1960

1970

1980

1990

2000

2010

2020

2030

2040

2050

* Plastic created from virgin, non-recycled materials

3,150,000,000,000,000 BOTTLE CAPS

GLOBAL TRENDS IN PLASTIC DISPOSAL

RATE

FUTURE PROJECTIONS 100%

— — —

6,150,000,000,000,000 2X2 LEGO BRICKS

90%

Discard Incinerate Recycle e

80% 70% 60% 50% 40% 30% 20% 10% 0%

SOURCE: “PRODUCTION, USE, AND FATE OF ALL PLASTICS EVER MADE,” SCIENCE ADVANCES, 2017

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YEAR

1980

1990

2000

2010

2020

2030

2040

2050

ALISON MACKEY/DISCOVER; ILLUSTRATIONS BY PANDA VECTOR/SHUTTERSTOCK

PAST

65 ❯ 

Earth’s Hot Pockets

TOP: MINGMING LI ET AL./NATURE COMMUNICATIONS 8, ARTICLE NUMBER: 177 (2017) CC BY 4.0. BOTTOM: MEDICAL WRITERS/SCIENCE SOURCE

A COUPLE OF DECADES AGO, seismologists noticed some strange behavior below Earth’s surface. Seismic waves that normally pass through the planet’s inner layers with ease got caught up in the rocky lower mantle, roughly halfway to Earth’s center. The waves slowed down by as much as 30 percent. Scientists surmised the ripples had hit partially molten pockets and dubbed the areas ultra-low velocity zones (ULVZs). In August, geologists reported in Nature Communications that they overlaid ULVZ locations with computer models of the heat flow through the mantle and spotted something interesting. The pockets aren’t situated in places hot enough to melt the lower mantle’s rock. Therefore, they must be made of minerals with a lower melting point, says Arizona State University geophysicist Mingming Li,

66 ❯ 

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Ultra-low velocity zones (ULVZs), shown in red, are pockets of molten rock roughly halfway to Earth’s center. Seismic waves slow down by as much as 30 percent when passing through them.

the study’s lead author. Although the regions’ precise composition remains unknown, their geological distinctiveness suggests mantle materials never fully mixed, even over billions of years. “Deciphering this mystery undoubtedly holds a key to understanding the evolution of our planet,” Li says. — JONATHON KEATS

A Better Way to Control Pain?

TODAY’S PAINKILLERS

target the brain and spinal cord. But in April, neuroscientists reported that there might be a way to block pain before it makes it to those central systems. An international team of researchers found that peripheral nerves play an unexpected role in processing pain. Experts had thought these cells merely relayed information to the spinal cord, which integrates other incoming pain signals and sends them to the brain for interpretation. During this process, both the brain and spinal cord use chemical messengers, or neurotransmitters, to turn pain up or down. Scientists believed this ability was limited to

Painkillers could one day target our peripheral nervous system (purple) instead of our central nervous system (red) thanks to one cell type’s newly discovered role in pain.

the brain and spinal cord. But the team noticed that in rodents, neurons near the spine used a neurotransmitter called gammaaminobutyric acid (GABA) to dial back pain signals before sending them on. When the researchers administered GABA to those neurons in rats, the animals hardly reacted to a painful injection into their paws. The finding, published in the Journal of Clinical Investigation, might radically change how we treat pain, assuming it holds up for humans, too, says senior author Nikita Gamper. Painkillers that act on peripheral nerves, he says, would have far fewer side effects and shouldn’t be addictive. — JESSICA MCDONALD

January/February 2018 DISCOVER

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67 ❯ 

A Towering Aztec Ritual Uncovered

ACCORDING TO AZTEC BELIEFS, gods died to

create the world, and people owed them a debt to be repaid through large-scale human sacrifices. Accounts by 16th-century Spanish colonists painted a grisly picture: miles-long lines of victims awaiting such a fate, and more than 100,000 severed heads strung along a

tzompantli, or skull rack, at Templo Mayor, the Great Temple. The colonists exaggerated the death tolls, but sacrifices and tzompantli were real. Some of the victims resurfaced in July, when archaeologists uncovered a tower made from more than 650 human skulls near the ruins of Templo Mayor in Mexico City. Skulls were likely added to the

A 16th-century illustration captures the scale of a tzompantli, a large rack on which the Aztecs displayed skulls of sacrificial victims.

tower after public display on the nearby tzompantli, indicated by rows of 10-inch holes that once held wooden posts supporting the skull rack. Of the 171 skulls studied so far, most victims were young men, likely captured enemy warriors, but some were women and children. DNA and isotopic analysis, currently underway, should determine where in Central America the victims originated.

Researchers (upper left) are analyzing more than 650 skulls found in the ruins of Templo Mayor, the great Aztec temple. The skulls formed a tower and were caked in lime (left). They were carefully removed (below).

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FROM TOP: DURAN CODEX VIA WIKIMEDIA; RAUL BARRERA (2); HECTOR-MONTANO/INAH

— BRIDGET ALEX

69

Famous Galaxy Hosts Bonus Black Hole

❯ 

CYGNUS A IS A GALAXY FAMOUS FOR harboring in

Cellular Atlas Paves Way for Precision Medicine

❯ 

THE HUMAN GENOME PROJECT, the audacious map of our genetic code that was completed 15 years ago, was inspired by another genetic map — that of a tiny worm. Scientists are hoping a new catalog of gene expression in each cell of the same worm, Caenorhabditis elegans, will herald the same kind of cellular atlas for humans. To create the catalog, scientists extracted cells from thousands of C. elegans larvae and chemically processed them in a way that assigned a unique “barcode” to each cell. The method revealed which genes were turned on or off. When the scientists categorized the cells by this so-called gene expression, they spotted 27 different types, including muscle, skin and intestine cells, the team reported in Science in August. This cellular atlas allows researchers to look for patterns. A similar human atlas, already in progress, could spot signatures linked to disease, enabling medical treatments tailored to individual patients. — KATHERINE KORNEI

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1989

2015 Something has changed in the central region of galaxy Cygnus A. The new area emitting radio waves is likely a dormant black hole waking up.

LEFT: AUGUSTO ZAMBONATO. RIGHT: PERLEY, ET AL., NRAO/AUI/NSF, NASA

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its center one of the most active black holes we know of. Astronomers have watched that galaxy for decades, so imagine their surprise when an observatory — New Mexico’s Very Large Array — spotted a new source of radio waves, reported in June in The Astrophysical Journal. The most likely explanation? A second, dormant black hole had awoken, flaming suddenly into view. The two black holes are just 1,500 light-years apart, one of the closest known pairs of supermassive black holes. They are also likely approaching each other and will eventually merge into a single entity. “If our conclusion is correct, this offers a new pathway to understand the process by which large black holes coalesce in galaxy centers,” says lead author Daniel Perley of Liverpool John Moores University in the U.K. — YVETTE CENDES

70 ❯ 

When Did Life Appear?

