When we brought our first baby home from the hospital, our pediatrician advised us to have her sleep in our room. We put our tiny new roommate in a crib near our bed (though other containers that were flat, firm and free of blankets, pillows or stuffed animals would have worked, too).

The advice aims to reduce the risk of sleep-related deaths, including sudden infant death syndrome, or SIDS. Studies suggest that in their first year of life, babies who bunk with their parents (but not in the same bed) are less likely to die from SIDS than babies who sleep in their own room. The reasons aren’t clear, but scientists suspect it has to do with lighter sleep: Babies who sleep near parents might more readily wake themselves up and avoid the deep sleep that’s a risk factor for SIDS.

That’s an important reason to keep babies close. Room sharing also makes sense from a logistical standpoint. Middle of the night feedings and diaper changes are easier when there’s less distance between you and the babe.

But babies get older. They start snoring a little louder and eating less frequently, and it’s quite natural to wonder how long this room sharing should last. That’s a question without a great answer. In November 2016, the American Academy of Pediatrics task force on SIDS updated its sleep guidelines. The earlier recommendation was that babies ought to sleep in parents’ bedrooms for an entire year. The new suggestion softens that a bit to say infants should be there for “ideally for the first year of life, but at least for the first 6 months.”

Rachel Moon, a SIDS expert at the University of Virginia in Charlottesville who helped write the revised AAP guidelines, says that the update “gives parents a little more latitude after the first 6 months.” The vast majority of SIDS deaths happen in the first six months of life, but the studies that have found benefits for room sharing lumped together data from the entire first year. That makes it hard to say how protective room sharing is for babies between 6 and 12 months of age.

But a new study raises a reason why babies ought to get evicted before their first birthday: They may get more sleep at night in their own rooms. Babies who were sleeping in their own rooms at ages 4 or 9 months got more nighttime sleep than babies the same ages who roomed with parents, researchers reported online June 5 in Pediatrics.

The team asked hundreds of mothers to take sleep surveys when their children were 4, 9, 12 and 30 months old. Some of the 230 children slept in their own rooms when they were younger than 4 months, others moved to their own rooms between 4 and 9 months, and the rest were still sharing their parents’ rooms at 9 months.
At 9 months, babies who had been sleeping alone since 4 months of age slept an average of 40 minutes more than room sharers. The researchers found no differences in sleep duration between the groups of babies at age 12 months. By 30 months of age, though, children who had been sleeping in their own rooms by either 4 or 9 months of age slept on average 45 minutes longer at night than children who had been sharing their parents’ rooms at 9 months. (Important caveat: At 30 months, total daily sleep time didn’t differ between the groups. The former room sharers were making up for missed nighttime sleep with naps.)

Parents who want their babies age 6 months and older to sleep in their own room ought to be encouraged to make the move, says study coauthor Ian Paul, a pediatrician at Penn State. “The guidelines should reflect data, not opinion,” Paul says.

He suspects that sharing a bedroom with babies interferes with everyone’s sleep because normal nocturnal rustlings turn into full-blown wake-ups. Babies and adults alike experience brief arousals during sleep. But when parents are right next to babies, they’re more likely to respond to their children’s brief arousals, which then wakes the baby up more. “This then sets up the expectation from the baby that these arousals will be met with a parent reaction, causing a bad cycle to develop,” he says.

There was another difference that turned up between the two groups of babies. Babies who roomed with parents were four times more likely to be moved into their parents’ beds at some point during the night than babies who slept in their own rooms. Bed sharing is a big risk factor for sleep-related infant deaths.

But Moon cautions that the Pediatrics study is preliminary, and doesn’t warrant a change in the AAP guidelines. She and coauthors point out in an accompanying commentary that other factors might be behind the difference in sleep between the two groups of babies. For instance, babies who slept in their own room were more likely to have consistent bedtime routines, be put to bed drowsy but awake, and have bedtimes of 8 p.m. or earlier. Those are all signs of good “sleep hygiene” for babies, and might be contributing to the longer sleep times. “We know that consistent bedtime routine and consistent bedtime are very important in terms of sleep quality in children,” Moon says. “They could very well make a difference.”

