Japanese great tits (Parus minor) communicate using at least 10 different notes on their own and in combination. Researchers played different calls for Japanese great tits in a forest in Nagano, Japan, to see how the birds responded — an indication of what the call might mean. The birds responded differently to individual notes than they did when played the same note in combination with other notes. And, when researchers reversed the note order, the birds didn’t respond the same way. By itself, a note means one thing to great tits, but in combination, it means something different, the team argues March 8 in Nature Communications. Similarly, among humans, the order of words in a sentence, its compositional syntax, matters.
Some primates combine calls to convey different messages, but individual notes don’t carry unique meaning in these species. Great tits are the first nonhuman species shown to use compositional syntax, the researchers write. In this recording, researchers played three types of calls for Japanese great tits: First, a call with three notes — A, B, and C — which signals danger; second, a one-note call (D), which attracts mates; and finally, a combination call, ABC-D, which causes the birds to scan the skies for predators and fly to the source of the sound. Researchers played an ABC-D call for great tits, and then reversed an ABC-D call. Birds responded differently in each case.
Buying a handgun in Connecticut means waiting — lots of waiting. First comes an eight-hour safety course. Then picking up an application at a local police department. Review of the application (which includes a background check and fingerprinting) can take up to eight weeks. If approved, the state issues a temporary permit, which the buyer trades in at state police headquarters for a permanent one. Then it’s back to the store for the gun.
Head west to Missouri, though, and buying a handgun is practically a cakewalk. Customers at Osage County Guns in Belle, Mo., for example, can walk into the store and walk out with a gun if they pass the FBI’s instant background check, says John Dawson, the store’s chief technical officer. “If a person knew exactly what they wanted,” he says, the store could, “in theory, complete the transaction in about 15 minutes.”
Missouri and Connecticut have staked out opposite ends of the gun law spectrum. Connecticut didn’t require handgun buyers to get a permit until 1995. Missouri had a tough law on the books, but repealed it in 2007. The states’ laws have flip-flopped, making for a fascinating natural experiment on gun laws’ effects on gun violence.
The states “had mirror image policy changes, and mirror image results,” says Daniel Webster, a health policy researcher at Johns Hopkins University.
Flipping the laws was associated with 15 percent fewer gun suicides in Connecticut and 16 percent more in Missouri, a statistical analysis by Webster and colleagues, published last year in Preventive Medicine, estimated. Similar analyses by Webster in 2014 and 2015 indicated a 40 percent reduction in Connecticut gun homicide numbers, and an 18 percent rise in Missouri. The evidence is very suggestive, says Harvard University researcher David Hemenway. But it’s not extensive enough to persuade everyone — or to move national policy.
In fact, questions loom about the impact of all sorts of policies, from background checks to assault weapons bans to gun buybacks. That’s partly because gun research faces roadblocks at every turn: Scientists have to deal with data shutouts, slashed funding and, occasionally, harassment.
For a few questions, however, researchers have come up with solid answers: There’s a convincing link between gun availability and gun suicide, for one. And studies from the United States and abroad suggest that some gun laws do rein in gun violence. To make firm conclusions, though, scientists are desperate for more data.
But the U.S. Centers for Disease Control and Prevention can’t collect gun data like it used to, and information about guns used in individual crimes is locked up tight. Under current federal laws, Hemenway says, “It’s almost impossible for researchers to get even the data that are available.”
Locked up In a squat brick building tucked in the hills of Martinsburg, W. Va., gun data are overflowing.
Thousands of cardboard boxes, stacked high in tidy columns, line the hallways of the federal government’s National Tracing Center. In the parking lot, steel shipping containers hold even more boxes. Each box contains about 2,000 pages of gun purchase records. To trace a gun, the center’s employees often search through these records by hand.
That’s their job: tracking when and where guns used in crimes were originally purchased, and by whom. It’s a huge undertaking: In 2015, the center, part of the Bureau of Alcohol, Tobacco, Firearms and Explosives, or ATF, received more than 373,000 gun trace requests from law enforcement. Such a mass of data is a researcher’s dream. But current laws keep gun traces secret. The agency shares traces only with law enforcement. The public can see just summaries or aggregate data.
Webster has used this data to paint a rough picture of how Missouri’s repeal affected the flow of guns to criminals. In 2006, when buying a handgun required a permit, 56.4 percent of guns recovered by police had been originally sold by a Missouri gun dealer. In 2012, five years after the state nixed the permit requirement, the number rose to 71.8 percent, Webster and colleagues reported in the Journal of Urban Health in 2014.
The findings suggest that it’s easier now for criminals in Missouri to get their hands on legally purchased guns. But Webster can’t say for certain whether more guns are moving to criminals — or whether legal gun owners are committing more crimes. For that, he’d need to see the individual gun traces.
About a decade ago, researchers who wanted such detailed data could get it. “We’d just hand them a DVD,” says ATF information specialist Neil Troppman. “Those days are long over.”
A handful of laws snarl the process, from how a gun trace begins to who can see the data.