AS A FAINT, YOUNG SUN

shone on our freshly formed Earth around 4 billion years ago, primitive creatures, each less than half the width of a human hair, were thriving around volcanic vents. That’s the conclusion of an international team of geoscientists who announced in March in Nature they’d unearthed these creatures’ remains. The microfossils, potentially the oldest discovered, were locked inside rocks in remote northern Canada that were 3.8 billion to 4.3 billion years old — roughly when scientists think life started. But that wasn’t the only finding this year that suggested life on

TOP: MATTHEW DODD. BOTTOM: MARK GARLICK/SCIENCE SOURCE

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Earth is older than we thought. In September, Japanese geoscientists, publishing in Nature, said they’d also found traces of 3.95 billionyear-old life-forms in different northern Canadian rocks. Some critics doubt the age claims of both studies and say the samples need more rigorous testing before anything can be confirmed. But the findings fit an emerging consensus that life began around 4 billion years ago, a period when comets and asteroids bombarded Earth. Until relatively recently, scientists thought such impacts would’ve sterilized our world until roughly 3.8 billion years ago. But new evidence is suggesting those

Tiny tubes of the mineral hematite, found around hydrothermal vent deposits, might be the oldest microfossils on Earth and evidence for when life on our planet came to be.

craters helped create hydrothermal vents that set the stage for life to emerge. “This makes life appear to be a relatively easy process to kickstart on the planet,” says Matthew Dodd of University College London and lead author on the March paper. — ERIC BETZ

A glimpse of what our primitive planet might have looked like when it was forming, more than 4 billion years ago.

January/February 2018 DISCOVER

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❯ 

ANCIENT EGYPT has

long been considered the domestic cat’s cradle. But when researchers sequenced DNA from more than 200 ancient cats, they discovered that, while Nile natives formed the most broadly distributed lineage, they were not the first. Paleogeneticist Claudio Ottoni, lead author of the June study in Nature Ecology & Evolution, says, according to DNA records, the first wave of feline domestication occurred about 6,400 years ago in southwest Asia through southeast Europe, but it remained a regional affair. Egyptian cats “conquered the household” sometime after that, Ottoni says. By the eighth century B.C., they’d spread rapidly via trade routes throughout the Mediterranean and across Asia and the Indian Ocean. The study also showed x that, unlike domesticated animals seen mostly as sources of meat or labor, cats served as companions and useful

pest-control agents aboard ships, hence their global dispersal. “The success of cats in spreading across long and short geographical ranges was linked to a strong relationship between them and humans,” Ottoni says. “Evolutionarily speaking, cats are one of the most successful species, but it happened because humans really liked them.” — GEMMA TARLACH

North Sea

x x

x x

x x Black Sea x x x xx x x

x x

x Mediterranean Sea x x x x x x

x x

x Arabian Sea

Indian Ocean

x

x

x x

x

MODERN WILDCAT RANGE & ANCIENT DNA SAMPLE AREAS European wildcat (Felis silvestris silvestris) African wildcat (F. s. lybica) Asiatic wildcat (F. s. ornata)

Ancient Egyptian cats, like the one depicted above, were not the first line humans domesticated, as experts had previously thought.

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Researchers studied remains of F. s. lybica, whose modern territory is shown above in orange, and found that humans first domesticated felines in southwest Asia and southeast Europe, not Egypt.

Southern African wildcat (F. s. cafra) Chinese Mountain cat (F. s. bieti) x DNA sample site

FROM TOP: PONGTORN SUKGASE/SHUTTERSTOCK; MAP ADAPTED BY PERMISSION FROM MACMILLAN PUBLISHERS LTD: C. OTTONI ET AL./NAT. ECOL. EVOL. 1, 0139 (2017); ASHMOLEAN MUSEUM, UNIVERSITY OF OXFORD, UK/BRIDGEMAN IMAGES

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Curiosity Killed the Cat — But Ancient DNA Revealed Its Backstory

73 NORMAL BRAIN SLICE

CTE BRAIN SLICE

LEFT: VICTOR ALVAREZ, MD, VA BOSTON, BU CTE CENTER. RIGHT: MATTHIEU PALEY/NATIONAL GEOGRAPHIC CREATIVE/ALAMY STOCK PHOTO

Sections of a normal brain (top), compared with a brain with severe chronic traumatic encephalopathy, or CTE (above), show the extent of the brain-shrinking damage CTE can do. New research finds the disease affects football players at nearly every level, including high school.

72 ❯ 

Football’s Latest Injury Report

IT’S HARD-HITTING NEWS: Of 111 former NFL players’ brains, 110 showed signs of chronic traumatic encephalopathy, or CTE. CTE is a brain disease caused by repeated hits to the head that leads to memory loss, and mood and personality changes such as increased impulsivity, violence and depression. The study, published in July in the Journal of the American Medical Association and the largest of its kind, examined the brains of 202 people who had all played football at some point in their lives. The disease permeated all levels of the sport; 48 of 53 college players’ and three of 14 high school players’ brains showed signs of CTE. However, because the sample included a number of brains donated by family members who noticed symptoms, it isn’t representative of all former football players. Still, Ann McKee, the study’s senior author, thinks the results warrant changes, such as introducing kids to the sport when they’re older and limiting the number of games and full-contact practices. “Even though this is a biased sample, the sheer volume of the numbers indicates that the problem is more prevalent than previously considered,” McKee says. “It’s concerning.” — TEAL BURRELL

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24-Hour Watch

❯ 

EARLY BIRD OR NIGHT OWL, you can thank evolution: Staggered natural sleep patterns, or chronotypes, may have kept our species alive. Having a few members of a group awake at all times can protect everyone from predators and other threats. This idea, known as the sentinel hypothesis, was proposed in the 1960s and demonstrated in some birds and rodents. In July, in Proceedings of the Royal Society B, researchers described the first evidence for the sentinel hypothesis in humans. The team used wrist monitors to track the sleep patterns of 33 members of Tanzania’s Hadza people, whose environment and hunter-gatherer lifestyle are similar to those of early humans. The findings: During more than 220 hours of data collection, there were only 18 one-minute increments when all participants were soundly asleep. Age had the strongest influence on chronotype; participants aged 50 and older were more likely to be early birds than those 30 and younger. “We’re incredibly different from our ancestors in so many ways,” says Duke University evolutionary anthropologist Charles Nunn, a researcher involved in the study. “Yet understanding that past can help us understand our behavior and physiology today.” — GEMMA TARLACH

The Hadza hunter-gatherer tribe in Tanzania took part in a study that supported the sentinel hypothesis, the idea that having someone awake at all times protects against threats.

January/February 2018 DISCOVER

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74 Valhalla or Bust ❯ 

ARCHAEOLOGISTS STRUCK GOLD — or at least iron, silver and bronze — in Dysnes, a town along a northern Iceland fjord, in June. Six Viking Age graves, two of them boat burials, held both human and animal remains, including horses and a dog. The dig also uncovered roughly

❯ 

Ticking Time Crystals

IN 2012, NOBEL LAUREATE

Frank Wilczek envisioned a new kind of matter based on a crystal. The ordered framework of a crystal is basically a pattern of atoms that repeats in space. In Wilczek’s time crystals, motion also repeats. Imagine a material with millions of electrons (or tiny bar

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DISCOVERMAGAZINE.COM

— GEMMA TARLACH

magnets, if it’s easier to picture) flipping back and forth in unison, like a crystalline clock. Some physicists thought it sounded ridiculous, but now two groups have created versions of the matter in their labs, publishing a pair of papers in Nature in March. At the University of Maryland, 10 ytterbium ions flip

around regularly, and at Harvard, it’s a million nitrogen atoms. While the crystals would need to last longer, their ticking could prove a solid way to store information, even possibly serving as memory for quantum computers. Meanwhile, we have a whole new kind of matter to explore. — SHANNON PALUS

AUÐUNN NÍELSSON

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1,000-year-old spears, swords, whetstones and jewelry. Among sites unearthed nearby over the past century, “Dysnes takes the prize — for the boats, the weapons, and the size and scale and complexity,” says archaeologist and dig team member Howell Roberts.