So that’s where we are. Some things are clear, like putting your baby to sleep on her back on a flat, firm surface clear of objects and having your baby nearby during the first six months. But other decisions come with skimpier science, and whether to evict your 6-month-old is one of them. Because science can take you only so far, it may just come down to the snoring, stirring and sleep deprivation.

BOSTON — Some aspects of speech are as Southern as pecan pie. Consider the vowel shift that makes the word pie sound more like “pah.” While that pronunciation is found from Florida to Texas, a new study reveals a surprising diversity in Southern vowel pronunciation that’s linked to a speaker’s age, social class, gender, race and geography.

The research, presented June 29 at a meeting of the Acoustical Society of America, could help software developers create better speech recognition tools for smartphones and other devices.
To understand the medley of southern vowel sounds, linguist Margaret Renwick of the University of Georgia in Athens dove into the Digital Archive of Southern Speech. The archive comprises almost 400 hours of interviews with 64 native Southerners representing a mix of ethnicities, social classes, education levels and ages.

Renwick’s analysis of more than 300,000 vowel sounds finds, for example, that Southern upper middle class women are often at the extreme end of variation in pronunciation. While Southern men and women are equally likely to shift the vowel in bet to “bay-ut,” upper middle class Southern women are more likely to stretch the vowel sound in bit to “bee-ut.” They are also most likely to pronounce bait as bite. The finding that women are more inclined to draw a sound out into two syllables — or change it entirely — is in line with other research suggesting that women are linguistic innovators, and less likely to adhere to the norms of standard American English, Renwick said.

With a final rip, an iceberg roughly the size of Delaware has broken off Antarctica’s Larsen C ice shelf. Anticipated for weeks, the fracture is one of the largest calving events ever recorded.

On July 12, satellite images confirmed a nearly 5,800-square-kilometer, 1-trillion-metric-ton chunk of ice, equivalent to 12 percent of Larsen C’s total area, split from the ice shelf. “[We] have been surprised how long it took for the rift to break through the final few kilometers of ice,” Adrian Luckman, a glaciologist at Swansea University in Wales, said in a blogpost for Project MIDAS, which has been tracking the effects of a warming climate on the ice shelf. Now the focus will shift to the stability of the remaining ice shelf and the fate of the giant iceberg.
Scientists had been monitoring Larsen C since 2014, when they noticed that a crack in the ice shelf had grown roughly 20 kilometers in less than nine months (SN: 7/25/15, p. 8). After a relative lull in 2015, the crack grew another 40 kilometers in 2016 and then 10 more in the first half of January 2017, bringing its total length to 175 kilometers. At that point, its tip was 20 kilometers from the Weddell Sea.
The crack grew another 17 kilometers between May 25 and May 31 — at times traveling parallel to the edge and ultimately putting it within 13 kilometers of the ice front. Then, in late June, the outer part of the ice shelf picked up speed, putting new pressure on the crack and the entire shelf. “It won’t be long now,” Project Midas tweeted June 30. Added Luckman, also in a tweet: “The remaining ice is strained near to breaking point.”

Yet the vigil lasted nearly two more weeks. By July 6, the crack had come within 5 kilometers of the edge of the ice. Then, sometime between July 10 and July 12, it finally reached the water, allowing the huge hunk of ice to splinter off into the sea.
The ice loss dramatically alters the landscape of Larsen C, Luckman notes. “Maps will need to be redrawn.” And that could be the least of the trouble ahead, says Adam Booth, a geophysicist at the University of Leeds in England also with Project MIDAS. “The calving event is significant because it is likely a precursor to something much bigger, potentially the collapse of the whole Larsen C ice shelf,” Booth says. The same thing happened to the neighboring Larsen B ice shelf in 2002, after it calved a Rhode Island-sized iceberg (SN: 3/30/02, p. 197).

“Glaciologists are keen to see how Larsen C will react,” says Luckman.

