CHICAGO — Cooling stars could shine some light on the nature of dark matter.

Certain types of stars are cooling faster than scientists expect. New research suggests that the oddity could hint at the presence of hypothetical particles known as axions. Such particles have also been proposed as a candidate for dark matter, the unknown substance that makes up most of the matter in the universe.

Researchers analyzed previous measurements of white dwarf variable stars, which periodically grow dimmer and brighter at a rate that indicates how fast the star is cooling. For all five stars measured, the cooling was larger than predicted. Likewise, red giant stars have also shown excess cooling.
Considering each result on its own, “each one is not that interesting,” says physicist Maurizio Giannotti of Barry University in Miami Shores, Fla., who presented the result at the International Conference on High Energy Physics on August 4. But taken together, the consistent pattern could indicate something funny is going on.

After evaluating several possible explanations for the cooling of the stars, the researchers concluded that the axion explanation was most likely — barring some more mundane explanation like measurement error. Axions produced within the star stream outward, carrying energy away as they go, and cooling the star.

Although it may be more likely that the phenomenon will eventually be chalked up to measurement errors, it’s important to take note when something doesn’t add up, Giannotti says. “We can’t ignore the small hints.”

Some guys really know how to kill a moment. Among Mediterranean fish called ocellated wrasse (Symphodus ocellatus), single males sneak up on mating pairs in their nest and release a flood of sperm in an effort to fertilize some of the female’s eggs. But female fish may safeguard against such skullduggery through their ovarian fluid, gooey film that covers fish eggs.

Suzanne Alonzo, a biologist at Yale University, and her colleagues exposed sperm from both types of males to ovarian fluid from female ocellated wrasse in the lab. Nesting males release speedier sperm in lower numbers (about a million per spawn), while sneaking males release a lot of slower sperm (about four million per spawn). Experiments showed that ovarian fluid enhanced sperm velocity and motility and favored speed over volume. Thus, the fluid gives a female’s chosen mate an edge in the race to the egg, the researchers report August 16 in Nature Communications.

While methods to thwart unwanted sperm are common in species that fertilize within the body, evidence from Chinook salmon previously hinted that external fertilizers don’t have that luxury. However, these new results suggest otherwise: Some female fish retain a level of control over who fathers their offspring even after laying their eggs.

WASHINGTON — To human thinking, songbird nests now seem to have evolved backwards: The most distant ancestor probably built complex, roofed structures. Simple open-top cup nests came later.

More than 70 percent of songbird species today build some form of that iconic open cup, evolutionary biologist Jordan Price said August 18 at the North American Ornithological Conference. Yet looking at patterns of nest style across recent bird family trees convinced him that the widespread cup style probably isn’t just a leftover from deepest bird origins.
Old bird lineages thought to have branched out near the base of the avian family tree tend to have plentiful roof-builders. Price, of St. Mary’s College of Maryland, and coauthor Simon Griffith of Macquarie University in Sydney reconstructed probable nest styles for various branching points in the tree. That reconstruction suggests that open cups showed up independently four times among songbirds, such as in bowerbirds and honeyeaters, the scientists conclude. Also, here and there, some of the earlier cup builders reverted to roofs.

Price said he began musing about nest history while reveling in Australia’s birds during a sabbatical with Griffith. Evolutionary biologists have proposed that the broader Australasia region was probably the starting point for the rise of songbirds. Price said that it isn’t clear what drove a switch from protective roofs to what looks like the quick and dirty alternative of open cups.

Swirling clouds blanket Jupiter’s northern and southern poles in the first closeup images of the planet taken by NASA’s Juno spacecraft. Such intimate views of Jupiter have never been seen before.

Juno snapped a shot of the gas giant’s northern side in an August 27 flyby, from a distance of 195,000 kilometers. The prominent bands that ring Jupiter’s middle fade at the poles, replaced with hurricane-like whorls. The poles are nearly invisible from Earth, making a specialized space mission like Juno necessary to capture such rare images.
Jupiter’s poles are unlike those of its fellow gas giant, Saturn. That planet has a giant cyclone encircling each of its poles (SN: 11/8/08, p. 9).

During the flyby, Juno’s eight science instruments were furiously collecting data. An infrared camera imaged Jupiter’s southern aurora, observing the phenomenon in detail for the first time. And another instrument recorded 13 hours of radio emissions from Jupiter’s auroras, which scientists converted into an eerie-sounding audio clip (listen to the audio clip in video below).