76 ❯ 

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Lost Flight’s Legacy: Stunning Seafloor Maps

IN 2014, MALAYSIA AIRLINES FLIGHT 370 disappeared en route

from Kuala Lumpur to Beijing. A massive, 34-month-long international search effort found no signs of the plane. But something positive still came of it: Survey ships involved in the hunt collected an enormous amount of data about a 100,000-square-mile strip of the southeastern Indian Ocean, and researchers turned that information into highresolution seafloor imagery. “Over 85 percent of our world’s oceans have yet to be explored in such detail,” says Geoscience Australia’s Kim Picard, whose team processed the data. And the MH370 search region is particularly remote and unexplored. Picard says the seafloor maps, released in July, may enable new discoveries about plate tectonics, ocean currents and unique sea life habitats. — ERIC BETZ

IND

ONES

IA

a

are

AUSTRALIA

ls

ea

rch

Specific search areas

Perth

ra

MAP: ALISON MACKEY/DISCOVER. SEAFLOOR RENDERINGS: GEOSCIENCE AUSTRALIA

Ind ian Ocean

Ge

ne

1,000 miles The massive search area for the missing MH370 flight covered a particularly remote region about 1,000 miles off the western Australian coast (above). Tragically, the international hunt found no sign of the lost aircraft. But data collected during the search effort allowed researchers to map the ocean floor at a much higher resolution than ever before, revealing numerous features for the first time (right).

Depth (in meters) High: -3,500 Low: -4,800 Outline of new image

January/February 2018 DISCOVER

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❯ 

An Astronaut’s Loving Tribute Finally Acknowledged

IN 1968, AS NAVIGATOR ON APOLLO 8 — the first mission around the moon — Jim Lovell carefully documented his path above the Sea of Tranquility, where NASA would land Apollo 11. He spotted a small, pyramid-shaped mountain near the landing site and named it Mount Marilyn, after his wife. Lovell knew he wouldn’t forget the landmark. Mount Marilyn proved vital on Apollo 11, when Neil Armstrong relied on it for navigation during a harrowing landing. And yet the mountain is among dozens of features named by astronauts but not on official moon maps.

For nearly half a century, astronomy’s official nomenclature group, the International Astronomical Union (IAU), wouldn’t make any of the names official; scientists used an asterisk if they cited them. But in July, after multiple applications by Lovell and Arizona State University astronomer Mark Robinson, the IAU reversed course for three of the landmarks, including Mount Marilyn, without explanation. Lovell, who kept the campaign Sea of a secret from Marilyn, enjoyed Tranquility revealing it at last. “She was quite amazed,” Lovell says. “In Apollo 11 exploration there’s romanticism, landing site too.” — ERIC BETZ

The love of astronaut Jim Lovell for his wife, Marilyn, shown together above in 1965 and 1995, was immortalized in 2017. During the Apollo 8 mission, Lowell (bottom, at far right) named a pyramid-shaped mountain (left) after Marilyn. The name was officially recognized in July.

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CLOCKWISE FROM BOTTOM LEFT: NASA (3); RALPH MORSE/THE LIFE PICTURE COLLECTION/GETTY IMAGES; RON GALELLA, LTD./WIREIMAGE/GETTY IMAGES; NASA

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TO THE MOON AND BACK:

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78 ❯ 

Super Solar Speeds

OUR SUN MAY literally be young at heart. New evidence suggests its core spins nearly four times faster than its outer layers. This finding sheds light on the initial conditions that formed the sun, which spun much faster overall when it was a young star. The window into the sun’s core comes from measuring elusive “gravity waves” that wash back and forth through the solar interior like a sloshing bathtub. (These are unrelated to cosmic gravitational waves; for more on those, see page 13.) But the sun

is a noisy place, and global pressure waves — more prominent and numerous — mask the gravity waves. Astronomer Eric Fossat and colleagues used some 16 years of data from the orbiting Solar and Heliospheric Observatory to study these clamoring pressure waves, reporting their findings in August in Astronomy & Astrophysics. By measuring tiny changes in how long the pressure waves take to race through the sun, scientists could reconstruct the sloshing motion of the gravity waves, and through them, scour the solar depths. — KOREY HAYNES

Pressure wave path

Gravity wave path

Quickly spinning core Quiet inner envelope

By studying the sloshing of the sun’s interior, astronomers learned its core spins much faster than its outer layers.

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ROEN KELLY/DISCOVER

Turbulent outer layers

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Going Deep

CLOCKWISE FROM BOTTOM LEFT: JAY SMITH; JOHN WEINSTEIN/THE FIELD MUSEUM; DAS, AJ ET AL./DOI.ORG/10.1371/JOURNAL.PONE.0179264, JULY 5, 2017 CC BY 4.0

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DEEP BRAIN STIMULATION is a valuable therapeutic tool, allowing experts to target specific brain cells to help treat disorders like Parkinson’s disease and obsessive-compulsive disorder. The catch? Activating specific buried neurons requires sticking electrodes directly into the brain — a technique that involves risky surgery. In June, an international team of researchers reported it had developed a noninvasive way to stimulate neurons deep in the brain using electrodes placed on the scalp. Their method relies on what’s called temporal interference. Essentially, the electrodes are set at two different frequencies that are normally too high to activate neurons. But in the spots where the currents cross paths, that interaction generates a lower frequency to which neurons respond. Since these slivers of low-frequency currents depend on the electrodes’ placement, researchers can easily arrange them on the scalp to get at those hard-to-reach neurons while leaving other neurons untouched. The work, published in Cell, has only been tested on mice, but if it proves viable in humans, it could open the door to therapy for people struggling to cope with neurological disorders. — LACY SCHLEY Electrodes at frequency #1

Electrodes at frequency #2

Neurons respond where frequencies cross paths

At Chicago’s Field Museum, researchers were able to scan the entire 5-foot-long skull of famous T. rex specimen Sue in just a couple of minutes using a new and affordable imaging technique (above). The approach pairs free software with a video game camera.

