Half a century ago, if you asked any teenage science fan to name the best popular science writers, you’d get two names: Isaac Asimov and George Gamow.

Asimov was prominent not only for his nonfiction science books, but also for his science fiction. Gamow was known not only for writing popular science, but was also a prominent scientist who had made important contributions both to physics and biology.

Fifty years ago this month, Gamow’s career ended when he died at the age of 64. His books and scientific papers survive him, leaving plenty of science and science writing worth celebrating. Nuclear physics, astrophysics, modern cosmology and molecular biology all benefited from Gamow’s fertile intellect.
Like Asimov, Gamow was born in Russia (Odessa). But while Asimov came to the United States as a child, Gamow grew up in Russia, went to college first in Odessa (studying math) and then to the university in Petrograd (soon to become Leningrad), where he became a physicist. At Leningrad he attended lectures by the mathematician Alexander Friedmann. Friedmann was the first to fully realize that Einstein’s new general theory of relativity implied a dynamic universe — one that would expand or contract — rather than the static never-changing cosmos that most experts (including Einstein) believed in at the time.

Gamow planned to pursue a career in relativity under Friedmann’s direction. But Friedmann died young, in 1925. So Gamow fell in with a group of students more interested in quantum physics than relativity. “We spent all our time following the new [quantum] publications and trying to understand them,” Gamow wrote in his autobiography.

While a visitor at one of Europe’s top centers for quantum theory — the University of Göttingen in Germany — he solved a mystery about radioactive decay by identifying one of the quantum world’s most important phenomena: tunneling. In one form of radioactive decay, an atomic nucleus emits alpha particles that are moving too slowly to have overcome an energy “barrier” supposedly preventing their escape. (The analogy is a hill too steep for a slow-moving ball to reach the top without rolling back down.) Gamow showed that the wave mechanics version of quantum physics permitted the alpha particle to “tunnel” through the energy-barrier hill. Quantum tunneling turned out to be important for many other features of nature, such as how the sun shines, how many chemical reactions proceed and maybe even how the universe began.
His work on tunneling impressed Niels Bohr, the leading quantum physicist in the world, earning Gamow a fellowship for study at Bohr’s Institute for Theoretical Physics in Copenhagen. During time there and at Cambridge University, Gamow became one of the world’s leading experts on nuclear physics theory. He also became well-known for his humor and irreverence, including a “relentless mockery of science’s solemnity,” as one biographical account put it.
Returning to the Soviet Union in 1929, Gamow found the political atmosphere for continuing his work unfavorable. He eventually managed to emigrate to the United States, where he obtained a position at George Washington University in Washington, D.C., in 1934. There he studied the evolution and energy production of stars, producing fruitful insights into the stellar explosions known as supernovas. Later, he turned his attention to the universe at large, developing early versions of what became the Big Bang theory (Gamow didn’t like the name) of the origin and evolution of the universe. In 1942, the historian Helge Kragh wrote, “Gamow clearly endorsed a big-bang picture and suggested that the gross material of the present world is the result of what happened some two billion years ago in a highly compressed primeval state.” Gamow’s timing was off (it was nearly 14 billion years ago), but his basic idea was right.
After World War II, Gamow found new fun with the “physics of biology.” He wondered, for instance, about the physical processes allowing cells to make proteins. Inspired by Watson and Crick’s 1953 paper on the structure of DNA — the molecule that makes genes — Gamow speculated that some sort of code could be translated from DNA to build the long chains of amino acids that constituted proteins. Nature provided merely 20 such amino acids for constructing thousands of distinct proteins.

Gamow realized that DNA’s four subcomponent “bases” could be thought of as numbers that could be translated into “words” specifying a chain of amino acids, linked in a specific order, chosen from their 20-letter “alphabet.” He saw that if you chose three DNA bases at a time, there were about 20 possible combinations, indicating that each three-base “triplet” might correspond to an amino acid. He couldn’t crack the code for which base combinations went with which amino acids, though, even with help from some U.S. Navy cryptologists. But Gamow had more or less the right idea, although he didn’t recognize at first that an intermediate molecule, RNA, had to “read” the DNA code first before transferring the information to the cell’s protein-making apparatus.