A complete collapse of Larsen C could have implications for sea level rise. Antarctica’s ice shelves act as buttresses, helping to slow the flow of the continent’s ice into the ocean. Since these shelves float on the water, calving icebergs don’t directly raise sea level. But calving or the collapse of an ice shelf allows glaciers and ice streams further inland to flow into the ocean, which can contribute to sea level rise.

Calving of icebergs is common, and over several decades, the shelves usually recover to their original size. But in the last two decades, ice shelves have instead continued to lose ice until collapsing, probably as a result of rising temperatures due to climate change, researchers suspect. In 2014, researchers concluded the collapse of Larsen B was the result of warming (SN: 10/18/14, p. 9).

Some computer simulations suggest Larsen C could suffer the same fate, possibly within a few years to decades, Luckman says. Still, the calving event that feeds a potential collapse may be hard to pin on climate change. “Not all ice-related stories have a clear global warming origin,” Luckman notes. Larsen C’s calving, he says, “may simply be a natural event that would have happened regardless of human activity.”
Not everyone is convinced that Larsen C will fall apart completely. Researchers from Europe predict major changes to the shelf would happen only if it loses 55 percent of its ice. At that point, a significant amount of ice could ooze from glaciers into the ocean. Still, understanding what allowed the recent rift to grow and calve will “give us insight regarding other fractures or rifts on the shelf,” says geoscientist Dan McGrath of Colorado State University in Fort Collins. While McGrath says a collapse is “very unlikely,” he adds that “these other dormant rifts are in locations where if they reinitiated, the subsequent calving event would be worrisome for the shelf’s stability.”

Discrepancies in the predictions of Larsen C’s fate raise an important point, says Richard Alley, a geologist at Penn State. Researchers don’t understand ice shelf calving and collapsing enough predict how any one individual ice shelf will behave after a break.

“The Larsen C ice shelf is, of course, just one small part of Antarctica,” Booth says. “What is worrying is that we’re seeing trends in several ice shelves that tend towards decreasing stability. Should they continue along these trends, we could be seeing the start of increased mass loss from the Antarctic continent.”

A genetic-engineering tool designed to spread through a population like wildfire — eradicating disease and even whole invasive species — might be more easily thwarted than thought.

Resistance to the tools, called CRISPR gene drives, arose at high rates in experiments with Drosophila melanogaster fruit flies, researchers at Cornell University report July 20 in PLOS Genetics. Rates of resistance varied among strains of fruit flies collected around the world, from a low of about 4 percent in embryos from an Ithaca, N.Y., strain to a high of about 56 percent in Tasmanian fruit fly embryos.
“At these rates, the constructs would not start spreading in the population,” says coauthor Philipp Messer, a population geneticist. “It might require quite a bit more work to get a gene drive that works at all.”

Gene drives are basically genetic copy-and-paste machines. These self-perpetuating machines are inherited by more than 50 percent of offspring of an individual carrying a gene drive. Working perfectly, they could transmit to 100 percent of offspring.

In its simplest form, a CRISPR gene drive consists of a piece of DNA that encodes both an enzyme called Cas9, which acts as molecular scissors, and a guide RNA that tells the Cas9 enzyme where to cut. That cutting may disrupt important genes. Researchers are experimenting with this as a way to sterilize malaria-carrying mosquitoes (SN Online: 12/7/15).

Some gene drives also carry a genetic payload. For instance, another approach to fighting malaria is to develop drives that carry genes to “vaccinate” mosquitoes against the disease (SN: 12/26/15, p. 6). Other drives might carry genes that make fluorescent proteins to indicate the gene drive’s presence; Messer and colleagues used such markers to follow two gene drives in fruit flies bred in the lab.
When an organism carrying the tool mates with one that doesn’t, gene drives go to work. Inside the fertilized egg, guide RNAs shepherd Cas9 produced by the engineered mate to a spot where it cuts the other mate’s chromosome.

If everything works correctly, cells repair that break by copying the gene drive onto the cut chromosome. But the slice can also be fixed by gluing the cut ends back together. That regluing sometimes leads to mistakes that destroy Cas9’s cutting site, creating a chromosome that is resistant to the gene drive’s insertion.