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Scan Is Fast and Budget-Friendly

SOMETIMES, TACKLING a large project on a small budget leads to a huge innovation. Forensic dentists wanted close-up scans of the jaw of Sue, the famed T. rex that resides at Chicago’s Field Museum. But their equipment wasn’t big enough to scan Sue’s 5-footlong skull, so the dino dentists turned to the group Camera Culture, part of MIT’s Media Lab. Their fix, announced in July: a video game camera, about the size of a can of tennis balls, that creates a 3-D map called a point cloud, plus some free software to analyze it. The cost: $150. An image from the new technique, which uses a Microsoft Kinect/Xbox One camera and MeshLab software, isn’t the best quality: Its resolution stops at 500 micrometers. (That’s just a bit bigger than the average grain of table salt.) High-end scanners, which cost $30,000, can go as low as 50 micrometers. But Camera Culture’s approach is cheap and fast — scanning Sue’s entire skull took just two minutes. Museums can now create virtual models for outreach and education without busting their budget, and possible research applications abound. — STEVEN POTTER

January/February 2018 DISCOVER

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81

Roman Neighborhood, Frozen in Time

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neighborhood in the Roman city of Vienne, 20 miles south of Lyon, France. The fire baked the buildings’ bricks and spread so quickly that inhabitants abandoned their belongings. Several other fires struck the area over the following centuries. Two millennia later, the same spot was selected for a housing development. As mandated by the French government, the land underwent archaeological inspection in April by a private company, Archeodunum, which found structures several meters below grade. The intensity of the first conflagration had preserved many aspects of the neighborhood, since fired brick doesn't crumble and heat treatment protects iron from corrosion. Archaeologists found ancient streets, mosaics, shops and multistory houses. Personal belongings like wine jugs and a wooden chest containing a Roman soldier’s armor were also unearthed. “This is an exceptional chance to analyze the houses of rich and poor alike, and study the architecture of multistory buildings,” says Archeodunum archaeologist Benjamin Clément.  JONATHON KEATS

Archaeologists excavate the ruins of an ancient Roman neighborhood (top and right) unearthed during construction of a housing development in Vienne, France. Wine jugs, mosaics and personal items are among the discoveries.

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TOP: ROBERT PRATTA/REUTERS. BOTTOM: JEAN-PHILIPPE KSIAZEK/AFP/GETTY IMAGES

LATE IN THE FIRST CENTURY A.D., a fire struck a

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82 Do You Need a Brain to Sleep? ❯ 

FALLING ASLEEP: So easy,

you don’t even need a brain. Jellyfish, brainless creatures with clusters of neurons throughout their bodies, display the same behavioral sleep traits as we do. Caltech researchers put the jellyfish Cassiopea through a series of tests to see if they fulfilled three requirements for a sleeplike state: lowered activity levels, slower reaction times and impaired performance after sleep deprivation. They achieved all three, according to an October paper in Current Biology. The findings indicate the behavior isn’t the sole province of brains, suggesting sleep is important enough to have survived the hundreds of millions of years since we diverged from jellyfish. In fact, sleep may be an intrinsic property of neurons themselves.

TOP: CALTECH. BOTTOM: REID ET AL., 2017, CURRENT BIOLOGY 27, 1825–1828, CC BY 4.0

 NATHANIEL SCHARPING

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Fetuses Track Facelike Shapes

NEWBORNS TEND to favor facelike patterns, such as top-heavy triangles, and researchers have now shown that third-trimester fetuses have similar preferences. Lighting conditions inside the womb have only recently been explored, so despite extensive research on fetal reaction to other sensory stimuli, visual response had remained unseen until now. In a study published in June in Current Biology, developmental

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1. An illustration depicts lights outside of the womb. 2. How those lights likely appear to a third-trimester fetus.

psychologist Vincent Reid of Lancaster University and his team carefully designed an LED array

that penetrates maternal tissue, showing the fetus an image of a drifting triangle made of three red dots. When observed with a 4-D ultrasound — in which a 3-D image is in motion — not only were 39 fetuses able to see and track the image, but they also preferred to watch the triangle when it was topheavy, in the facelike orientation. Researchers now aim to replicate in fetuses newborn studies that have had visual aspects.  SYLVIA MORROW

January/February 2018 DISCOVER

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Breathless Wonders

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A New Look at Mega-Eruptions

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SOMEHOW, NAKED MOLE RATS got even weirder in 2017.

It turns out the coldblooded, cancer-resistant, pain-immune and conspicuously long-lived rodents also can survive for extended periods of time without oxygen. In tests at the University of Illinois at Chicago, biologists (carefully) deprived naked mole rats of oxygen for 18 minutes; in a separate test, the researchers kept them for more than five hours at dangerously low oxygen levels. Both times, the naked mole rats were unharmed. Most animals need oxygen to survive because it helps convert blood sugar, or glucose, into energy — no oxygen, no life. In the study published in April in Science, researchers found that naked mole rats use glucose this way, too, but it turns out their bodies can switch things up and efficiently metabolize fructose. It’s a different kind of sugar that doesn’t require oxygen to provide life-sustaining energy. These insights into oxygenless survival could one day help stroke and heart attack patients, for whom every minute without oxygen is critical.  NATHANIEL SCHARPING

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a large igneous province (LIP) — formed when a massive volcanic eruption spread lava over hundreds of thousands of square miles. The event also released toxic gases and altered Earth’s temperature, helping to kill off the dinosaurs some 66 million years ago. But the Deccan Traps are not unique. Remnants of similar LIPs, spawned during world-altering eruptions, exist from Siberia to Australia. In March, researchers released a new map of them, including previously unknown sites. To create the map, Carleton University geologist Richard Ernst documented telltale signs of LIPs: large fractures in Earth’s crust. He then dated the volcanic events using rock samples from colleagues. “My lesson from this is that the Earth can go through dramatic changes,” he says. “The planet doesn’t particularly care about the biology on it.”  ERIC BETZ 10

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Largest eruptions, showing extent of lava flow 1. Widgiemooltha 2.42 billion years 2. Ungava 2.22 billion years 3. Bushveld 2.05 billion years 4. Timpton 1.75 billion years 5. Essakane 1.52 billion years 6. Dashigou 920 million years 7. Gairdner 820 million years 8. Franklin 725 million years

9. Kola-Dneiper 370 million years 10. Siberian Traps 252 million years 11. Central Atlantic Magmatic Province 200 million years 12. Ontong Java 120 million years 13. Deccan Traps 66 million years 14. Afro-Arabian 30 million years 15. Columbia River 17 million years

FROM TOP: ARCTIC IMAGES/ALAMY STOCK PHOTO; THOMAS PARK/UIC; JAY SMITH, ADAPTED BY PERMISSION FROM MACMILLAN PUBLISHERS LTD: NATURE NEWS 543, 7645, MARCH 16, 2017

INDIA’S DECCAN TRAPS — geologically defined as

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86 Zika Kills Brain Cancer Cells ❯ 

ZIKA RECENTLY PROMPTED A GLOBAL HEALTH PANIC, but the virus could have a

silver lining — as an effective combatant against brain cancer in humans. Mostly spread by infected mosquitoes, the Zika virus caused near hysteria in 2015 after cases of microcephaly — which impairs brain function — were reported in infants. The condition is a result of Zika’s ability to target developing brain cells in fetuses. Because it homes in on young cells, the virus may be effective against glioblastoma, a deadly form of brain cancer in adults. Zika seems to attack the still-developing cells that cause glioblastoma, while leaving mature brain cells unharmed. Researchers reported in September in the Journal of Experimental Medicine that Zika extended the lives of mice with brain tumors and killed tumor cells in human brain tissue in a lab.  NATHANIEL SCHARPING

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Sweet Science: A Cross-Cultural Marshmallow Test