Throughout his career, Gamow desired to share his enthusiasm for the science he investigated, not only with fellow scientists but with people in general. Today, it is fairly common for prominent scientists to write popular books. But it was not that way in the 1930s, when Gamow first tried to explain relativity and quantum physics through the eyes of his fictional character, Mr. Tompkins. Mr. Tompkins lived in worlds where the speed of light was small or Planck’s constant was large, allowing Gamow to illustrate the strangeness of the new physics in an entertaining and intuitively accessible way. To learn about Heisenberg’s uncertainty principle, for instance, Mr. Tompkins visited a billiard parlor where a professor placed a ball inside a wooden triangle. The ball began to move rapidly at varying speeds within the triangle, because restricting its position to the triangular space increased the uncertainty about its velocity. (And then the ball escaped the triangle, not by jumping over its wooden wall, but by “leaking” through it. Tunneling.)

After many rejections, Mr. Tompkins in Wonderland appeared in 1940, followed by Mr. Tompkins Explores the Atom in 1944. Later Gamow produced other more straightforward accounts of the frontiers of physics, and science more generally, in such books as One Two Three … Infinity and Matter Earth and Sky.

Gamow moved to the University of Colorado in 1956, focusing on his popular books as his prominence in science diminished. His nonconformity and irreverent attitude, along with his emphasis on popularization, did not play well with many of his peers. And he was a heavy drinker, impairing his ability to engage with other physicists and possibly contributing to his death.

Still, his science was substantial. And even if it hadn’t been, his writing contributed to the scientific enterprise via another important avenue — by opening the wonders of the world of science to a great many teenagers who are scientists, or science writers, today.

A scientific takedown of a famous finding known as the 30-million-word gap may upend popular notions of how kids learn vocabulary.

Research conducted more than 20 years ago concluded that by age 4, poor children hear an average of 30 million fewer words than their well-off peers. Since then, many researchers have accepted the reported word gap as a driver of later reading and writing problems among low-income youngsters. A Providence, R.I., program inspired by the study, for example, now teaches poor parents how to talk more with their kids.
But here’s the rap on the word gap: It doesn’t exist, says a team led by psychologist Douglas Sperry of Saint Mary-of-the-Woods College in Indiana. In a redo of the original study, virtually no class differences appeared in the number of words addressed to young children by a primary caregiver, Sperry and colleagues report in a study to be published in Child Development.

What’s more, after including speech spoken directly to children by various caretakers as well as family members’ conversations that the youngsters could easily overhear, kids in some poor and working-class communities heard more words on average than middle-class youngsters, the scientists say. Within each of those communities, some children heard many more words than others did despite belonging to the same social class, Sperry’s team adds.

“It’s time to turn a skeptical eye to the word-gap claim,” Sperry says.

Researchers usually treat word learning as a product of one or both parents regularly talking to a child. But different, equally effective ways exist for children to learn vocabulary, Sperry contends. Depending on culture and community, word learning depends to varying extents on a main caretaker talking to a child, many caretakers talking to a child and youngsters overhearing family members talking, he says (SN: 2/17/18, p. 22).
The original word-gap study included 42 children in Kansas from either of four communities — poor, working class, middle class or wealthy professional. Sperry’s group analyzed data on word use collected during home observations of 42 children in five communities — poor whites in South Baltimore, poor blacks in Alabama, working-class (largely blue-collar) whites in Indiana and Chicago, and middle-class (largely white-collar) whites in Chicago.
Videotaped home observations began when children were 18 to 30 months old. Intermittent observations continued until kids reached ages 32 to 48 months. Most primary caregivers were children’s mothers.

Primary caregivers in poor, black Alabama families directed an average of 1,838 words per hour to their children, close to the corresponding figure of 2,153 words per hour for high-income, white caregivers in Kansas in the original word-gap study. The earlier study reported that primary caregivers on welfare in Kansas spoke an average of 616 words per hour to their children, about one-third the total spoken to poor, black children in the new study. Primary caregivers from working-class and middle-class families in the new study uttered an average of 1,048 to 1,491 words per hour to youngsters.