Juno is designed to study Jupiter’s interior, to better understand what lies beneath its clouds (SN: 6/25/16, p. 16). The spacecraft arrived at Jupiter on July 4. Its science instruments were switched off during its approach, so this is the first nearby glimpse scientists have seen. Juno will perform 37 orbits of Jupiter during its mission.

On the dock in Buenaventura, Colombia, the fisherman needed help identifying his catch. “I don’t have any clue what this is,” he said, holding a roughly 50-centimeter-long, grayish-brown fish. Gustavo Castellanos-Galindo, a fish ecologist, recalls the conversation from last October. “I said, ‘Well, this is a cobia, and it shouldn’t be here.’ ”

The juvenile cobia had probably escaped from a farm off the coast of Ecuador that began operating earlier in 2015, Castellanos-Galindo and colleagues at the World Wildlife Fund in Cali, Colombia, reported in March in BioInvasions Records. Intruders had probably cut a net cage, perhaps intending to catch and sell the fish. Roughly 1,500 cobia fled, according to the aquaculture company Ocean Farm in Manta, Ecuador, which runs the farm. Cobia are fast-swimming predators that can migrate long distances and grow to about 2 meters long. The species is not native to the eastern Pacific, but since the escape, the fugitives have been spotted from Panama to Peru.
The cobia getaway is not an isolated incident. Aquaculture, the farming of fish and other aquatic species, is rapidly expanding — both in marine and inland farms. It has begun to overtake wild-catch fishing as the main source of seafood for the dinner table. Fish farmed in the ocean, such as salmon, sea bass, sea bream and other species, are raised in giant offshore pens that can be breached by storms, predators, fish that nibble the nets, employee error and thieves. Global numbers for escapes are hard to come by, but one study of six European countries over three years found that nearly 9 million fish escaped from sea cages, according to a report published in Aquaculture in 2015.

Researchers worry that these releases could harm wildlife, but they don’t have a lot of data to measure long-term effects. Many questions remain. A study out of Norway published in July suggests that some domesticated escapees have mated extensively with wild fish of the same species, which could weaken the wild population. Scientists also are investigating whether escaped fish could gobble up or displace native fish.

Worst-case scenario: Escaped fish spread over large areas and wreak havoc on other species. From toxic toads overrunning Australia and Madagascar (SN Online: 2/22/16) to red imported fire ants in the United States, invasive species are one of the planet’s biggest threats to biodiversity, and they cost billions of dollars in damage and management expenses. Not every introduced species has such drastic effects, but invasives can be tough to eliminate.
While researchers try to get a handle on the impact of farm escapes, farmers are working to better contain the fish and reduce the ecological impact of the runaways. Some countries have tightened their aquaculture regulations. Researchers are proposing strategies ranging from new farm designs to altering fish genetics. As aquaculture becomes a widespread means to feed the planet’s protein-hungry people, the ecological effects are getting more attention.
If escapees weaken native wildlife, “we’re solving a food issue globally and creating another problem,” says population geneticist Kevin Glover of Norway’s Institute of Marine Research in Bergen. Norway, a top producer of marine fish, has done much of the research on farm escapes.

Not born to be wild
Fish farming is big business. In 2014, the industry churned out 73.8 million metric tons of aquatic animals worth about $160 billion, according to a report in July from the Food and Agriculture Organization of the United Nations in Rome.

Nearly two-thirds of this food comes from inland freshwater farms such as ponds, used in Asia for thousands of years. The rest is grown on marine and coastal farms, where farmed fish live in brackish ponds, lagoons or cages in the ocean.
Freshwater fish can escape from pond farms during events such as floods. Some escapees, such as tilapia, have hurt native species by competing with and eating wild fish. But sea farming has its own set of problems. The physical environment is harsh and cages are exposed to damaging ocean waves and wind, plus boats and predator attacks.

Salmon is one of the most heavily farmed marine fish. In some areas, the number of farmed salmon dwarfs wild populations. Norway’s marine farms hold about 380 million Atlantic salmon, while the country’s rivers are home to only about 500,000 wild spawning Atlantic salmon.

In the four decades that farmers have been cultivating Atlantic salmon, farmed strains have diverged from their wild cousins. When both are raised in standard hatchery conditions, farm-raised salmon can grow about three to five times heavier than wild salmon in the first year of life.

