SEATTLE — Tyrannosaurus rex may have had small arms, but it was no pushover.

This fierce dinosaur is known for its giant head, powerful jaws and overall fearsome appearance — except for those comical-looking arms. But the roughly meter-long limbs weren’t just vestigial reminders of a longer-armed past, paleontologist Steven Stanley of the University of Hawaii at Manoa said October 23 at the Geological Society of America’s annual meeting. Instead, the limbs were well-adapted for vicious slashing at close quarters, he argued.
T. rex ancestors had longer arms that the dinos used for grasping. But at some point, T. rex and other tyrannosaurs began to use their giant jaws for grasping instead, and the limbs eventually atrophied. Many people have hypothesized that the shrunken arms were, at best, used for mating or perhaps pushing the animal up off the ground; at worst, they were completely functionless.

But Stanley noted that the arms were quite strong, with robust bones that could sustain the impact of slashing. Each arm ended in two sharp claws about 10 centimeters long. Two claws give more slashing power than three, because each one can apply heavier pressure. Furthermore, the edges of the claws are beveled and sharp like those of a bear rather than flat like the grasping claws of an eagle. Those traits support the slasher hypothesis, Stanley concluded.

Many scientists aren’t convinced. While an interesting idea, it’s still unlikely that an adult T. rex would have used its arms as a primary weapon, says vertebrate paleontologist Thomas Holtz of the University of Maryland in College Park, who was not involved in the study. Although strong, the arm of a fully grown T. rex would barely reach past its chest, greatly reducing its potential strike zone. But a T. rex’s arms grew more slowly than its body, so younger dinos would have had proportionally longer arms. It’s possible the juveniles might have found them useful for slashing prey, he says.

At the beginning of 2017, parents and pediatricians got new peanut guidelines that, for most kids, are very pro-peanut. My colleague and fellow mom Meghan Rosen wrote about the recommendations, issued from the National Institute of Allergy and Infectious Diseases.

This “let them eat nuts” advice is based in part on a large and unusually clear dataset from a study that looked at babies at high risk of developing an allergy to peanuts. In the study, some of the children were regularly fed peanut-containing foods until their fifth birthdays. The others avoided any food with peanuts. By the end of the study, the kids who regularly ate peanut-containing food were way less likely to have a peanut allergy than the kids who had avoided the nut, the researchers found.
In a nutshell, parents of low-risk babies (infants without an egg allergy or severe eczema) should feel free to put peanut-containing food in the rotation as soon as their babies are ready for solid foods, around 4 to 6 months of age.

Whole peanuts and peanut butter are both choking hazards and shouldn’t be fed to babies. Instead, peanut butter (or peanut flour or peanut butter powder) can be mixed into breast milk, formula, fruit, yogurt or purees.

Babies with severe eczema or who are allergic to eggs ought to be seen by an allergist who can help guide the introduction of peanuts to the diet. Those appointments may reveal that some babies are in fact already allergic to peanuts. For those kids, peanuts may need to be avoided altogether.

When the recommendations were released, health officials were optimistic that the advice would lead to a reduction in peanut allergy in kids, given the study that found an early peanut introduction curbed this allergy. But that intro may not be happening as early or often as officials had hoped.
Bryce Hoffman, an allergist in New York City, suspected that the guidelines weren’t being used. Anecdotally, he and his colleagues hadn’t seen many infants coming into his allergy office with referrals for peanut allergy testing.

To get an idea of whether the guidelines were being applied (or not), Hoffman and his colleagues surveyed pediatricians about their advice to parents on peanuts. The results, which he presented October 30 at the annual meeting of the American College of Allergy, Asthma and Immunology, were discouraging.

Of the 79 pediatricians who responded, 30, or 38 percent, were not using the new guidelines in their practice. What’s more, 61, or 77 percent, of the pediatricians recommended high-risk patients eat peanuts later than ages 4 to 6 months, instead of sending those children to an allergist first for testing. Close to half (44 percent) of the pediatricians said they didn’t routinely test high-risk patients for allergy or send them to an allergist for testing.

This reluctance to test poses a problem for infants who “may have a dangerous anaphylactic reaction if given peanut,” Hoffman says. Testing can help clear up whether these infants should strictly avoid peanuts or be exposed to the nut first in an allergist’s office.

Peanuts got a bad rap for a long time, so it’s not surprising that parents and pediatricians might not jump at the chance to get peanut-containing food on the menu. The survey suggested that pediatricians aren’t familiar enough with the guidelines and, what’s more, are often too rushed to delve into the details during checkups. But for the new guidelines to do any good, they need to be used.