In the fruit fly experiments, some mistakes created resistance during or before fertilization. Others took place in early embryos because cells produced Cas9 for too long, allowing the enzyme to chop chromosomes again and again, Messer and colleagues discovered. That was especially a problem when females produced Cas9, they found.

Some uses of gene drives, such as those that would sterilize or kill mosquitoes, can’t tolerate any amount of resistance no matter when it arises, Messer says. Because those types of gene drives damage the organism’s fertility or viability, mosquitoes carrying resistance would have an advantage and quickly outcompete insects vulnerable to the drives.

In a separate study posted June 14 at BioRxiv.org, Messer and colleagues tested several approaches to overcoming gene drive resistance. They found that using multiple guide RNAs and turning on Cas9 only in males could reduce resistance rates.

“This is a very important and elegant set of experiments,” says MIT evolutionary engineer Kevin Esvelt.

But the conclusions aren’t news to most gene drive researchers.

“We’re aware of all these problems, and the essence of how to deal with them hasn’t been changed by these studies,” says geneticist Ethan Bier of the University of California, San Diego. Bier and lab colleague Valentino Gantz created the first gene drive in fruit flies in 2015, and have worked with other researchers to develop gene drives that would prevent mosquitoes from carrying malaria (SN: 12/12/15, p. 16).

Messer’s group is, however, the first to experimentally confirm predictions about resistance and how to avoid it, Esvelt says. “They show what’s been apparent to some people in the field for a very long time.”

Some people might think that high rates of resistance mean that gene drives are safe to release because they won’t spread easily in the wild. But that notion is misguided, says Bier. Even if a gene drive is able to affect only a small percentage of a local pest population, it could still spread around the world, Esvelt adds. “It could still screw us all over in the current form.”

Researchers should continue to conduct gene drive experiments under tight containment, he and Bier caution.

For a glue that holds up inside the body, turn to the humble slug, Arion subfuscus. A new super-sticky material mimics slug slime’s ability to stick on slick wet surfaces and could lead to more effective medical adhesives.

The material has two parts: a sticky layer that attaches to a surface, and a shock-absorbing layer that reduces strain. That makes the adhesive less likely to snap off.

Researchers tested the material as a surgical adhesive in a number of different scenarios: It stuck to pig skin and liver. It latched on to a beating pig’s heart, even when the surface was coated in blood. It sealed up a heart defect, preventing liquid from leaking even when the organ was inflated and deflated tens of thousands of times. And it was less toxic in the body than a commonly used commercialized tissue adhesive, researchers report July 28 in Science.

The researchers hope the material could someday be used in surgical procedures in place of invasive sutures and staples.

Famously sneaky particles have been caught behaving in a new way.

For the first time, scientists have detected neutrinos scattering off the nucleus of an atom. The process, predicted more than four decades ago, provides a new way to test fundamental physics. It will also help scientists to better characterize the neutrino, a misfit particle that has a tiny mass and interacts so feebly with matter that it can easily sail through the entire Earth.
The detection, reported online August 3 in Science, “has really big implications,” says physicist Janet Conrad of MIT, who was not involved with the research. It fills in a missing piece of the standard model, the theory that explains how particles behave: The model predicts that neutrinos interact with nuclei. And, says Conrad, the discovery “opens up a whole new area of measurements” to further test the standard model’s predictions.

Scientists typically spot neutrinos when they interact with a single proton or neutron. But the new study measures “coherent” scattering, in which a low-energy neutrino interacts with an entire atomic nucleus at once, ricocheting away and causing the nucleus to recoil slightly in response.

“It’s exciting to measure it for the first time,” says physicist Kate Scholberg of Duke University, spokesperson for the collaboration — named COHERENT — that made the new finding.

In the past, neutrino hunters have built enormous detectors to boost their chances of catching a glimpse of the particles — a necessity because the aloof particles interact so rarely. While still rare, coherent neutrino scattering occurs more often than previously detected types of neutrino interactions. That means detectors can be smaller and still catch enough interactions to detect the process. COHERENT’s detector, a crystal of cesium and iodine, weighs only about 15 kilograms. “It’s the first handheld neutrino detector; you can just carry it around,” says physicist Juan Collar of the University of Chicago.