THE UNIVERSAL STRUGGLE: choosing

TOP: MARIO TAMA/GETTY IMAGES. BOTTOM: FLOORTJE/ISTOCK

Twins Heloisa and Heloa Barbosa of Brazil were born with microcephaly after their mother contracted Zika during pregnancy.

between immediate gratification and long-term rewards. The “marshmallow test,” a psychology classic from the early ’70s, evaluates this skill, called self-regulation, in children. A researcher asks a child to sit alone in a room with a treat. The kid can eat it right away, but waiting 10 to 15 minutes for the researcher to return will grant the child a second treat. Previously, experts tested primarily Western children. But in June, German psychologists published the first marshmallow test using Western and

non-Western participants, about 200 kids total. The team found that 4-yearolds from Cameroonian farming families in West Africa bested their German middle-class counterparts. Only 28 percent of the German children earned an extra treat, whereas 70 percent of the Cameroonian children scored a second one; 10 percent even fell asleep waiting. These children differ in many ways, so the dramatic results, reported in Child Development, likely stem from a blend of influences. Next, the researchers say they want to investigate strategies the children used to help them wait.  SYLVIA MORROW

January/February 2018 DISCOVER

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88 I Saw the Sign ❯ 

dexterity. Even the letters of the alphabet, gesticulated with one hand, require precise coordination of all five fingers. Already looking for ways to develop low-cost electronic gloves to interact with computers, University of California, San Diego, nanoengineer Darren Lipomi saw ASL letters as the perfect proof of concept for a smart glove. He and colleagues described the completed project in a paper in July in PLOS ONE. Lipomi’s glove — made entirely from offthe-shelf components at a cost of under $100 — calculates joint position based on electrical fluctuations in stretch-sensitive polymers. With an accelerometer reading hand movement and a microprocessor, the glove can translate ASL letters into characters on a computer screen. For Lipomi, understanding sign language is only the first step for a glove that will soon also include tactile feedback — simulated touching. “We want the user to be able to interact with virtual objects,” he explains, “to feel a cold Coke can or the biological milieu inside a virtual patient during surgical training.”  JONATHON KEATS

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Pulling Water From Thin Air

A NEW MATERIAL can suck drinking water out of thin air, no power required. The mesh, called a metal-organic framework, contains tiny spaces perfect for grabbing and holding onto water molecules. Just a couple of pounds of the stuff can draw nearly a gallon of water from the air each day — even in conditions drier than most deserts. Better yet, the sun’s heat is all that’s needed to retrieve the water for

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Fabric

Researchers have built a water harvester that can pull quarts of the liquid from the air using only sunlight.

drinking. This makes it an attractive option for developing countries with little infrastructure. Researchers have proposed similar water collectors before, but most need electricity or high humidity to function. By further fine-tuning the tiny spaces, the project’s engineers hope one day to harvest even more water. The work, led by researchers at MIT and the University of California, Berkeley, appeared in Science in April.  NATHANIEL SCHARPING

TOP: TIMOTHY O'CONNOR/UC SAN DIEGO JACOBS SCHOOL OF ENGINEERING (5). BOTTOM: MIT/EVELYN WANG LABORATORY

COMMUNICATING IN AMERICAN SIGN LANGUAGE takes considerable

TOP: JIAN HAN/NORTHWEST UNIVERSITY, CHINA. BOTTOM: S CONWAY MORRIS AND JIAN HAN

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Our Oldest Ancestor

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VIEWED THROUGH AN ELECTRON MICROSCOPE,

the newly discovered Saccorhytus coronarius is the oldest and most primitive deuterostome, a major branch of the animal kingdom that includes all vertebrates. At about 540 million years old, the millimeter-long specimen from China (top), described in January in Nature, pushes back the deuterostome record by tens of millions of years. Co-author and Cambridge University paleobiologist Simon Conway Morris believes an unusual chemical environment in its seabed home preserved the saclike animal in “jaw-dropping” detail. Structures around its large mouth may look like eyes and nostrils, but the researchers believe these “body cones” (better seen in the illustration) may have been early precursors to gills, flushing out water that Saccorhytus swallowed.  GEMMA TARLACH

January/February 2018 DISCOVER

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AS A JAZZ MUSICIAN and

neurologist at Swedish Medical Center in Seattle, Thomas Deuel has always been sensitive to the plight of performers paralyzed by brain and spinal injuries. He also has a lot of experience with electroencephalography (EEG), a noninvasive way of measuring brain activity, which can be harnessed to control wheelchairs. Several years ago, he started to wonder: Could the technology apply to musical instruments, too? Thus was born his new instrument, the encephalophone, described in April in Frontiers in

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Human Neuroscience. It’s the first device to translate electrical brain activity directly to a musical scale, allowing performance without physical movement. Patients control the encephalophone by imagining their right hand grasping and releasing; a sensor cap detects the changing brain patterns, which alter the frequency of a continuous tone on a synthesizer speaker. The sensation is “very bizarre” at first, but competence improves with practice, Deuel says. He’s already planning for his patients to perform live alongside ensemble musicians at

After studying musicians’ brain activity (above), Thomas Deuel (top) created a new instrument played entirely with the mind: the encephalophone.

the University of Washington. The encephalophone may have its greatest impact on physical therapy, potentially benefiting even non-performers. “The hope is that there will be accelerated recovery of the motor cortex,” Deuel says. The stimulation of playing may help stroke patients regain motor control.  JONATHON KEATS

TOP: ALIBI PICTURES. BOTTOM: ALAN BERNER/SEATTLE TIMES

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Music to My Brain

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The Moon’s Magnetic Personality

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Watery Weirdness

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“WATER IS STRANGE,” says Anders

❯  FROM LEFT: NICK ROMANENKO/RUTGERS UNIVERSITY; NASA; MATTIAS KARLÉN

NEW TESTS ON A MOON ROCK brought back by

Apollo 15 reveal surprising evidence for a magnetic field baked into the rock between 1 billion and 2.5 billion years ago. Scientists knew the moon hosted Sonia Tikoo (top) studied a powerful magnetic field until pieces of a moon rock about 3.6 billion years ago, when it obtained during the Apollo 15 mission (above) seemed to abruptly shut off. But the to learn how long the new finding, published in August in moon’s magnetic field Science Advances, extends the moon’s really lasted. magnetic life by more than a billion years, though at a shadow of its former self. The work of Rutgers University researcher Sonia Tikoo and her team was twofold: They argon-dated the rock, and separately used a magnetometer to measure the magnetic field recorded within the rock at the time it formed. Researchers speculate that one activity — perhaps Earth’s tidal tug — might have powered the moon’s young and strong magnetic field, while a different mechanism — such as the moon’s slow cooling — could have taken over and caused the moon’s dim but persistent field later on.  KOREY HAYNES

Nilsson, a physicist at Stockholm University in Sweden. It expands when it cools, for example, and it has a strangely high boiling point. In a June paper in the Proceedings of the National Academy of Sciences, Nilsson and his team described a new oddity they discovered: Water can exist in at least two distinct liquid states, each with different physical properties. It takes some coaxing to witness. Nilsson has to bring water well below its freezing point and then fiddle with the pressure, eventually resulting in a liquid that gets less dense as heat is added — proof that liquid water can take on a different physical form. Nilsson even thinks this newly discovered form of water may exist naturally in tiny, shifting pockets within ordinary room-temperature water. Now he’s gathering more evidence. Even humble water, essential for life and thoroughly studied, still has secrets to tell.  SHANNON PALUS

January/February 2018 DISCOVER

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Sniffing Out the Truth

Does This Dust Make Me Look Fat?