Taking multiple caregivers into account, average hourly words spoken to children in each community increased by 17 percent or more. An increase of 58 percent occurred in Alabama’s poor, black households. In addition, kids in poor families overheard an average of 3,203 words per hour. Eavesdropping figures reached no higher than about 2,500 words per hour in the other households. Greater numbers of older siblings in the poor, black families contributed to that disparity, the researchers suspect.

The new study convincingly rejects claims of a word-gap for poor children, says cultural anthropologist Jennifer Keys Adair of the University of Texas at Austin.

White, middle-class parents and many educators wrongly assume that vocabulary learning always proceeds best via one-on-one interactions of parents with children, or teachers with grade-school students, Adair says. That assumption may not apply to kids from other cultural backgrounds. Adair has found, for instance, that first-graders from Latin American immigrant families — who were allowed to devise classroom projects, collaborate with one another and ask questions without raising their hands — did especially well three years later on state English assessments.

But some child researchers say the new study falls short of showing that poor kids are generally exposed to as much language as better-off peers.

Sperry’s group, for example, did not study children in upper-class, professional households, as researchers did in the 1990s. And other studies of early word learning point to a need for programs that help low-income parents engage their children in language-boosting conversations, conclude psychologist Roberta Golinkoff of the University of Delaware in Newark and colleagues in comment that will appear in the same journal.

“Overhearing language about death and taxes — topics of interest to adults — can never be as effective for language learning as participating in conversations about what matters to children,” Golinkoff and her colleagues write in their comment.

Kids frequently eavesdrop, Sperry responds. Ongoing research shows that “young children are very interested in talk that occurs around them, particularly when parents or siblings are talking about the child.”

While that may be so, little is known about the role of overheard speech and social context in language learning. Sperry and his colleagues plan to take a closer look at the difficult-to-study issue of how eavesdropping on family members influences later reading and writing skills.

Late-night comedians skewered Vice President Mike Pence in August when he announced preliminary plans for a new branch of the U.S. military dubbed the “Space Force.” Jimmy Kimmel likened the idea to a Michael Bay action movie, while Jimmy Fallon quipped that the Space Force’s chain of command would go “E.T., Yoda, then Groot.”

But, as a new book by astrophysicist Neil deGrasse Tyson and researcher-writer Avis Lang demonstrates, the militarization of space is no joke.
In Accessory to War, Tyson and Lang chronicle how war-makers have long wielded knowledge of outer space as a weapon. This bloody history features Christopher Columbus exploiting his awareness of an upcoming lunar eclipse to threaten natives on the island of Hispaniola with divine retribution, as well as the United States using satellite intelligence to fight the Gulf War.

“As for America’s forthcoming wars,” Tyson and Lang predict, “they will be waged with even more formidable space assets.”

But just as militaries have long used space science and space-based technology to their advantage, astronomers and astrophysicists have reaped the rewards of military investment. James Cook, a captain in the British Navy, for example, established an observatory in Tahiti. Observations of Venus passing across the face of the sun in 1769 from that observatory helped astronomers pin down the distance between Earth and the sun. During the Cold War, U.S. military satellites designed to watch for nuclear detonations discovered gamma-ray bursts, some of the most spectacular explosions in the universe (SN: 1/10/15, p. 15).
Tyson and Lang’s millennia-long world history is sprawling. The book is exhaustively researched, almost to the point of information overload. It’s easy to get bogged down in parenthetical asides about minor characters or paragraph-long lists. The book is the antithesis of Tyson’s starry-eyed, bite-sized Astrophysics for People in a Hurry and may end up on the shelves of more history buffs than astro nerds.

Still, Accessory to War lives up to much of the promise of a Neil deGrasse Tyson read: Written from Tyson’s perspective, the narration is rich with wry humor and vivid descriptions of cosmic goings-on. For anyone who is, like Tyson, “smitten by the cosmos,” the book is a stark reminder that astrophysics has been both a benefactor and beneficiary of human conflict — and that the final frontier will likely be the battleground of many future skirmishes.

