Rooting out terrorism
Anthropologists have moved to the front lines to determine what drives people to join terrorist organizations such as the Islamic State. New research shows that the most committed ISIS fighters revere Islamic law and identify closely with a small group of comrades, Bruce Bower reported in “Deadly devotion” (SN: 7/9/16, p. 18).

Some readers noted similarities between researcher Scott Atran’s work and philosopher Eric Hoffer’s 1951 book The True Believer. The book discusses the psychological causes of fanaticism that can be seen in political and religious movements throughout history. “It’s nice to have a scientific patina applied to Hoffer’s work, but his contributions to explaining the p-sychological bases for mass movements should always be credited,” wrote Michael Rethman.
Atran agrees with some of Hoffer’s ideas about the general conditions of fanatic devotion, including unity and self-sacrifice. But he is skeptical of other proposed conditions such as self-alienation and insecurity. “In any event, our research was driven more by trying to figure out, test and validate the cognitive and social conditions of devotion unto death regardless of personality factors,” he writes. “Hoffer provides historical comparison and depth to some of these ideas. But our task is to see what can be scientifically validated as right.”

Diet dilemma
Some microbes that live in the gut might cause obesity by converting fats in food into chemical signals that tell the brain to pack on the pounds, Tina Hesman Saey reported in “Microbial signals influence obesity” (SN: 7/9/16, p. 7).

“Then why do the olive oil fats in the Mediterranean diet not cause obesity? Why do the blubber fats in traditional Inuit diets not cause obesity? Lots more research to be done,” reader Laura Hamilton wrote online.

Saey agrees that more research is needed, but the answer may be more complex than microbes alone. Some research, for example, is already hinting that a diet’s effects may depend more on who is doing the eating than on what they are eating. Rodents on the same diet, but with different genetic makeups, may not be equally prone to g-aining weight, a recent study suggests (SN: 8/20/16, p. 13). The same could be true for people. “So while Inuit diets may not promote obesity for them, someone else may pack on pounds after munching on blubber. Olive oil may not be healthy for everyone either,” Saey says. “Researchers are just at the beginning of understanding how genetics, microbes and diet work together to influence health.”
Dog days of yore
Dogs may have been domesticated at least twice, in Europe and Asia, during the Stone Age. G­enetic analysis revealed that over time, East Asian dogs replaced dogs native to Europe, Tina Hesman Saey reported in “DNA tells of dual origins for dogs” (SN: 7/9/16, p. 15).

Some online readers wondered if disease played a role in shaping the ancient dog populations. “Given the ability of wolves, dogs and humans to travel long distances, it wouldn’t be surprising if the Asian proto-dogs carried in fleas, internal parasites or other diseases and killed off a good portion of the European proto-dogs,” Onyxhawke wrote. Online reader kudjomojo agreed, suggesting that East Asian dogs’ genomes could have offered disease resistance.

Disease spread often comes with migration to new lands. “It may also have been that the Asian dogs didn’t bring the diseases but were less susceptible to diseases that may have killed European dogs,” Saey says. Other factors could have played a part, too: Asian dogs may have had physical or behavioral traits that made them more appealing to humans and helped them become the top dogs in Europe. “It’s never a gene-to-gene or genome-to-genome fight, but rather what traits the underlying genetic makeup influences that decide which dogs will have their day,” she says.

Freddie Mercury, the late lead singer for the band Queen, once sang: “I’m a shooting star leaping through the sky.” Turning lyrics into reality, the rock legend now has a hunk of space rock named after him. The International Astronomical Union has renamed asteroid 1991 FM3 as (17473) Freddiemercury. Bandmate Brian May, who has a Ph.D. in astrophysics and his own eponymous asteroid, announced the change online September 4, one day before what would have been Mercury’s 70th birthday. The asteroid was discovered in 1991, the same year that Mercury died.