NASA’s New Horizons mission needs a catchier nickname for its next destination. The bar isn’t exactly high.

On New Year’s Day 2019, the spacecraft will fly by the tiny Kuiper Belt world that bears the official designation of (486958) 2014 MU69. NASA announced Monday that it is asking the public for an easier-to-remember nickname. The SETI Institute is hosting the contest.

As with similar crowdsourced naming campaigns, the name options vary widely. Current candidates range from Mjölnir (the hammer of the Norse god Thor) to Z’ha’dum (a planet from Babylon 5) to Peanut, Almond and Cashew — multiple name options may be necessary if the object is a binary pair. Whatever the object is named, it will be the most distant solar system body ever visited.
NASA will submit a formal name (or names) to the International Astronomical Union after the flyby, based on whether MU69 turns out to be a single body, binary pair or other system.

While anyone is welcome to submit a name or vote on existing options, SETI must approve any options before they appear on the ballot. So the odds don’t look good for Planet McPlanetface.

The naming campaign will close at 3 p.m. EST on December 1. The winner will be announced in early January.

Eggs, long condemned for making raw cookie dough a forbidden pleasure, can stop taking all the blame. There’s another reason to resist the sweet uncooked temptation: flour.

The seemingly innocuous pantry staple can harbor strains of E. coli bacteria that make people sick. And, while not a particularly common source of foodborne illness, flour has been implicated in two E. coli outbreaks in the United States and Canada in the last two years.

Pinning down tainted flour as the source of the U.S. outbreak, which sickened 63 people between December 2015 and September 2016, was trickier than the average food poisoning investigation, researchers recount November 22 in the New England Journal of Medicine.
Usually, state health departments rely on standard questionnaires to find a common culprit for a cluster of reported illnesses, says Samuel Crowe, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta, who led the study. But flour isn’t usually tracked on these surveys. So when the initial investigation yielded inconclusive results, public health researchers turned to in-depth personal interviews with 10 people who had fallen ill.

Crowe spent up to two hours asking each person detailed questions about what he or she had eaten around the time of getting sick. Asking people what they ate eight weeks ago can be challenging, Crowe says: Many people can’t even remember what they ate for breakfast that morning.

“I got a little lucky,” Crowe says. Two people remembered eating raw cookie dough before getting sick. They each sent Crowe pictures of the bag of flour they had used to make the batter. It turned out that both bags had been produced in the same plant. That was a “pretty unusual thing,” he says.
Follow-up questioning helped Crowe and his team pin down flour as the likely source. Eventually, U.S. Food and Drug Administration scientists analyzed the flour and isolated strains of E. coli bacteria that produce Shiga toxins, which make E. coli dangerous.

Disease-causing bacteria, including E. coli, usually thrive in moist environments, like bags of prewashed lettuce (SN: 12/24/16, p. 4). But the bacteria can also survive in a desiccated state for months and be re-activated with water, says Crowe. So as soon as dry flour mingles with eggs or oil, dormant bacteria can reawaken and start to replicate.

Cookie dough wasn’t the culprit in every case. A few children who got sick had been given raw tortilla dough to play with while waiting for a table at a restaurant. The cases all involved wheat flour from the same facility, leading to a recall of more than 250 flour-containing products.

There are ways to kill bacteria in flour before it reaches grocery store shelves, but they aren’t in use in the United States. Heat treatment, for example, will rid flour of E. coli and other pathogens. But the process also changes the structure of the flour, which affects the texture of baked goods, says Rick Holley, a food safety expert at the University of Manitoba in Canada who wasn’t part of the study. Irradiation, used to kill parasites and other pests in flour, might be a better option, Holley says. But it takes a higher dose of radiation to zap bacteria than it does to kill pests.

Or, of course, people could hold out for warm, freshly baked cookies.

Ask a classroom of children to draw a scientist, and you’ll see plenty of Crayola-colored lab coats, goggles and bubbling beakers. That image hasn’t changed much since the 1960s. But the person wearing the lab coat is shifting.

A new analysis finds that more female scientists have appeared in kids’ drawings in recent decades — going from nearly nonexistent in the 1960s to about a third in 2016.