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DUST BUNNIES may be more than a nuisance that irritates your allergies and adds to your chore list — they may also be making you chubby. House dust is full of pollutants, including industrial chemicals such as bisphenol A (BPA), that can leach from containers of household products. Researchers tested 40 substances commonly found in the home that they “suspected have some sort of impact on metabolic health,” says Duke University’s Christopher Kassotis, a co-author of the study, published in July in Environmental Science & Technology. Although the research was limited to mouse cells in a petri dish, Kassotis says the team found that two-thirds of the chemicals tested drove fat cells to develop and proliferate. However, researchers need more testing before we know the effect on humans — and if we can trade in our gym memberships for a dust mop.  STEVEN POTTER

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McGann, an olfaction researcher, has long been puzzled by claims that people have a feeble sense of smell. In his lab, humans perform as well as rodents and dogs in some tests. Research by his colleagues suggests our species can distinguish a trillion different odors. In a May review published in Science, McGann finally sniffed out the source of the foul-smelling rumor. The main culprit is Paul Broca, a leading 19th-century anatomist, who observed that the brain’s olfactory bulb — where we detect smells — is proportionally puny compared with other mammals. “He accepted the nearuniversal belief in human exceptionalism and looked in the brain for evidence of it,” says McGann. For Broca, a weak sense of smell elevated us above brute animal instinct. His beliefs were adopted by others — even Sigmund Freud. What Broca missed, McGann points out, is that relative bulb size doesn’t matter. Bigger animals have bigger noses, but that doesn’t mean they also need bigger olfactory systems. When it comes to smell, we’re animals. And knowing that could help scientists better understand human behavior, emotion and even memory.  JONATHON KEATS

LEFT: AUGUSTO ZAMBONATO. RIGHT: SCHANKZ/SHUTTERSTOCK

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RUTGERS UNIVERSITY NEUROSCIENTIST John

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Human-Caused Minerals Make Case for New Epoch

OF THE WORLD’S 5,000PLUS MINERALS, 208 are

unique: They’re the result of human activities. Without us, geologists discovered, they wouldn’t exist. To be a mineral, a compound must be inorganic, chemically distinct and naturally occurring. So these stretch the definition a bit, though technically they could

have occurred naturally — we just happened to tip the scales. Most minerals on the newly compiled list come from mine tunnels and slag heaps, where byproducts of the industry mingle in unconventional ways. Others, however, were found in a shipwreck and even a museum cabinet, again representing situations that betray the hand of humanity.

The list, published in March in American Mineralogist, adds more evidence for the Anthropocene, the “age of humans.” New minerals are appearing much faster than ever before, and the authors say it’s a sign of how much we’ve rearranged and recombined Earth’s surface. Even the rocks are different now.  NATHANIEL SCHARPING

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1. Simonkolleite, found in an Arizona copper mine. 2. Nealite, recovered from an ancient Greek seaside slag site. 3. Chalconatronite, formed at a quarry in Quebec. 4. Abhurite, discovered at an English shipwreck. 5. Metamunirite, from a mine in Colorado.

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RRUFF (5)

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January/February 2018 DISCOVER

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97 ❯ 

Tubular Technology

WITH A PUFF OF AIR, this

to those water snake toys from the ’90s. Another version of the bot has a chamber on either side; inflating just one enables it to turn. The tube-bot’s design enhances its versatility, as its outer layer remains stationary rather than needing to slide over surfaces. In early tests, the robot could extend from a compressed length of just 11 inches to over 200 feet and could carry objects inside

This robot carries cameras (above) and winds around corners (below), just two of its helpful skills for scenarios like search-and-rescue situations.

it, such as a length of wire to serve as an antenna or water to put out a fire. Researchers say it could search through rubble, serve as a catheter or even deliver devices inside the body.  NATHANIEL SCHARPING

FROM TOP: SANTIAGO MEJIA/SAN FRANCISCO CHRONICLE/POLARIS.; ERNIE MASTROIANNI/DISCOVER; L.H. BLUMENSCHEIN

vine-inspired robot can nose itself into a number of tight situations. Created by researchers at Stanford University and reported in July, the contraption is essentially a plastic tube connected to an air pump. It moves by turning itself inside out, drawing material from the inside to extend Water the tube farther — similar snake toy

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98 Birds’ Egg Shapes Eggs-plained ❯ 

THE EGGS WE SCRAMBLE AND FRY

FROM TOP: DENISE APPLEWHITE/PRINCETON OFFICE OF COMMUNICATIONS (2); HERVÉ SAUQUET AND JÜRG SCHÖNENBERGER

Mary Caswell Stoddard (left) and her team studied thousands of bird eggs, finding a link between egg shape and flight ability.

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typically span a humdrum range of colors, sizes and shapes. But the avian kingdom lays eggs of vast variation. When it comes to shape, biologists have long wondered why, say, murres have pointy eggs, yet ostrich eggs are rounder. Aristotle suggested males come from rounder eggs, and others suggested elongated eggs wouldn’t roll off cliffs. In a June paper in Science, researchers finally cracked the case. Princeton’s Mary Caswell Stoddard and her team examined some 50,000 eggs from 1,400 species provided by the Museum of Vertebrate Zoology at Berkeley. They found no nesting habit links, but did see a pattern correlating with flight ability. Frequent fliers, like murres, have streamlined bodies and more elliptical eggs, while birds who like their feet on the ground — say, ostriches — have rounder ones. So overall it’s the bird that shapes the egg, forever proving which comes first.  ERIC BETZ

The First Bud

NO FOSSIL? NO PROBLEM!

Without any preserved evidence, researchers hunting for the elusive ancestral flower — the first flowering plant from which all others evolved — had to get creative. A team collected data on nearly 13,500 floral characteristics, the largest such data set ever assembled, and ran it through sophisticated statistical analysis to model what the first flower looked like more than 140 million years ago. The result, published in August in Nature Communications: a bisexual, radially symmetric bloom.  GEMMA TARLACH

January/February 2018 DISCOVER

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100

Century-Old Pentagon Mystery Solved

❯ 

FACT: TILES MADE OF REGULAR PENTAGONS — equal angles,

equal sides — can’t completely cover an infinite flat plane, no matter how you spin them. But squish and stretch the shapes a little, and things get interesting. In 1918, German mathematician Karl Reinhardt described five irregular pentagons that could each tile a plane. His work raised the question: How many such pentagons could there be? In July, French computer scientist Michaël Rao of the École Normale Supérieure in Lyon, France, posted a solution online to that century-old pentagon puzzler. Using a computer algorithm to digitally scour all the possible misshapen pentagons, he showed that only 15 types work, with the last discovered just two years ago. Rao’s process took two years, but without computers, it would have taken more than a decade. “There are some problems which resist a nice, short proof,” he says. Because mathematicians had already figured out all possible tilings for every other convex polygon — shapes where all vertices point outward — this discovery effectively closes the book on the subject.  STEPHEN ORNES