Salmon raised in farms also tend to be less careful; for instance, after being exposed to an artificial predator, they emerge more quickly from hiding places than wild fish. This risky behavior may have arisen partly because the fish haven’t faced the harsh challenges of nature. “The whole idea of a hatchery is that everything gets to survive,” says Philip McGinnity, a molecular ecologist at University College Cork in Ireland. Farmed fish don’t know better.
These differences are bad news for hybrid offspring and wild fish. In early experiments, hybrid offspring of farmed and wild salmon tended to fare poorly in the wild. In the 1990s, McGinnity’s team measured these fish’s “lifetime success” in spawning rivers and the ocean. Compared with wild salmon, hybrid offspring had a lifetime success rate about a fourth to a half as high. Around the same time, a team in Norway found that when wild fish swam with farmed fish in their midst, the number of wild offspring that survived long enough to leave the river to head to the ocean was about one-third lower than expected, perhaps because the fast-growing farmed offspring gobbled a lot of food or claimed territory.

“There was truly reason to be concerned,” says Ian Fleming, an evolutionary ecologist at Memorial University of Newfoundland in St. John’s, Canada, who was part of the Norway team.

Recent work supports the idea that farmed fish could crowd out wild fish by hogging territory in a river. In a study published last year in the Journal of Fish Biology, researchers found that the survival rate of young wild salmon dropped from 74 to 53 percent when the fish were raised in the same confined stream channels as young farmed salmon rather than on their own. When the channels had an exit, more wild fish departed the stream when raised with farmed salmon than when raised alone.

“These are fish that give up the territory and have to leave,” says study coauthor Kjetil Hindar, a salmon biologist at the Norwegian Institute for Nature Research in Trondheim.

A weaker mix
To find out how much escaped fish had genetically mingled with wild fish, Glover’s team obtained historical samples of salmon scales collected from 20 rivers in Norway before aquaculture became common. The researchers compared the DNA in the scales with that of wild salmon caught from 2001 to 2010 in those rivers.

Wild salmon in five of the 20 rivers had become more genetically similar to farmed fish over about one to four decades, the team reported in 2013 in BMC Genetics. In the most affected population, 47 percent of the wild fish’s genome originated from farmed strains. “We’re talking about more or less a complete swamping of the natural gene pool,” Glover says. Imagine buckets of paint — red, blue, green — representing each river, he says, and pouring gray paint into each one.

Interbreeding was less of an issue where wild fish were plentiful. The farmed fish aren’t good at spawning, so they won’t mate much if a lot of wild competitors are present. But in sparse populations, the farm-raised salmon may be able to “muscle in,” Glover says.
A larger study by Hindar’s team, published in July in the ICES Journal of Marine Science, showed that genetic mixing between wild and farmed salmon is happening on a large scale in Norway. Among 109 wild salmon populations, about half had significant amounts of genetic material from farmed strains that had escaped. In 27 populations, more than 10 percent of the fish’s DNA came from farmed fish.

What does that mean for the offspring? Each salmon population has adapted to survive in its habitat — a certain river, at a specific temperature range or acidity level. When farmed fish mate with wild fish, the resulting offspring may not be as well-suited to live in that environment. Over generations, as the wild population becomes more similar to farmed salmon, scientists worry that the fish’s survival could drop.

Scientists at several institutions in Norway are exploring whether genetic mixing changes the wild salmon’s survival rates, growth and other traits. Making a definitive link will be difficult. Other threats such as climate change and pollution also are putting stress on the fish.

If escapes can be stopped, wild salmon may rebound. Natural selection will weed out the weakest fish and leave the strongest, fish that got a lucky combination of hardy traits from their parents. But Glover worries that, just as a beach can’t recover if oil is spilled every year, the wild population can’t rally if farmed fish are continually pumped in: “Mother Nature cannot clean up if you constantly pollute.”

Uncertain consequences
In places where the species being farmed is not naturally abundant, researchers are taking a look at whether escapes could upset native ecosystems. For instance, European sea bass sometimes slip away from farms in the Canary Islands, where (except for a few small populations on the eastern end) the species doesn’t normally live.

In February 2010, storms battered cages at the island of La Palma, “like a giant tore up all the nets,” says Kilian Toledo-Guedes, a marine ecologist at the University of Alicante in Spain. About 1.5 million fish — mostly sea bass — reportedly swam free.