Collar, Scholberg and colleagues installed their detector at the Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee. The facility generates bursts of neutrons and, as a by-product, produces neutrinos at energies that COHERENT’s detector can spot. When a nucleus in the crystal recoils due to a scattering neutrino, a flash of light appears and is captured by a light sensor. The signal of the recoiling nucleus is incredibly subtle — like detecting the motion of a bowling ball when hit by a ping-pong ball — which is why the effect remained undetected until now.
The amount of scattering the researchers saw agreed with the standard model. But such tests are still in their early stages, says physicist Leo Stodolsky of the Max Planck Institute for Physics in Munich, who was not involved with the research. “We’re looking forward to more detailed studies to see if it really is accurately in agreement with the expectations.” Physicists hope to find a place where the standard model breaks down, which could reveal new secrets of the universe. More precise tests may reveal discrepancies, he says. “That would be extremely interesting.”

Measuring coherent neutrino scattering could help scientists understand the processes that occur within exploding stars, or supernovas, which emit huge numbers of neutrinos (SN: 02/18/17, p. 24). The process could be used to detect supernovas as well — if a supernova explodes nearby, scientists could spot its neutrinos scattering off nuclei in their detectors.

Similar scattering might also help scientists detect dark matter, an invisible source of mass that pervades the universe. Dark matter particles could scatter off atomic nuclei just as neutrinos do, causing a recoil. The study indicates that such recoils are detectable — good news since several dark matter experiments are currently attempting to measure recoils of nuclei (SN: 11/12/16, p. 14). But it also suggests a looming problem: As dark matter detectors become more sensitive, neutrinos bouncing off the nuclei will swamp any signs of dark matter.

Coherent neutrino scattering detectors could lead to practical applications as well: Small-scale neutrino detectors could eventually detect neutrinos produced in nuclear reactors to monitor for attempts to develop nuclear weapons, for example.

Physicist Daniel Freedman of MIT, who predicted in 1974 that neutrinos would scatter off nuclei, is pleased that his prediction has finally been confirmed. “It’s a thrill.”

Speed has its limits — on the open road and the Serengeti. Midsize animals tend to be the speedsters, even though, in theory, the biggest animals should be the fastest. A new analysis that relates speed and body size in 474 species shows that the pattern holds for animals whether they run, fly or swim (see graphs below) and suggests how size becomes a liability.

This relationship between speed and size has long stumped scientists. Big animals have longer legs or flippers to get from point A to point B. And bigger bodies have higher metabolic rates and more fast-twitch muscle cells, needed to convert chemical energy into mechanical energy and rapidly accelerate. So, why aren’t wildebeests faster than cheetahs?
The make-or-break factor is the time it takes an animal to accelerate to its top theoretical speed, an upper limit based on mass and metabolic rate, researchers report July 17 in Nature Ecology & Evolution. Fast-twitch muscle cells provide the power for acceleration but tire quickly. When an animal gets too big, it takes too long to accelerate, and these cells use up their energy before hitting top speeds. More modestly built critters need less time to accelerate to those speeds.

The researchers gathered speed and size data from past lab and field studies. The animals (some shown as icons in the slideshow below) ranged in mass from 30-microgram Spanish mites to a blue whale weighing 108 metric tons.

Maybe it’s more than reptile fashion. The high percentage of citified sea snakes wearing black might be a sign that pollution is an evolutionary force.

Off the coasts of Australia and New Caledonia, some turtle-headed sea snakes (Emydocephalus annulatus) sport pale bands on their dark skins. Others go all black. In 15 places surveyed, the all-black form was more likely to predominate in waters near cities, military sites or industrial zones than along reefs near less built-up coastlines, says evolutionary ecologist Rick Shine of the University of Sydney.
That trend plus some analysis of trace elements in snakes’ skin suggests that the abundant dark forms could turn out to be an example of industrial melanism, Shine and his colleagues propose August 10 in Current Biology.