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Perhaps the most unsettling scene in Poached, by science journalist Rachel Love Nuwer, comes early in the book, in a fancy restaurant in Ho Chi Minh City, Vietnam. The author and two friends sit down and are handed leather-bound menus offering roasted civet, fried tortoise, stewed pangolin and other delicacies made from rare or endangered species. The trio makes an abrupt exit, but only after seeing a live cobra gutted at one table and a still-living civet brought out to feed another group of diners.
Statistics on the illegal wildlife trade can be mind-numbing. Rhinos have dwindled to just 30,000 animals globally and tigers to fewer than 4,000. Over a million pangolins — scaly anteaters found in Africa and Asia — have been killed in the last 10 years. Just last month came a report from the Humane Society of the United States and the Humane Society International that the United States imported some 40,000 giraffe parts, from about 4,000 animals, between 2006 and 2015.

But in Poached, Nuwer gives readers a firsthand view of what the illegal wildlife trade is like on the ground and what, if anything, can be done to stop it. She accompanies a poacher into the U Minh forest of Vietnam in search of water monitors, cobras and civets. (Thankfully, they don’t find any.) She has dinner with a man who keeps a rhino horn in an Oreo tin. She visits a zoo in Japan that may have helped popularize trade in the rare earless monitor lizard. And she attends numerous meetings of wildlife officials and conservationists as they attempt to fight back against the illegal trade.

Poached isn’t all gloom and doom; there are a few success stories. Nuwer, for instance, visits Zakouma National Park in Chad where managers have halted the slaughter of elephants. This hard-won accomplishment exemplifies the book’s underlying message: There are no easy solutions to stopping wildlife trafficking. The effort in Zakouma required a lot of money and training for its rangers, which is not available in most places.

What’s most needed, Nuwer argues, is changing how we think about wildlife crime. Many people view poaching as belonging to a special category of illegal activity. But it’s not; it’s just crime. Those involved are often also dealing in drugs or conflict diamonds or human trafficking. A change in mind-set could help overcome a major conservation obstacle, Nuwer notes. Rather than detectives and the courts being tasked with handling this sort of crime, the job has been left to rangers, wildlife managers and conservationists. “As some have put it,” she writes, “it is like asking botanists to stop the cocaine trade.” The world’s wildlife deserves better than that.

A strand of spaghetti snaps easily, but an exotic substance known as nuclear pasta is an entirely different story.

Predicted to exist in ultradense dead stars called neutron stars, nuclear pasta may be the strongest material in the universe. Breaking the stuff requires 10 billion times the force needed to crack steel, for example, researchers report in a study accepted in Physical Review Letters.

“This is a crazy-big figure, but the material is also very, very dense, so that helps make it stronger,” says study coauthor and physicist Charles Horowitz of Indiana University Bloomington.
Neutron stars form when a dying star explodes, leaving behind a neutron-rich remnant that is squished to extreme pressures by powerful gravitational forces, resulting in materials with bizarre properties (SN: 12/23/17, p. 7).

About a kilometer below the surface of a neutron star, atomic nuclei are squeezed together so close that they merge into clumps of nuclear matter, a dense mixture of neutrons and protons. These as-yet theoretical clumps are thought to be shaped like blobs, tubes or sheets, and are named after their noodle look-alikes, including gnocchi, spaghetti and lasagna. Even deeper in the neutron star, the nuclear matter fully takes over. The burnt-out star’s entire core is nuclear matter, like one giant atomic nucleus.

Nuclear pasta is incredibly dense, about 100 trillion times the density of water. It’s impossible to study such an extreme material in the laboratory, says physicist Constança Providência of the University of Coimbra in Portugal who was not involved with the research.
Instead, the researchers used computer simulations to stretch nuclear lasagna sheets and explore how the material responded. Immense pressures were required to deform the material, and the pressure required to snap the pasta was greater than for any other known material.

Earlier simulations had revealed that the outer crust of a neutron star was likewise vastly stronger than steel. But the inner crust, where nuclear pasta lurks, was unexplored territory. “Now, what [the researchers] see is that the inner crust is even stronger,” Providência says.

Physicists are still aiming to find real-world evidence of nuclear pasta. The new results may provide a glimmer of hope. Neutron stars tend to spin very rapidly, and, as a result, might emit ripples in spacetime called gravitational waves, which scientists could detect at facilities like the Advanced Laser Interferometer Gravitational-wave Observatory, or LIGO. But the spacetime ripples will occur only if a neutron star’s crust is lumpy — meaning that it has “mountains,” or mounds of dense material either on the surface or within the crust.