The asteroid named after Mercury (no relation to the planet) sits in the asteroid belt between Mars and Jupiter, and the 3.4-kilometer-wide rock loops around the sun once every 3.69 years. Mercury joins a long list of celebrity musicians to be immortalized with a small piece of the solar system, including Louie Armstrong, Frank Sinatra, David Bowie and all of the Beatles (John, Paul, George and Ringo).

Watch a video of the announcement on YouTube.

PASADENA, Calif. — Venus is already known to host a hellish landscape with stifling temperature and suffocating pressure — and, a new study now hints, possibly rivers of lava oozing out of a volcano.

Several lava flows appear to be recently or currently active on a Venusian volcano known as Idunn Mons, planetary scientist Piero D’Incecco reported October 17 at a meeting of the American Astronomical Society’s Division for Planetary Sciences. Hot spots first detected by the Venus Express spacecraft, which orbited the planet from 2006 to 2015, had already hinted that the volcano might be active. But Venus guards its secrets tightly. Orbiters have trouble peering through the thick clouds that blanket the planet, and landers don’t last long because of the extreme environment.

Venus Express couldn’t see the source of the heat, so the researchers combined its data with maps from the Magellan spacecraft, which orbited from 1990 to 1994, and computer simulations to figure out how Idunn Mons could create the hot spots. D’Incecco, of the German Aerospace Center Institute of Planetary Research in Berlin, and colleagues deduced that five lava flows — one on top of the mountain and four running down the flanks — are responsible.

Researchers have long suspected that Venus is volcanically active, but don’t have any direct evidence yet (SN Online: 6/19/15). Testing whether Idunn Mons, or anywhere else, is belching lava will have to wait for future spacecraft. Both NASA and the European Space Agency are currently considering proposals for several Venus orbiters that could visit sometime in the next decade.

True intelligence, Meghan Rosen notes in this issue’s cover story “Robot awakening” (SN: 11/12/16, p. 18), lies in the body as well as the brain. And building machines with the physical intelligence that even the clumsiest human takes for granted — the ability to sense, respond to and move through the world — has long been a stumbling block for artificial intelligence research. While more sophisticated software and ultrafast computers have led to machine “brains” that can beat a person at chess or Go, building a robot that can move the pieces, fetch an iced tea or notice if the chessboard has turned into Candy Land has been difficult.

Rosen explores several examples of how roboticists are embodying smarts in their creations, crucial steps in creating the autonomous machines most of us imagine when we hear “robot.” Of course, we are already, if unwittingly, living in a world of robots. As AI researcher Richard Vaughan of Simon Fraser University in Burnaby, Canada, pointed out to me recently, once a machine becomes part of everyday life, most people stop thinking of it as a robot. “Driverless cars are robots. Your dishwasher is a robot. Drones are extremely cheap flying robots.”
In fact, Vaughan says, in the last few decades, robots’ intelligence and skills have grown dramatically. Those advances were made possible by major developments in probabilistic state estimation — which allows robots to figure out where they are and what’s going on around them — and machine learning software.

Probabilistic state estimation has enabled better integration of information from a robot’s sensors. Using the math of Bayesian reasoning, robots can compare sensor data against a model of the world, and interpret their likelihood of being right. For example, a robot in a building can use its laser sensors to assess the space around it, compare that with its inner map of the building and determine that it’s not in Hall A but has equal chances of being in Hall B or C.

Robots could do that in the 1990s. Scientists then asked a tougher question: How do you know where you are if you have no map? In two dimensions, researchers solved that by integrating sensory information with a set of all possible maps. But only recently was the problem solved in three dimensions, and challenges still remain for robots in less-structured or harsh environments.

Machine learning advances have aided aspects of AI such as computer vision, much improved by work done on boosting search engines’ ability to identify images (so you can search “birthday party” to find images of candled cakes, for example). This research has helped to make robot senses smarter.

Progress is swift, as Rosen makes clear in her story, but many challenges remain. Roboticists still struggle with hardware, especially for humanoid robots, which remain rather clunky. Walking, climbing stairs, picking things up and getting back up after a fall are still hard. Providing independent power sources is also a big deal — batteries aren’t yet good enough. But to build the robots that can do all that people want them to do, whether that’s driving us to work, helping the elderly up from a chair or collaborating safely with human workers in factories or warehouses, will take even better senses. Intelligence is not simply processing information or even learning new information. It’s also about noticing what’s going on around you and how to best respond.