A couple of weeks later, the number of sea bass in nearby waters was “astounding,” he says. “I couldn’t see the bottom.” Sea bass density in waters near the farm was 162 times higher than it had been at the same time the previous year, his team reported in 2014 in Fisheries Management and Ecology. Fisheries data showing a spike in catches of sea bass by local fishermen that January also suggested that large unreported escapes had occurred before the storm.

Despite being raised in captivity, where they are fed pellets, some of the farmed fish learn to hunt. The researchers found that escaped sea bass caught four months after the 2010 farm breakdown had eaten mostly crabs. Sea bass from earlier escapes that had been living in the wild for several years had eaten plenty of fish as well. The results, reported in 2014 in Marine Environmental Research, suggest that escapees start by catching easy targets such as crustaceans and then learn to nab faster-moving fish.

So far, though, scientists have not seen clear signs that the escapees damaged the ecosystem. The density of sea bass around La Palma had fallen drastically by October 2010 and continued to decline the next year, probably because some fish couldn’t find enough to eat, while others were caught by fishermen or predators, according to a 2015 study by another team in the Journal of Aquaculture Research & Development.

Catches of small fish that sea bass eat, such as parrot fish, did not drop significantly after the 2010 escape or after a similar large escape in 1999, says study coauthor Ricardo Haroun, a marine conservation researcher at the University of Las Palmas de Gran Canaria in Spain. While he agrees that the industry should try to prevent escapes, he sees no evidence that the runaways are suppressing wild species.
If the escaped fish can breed and multiply, the risk of harming native species rises. In a study published in Marine Ecology in 2012, Toledo-Guedes and colleagues reported finding sexually mature sea bass around the central island of Tenerife. But Haroun says the water is too warm and salty for the fish to reproduce, and his team did not see any juveniles during their surveys of La Palma, nor have they heard any reports of juveniles in the area. Toledo-Guedes says that more extensive studies, such as efforts to catch larvae, are needed before reproduction can be ruled out.

Similarly, researchers can’t predict the consequences of the cobia escape in Ecuador. The water is the right temperature for reproduction, and these predators eat everything from crabs to squid. Castellanos-Galindo believes that farming cobia in the area is a mistake because escapes will probably continue, and the fish may eventually form a stable population in the wild that could have unpredictable effects on native prey and other parts of the ecosystem. He points to invasive lionfish as a cautionary tale: These predators, probably released from personal aquariums in Florida, have exploded across the Caribbean, Gulf of Mexico and western Atlantic and are devouring small reef fish.

The situation for cobia may be different. Local sharks and other predators will probably eat the escapees, whereas lionfish have few natural predators in their new territory, argues Diego Ardila, production manager at Ocean Farm. Milton Love, a marine fish ecologist at the University of California, Santa Barbara, also notes that lionfish settle in one small area, but cobia keep moving, so prey populations might recover after the cobia have moved on.

Not all introduced species become established or invasive, and it can take decades for the effects to become apparent. “Time will tell what happens,” says Andrew Sellers, a marine ecologist at the Smithsonian Tropical Research Institute in Panama City. “Basically, it’s just up to the fish.”

A slippery problem
Once fish have fled, farmers sometimes enlist fishermen to help capture the escapees. Professional fishermen caught nearly one-quarter of the sea bass and sea bream that escaped after the Canary Islands breach. On average, though, only 8 percent of fish are recaptured after an escape, according to a study published in June in Reviews in Aquaculture. Given the recapture failures, farmers and policy makers should focus on preventing escapes and maintaining no-fishing zones around farms to create a “wall of mouths,” local predators that can eat runaway fish, says coauthor Tim Dempster, a sustainable aquaculture researcher at the University of Melbourne in Australia.

Technical improvements could help. The Norwegian government rolled out a marine aquaculture standard in 2004 that required improvements, such as engineering nets, moorings and other equipment to withstand unusually strong storms. Compared with the period 2001–2006, the average number of Atlantic salmon escaping annually from 2007–2009 dropped by more than half. Ocean Farm in Ecuador has tightened security, increased cage inspections and switched to stronger net materials; no cobia have escaped since last year’s break-in, says Samir Kuri, the company’s operations manager.
Some companies raise fish in contained tanks on land to avoid polluting marine waters, reduce exposure to diseases and control growth conditions. But the industry is largely reluctant to adopt this option until costs come down. The money saved from reducing escapes probably wouldn’t make up for the current start-up expense of moving to land. The 242 escape events analyzed in the 2015 Aquaculture study cost farmers about $160 million. By one estimate, establishing a land-based closed-containment farm producing about 4,000 metric tons of salmon annually — a small haul by industry standards — would cost $54 million; setting up a similar-sized sea-cage farm costs $30 million.