“A lot has changed since the 1960s,” says David Miller, a Ph.D. candidate in psychology at Northwestern University who reports the findings with colleagues March 20 in Child Development.
The first of many “draw-a-scientist” studies asked nearly 5,000 children to draw a scientist between 1966 and 1977. “Of those 5,000 drawings,” Miller says, “only 28 … depicted a female scientist.” That’s just 0.6 percent.

Today, “more women are becoming scientists, and there’s some evidence that female scientists are being represented more in the media,” he says. For instance, in a content analysis of the magazine Highlights for Children, 13 percent of people pictured in science feature stories of the 1960s were women or girls, compared with 44 percent in the 2000s.
To look for changes in children’s perceptions over time, the researchers conducted a meta-analysis, combining data from 78 studies that included a total of more than 20,000 U.S. children in kindergarten through 12th grade.

On average, 28 percent of children drew female scientists in studies conducted from 1985 to 2016, the researchers found.

What hasn’t changed much: Kids pick up stereotypes by gender as they grow up. At age 6, girls in the more recent studies drew female scientists about 70 percent of the time. By age 16, 75 percent drew male scientists.

“This is a critical period in which kids are learning stereotypes,” Miller says. “It’s important that teachers and parents present diverse examples of both male and female scientists.”

Editors’ note: This story was corrected on March 21, 2018, to note that by age 16, girls drew only 25 percent of scientists as female.

Off the Kohala coast on the Big Island of Hawaii, Christine Gabriele spots whale 875. The familiar propeller scar on its left side and the shape of its dorsal fin are like a telltale fingerprint. Gabriele, a marine biologist with the Hawaii Marine Mammal Consortium, confirms the whale’s identity against her extensive photo catalog. Both Gabriele and this male humpback have migrated to this Pacific Island from Southeastern Alaska.

In those Alaska summer feeding grounds, Gabriele sees the same 300 or so whales “again and again.” But winter brings more than 10,000 whales to the waters of Hawaii from all over the North Pacific. Spotting 875 is like finding a needle in a haystack.
Gabriele is here today to focus on the slew of worrisome bumps on the familiar traveler’s flank. The bumps are separate from the usual ones bulging from the head of a humpback ( Megaptera novaeangliae ). Those iconic oversize hair follicles are thought to be part of the sensory system. The smaller body bumps look more like bad acne or an allergic reaction. Noted on rare occasions in the 1970s, the condition called nodular dermatitis has become much more prevalent. These days, Gabriele and colleagues see these skin lesions on over 75 percent of Hawaii’s humpback visitors.
The bumps coincide with other suggestions of declining health in the whales. In the nearly three decades that Gabriele has been studying whales, she would not describe the animals as skinny. Now, often “you can see their shoulder blades,” she says. “They look angular rather than round.”
Gabriele’s team is trying to figure out the cause of the bumps, comparing tissue samples from bumpy and nonbumpy whales. Several times per week, a small team sets out on the water, research permits in hand. Once a whale pod is spotted, Gabriele’s colleague Suzanne Yin zooms in with a camera and volunteer Kim New enlarges the image on her iPad, examining skin on the whale’s flanks and behind the blowhole to confirm if it’s bumpy or not. Gabriele carefully steers the boat so that Yin can shoot a biopsy dart from a crossbow.
The dart “takes a little plug of skin and blubber … about the size of a pencil eraser,” Gabriele says. The dart bounces off the whale and floats until the researchers can grab it. When darted, some whales dive; others show no reaction at all.

Collaborators from the National Institute of Standards and Technology’s Hollings Marine Laboratory in Charleston, S.C., are analyzing the skin for trace elements. National Marine Fisheries Service lab staff are studying the blubber for organic pollutants like PCBs and flame retardants. Preliminary results suggest that bumpy whales differ from nonbumpy in levels of manganese and a few other trace elements. Gabriele eagerly awaits the full analyses to make sense of what she’s seeing among the migratory creatures.

A chicken eggshell has a tricky job: It must protect a developing chick, but then ultimately let the chick break free. The secret to its success lies in its complex nanostructure — and how that structure changes as the egg incubates.