A preschool classroom is an ecosystem unlike any other. Scents of glue and snack time waft through the air. Bright, clunky art papers the walls. Fun-sized furniture makes visiting adults feel like awkward giants. In the name of science, a team of psychologists spent an entire year inside two such rooms, meticulously documenting changes in preschoolers’ personalities.

By the end of the year, the team had found that kids were sharing a lot more than runny noses with their friends. Preschoolers’ sunny dispositions may actually be contagious. Over the course of a school year, kids who hung out with happy, smiley friends took on more of these traits themselves, the observant scientists found. The results suggest that young children’s personalities rub off on their pals.

Psychologist Jennifer Watling Neal of Michigan State University in East Lansing and colleagues suspected that both inborn temperament and environment help shape kids’ outlooks. “We know that it’s probably a little bit of nature and a little bit of nurture,” Neal says.

Some evidence suggests that personality traits exhibited early in life stick around. Those cruel and entertaining marshmallow tests are a great example of this personality persistence: In a test of self-control, children who held out for an additional marshmallow (or, originally, a cookie) could still keep themselves in check 40 years later, a study found.

But of course, personalities aren’t carved in stone. They can shift, even through adulthood. “There’s more and more research coming out that personalities aren’t just ingrained,” Neal says.

In an ultimate Billy Madison move, Neal and colleagues went to preschool four days a week. Two trained teams of observers lurked in two classrooms (one class of 3-year-olds and one of 4-year-olds) and watched children during free-play time. One team monitored children’s temperaments, while the other focused on who each child was playing with.

At the year’s end, this careful scrutiny revealed that children’s positive emotions became more similar to those of their friends. Also catching was a trait called effortful control, a measure of how well a child works hard and stays on task, the researchers report February 2 in the Journal of Personality and Social Psychology.
Children’s friends didn’t affect their negative traits, such as sadness, fear or anger. But these emotions did seem to influence how social children were. Those who showed the most frequent negative traits were less likely to play with anyone. In contrast, happy kids tended to select happy playmates. “Personality shapes who you pick as a playmate, and also, your playmates shape your personality,” Neal says.

These personality shifts were noticeable to the researchers, who had boatloads of observations and statistical methods to sort through. It’s not clear whether the changes would be obvious to parents, Neal says.

When analyzed in different ways, the dataset may hold other clues to children’s personalities and social interactions — whether, for instance, the length of time in preschool matters for friendships. It’s possible that children who attend for half-day sessions might form different relationships than kids who attend preschool for the whole day.

By deeply observing preschoolers without parents lurking, the researchers caught a glimpse of something that, when you stop to think about it, is profound. They saw personalities being formed, by friends.

In August, the United States will experience its first coast-to-coast total solar eclipse in nearly a century. Over the course of an hour and a half, the moon’s narrow shadow will slice across 12 states, from Oregon to South Carolina (SN: 8/20/16, p. 14). As many as 200 million people are expected to travel to spots where they can view the spectacle, in what could become one of the most watched eclipses in history. Excitement is building, hence the flurry of new books about the science, history and cultural significance of what is arguably one of Earth’s most awesome celestial phenomena.