The most famous example of this evolutionary phenomenon comes from a dark form of peppered moth that overtook pale populations in 19th century England (SN: 6/25/16, p. 6). Dark wings created better camouflage from hungry birds in the grimy industrializing landscape.
Shine doesn’t think the sea snakes are going for camouflage, though. Instead, the snakes could be more like the dark-feathered pigeons of Paris. The melanin that gives that city’s feral birds their urban chic also does a great job of binding traces of toxic metals such as zinc, explains evolutionary ecologist Marion Chatelain of the University of Warsaw. When birds molt, getting rid of darker feathers lets them unload more of the unhealthful urban pollutants, she and colleagues have reported.
This could explain why marine biologist and study coauthor Claire Goiran has so many dark turtle-headed sea snakes in a lagoon not far from her campus, the University of New Caledonia in Nouméa. Earlier studies had found only downsides to dark coloration: Seaweed spores preferentially settle on dark snakes and sprout fuzz that can cut swimming speed by 20 percent and cause a snake to shed its skin more often than normal.
To test a scenario of industrial melanism, or darkening due to pollution, the researchers collected data on skin colors for a total of about 1,450 snakes, both live and museum specimens, from 15 sites in New Caledonia and Australia. Higher percentages of all-dark snakes wriggled around the nine polluted sites surveyed. At one, a remote Australian reef that the military had long used as a bombing range, all 13 specimens were dark.

To test shed skins for trace metals, Goiran and Shine enlisted Paco Bustamante of the University of La Rochelle in France, who studies trace metal contamination in marine life.

Researchers managed to collect sloughed skins from 17 turtle-headed snakes, which inconveniently shed their skin underwater. To compare light and dark patches, the scientists turned to two local species of sea kraits, which have banded skin and visit land to shed it.
Overall, skins held concentrations of trace elements higher than those that can cause health problems in birds and mammals, the researchers report. In the krait skins, dark zones had slightly more of some contaminants, such as zinc and arsenic, than the pale bluish-white bands did.

The idea that polluted water favors melanized sea snakes “is a reasonable hypothesis based on what we know,” Chatelain says. Definitive tests will require more data and different approaches. Genetic testing, for example, would clarify whether dark populations arose instead from small groups of pioneers that happened to have a lot of black snakes.

That testing could be a long way off. Sea snakes are evolutionary cousins of cobras and mambas, and some of the species swimming around Australia and New Caledonia are “bowel-looseningly large,” Shine says. At least the little turtle-headed ones, which eat eggs of small reef fishes, have venom glands that have atrophied and “probably couldn’t fit a human finger in their mouths.” But until someone figures out how to keep them alive in captivity for more than a few days, Shine isn’t expecting definitive genetics.

China’s first emperor broke the mold when he had himself buried with a terra-cotta army. Now insight into the careful crafting of those soldiers is coming from the clays used to build them. Custom clay pastes were mixed at a clay-making center and then distributed to specialized workshops that cranked out thousands of the life-size figures, new research suggests.

Roughly 700,000 craftsmen and laborers built Emperor Qin Shihuang’s palatial mausoleum in east-central China between 247 B.C. and 210 B.C. A portion of those workers gathered clay from nearby deposits and prepared it in at least three forms, researchers propose in the August Antiquity. On-site or nearby workshops used different signature clay recipes for terra-cotta warriors, parts of mostly bronze waterfowl figures and paving bricks for pits in which the soldiers originally stood.
Around 7,000 ceramic foot soldiers, generals and horses — equipped with a variety of bronze weapons — make up the army, which was accidentally discovered in 1974 by farmers digging a well. The emperor would have regarded the ceramic statues as a magic army that would protect him as he ruled in the afterlife, many researchers suspect.

Building and assembling the multitude was an enormous task. Workers poured clay mixtures into casts of torsos, limbs and other body parts, and then assembled the bodies, taking care to create different facial features for each soldier. Finished statues, now mostly gray, were covered in colored lacquers and likely fired in kilns. Most figures were placed inside one giant pit. Earthen walls formed 11 parallel corridors where statues stood in battle-ready rows.