“The tricky part is, you need a big mountain,” says physicist Edward Brown of Michigan State University in East Lansing. A stiffer, stronger crust would support larger mountains, which could produce more powerful gravitational waves. But “large” is a relative term. Due to the intense gravity of neutron stars, their mountains would be a far cry from Mount Everest, rising centimeters tall, not kilometers. Previously, scientists didn’t know how large a mountain nuclear pasta could support.

“That’s where these simulations come in,” Brown says. The results suggest that nuclear pasta could support mountains tens of centimeters tall — big enough that LIGO could spot neutron stars’ gravitational waves. If LIGO caught such signals, scientists could estimate the mountains’ size, and confirm that neutron stars have superstrong materials in their crusts.

Mayflies swarming a central Pennsylvania bridge over the Susquehanna River are a good thing, and a bad thing. Before the 1972 Clean Water Act, the river was too polluted to support the primitive aquatic insects. So their comeback is a sign that the water is healthier, says forensic entomologist John Wallace of nearby Millersville University.

But those swarms have become a nighttime menace for people driving or walking across the Columbia-Wrightsville bridge — thanks to the 2014 installation of large, 1930-era lamps along the two sides of the bridge. Soon after the lights were added, adult mayflies of the species Hexaginia bilineata began invading — causing blizzard-like conditions on the 2-kilometer overpass. The swarms were so intense in 2015, the bridge was closed following three accidents, and bulldozers were brought in to remove knee-deep piles of insect carcasses.
Local officials have since tried to cope by occasionally turning off the lights, but this is problematic on a high-traffic bridge, says Wrightsville borough president Eric White. So Wallace was called in this year to make sense of the mayfly madness.

Wallace says he and undergraduate student Marisa Macchia have been collecting specimens from both sides of the bridge, and “comparing the mayfly abundance and diversity when lights are on versus when lights [are] off.” The researchers are trying to determine the swarm density per hour from the start of the emergence to the end.
As larvae, mayflies drift downstream with the water current, Wallace says. When the adults emerge from the water, they fly upriver, following the water’s moonlit path of polarized light. At the end of their adult life spans of 24-48 hours, the insects mate and the females drop to the water’s surface — dying while releasing their eggs to the silt below.
But that bridge, with those lamps, is breaking that path of polarized light, luring the mayflies up to the structure and causing the confused insects to perform their “drop, deposit and die” routine on the road.

“Any human light … car light, street light — are examples of unpolarized light,” Wallace says. But when reflected off asphalt or car paint, it resembles the river’s polarized light.

Wallace’s research will inform blueprints for renovating the historic bridge, White says. The goal is ultimately to guide the mayflies back to the river’s surface.

Hubble’s in trouble again.

The 28-year-old space telescope, in orbit around the Earth, put itself to sleep on October 5 because of an undiagnosed problem with one of its steering wheels. But once more, astronomers are optimistic about Hubble’s chances of recovery. After all, it’s just the latest nail-biting moment in the history of a telescope that has defied all life-expectancy predictions.

There is one major difference this time. Hubble was designed to be repaired by astronauts on the space shuttle. Each time the telescope broke previously, a shuttle mission fixed it. “That we can’t do anymore, because there ain’t no shuttle,” says astronomer Helmut Jenkner of the Space Telescope Science Institute in Baltimore, who is Hubble’s deputy mission head.
The most recent problem started when one of the three gyroscopes that control where the telescope points failed. That wasn’t surprising, says Hubble senior project scientist Jennifer Wiseman of NASA’s Goddard Space Flight Center in Greenbelt, Md. That particular gyroscope had been glitching for about a year. But when the team turned on a backup gyroscope, it didn’t function properly either.

Astronomers are working to figure out what went wrong and how to fix it from the ground. The mood is upbeat, Wiseman says. But even if the gyroscope doesn’t come back online, there are ways to point Hubble and continue observing with as few as one gyroscope.

“This is not a catastrophic failure, but it is a sign of mortality,” says astronomer Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Like cataracts, he says, it’s “a sign of aging, but there’s a very good remedy.”
While we wait for news of how Hubble is faring, here’s a look back at some of its previous hiccups and repair missions.