Total solar eclipses happen when the moon passes in front of the sun as seen from Earth, and the moon blocks the entire face of the sun. This event also blocks sunlight that would otherwise scatter off the molecules in our atmosphere, reducing a source of glare and so allowing an unfettered view of the sun’s outer atmosphere, or corona. Total solar eclipses arise from a fluke of geometry that occurs nowhere else in the solar system, astronomer Anthony Aveni explains in In the Shadow of the Moon. Only Earth has a moon that appears, from the planet’s viewpoint, to fit so neatly over the sun — a consequence of the fact that the sun is a whopping 400 times as large as the moon but also 400 times farther away. Moons orbiting other planets are either too small to fully cover the sun’s face or are so large that they fully block any view of the corona.
In fact, the fluke of geometry is also a fluke of history: Because the moon’s orbit drifts about four centimeters farther from Earth each year, there will come a time when the moon will no longer appear to cover the sun, notes planetary scientist John Dvorak in Mask of the Sun. We already get a preview of that distant day: When the moon passes in front of the sun during the most distant portions of its orbit (and thus appears its smallest), Earth is treated to a ring, or annular, eclipse.
In the Shadow of the Moon, Mask of the Sun and physicist Frank Close’s Eclipse all do a good job of explaining the science behind total solar eclipses. That includes clarifying why one is seen somewhere on Earth once every 18 months or so, on average, instead of every time the moon crosses paths with the sun during the new moon. In short, it’s because the moon’s orbit is slightly tilted compared with Earth’s orbit around the sun, making the moon pass either above or below the sun during most new moons.

Many solar eclipses are preceded by a lunar eclipse about two weeks earlier — a coincidence that may have helped ancient astrologers “predict” an eclipse, Close writes. Additional observations, Dvorak notes, may have helped these nascent astronomers notice the long-term pattern in solar eclipses with similar paths, which tend to recur roughly every 18 years. While ancient Babylonians could predict the onset of a solar eclipse within a few hours — and ancient Greeks to within about 30 minutes — today’s astronomers can pin down eclipses to within a second.

That precision has fueled the craze of “eclipse chasing,” in which scientists and nonscientists alike trek to often remote regions to gather data or to simply experience the brief darkness — rarely more than seven minutes, and sometimes less than one second — of totality. In 1925, scientists chased an eclipse with an airship; in 1973, they did so at supersonic speed in a Concorde. All three books describe in detail various historical expeditions to view eclipses, everywhere from New York’s Central Park to exotic hot spots such as the South Pacific and Pike’s Peak in Colorado (which was pretty remote and exotic in 1878).

Each book shares many of the same anecdotes and recounts many of the same scientific breakthroughs that resulted from eclipse research. Both In the Shadow of the Moon and Mask of the Sun take readers on a largely chronological path through eclipse history. But their organizations differ slightly: The science of eclipses is deftly scattered throughout Mask of the Sun, while In the Shadow of the Moon addresses various scientific topics in wonderfully thorough chapters of their own.
Of this trio of books, Eclipse — more a memoir of Close’s lifetime fascination and personal experiences with eclipses than a detailed chronicle of historical lore — provides the most amusing and insightful descriptions of eclipse chasers. They are, Close writes, “an international cult whose members worship the death and rebirth of the sun at moveable Meccas, about half a dozen times every decade.”

A teacher kindled Close’s love of eclipses in 1954 when Close was an 8-year-old living north of London. He reached his 50s before experiencing a total eclipse (1999 in extreme southwestern England), but since then has seen a handful more, including from a cruise ship southwest of Tahiti and a safari camp in Zambia.

Who knows how many budding young scientists the Great American Eclipse of 2017 — or these books — will inspire.

People hunted giant sloths in the center of South America around 23,120 years ago, researchers say — a find that adds to evidence that humans reached South America well before Clovis hunters roamed North America 13,000 years ago.

Evidence of people’s presence at Santa Elina rock-shelter, in central-west Brazil, so long ago raises questions about how people first entered South America. Early settlers may have floated down the Pacific Coast in canoes before heading 2,000 kilometers east to the remote rock-shelter, or they might have taken an inland route from North America, Denis Vialou of the National Museum of Natural History in Paris and colleagues report in the August Antiquity. Other proposed Stone Age South American sites lie much closer to the coast than Santa Elina does.

Excavations revealed remains of hearths, stone artifacts and bones of giant sloths. Sloth remains included small, bony plates from the skin that humans apparently made into ornaments of some kind by adding notches and holes.

Three different dating methods indicate that people reached Santa Elina over 20,000 years ago.