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STATEMENT OF OWNERSHIP, MANAGEMENT, AND CIRCULATION (ALL PERIODICALS PUBLICATIONS EXCEPT REQUESTER PUBLICATIONS) 1. Publication Title: DISCOVER 2. Publication Number: 555-190 3. Filing Date: Oct. 1, 2017 4. Issue Frequency: 10x per year 5. Number of Issues Published Annually: 10 6. Annual Subscription Price: $29.95 7. Complete Mailing Address of Known Office of Publication: 21027 Crossroads Circle, Waukesha, WI 53186 Contact Person: Liz Runyon, 262-798-6607 8. Complete Mailing Address of Headquarters or General Business Office of Publisher: 21027 Crossroads Circle, Waukesha, WI 53186 9. Full Names and Complete Mailing Addresses of Publisher, Editor, and Managing Editor Publisher: Dan Lance, 21027 Crossroads Circle, Waukesha, WI 53186 Editor: Becky Lang, 21027 Crossroads Circle, Waukesha, WI 53186 10. Stockholders owning or holding one percent (1%) or more of total amount of stock are: Deborah H.D. Bercot, 22012 Indian Springs Trail, Amberson, PA 17210; Gerald and Patricia Boettcher Trust, 8041 Warren Ave., Wauwatosa, WI 53213; Alexander & Sally Darragh, 145 Prospect Ave., Waterloo, IA 50703; Melanie J. Kirrene Trust, 9705 Royston Ct., Granite Bay, CA 95746; Harold Edmonson, 6021 N. Marmora Ave., Chicago, IL 60646-3903; Laura & Gregory Felzer, 3328 S. Honey Creek Dr., Milwaukee, WI 53219; Susan E. Fisher Trust, 3430 E. Sunrise Dr., Ste. 200, Tucson, AZ 85718; Bruce H. Grunden, 255 Vista Del Lago Dr., Huffman, TX 77336-4683; Linda H. Hanson Trust, P.O. Box 19, Arcadia, MI 49613; Mary Kay Herrmann, 1530 Tallgrass Circle, Waukesha, WI 53188; George F. Hirschmann Trusts, P.O. Box 19, Arcadia, MI 49613; James & Carol Ingles, 1907 Sunnyside Dr., Waukesha, WI 53186; Charles & Lois Kalmbach, 7435 N. Braeburn Ln., Glendale, WI 53209; Kalmbach Profit Sharing/401K Savings Plan & Trust, P.O. Box 1612, Waukesha, WI 53187-1612; James & Elizabeth King, 2505 E. Bradford Ave., #1305, Milwaukee, WI 53211-4263; Mahnke Family Trust, 4756 Marlborough Way, Carmichael, CA 95608; Milwaukee Art Museum, Inc., 700 N. Art Museum Dr., Milwaukee, WI 53202; James W. Mundschau, N24 W30420 Crystal Springs Dr., Pewaukee, WI 53072; Lois E. Stuart Trust, 1320 Pantops Cottage Ct., #1, Charlottesville, VA 22911-4663; David M. Thornburgh Trust, 8855 Collins Ave., Apt. 3A, Surfside, FL 33154-0436. 11. Known Bondholders, Mortgagees, and Other Security Holders Owning or Holding 1 Percent or More of Total Amount of Bonds, Mortgages, or Other Securities: N/A 12. Tax Status: Has not changed during preceding 12 months 13. Publication Title: DISCOVER 14. Issue Date for Circulation Data: September 2017 15. Extent and nature of circulation Average No. Copies Each Issue During Preceding 12 Months a. Total Number of Copies 468,188 b. Paid Circulation (By Mail and Outside the Mail) (1) Mailed Outside-County Paid Subscriptions Stated on PS Form 3541 (2) Mailed In-County Paid Subscriptions Stated on PS Form 3541 (3) Paid Distribution Outside the Mails Including Sales Through Dealers and Carriers, Street Vendors, Counter Sales, and Other Paid Distribution Outside the USPS® (4) Paid Distribution by Other Classes of Mail Through the USPS (e.g., First-Class Mail®) c. Total Paid Distribution (Sum of 15b (1), (2), (3), and (4)) d. Free or Nominal Rate Distribution (By Mail and Outside the Mail) (1) Free or Nominal Rate OutsideCounty Copies Included on PS Form 3541 (2) Free or Nominal Rate In-County Copies Included on PS Form 3541 (3) Free or Nominal Rate Copies Mailed at Other Classes Through the USPS (e.g., First-Class Mail) (4) Free or Nominal Rate Distribution Outside the Mail (Carriers or other means) e. Total Free or Nominal Rate Distribution (Sum of 15d (1), (2), (3), and (4)) f. Total Distribution (Sum of 15c and 15e) g. Copies Not Distributed h. Total (Sum of 15f and g) i. Percent Paid (15c divided by 15f times 100)

No. Copies of Single Issue Published Nearest to Filing Date 437,761

273,420

260,319

0

0

41,697

36,976

0

0

315,117

297,295

0

0

0

0

271

268

0

0

271

268

315,388 152,800 468,188

297,563 140,198 437,761

99.91%

99.91%

Average No. Copies Each Issue During Preceding 12 Months

No. Copies of Single Issue Published Nearest to Filing Date

DAN BISHOP/DISCOVER

16. Electronic Copy Circulation

a. Paid Electronic Copies b. Total Paid Print Copies (Line 15c) + Paid Electronic Copies (Line 16a) c. Total Print Distribution (Line 15f) + Paid Electronic Copies (Line 16a) d. Percent Paid (Both Print & Electronic Copies) (16b divided by 16c x 100)

19,299

14,670

334,416

311,965

334,687

312,233

99.92%

99.91%

17. Publication of Statement of Ownership: If the publication is a general publication, publication of this statement is required. Will be printed in the Jan/Feb 2018 issue of this publication. 18. Signature and Title of Editor, Publisher, Business Manager, or Owner: Nicole McGuire, Date: 9/29/17

January/February 2018 DISCOVER

93

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FOR ITS MISSION to study Jupiter’s composition, magnetic field and other characteristics, NASA’s Juno probe technically did not require a camera. But principal investigator Scott Bolton pushed to have one on board anyway as an education and public outreach tool. Plus, he just didn’t want to miss the views from Jupiter. Ever since Juno entered the gas giant’s orbit in 2016, its photos have been uploaded to an online public gallery where citizen scientists can download the raw images and process them into compelling pictures. This image, originally taken

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May 19 and produced by German mathematician Gerald Eichstädt, shows remarkable detail in Jupiter’s southern polar region (in blue at left). Planetary geologist Justin Cowart of Stony Brook University then built on Eichstädt’s picture by adjusting the color to match how Jupiter appears through a telescope eyepiece. He also enhanced other details, like the violent and enormous storms that blanket the planet.  ERNIE MASTROIANNI For more on the mission’s findings and the questions they raise, see “Juno Delivers Jupiter’s Secrets,” page 32.

NASA/SWRI/MSSS/GERALD EICHSTÄDT/JUSTIN COWART. INSET: NASA/SWRI/MSSS

In their rawest form, Juno’s images are a cipher, delivered as long, shallow strips taken through red, green and blue filters. It takes artists like Gerald Eichstädt and Justin Cowart to tease out their beauty. The Juno probe orbits Jupiter every 53.5 days and skims as close as 2,600 miles above Jupiter’s swirling clouds, screaming along at nearly 130,000 mph.