Chicken eggshells are about 95 percent calcium carbonate by mass. But they also contain hundreds of different kinds of proteins that influence how that calcium carbonate crystalizes. The interaction between the mineral crystals and the proteins yields an eggshell that’s initially crack-resistant, while making nanoscale adjustments over time that ultimately let a chick peck its way out, researchers report online March 30 in Science Advances.
Researchers used a beam of ions to cut thin cross sections in chicken eggshells. They then analyzed the shells with electron microscopy and other high-resolution imaging techniques. The team found that proteins disrupt the crystallization of calcium carbonate, so that what seems at low resolution to be neatly aligned crystals is actually a more fragmented jumble. This misalignment can make materials more resilient: Instead of spreading unimpeded, a crack must zig and zag through scrambled crystals.
Lab tests back up that finding: The researchers added a key shell-building protein called osteopontin to calcium carbonate to yield crystals like those seen in the eggshells. The presence of that protein makes calcium carbonate crystals form in a nanostructured pattern, rather than smooth and even crystal, study coauthor Marc McKee, a biomineralization researcher at McGill University in Montreal, and colleagues found.

The team also found structural variation on a minute scale throughout the eggshell, though it’s only about a third of a millimeter thick. Inner layers have less osteopontin, leading to bigger nanostructures. That may make the inner shell less resilient than the outer shell, which makes sense, McKee says­­. The outer shell needs to be hard enough to protect the chick, while the inner shell nourishes the developing chick.

Over time, the inner layers of the shell dissolve through a chemical reaction, releasing calcium to build a chick’s developing bones. The eggshell undergoes structural changes to facilitate that process, McKee and his colleagues found.

The researchers compared fertilized eggs incubated for 15 days to nonfertilized eggs. Over time, the nanostructures toward the inner shell became smaller in fertilized eggs, but remained the same in the nonfertilized eggs. The change gives the inside of the eggshell a bumpier texture, and by extension, more surface area. That provides more space for that shell-dissolving chemical reaction to take place, the researchers propose. The reaction also thins the shell overall, making it easier for a chick to break through from the inside when it’s time to hatch.

Advances in imaging technology are helping scientists find new details like this even in objects as familiar as a chicken eggshell, says Lara Estroff, a materials scientist at Cornell University who wasn’t part of the research. In connecting the eggshell’s functionality with its fine-grain structure, the new study could provide inspiration for designing new kinds of materials with specific properties.

Your brain might make new nerve cells well into old age.

Healthy people in their 70s have just as many young nerve cells, or neurons, in a memory-related part of the brain as do teenagers and young adults, researchers report in the April 5 Cell Stem Cell. The discovery suggests that the hippocampus keeps generating new neurons throughout a person’s life.

The finding contradicts a study published in March, which suggested that neurogenesis in the hippocampus stops in childhood (SN Online: 3/8/18). But the new research fits with a larger pile of evidence showing that adult human brains can, to some extent, make new neurons. While those studies indicate that the process tapers off over time, the new study proposes almost no decline at all.
Understanding how healthy brains change over time is important for researchers untangling the ways that conditions like depression, stress and memory loss affect older brains.

When it comes to studying neurogenesis in humans, “the devil is in the details,” says Jonas Frisén, a neuroscientist at the Karolinska Institute in Stockholm who was not involved in the new research. Small differences in methodology — such as the way brains are preserved or how neurons are counted — can have a big impact on the results, which could explain the conflicting findings. The new paper “is the most rigorous study yet,” he says.

Researchers studied hippocampi from the autopsied brains of 17 men and 11 women ranging in age from 14 to 79. In contrast to past studies that have often relied on donations from patients without a detailed medical history, the researchers knew that none of the donors had a history of psychiatric illness or chronic illness. And none of the brains tested positive for drugs or alcohol, says Maura Boldrini, a psychiatrist at Columbia University. Boldrini and her colleagues also had access to whole hippocampi, rather than just a few slices, allowing the team to make more accurate estimates of the number of neurons, she says.
To look for signs of neurogenesis, the researchers hunted for specific proteins produced by neurons at particular stages of development. Proteins such as GFAP and SOX2, for example, are made in abundance by stem cells that eventually turn into neurons, while newborn neurons make more of proteins such as Ki-67. In all of the brains, the researchers found evidence of newborn neurons in the dentate gyrus, the part of the hippocampus where neurons are born.

Although the number of neural stem cells was a bit lower in people in their 70s compared with people in their 20s, the older brains still had thousands of these cells. The number of young neurons in intermediate to advanced stages of development was the same across people of all ages.

Still, the healthy older brains did show some signs of decline. Researchers found less evidence for the formation of new blood vessels and fewer protein markers that signal neuroplasticity, or the brain’s ability to make new connections between neurons. But it’s too soon to say what these findings mean for brain function, Boldrini says. Studies on autopsied brains can look at structure but not activity.