Still, no workshops or debris firmly linked to the statue-making process have been found. As a result, the number, size, location and organization of workshops involved in producing the emperor’s ceramic troops remain uncertain.

Archaeologist Patrick Quinn of University College London and three Chinese colleagues studied the composition of clay samples from the site. The pieces were taken from 12 terra-cotta warriors, two acrobat statues found in a second pit, five clay bricks from the floor of the largest pit, clay fragments from inside three bronze waterfowl statues found in a third pit and part of an earthen wall in the acrobat pit.

Microscopic analysis of the samples revealed that the clay came from deposits near the tomb’s location, the scientists say. But the recipes for different parts varied. Paving bricks contained only a mixture of dark and light clays, while the clay used for warriors and acrobats had sand worked in. Sand and plant fragments were folded into a clay mixture that formed the core of the bronze waterfowl.
Sand may have made the clay more malleable for shaping into ornate figures and increased statues’ durability, the researchers speculate. Plant pieces may have helped reduce the weight of birds’ clay cores. A clay-processing site at or just outside the emperor’s mausoleum must have doled out the appropriate clay pastes to an array of workshops where potters made statues, bricks or other objects, the scientists propose.

What’s more, many statue and waterfowl samples show signs of having been slowly heated in kilns at maximum temperatures of no more than 750˚ Celsius. That’s lower by 150˚ C or more than some previous estimates, the investigators say. Fires set in an attack on the tomb after the emperor’s death may have refired some of the clay, accounting for the temperature discrepancy, the researchers say.

“I’m not at all surprised by the new findings,” says East Asian art historian Robin D.S. Yates of McGill University in Montreal. Legal and administrative documents previously found at two other Qin Empire sites describe workshops that specialized in various types of craft production, Yates says.

In some cases, artisans’ stamps and inscriptions on terra-cotta warriors match those on excavated roof tiles from Emperor Qin’s mausoleum. The markings suggest that some workshops made several types of ceramic objects, says East Asian art historian Lothar Ledderose of Heidelberg University in Germany. Inscriptions on statues also indicate that artisans working at off-site factories during the Qin Empire collaborated with potters at local workshops to produce the terra-cotta army, Ledderose says.

Early in Inferior, science writer Angela Saini recalls a man cornering her after a signing for her book Geek Nation, on science in India. “Where are all the women scientists?” he asked, then answered his own question. “Women just aren’t as good at science as men are. They’ve been shown to be less intelligent.”

Saini fought back with a few statistics on girls’ math abilities, but soon decided that nothing she could say would convince him. It’s a situation that may feel familiar to many women. “What I wish I had was a set of scientific arguments in my armory,” she writes.
So she decided to learn the truth about what science really does tell us about differences between the sexes. “For everyone who has faced the same situation,” she writes, “the same desperate attempt to not lose control but have at hand some real facts and a history to explain them, here they are.”

In Inferior, Saini marshals plenty of facts and statistics contradicting sexist notions about women’s bodies and minds. She cites study after study showing little or no difference in male and female capabilities.

But it’s the book’s historical perspective that makes it most compelling. Only by understanding the cultural context of the men whose studies and ideas first pointed to gender imbalances can we see how deeply biases run, Saini argues.

Charles Darwin’s influential ideas reflected his times, for instance. In The Descent of Man, he wrote that “man has ultimately become superior to woman” via evolution. To a woman active in her local women’s movement, Darwin wrote, “there seems to me to be a great difficulty from the laws of inheritance … in [women] becoming the intellectual equals of man.”

If that idea sounds absurd now, don’t fool yourself into thinking it has vanished. Saini’s book is full of examples right up to today of scientists who have started from this and other flawed premises, which have led to generations of flawed studies and results that reinforce stereotypes. But the tide has been turning, as more women have entered science and more scientists of both sexes seek to remove bias from their work.
Saini does an excellent job of dissecting research on evolution, neuroscience and even the long-standing notion that women’s sexual behavior is driven by their interest in stable, monogamous relationships. By the end, it’s clear that science doesn’t divide men and women; we’ve done that to ourselves. And as scientists become more rigorous, we get closer to seeing ourselves as we really are.