Another solution is to raise fish that have three sets of chromosomes. These triploid fish, produced by subjecting fertilized eggs to a pressure shock, can’t reproduce and therefore wouldn’t proliferate or pollute the wild gene pool.

“The only ultimate solution is sterility,” Norway’s Glover says. “Accidents happen.” Escaped triploid salmon are less likely to disrupt mating by distracting females from wild males, the researchers wrote in Biological Invasions in May. But triploid fish don’t grow as well when the water is warmer than about 15° Celsius, and consumers might be reluctant to accept these altered salmon.

Although the ecological effects of fish farm escapes may take a long time to play out, most researchers agree that we shouldn’t take chances with the health of the oceans, which already face threats such as climate change, pollution and overfishing. With the aquaculture industry expanding at about 6 percent per year, farmers will have to keep improving their practices if they are to stay ahead of the runaway fish.

Don’t drive and play Pokémon Go.

Catching Pokémon — by flicking cartoon balls at cartoon creatures on the screen of a mobile device — while behind the wheel isn’t safe, a new study suggests. That conclusion is hardly surprising. “Most people would say it’s not a good idea,” says David Strayer, a cognitive neuroscientist at the University of Utah in Salt Lake City not involved in the study. Playing an immersive video game such as Pokémon Go while driving may be even more dangerous than reading a text message while driving, because it pulls attention away from the road longer and with more lasting effects, he says.
Yet alarming numbers of people are doing just that, researchers report online September 16 in JAMA Internal Medicine. A search of Twitter posts that contained “Pokémon” and “driving,” “drives,” “drive” or “car” turned up more than 345,000 tweets during a 10-day period in July. Of those, 113,993 tweets indicated that a driver, passenger or pedestrian was distracted by the augmented-reality game. “This is an incredibly large number,” says study coauthor John Ayers of San Diego State University, and likely an underestimate of the number actually playing the game while driving.

Some 18 percent of those tweets indicated a driver was playing the game; 11 percent came from distracted passengers and 4 percent from pedestrians, Ayers and colleagues found. News reports during that same time period showed that drivers playing Pokémon Go caused 14 car crashes.

Pokémon Go was designed to encourage people to explore their neighborhoods. Scattered PokéStops dispense Pokémon-catching tools, and the virtual creatures pop into existence as a player moves. Players incubate and hatch eggs containing the creatures by covering more ground. Rewards for playing in motion are unique to the game, Ayers says. “When you text, the more you drive or the more you walk you don’t get more messages, but with Pokémon Go, the feedback mechanism fosters dangerous behaviors.”

Passengers trying to “catch them all” may direct drivers to stop, turn or make other dangerous maneuvers, Strayer says. Pedestrians playing the game may walk into traffic.

The game does ask players to confirm they are passengers if it senses too-fast motion. But game makers could build more safety restrictions into the game such as freezing it at driving speeds and keeping it inaccessible for a short while after a car comes to a stop to discourage stoplight play breaks, Ayers suggests.

A summertime cold snap can, quite literally, take the bloom off the rose. Not so for Scotch heather — and now scientists know why.

Thick cell walls and narrow plumbing in the alpine shrub’s stems stop deadly ice crystals from spreading to its fragile flowers during sudden summer freezes, researchers report September 15 in PLOS ONE. That lets the flowers survive and the plant make seeds even if temperatures dip below freezing.