Journalist Maryn McKenna opens Big Chicken by teasing our taste buds with a description of the succulent roasted chickens she bought at an open-air market in Paris. The birds tasted nothing like the bland, uniform chicken offered at U.S. grocery stores. This meat had an earthy, lush, animal flavor. From this tantalizing oh-so-European tableau, McKenna hits us with a sickening contrast — scientists chasing outbreaks of drug-resistant Salmonella infections in humans, and ailing chickens living in crowded conditions and never seeing the light of day.

Antibiotics are at the root of both nightmares, McKenna argues. She draws clear connections between several dramatic foodborne outbreaks and the industrialization of chicken production, made possible, in large part, by the heavy use of the drugs. That reliance on antibiotics has also spurred the rise of drug-resistant bacteria. In fact, the overuse of antibiotics in livestock is a bigger driver of resistance than the overuse of antibiotics in people.

Farmers began using the drugs after studies in the 1940s showed that antibiotics boosted muscle mass. For chickens, that meant the birds got bigger and grew faster with less feed. Today, a meat chicken weighs twice what it did 70 years ago at slaughter and reaches that weight in half the time. Once farmers saw opportunity for growth and packed more birds into barns, the drugs took on a new role: to protect crowded animals from illness.

McKenna weaves in real people’s stories with clearly explained scientific details and regulatory history. If this story has a villain, it’s Thomas Jukes, whose noble goal was to feed the world with cheap protein. In the ’50s, Jukes was a researcher at Lederle Laboratories, one of the first manufacturers of antibiotics. He did some of the early studies testing the drugs as growth promoters. He saw signs that bacteria were developing resistance, but he saw no risk to the chickens, McKenna writes. Jukes railed against efforts in the ’70s to regulate antibiotic use in livestock and, up until he died in 1999, refused to acknowledge any downsides.

In addition to profiling farmers who embraced industrialization, McKenna introduces those who have turned their backs on antibiotics. These farmers, including many in the United States, have learned to raise drug-free chickens, mainly by going back to the old ways — letting chickens roam free, day and night, pecking at grubs in the ground. Some farms in the Netherlands even manage to raise industrial numbers of chickens without propping them up with antibiotics.

McKenna’s story almost has a happy ending. In 2014, the fast-food restaurant Chick-fil-A announced it would, within five years, stop serving chicken raised with antibiotics. Chicken producers, as well as McDonald’s, Subway, Costco and Walmart, followed suit.
But we’re not out of the woods yet, McKenna warns. She likens antibiotic resistance to climate change, calling it “an overwhelming threat, created over decades by millions of individual decisions and reinforced by the actions of industries.” The book might not make you give up chicken, but you may be more likely to look for sustainably raised birds to put on the dinner table.

Nature has no shortage of animal camouflage tricks. One newly recognized form of deception, used by plant-eating insects called leafhoppers, was thought to have a whole different purpose.

Leafhoppers are found worldwide in temperate and tropical regions. Most of the insects, of which there are about 20,000 described species, produce small quantities of microspheres called brochosomes — tiny soccer ball–like particles with honeycomb indentations. Researchers figured out that the brochosomes, which leafhoppers rub on their bodies, were used primarily to make the insects water-repellent. But why the bugs also used the balls to cover their eggs, which the insects lay on young leaves, was a mystery.
Now, using a novel method to manufacture brochosomes in large quantities, engineers found that the microparticles have the exact shape and size to prevent reflection of light in any direction. As a result, surfaces covered with brochosomes appear similar to a leaf in the spectrum of light that is visible to insects, mechanical engineer Tak-Sing Wong and his team at Penn State report online November 3 in Nature Communications. That suggests that the antireflective property of the spheres functions as camouflage for the eggs, protecting them from would-be predators such as birds or other insects.

The manufactured brochosomes have many potential applications, the researchers say, such as solar energy harvesting, where antireflective surfaces are needed.