1990: The blurry mirror
On June 27, 1990, three months after the space telescope launched, astronomers discovered an aberration in Hubble’s primary mirror. Its curvature was off by two micrometers, making the images slightly blurry.

The telescope soldiered on, despite being the butt of jokes on late-night TV. It observed a supernova that exploded in 1987 (SN: 2/18/17, p. 20), measured the distance to a satellite galaxy of the Milky Way and took its first look at Jupiter before the space shuttle Endeavour arrived to fix the mirror in December 1993.
1999: The first gyroscope crisis
On November 13, 1999, Hubble was put into safe mode after the fourth of its six gyroscopes failed, leaving it without the three working gyros necessary to point precisely.
An already planned preventative maintenance shuttle mission suddenly became more urgent. NASA split the mission into two parts to get to the telescope more quickly. The first part became a rescue mission: Astronauts flew the space shuttle Discovery to Hubble that December to install all new gyroscopes and a new computer.

2004: Final shuttle mission canceled
After the space shuttle Columbia disintegrated while re-entering Earth’s atmosphere in 2003, NASA canceled the planned fifth and final Hubble reservicing mission. “That could really have been the beginning of the end,” Jenkner says.

The team has known for more than a decade that someday Hubble will have to work with fewer than three gyroscopes. To prepare, Hubble’s operations team deliberately shut down one of the telescope’s gyroscopes in 2005, to observe with only two.

“We’ve been thinking about this possibility for many years,” Wiseman says. “This time will come at some point in Hubble’s mission, either now or later.”

Shutting down the third gyroscope was expected to extend Hubble’s life by only eight months, until mid-2008. In the meantime, two of the telescope’s scientific instruments — the Space Telescope Imaging Spectrograph and the Advanced Camera for Surveys — stopped working due to power supply failures.
2009: New lease on life
Fortunately, NASA restored the final servicing mission, and the space shuttle Atlantis visited Hubble in May 2009 (SN Online: 5/11/09). That mission restored Hubble’s cameras, installed new ones and crucially, left the space telescope with six new gyroscopes, three for immediate use and three backups. The three gyroscopes still in operation (including the backup that is currently malfunctioning) are of a newer type, and are expected to live five times as long as the older ones, which last four to six years.

The team expects Hubble to continue doing science well into the 2020s and to have years of overlap with its successor, the James Webb Space Telescope, due to launch in 2021. “We are always worried,” says Jenkner, who has been working on Hubble since 1983. “At the same time, we are confident that we will be running for quite some time more.”

Call it an October surprise: Hurricane Michael strengthened unusually quickly before slamming into the Florida panhandle on October 10 and remained abnormally strong as it swept into Georgia. The storm made landfall with sustained winds of about 250 kilometers per hour, just shy of a category 5 storm, making it the strongest storm ever to hit the region, according to the National Oceanographic and Atmospheric Administration’s National Hurricane Center, or NHC.

Warm ocean waters are known to fuel hurricanes’ fury by adding heat and moisture; the drier air over land masses, by contrast, can help strip storms of strength. So hurricanes nearing the Florida panhandle, a curving landmass surrounding the northeastern Gulf of Mexico, tend to weaken as they pull in drier air from land. But waters in the Gulf that were about 1 degree to 2 degrees Celsius warmer than average for this time of year, as well as abundant moisture in the air over the eastern United States, helped to supercharge Michael. Despite some wind conditions that scientists expected to weaken the storm, it strengthened steadily until it made landfall, which the NHC noted “defies traditional logic.” The fast-moving storm weakened only slightly, to a category 3, before hurtling into Georgia.
Although it is not possible to attribute the generation of any one storm to climate change, scientists have long predicted that warming ocean waters would lead to more intense tropical cyclones in the future. More recent attribution studies have borne out that prediction, suggesting that very warm waters in the tropical Atlantic helped to fuel 2017’s powerful storm season, which spawned hurricanes Irma and Maria.

Hurricane Harvey, fueled by unusually warm waters in the Gulf of Mexico in August 2017, also underwent a rapid intensification, strengthening from a tropical storm to a category 4 hurricane within about 30 hours. And this year, scientists reported that Hurricane Florence, which slammed into the Carolinas in September, was probably warmer and wetter due to warmer than average sea surface temperatures in the Atlantic Ocean.