Once ice crystals start to form inside of a plant, they can spread very quickly, says Gilbert Neuner, a botanist at the University of Innsbruck in Austria who led the study. Those sharp crystals can destroy plant cells — and flowers are particularly sensitive. So plants living in cold climes have developed strategies to confine ice damage to less harmful spots.
Neuner and his team used infrared imaging to measure heat given off by Scotch heather (Calluna vulgaris) plants as they freeze. That technique revealed where and when ice was forming. And looking at thin slices of the plant under a microscope let the scientists pick apart the structure of the plant’s ice barrier.
Cells at the base of the flower stalks had thicker walls and were packed more closely together than elsewhere in the plant, the team found. In the same area, the pipelines that carry water up the plant — called xylem — were narrower and had fewer points where ice could potentially sneak through. Those modifications let the plants “supercool” their flowers. That is, even when the flowers chilled to below zero degrees Celsius, they contained liquid water instead of ice. Ice didn’t form in the Scotch heather flowers until far below normal freezing temperatures, ‒22° C, and ice that formed elsewhere in the plant didn’t spread to the flowers.
Other species sometimes put up temporary ice blockades, for instance to protect overwintering buds. But that usually cuts off the flow of water through the xylem — fine if a plant is dormant over the winter, but flowers facing a sudden summer freeze need a continuous supply of water. Scotch heather gets around this problem by threading its xylem right through the icy barrier.

Membranes let water pass between the xylem cells, and these membranes might ultimately control the spread of ice crystals in C. vulgaris, Neuner suspects. Tiny pores in the membranes are too small to let ice crystals through the barrier. And when water molecules are found inside such small holes, the molecules are bound so tightly to the structures around them that they behave more like a gel instead of crystalizing into ice. The team hopes to test the idea in future studies.
Other flowering alpine plants could use a similar strategy. “I don’t think that this is unique to this plant,” says Sanna Sevanto, a tree physiologist at Los Alamos National Laboratory in New Mexico who wasn’t involved in the study. “It’s just that nobody has looked at it.”

Concussions, particularly those among children playing sports, are on parents’ minds. The fervor over NFL players’ brains and those of other elite athletes has trickled all the way down to mini-kicker soccer teams and peewee football leagues. And parents are right to be worried. Concussions seem to be on the rise. From 1990 to 2014, the rate of concussions in youth soccer players jumped by over 1,000 percent, a recent study estimated.

This increase might be driven in part by more inclusive definitions of concussion, a common form of traumatic brain injury that can come with headaches, confusion and memory trouble. More awareness might also drive numbers up; because parents, coaches and referees are more alert to the possibility of a concussion, more kids might be getting the diagnosis. But games may have become more competitive, too, leading to more body clashes that jolt the brain.

When a kid gets concussed, the instinct of many parents, myself included, is to cocoon their child, limiting social interaction, activity and even sleep, a recent poll conducted by researchers at UCLA suggests. The survey asked about 500 parents about how they would handle a child who had symptoms a week after a concussion. Eighty-four percent of the respondents said they would restrict their child’s physical activity for the week after the injury, 62 percent said they would take away their child’s electronics and 77 percent said they’d even wake their child up during the night. But those measures “can certainly be unhelpful,” says pediatric neurologist Christopher Giza of UCLA. “There’s some evidence it may be harmful.”

Giza points out that each child is unique, and the recovery process ought to be tailored by his or her medical team to best help the individual. But in general, excessive rest and isolation might work against kids. Last year, scientists found that children and teenagers who strictly rested for five days reported more symptoms than those who rested for one to two days. What’s more, recovery took longer for the kids who got the five-day break.

Complete isolation and rest may cause children to grow anxious and despondent, Giza says. With their normal routines interrupted, they may focus more on their symptoms. Social interactions, even those that come via a screen, may help kids feel better sooner. Gentle exercise, such as walks and swimming, is also a good thing. And despite what parents may have heard, children with concussions need sleep to recover. “Waking the kid up every few hours only worsens symptoms,” Giza says. It’s not surprising that a week of poor sleep can dial up fatigue, irritability and slow thinking.

There is one very important limit that should still be respected for kids recovering from concussions: No more head knocks. Concussions in quick succession can be extra pernicious for the brain. That means kids shouldn’t return to any sport that puts them at risk for a second concussion until they are fully recovered. In a concussion’s aftermath, reflexes are blunted, balance may be off and thinking may be slow, Giza says. Those deficits put children at more risk for getting hit.

Some sports leagues have begun changing their rules to make the game safer. This season, 5- to 10-year-olds playing in a Pop Warner football game, for instance, will no longer have kickoffs, a game-starting play responsible for an inordinate amount of concussions. Game tweaks like that, along with more vigilant coaches and parents, will help protect these little brains.

Like two siblings with divergent personalities, a type of particle has shown signs of behaving differently than its antimatter partner. It’s the first time evidence of matter-antimatter differences have been detected in decays of a baryon — a category of particle that includes protons and neutrons. Such matter-antimatter discrepancies are key to explaining how the universe came to be made mostly of matter, scientists believe.