In a remote corner of Brazil’s Amazon rainforest, researchers have spent decades catching and measuring birds in a large swath of forest unmarred by roads or deforestation. An exemplar of the Amazon’s dazzling diversity, the experimental plot was to act as a baseline that would reveal how habitat fragmentation, from logging or roads, can hollow out rainforests’ wild menagerie.

But in this pristine pocket of wilderness, a more subtle shift is happening: The birds are shrinking.

Over 40 years, dozens of Amazonian bird species have declined in mass. Many species have lost nearly 2 percent of their average body weight each decade, researchers report November 12 in Science Advances. What’s more, some species have grown longer wings. The changes coincide with a hotter, more variable climate, which could put a premium on leaner, more efficient bodies that help birds stay cool, the researchers say.

“Climate change isn’t something of the future. It’s happening now and has been happening and has effects we haven’t thought of,” says Ben Winger, an ornithologist at the University of Michigan in Ann Arbor who wasn’t involved in the research but has documented similar shrinkage in migratory birds. Seeing the same patterns in so many bird species across widely different contexts “speaks to a more universal phenomenon,” he says.

Biologists have long linked body size and temperature. In colder climates, it pays to be big because having a smaller surface area relative to one’s volume reduces heat loss through the skin and keeps the body warmer. As the climate warms, “you’d expect shrinking body sizes to help organisms off-load heat better,” says Vitek Jirinec, an ecologist at the Integral Ecology Research Center in Blue Lake, Calif.

Many species of North American migratory birds are getting smaller, Winger and colleagues reported in 2020 in Ecology Letters. Climate change is the likely culprit, Winger says, but since migrators experience a wide range of conditions while globe-trotting, other factors such as degraded habitats that birds may encounter can’t be ruled out.

To see if birds that stay put have also been shrinking, Jirinec and colleagues analyzed data on nonmigratory birds collected from 1979 to 2019 in an intact region of the Amazon that spans 43 kilometers. The dataset includes measurements such as mass and wing length for over 11,000 individual birds of 77 species. The researchers also examined climate data for the region.
All species declined in mass over this period, the researchers found, including birds as different as the Rufous-capped antthrush (Formicarius colma), which snatches insects off the forest floor, and the Amazonian motmot (Momotus momota), which scarfs down fruit up in trees. Species lost from about 0.1 percent to nearly 2 percent of their average body weight each decade. The motmot, for example, shrunk from 133 grams to about 127 grams over the study period.

These changes coincided with an overall increase in the average temperature of 1 degree Celsius in the wet season and 1.65 degrees C in the dry season. Temperature and precipitation also became more variable over the time period, and these short-term fluctuations, such as an especially hot or dry season, better explained the size trends than the steady increase in temperature.

“The dry season is really stressful for birds,” Jirinec says. Birds’ mass decreased the most in the year or two after especially hot and dry spells, which tracks with the idea that birds are getting smaller to deal with heat stress.

Other factors, like decreased food availability, could also lead to smaller sizes. But since birds with widely different diets all declined in mass, a more pervasive force like climate change is the likely cause, Jirinec says.

Wing length also grew for 61 species, with a maximum increase of about 1 percent per decade. Jirinec thinks that longer wings make for more efficient, and thus cooler, fliers. For instance, a fighter jet, with its heavy body and compact wings, takes enormous power to maneuver. A light and long-winged glider, by contrast, can cruise along much more efficiently.

“Longer wings may be helping [birds] fly more efficiently and produce less metabolic heat,” which can be beneficial in hotter conditions, he says. “But that’s just a hypothesis.” This body change was most pronounced in birds that spend their time higher up in the canopy, where conditions are hotter and drier than the forest floor.

Whether these changes in shape and size represent an evolutionary adaptation to climate change, or simply a physiological response to warmer temperatures, remains unclear (SN: 5/8/20). Whichever is the case, Jirinec suggests that the change shows the pernicious power of human activity (SN: 10/26/21).

“The Amazon rainforest is mysterious, remote and teeming with biodiversity,” he says. “This study suggests that even in places like this, far removed from civilization, you can see signatures of climate change.”