Not all neuroscientists are convinced by the findings. “We don’t think that what they are identifying as young neurons actually are,” says Arturo Alvarez-Buylla of the University of California, San Francisco, who coauthored the recent paper that found no signs of neurogenesis in adult brains. In his study, some of the cells his team initially flagged as young neurons turned out to be mature cells upon further investigation.

But others say the new findings are sound. “They use very sophisticated methodology,” Frisén says, and control for factors that Alvarez-Buylla’s study didn’t, such as the type of preservative used on the brains.

Composting waste is heralded as being good for the environment. But it turns out that compost collected from homes and grocery stores is a previously unknown source of microplastic pollution, a new study April 4 in Science Advances reports.

This plastic gets spread over fields, where it may be eaten by worms and enter the food web, make its way into waterways or perhaps break down further and become airborne, says Christian Laforsch, an ecologist at the University of Bayreuth in Germany. Once the plastic is spread across fields, “we don’t know its fate,” he says.
That fate and the effects of plastic pollution on land and in freshwater has received little research attention compared with marine plastic pollution, says ecologist Chelsea Rochman of the University of Toronto. Ocean microplastics have gained notoriety thanks in part to coverage of the floating hulk of debris called the great Pacific garbage patch (SN Online: 3/22/18).

But current evidence suggests that plastic pollution is as prevalent in land and freshwater ecosystems as it is in the oceans, where it’s found “from the equator to the poles,” says Rochman, author of a separate commentary on the state of plastic pollution research published in the April 6 Science. Plastic “is seen in the high Arctic, where we suspect it comes down in rain. We know it’s in drinking water, in our seafood and spread on our agricultural fields,” she says.

Laforsch and his colleagues looked at several different kinds of biowaste that’s composted and spread on farmland in Germany, including household compost and grass clippings, supermarket waste and grain silage leftover from biogas production.

Compost samples taken from supermarket waste contained the greatest amount of plastic particles, with 895 pieces larger than 1 millimeter found per kilogram of dry weight. Household compost in contrast contained 20 and 24 particles per kg of dry weight, depending on the size of the sieves used to sift the compost. The detritus included bits of polyester and a lot of styrene-based polymers, commonly used in food packaging. Almost no particles were found in samples of silage from biogas production.
“I never thought about plastic in compost ending up as fertilizer. But when you think about it, it makes sense,” says environmental scientist Ad Ragas of Radboud University in Nijmegen, The Netherlands, who wasn’t involved in the work. A crate of rotting cucumbers wrapped in plastic that gets chucked, those stickers on every tomato in a bunch — that packaging doesn’t disappear.

Ragas says compost probably doesn’t contribute as much plastic to the environment as other sources, such as sewage treatment plant sludge, which contains polyester debris from clothes washers, and runoff from streets, which can be loaded with particles of synthetic rubber used in tires. But the compost contribution deserves investigation, Ragas says. “This triggers a lot of questions we haven’t studied yet.”

Those questions include possible effects on different organisms, from plants to earthworms to birds to people, Rochman says. Those effects will likely differ depending on the kind of plastic, which varies depending on its starting polymer and the additives used to impart certain qualities such as flexibility, sturdiness or durability under ultraviolet light.

“We are not saying we should get rid of all plastics,” Rochman says. “But we do need to start thinking of plastics as a persistent global pollutant.”

A hellishly unprecedented scene — what anthropologists suspect is the largest known child sacrifice — has been unearthed on a bluff overlooking Peru’s northern shoreline.

Around 550 years ago, members of the Chimú empire ritually killed and buried at least 140 children, ages 5 to 14, and 200 young llamas, says a team led by Gabriel Prieto of the National University of Trujillo in Peru and John Verano of Tulane University in New Orleans.

“There are no other examples of child sacrifices anywhere in the world that compare to the magnitude of this Chimú event,” Verano says. The discovery was announced April 26 by National Geographic in Washington, D.C.
Except for a few incomplete skeletons, excavated children and llamas displayed cuts on their breast bones and dislocated ribs indicating that their chests had been sliced open. Three adults buried nearby on the bluff, including two women with violent head wounds, may have participated in the sacrifice.

Radiocarbon dating, mainly of ropes left around the llamas’ necks, puts the event at around 1450, shortly before the Inca conquered the Chimú in 1470.

A dried mud layer covering some of the sandy graves possibly resulted from flooding caused by massive rains. Agricultural crises triggered by repeated flooding might have led Chimú leaders to sacrifice children to their gods, Verano suggests.