We may truly be led by our noses. A sense of smell and a sense of navigation are linked in our brains, scientists propose.

Neuroscientist Louisa Dahmani and colleagues asked 57 young people to navigate through a virtual town on a computer screen before being tested on how well they could get from one spot to another. The same young people’s smelling abilities were also scrutinized. After a sniff of one of 40 odor-infused felt-tip pens, participants were shown four words on a screen and asked to choose the one that matched the smell. On these two seemingly different tasks, the superior smellers and the superior navigators turned out to be one and the same, the team found.

Scientists linked both skills to certain spots in the brain: The left orbitofrontal cortex and the right hippocampus were both bigger in the better smellers and better navigators. While the orbitofrontal cortex has been tied to smelling, the hippocampus is known to be involved in both smelling and navigation. A separate group of nine people who had damaged orbitofrontal cortices had more trouble with navigation and smell identification, the researchers report October 16 in Nature Communications. Dahmani, who’s now at Harvard University, did the work while she was at McGill University in Montreal.

A sense of smell may have evolved to help people find their way around, an idea called the olfactory spatial hypothesis. More specific aspects of smell, such as how good people are at detecting faint whiffs, could also be tied to navigation, the researchers suggest.

Climate change may be flipping good Arctic neighborhoods into killing fields for baby birds.

Every year, shorebirds migrate thousands of kilometers from their southern winter refuges to reach Arctic breeding grounds. But what was once a safer region for birds that nest on the ground now has higher risks from predators than nesting in the tropics, says Vojtěch Kubelka, an evolutionary ecologist and ornithologist at Charles University in Prague. With many shorebird populations dwindling, nest success matters more every year.
A longtime fan of shorebirds, Kubelka had heard about regional tests of how predator risk changes by latitude for bird nests. He, however, wanted to go global. Shorebirds make a great group for such a large-scale comparison, he says, because there’s not a lot of variation in how nests look to predators. A feral dog in the United States and a fox in Russia are both creeping up on some variation of a slight depression in the ground.
So Kubelka and his colleagues crunched data from decades of records of predator attack rates on about 38,000 nests of various sandpipers, plovers and other shorebirds. After a massive literature search, the study zeroed in on the experiences of 237 populations of a total of 111 shorebird species at 149 places on six continents. It’s the first attempt at a global comparison by latitude of predator attack rates on shorebird nests over time, he says.

Historical data of predator attack rates worldwide averaged about 43 percent before 1999, but has since reached 57 percent, the team reports in the Nov. 9 Science. The most dramatic upward swoop came from the Arctic nest reports. There, the rate of predator attacks averaged around 40 percent in the last century, jumping to about 65 or 70 percent since 1999. Meanwhile, tropical perils in the Northern Hemisphere changed “only modestly” the researchers say, from around 50 percent to about 55 percent.
Researchers also looked at how much, and how erratically, temperatures had changed at each site. Overall, the growing dangers to nests fit with climate change trends.
Biologists have discussed the idea that nest predation generally lessens when birds move out of the tropics. One advantage of migrating toward the pole to breed was, in theory, to escape from tropical abundance of snakes, rodents and other egg-lovers.

But rapid warming in the Arctic might have discombobulated some of the old predator-prey relationships, says coauthor Tamás Székely, a conservation biologist at the University of Bath in England. For instance, Arctic foxes used to get much of their nourishment from lemmings, voles and other small rodents. Skimpy snow cover in warmer winters, however, doesn’t insulate little rodents as well as it used to. Boom-and-bust cycles of lemming populations are in many places now “mostly bust,” he says. Foxes and other predators may be shifting more to bird eggs and nestlings.

That scenario of rodent-loving predators hunting more birds sounds “highly probable,” but may be just part of what’s going on, says Dominique Fauteux, an ecologist at the Canadian Museum of Nature in Ottawa who studies small mammals. Lemming collapses haven’t been reported across the whole Canadian Arctic, he says.

Instead, some researchers have proposed that shorebird nest failures come from a boom in geese that attract more bird predators overall. Also, a 2010 study suggests that nest predation in the Canadian Arctic was still lower than in temperate areas. There may be some global pattern, but on the ground, Fauteux says, “there clearly are nuances.”