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INDEX

p.13

#2 #8 #12 #16 #26 #27 #37 #40 #41 #52 #57 #67 #70 #71 #73 #74 #81 #90 #99

Refining the origin story of our ancestors ................................ 10 Fossilized footprints could change hominin tale ....................... 19 Collagen identified in 195 million-year-old fossil........................23 Rewriting dinosaurs’ family tree ............................................ 26 Ancient human DNA extracted from dirt ................................. 34 Well-preserved dino fossil turns heads.................................... 36 Full genomes of Egyptian mummies recovered......................... 44 100 million-year-old dinosaur could be largest ever .................. 46 Skull could be common ancestor of all living apes .................... 48 Tick carries oldest blood ever found ....................................... 57 H. naledi, contemporary of archaic H. sapiens .......................... 61 Aztec skull towers show evidence of mass human sacrifices ...... 68 Microfossils push back timeline of life’s emergence .................. 71 The rise and global dispersal of domesticated cats.................... 72 Staggered sleep patterns helped keep early humans alive .......... 73 Icelandic Viking discovery best in a century ............................. 74 Ancient Roman neighborhood unearthed ................................ 80 540 million-year-old animal fossil .......................................... 85 Scientists model the first flower ............................................ 91

Earth/Environment/Energy p. 26

p. 40

#10 #18 #21 #22 #33 #46 #54 #59 #64 #65 #76 #85 #96

Two colors added to rainfall chart after Texas storm.................. 21 Slow but steady sea rise predicted ......................................... 27 Antarctic ice shelf calves massive berg ................................... 30 Scores of volcanoes discovered under Antarctic ice ................... 31 Oldest ice discovered in polar region ...................................... 40 Deadly heat in forecast for Earth’s tropics ............................... 52 Tests reveal future marine impact of oceanic warming .............. 58 Species of trees spread westward .......................................... 63 Billions of tons of plastics discarded on Earth .......................... 66 Mystery of Earth’s molten pockets revealed ............................. 67 Seafloor map created from Malaysian airline search ................. 75 Mapping Earth’s biggest volcanic eruptions............................. 82 Humans create over 200 minerals.......................................... 89

Living World #31 #44 #82 #84 #95 #98

p.45

p.48

Octopuses self-edit their RNA for survival advantage ................ 38 New species show abilities for staying out of sight ................... 50 Jellyfish do sleep................................................................. 81 Naked mole rats survive with no oxygen for extended periods .... 82 A trillion reasons to praise the human nose ............................. 88 Birds’ egg shapes suggest flight ability ................................... 91

Math/Physical Sciences #17 #20 #30 #34 #38 #56 #63 #75 #93 #100

The math behind gerrymandering .......................................... 27 Tabletop device detects neutrinos .......................................... 28 Physicists identify new particle .............................................. 37 2-D magnet made from single layer of carbon atoms ................ 41 Hottest liquid is also the fastest spinning ................................ 45 Math proof offers way to map an object’s interior .................... 60 A building block of matter loses a little weight ........................ 65 Time crystals: A new kind of matter to explore ......................... 74 Water can exist in two liquid states at once............................. 87 Closing the book on irregular pentagons ................................ 92

Medicine/Genetics #5 Gene editing tool modifies human embryos in U.S. ................... 16 #6 FDA approves immunotherapy for resistant cancer ................... 17

p.84

98

#13 #14 #19 #25 #28 #35 #36 #39 #43 #50 #51 #68 #72 #83 #86 #94

Artificial placentas grow healthy lamb fetuses ......................... 24 Era of superbugs arrives ....................................................... 24 CRISPR knocks out retroviral DNA in pigs................................ 28 Storing data in living bacteria ............................................... 33 Global sperm counts drop precipitously .................................. 36 A step closer to artificial blood .............................................. 41 Mice with printed ovaries birth healthy young ......................... 42 Probiotics treatment fights infection in newborns ..................... 45 Genetic factors for insomnia identified ................................... 49 Multiple sclerosis drug takes novel approach ........................... 55 Finding genes that cancer exploits ......................................... 56 Cellular map of humans in the making ................................... 70 Postmortems show brain disease in most NFL players ............... 73 Human fetuses are drawn to face shapes ................................ 81 Zika fights brain tumors ....................................................... 83 Is house dust making you fat?............................................... 88

Neuroscience/Behavior #24 #42 #48 #53 #61 #66 #79 #87

Stem cells in brain region orchestrate aging ............................ 33 Genetic risk for PTSD ........................................................... 49 Neurons respond to specific features to recognize faces ............ 54 Long-term memories can form in one day ............................... 57 Model predicts which infants will develop autism .................... 64 Blocking pain before it hits a nerve ........................................ 67 Noninvasive brain electrode stimulation ................................. 79 Culture matters in famous marshmallow test........................... 83

Policy #4 #29 #45 #60

Science takes hit under Trump administration .......................... 14 Treating PTSD with help from psychedelic drug ........................ 37 Goldwater Rule revisited during Trump’s presidency.................. 52 A flu drug falls out of favor................................................... 63

Space/Cosmology #3 #7 #9 #11 #15 #23 #32 #47 #49 #58 #62 #69 #78 #92

Gravitational wave is relic of ancient star collision.................... 13 Earth-sized worlds orbit star in nearby galaxy .......................... 18 Space probe’s 13-year study of Saturn ends............................. 20 A Saturn moon could theoretically support life......................... 22 Radio bursts coming from distant galaxy ................................ 25 NASA probe reveals Jupiter’s mysteries .................................. 32 Space sperm produces healthy mice ....................................... 39 Asteroid travels wrong way in Jupiter’s orbit ........................... 53 Astronomers weigh distant star............................................. 55 Space dust falls like rain on Earth .......................................... 62 The cold truth about Martian precipitation .............................. 65 Galactic surprise: Cygnus A home to second black hole ............. 70 Probing the sun’s spinning inner core ..................................... 78 Moon’s magnetic life gets an extension .................................. 87

Tech/Entertainment/Culture #1 #55 #77 #80 #88 #89 #91 #97

Solar eclipse captures America’s attention ................................. 7 Snail slime inspires synthetic adhesive.................................... 60 Moon’s Mount Marilyn becomes official ................................. 76 Creating 3-D models of fossils on the cheap ............................ 79 Smart glove translates sign language to screen........................ 84 Material harvests water using sunlight ................................... 84 Making music with only the brain .......................................... 86 Vine-inspired robot snakes into tight places ............................ 90

DISCOVER (ISSN 0274-7529, USPS# 555-190) is published monthly, except for combined issues in January/February and July/August. Vol. 39, no. 1. 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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FROM BOTTOM: TIMOTHY O’CONNOR/UCSD JACOBS SCHOOL OF ENGINEERING; CHRISTOPHER KIARIE AND ISAIAH NENGO; BROOKHAVEN NATIONAL LABORATORY; YUZHEN YAN/PRINCETON UNIVERSITY DEPARTMENT OF GEOSCIENCES; GABRIEL LÍO; NSF/LIGO/A. SIMONNET/SONOMA STATE UNIVERSITY

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