The result is “the first measurement of its kind,” says theoretical physicist Yuval Grossman of Cornell University. “Wow, we can actually see something that we’ve never seen before.”
Evidence of matter-antimatter differences in decays of baryons — particles which are composed of three smaller particles known as quarks — has eluded scientists until now. Previous experiments have found differences between matter and antimatter varieties of mesons, which are made up of one quark and one antiquark, but never in baryons.

For most processes, the laws of physics would be the same if matter were swapped with antimatter and the universe’s directions were flipped, as if reflected in a mirror. But when this principle, known as CP symmetry (for “charge parity”), is violated, matter and antimatter act differently. Now, scientists have found hints of CP violation in the decays of a particle known as a lambda-b baryon.

Scientists with the LHCb experiment, located at the Large Hadron Collider near Geneva, reported the result online September 16 at arXiv.org. They found that when the lambda-b baryon decays, the particles produced by the decay speed away at different angles and momenta for matter and antimatter versions of the baryon. (LHCb scientists declined to comment for this article, citing the embargo policy of Nature Physics, the journal to which the paper was submitted.)

After the Big Bang, the universe initially held equal parts antimatter and matter. But as the universe evolved, the laws of physics favored matter through CP violation, and antimatter became a rarity. Scientists’ well-tested theory of particle physics, the standard model, includes some CP violation, but not enough to explain the current imbalance. So physicists are searching for additional sources of the discrepancy.

It’s not surprising that differences in matter and antimatter appeared in baryons as well as mesons, says theoretical physicist David London of the University of Montreal. But precise measurements of baryons might eventually reveal deviations from the predictions of the standard model. Such a result could point the way to additional asymmetry that allowed the universe as we know it to form. “It’s just the first step, and hopefully there will be more such measurements,” says London.

Some ancient birds may have sounded like honking ducks.

For the first time, scientists have discovered the fossilized remains of a voice box from the age of the dinosaurs. The sound-making structure, called a syrinx, belonged to Vegavis iaai, a bird that lived 68 million to 66 million years ago, researchers report October 12 in Nature.

“It may be a once-in-a-lifetime discovery,” says evolutionary biologist Patrick O’Connor of Ohio University in Athens, who wrote a commentary in Nature about the fossil. Now, he says, the hunt will be on to find voice boxes in other fossils.
The new work helps fill in the soundscape of the Late Cretaceous Epoch. It could also offer hints about sounds made by all sorts of dinosaurs, says study coauthor Julia Clarke of the University of Texas at Austin.

Unlike in humans, where the larynx lies below the throat, birds’ voice boxes rest inside the chest at the base of the windpipe. Stacked rings of cartilage anchor vibrating membranes that make sound when air whooshes through.

This delicate structure doesn’t typically fossilize. In fact, scientists have previously spotted just a few syrinxes in the fossil record. The oldest known, from a wading bird, was about 50 million years old. Clarke’s team examined that syrinx, which hadn’t been studied before, and the one from V. iaai.
The V. iaaifossil, a partial skeleton discovered on an island off the coast of Antarctica, was removed from a rock about the size of a cantaloupe, Clarke says. Just one small area remained encased in rocky material. Everyone thought that bit was trivial, she says. But “it was within that tiny little section that I saw the syrinx.” Three-dimensional CT scans let her peer within the rock and see the telltale rings of a voice box, a structure roughly half the size of a multivitamin pill. “It was one of the biggest, happiest days of my career,” Clarke says.
Biologist Philip Senter of Fayetteville State University in North Carolina, who was not involved in the study, echoes Clarke’s enthusiasm. “It’s quite exciting to find such a rarely preserved structure,” he says. Seeing it in 3-D will make paleontologists “chortle joyously.”

Comparing the fossil with living birds helped Clarke and her team figure out what sounds the ancient bird might have made. Both the bird’s skeleton and its syrinx suggest it squawked like today’s ducks and geese.

The find also proves that voice boxes from dinosaurs’ time can indeed fossilize. No one has found the structures in nonavian dinosaurs, Clarke says. “That suggests that most dinosaurs may not have had a syrinx.”

Instead, she proposes, dinosaurs like Tyrannosaurus rex and Stegosaurus might have made noises like crocodiles: deep “booming” sounds generated in the back of the mouth.