One big hitch in the system: Police officers who find a gun at a crime scene can’t always look up the owner’s name on a computer. That’s because there is no national registry — no searchable database of guns and their owners. To set one up would be illegal. So police have to submit a request to the tracing center, which tracks the gun’s movement from manufacturer or importer to dealer. Then the ATF can ask the dealer who bought the gun. If the dealer has gone out of business, ATF employees dig for the answer themselves, in old gun purchase records stockpiled at the tracing center. The process takes an average of five days. And after law enforcement gets the data, federal law makes sure no one else can see it.
Federal constraints In 2003, Congress unleashed a beast of a bill with an amendment that effectively tore out the ATF’s tongue. The Tiahrt amendment was the first in a series of provisions that drastically limited the agency’s ability to share its crime gun data — no giving it to researchers, no making it public, no handing it over under Freedom of Information Act requests (the public’s channel for tapping into information from the federal government).
Funding for gun control research had dried up a few years earlier. There’s no outright ban, but a 1996 amendment had nearly the same effect. It’s known as the Dickey amendment, and it barred the CDC from using funds to “advocate or promote gun control.” According to a 2013 commentary in JAMA, that meant almost any research on guns. If the 1996 law’s language was vague, Congress made the message clear by cutting the CDC’s budget by $2.6 million — exactly the same amount the agency had spent the previous year on gun violence research. The funds were later reinstated, but earmarked for other things. So the CDC largely backed off, except for some basic tallying, says spokesperson Courtney Lenard, because of the funding cuts and because Congress “threatened to impose further cuts if that research continued.”
In 2011, Congress hit the National Institutes of Health with similar restrictions. About a year later, President Obama tried to ease the choke hold: He ordered the CDC to research the causes and prevention of gun violence, and called on Congress to provide $10 million in funding. Finally, 17 years after the CDC cuts, news reports proclaimed that the ban had been lifted and research could resume. But Congress never authorized the money, and the CDC remained on the sidelines. This April, nearly 150 health and science organizations, universities and other groups signed a letter urging Congress to restore the CDC’s funding.
Meanwhile, research on gun violence and gun control trudges forward: Researchers can sometimes convince law enforcement agencies to share data on guns linked to crimes, and grants can come from private foundations. Yet even with limits on research, the science in some cases is solid: A gun in the home, for example, increases the odds a person will commit suicide by about 3-to-1. Here, Hemenway says, “The weight of the evidence is overwhelming.”
But how to use laws to reduce gun violence remains hotly contested, and opinions among the public, and even scientists, are polarized.
Critics of gun control laws think the matter is clear: Again and again studies show that gun control policies just don’t work, says economist John Lott, who has written extensively on the subject. Take background checks, he says, “Given that these laws are costly, you’d like to believe there’s some evidence that they produce a benefit.”
Webster acknowledges the divisive split in opinions. “The vast majority of people are on one side of the fence or the other,” he says. “They’ll point to a study that is convenient to their political arguments and call it a day.”
Bad for your health For researchers who manage to navigate the legal tangles and funding troubles of gun research, actually doing the research itself isn’t easy.
Unlike clinical trials in medicine, where scientists can give, for example, a cholesterol drug to half a study’s participants and then compare the effects between users and nonusers, scientists studying gun violence can’t dole out new handguns to one group and none to another and see what happens.
Instead, researchers turn to observational studies. That means looking at how — and if — suicides track with gun ownership in different groups of people and over time, for example. Finding a link between two observations doesn’t necessarily mean they’re connected. (People have linked the yearly number of Nicolas Cage movies to swimming pool drownings, after all.) But finding a lot of links can be telling.
For suicides, the link to gun access holds strong — among old people, young people, women, adolescents, “you name it,” Hemenway says. Lots of guns means lots of suicides by gun, he says. In 2007, Hemenway and colleagues examined gun ownership rates and statewide suicide data from 2000 to 2002. People in states with a high percentage of gun owners (including Wyoming, South Dakota and Alaska) were almost four times as likely to kill themselves with guns as people living in states with relatively few gun owners (such as Hawaii, Massachusetts and Rhode Island), the researchers reported in the Journal of Trauma Injury, Infection and Critical Care.
More recently, a 2013 study in Switzerland compared suicide rates before and after an army reform that cut the number of Swiss soldiers by half. After the reform, fewer people had access to army-issued guns — and the suicide rate dipped down by about two per 100,000 men age 18–43. That’s about 30 men each year who didn’t die from suicide, the study’s authors estimated in the American Journal of Psychiatry.
A 2014 review of 16 such studies, published in the Annals of Internal Medicine, came to the same conclusion, again: Access to guns meant higher risk of suicide.
“The evidence is unassailable,” says Stanford University criminologist John Donohue. “It’s as strong as you can get.”
Mental illness factors into suicide too, says Jeffrey Swanson, a medical sociologist at Duke University. (Some 21 to 44 percent of suicides reported to the CDC are committed by people with mental health problems.) And federal laws aren’t particularly good at keeping guns away from mentally ill people. A 1968 law prohibits gun sales to a narrow slice of people with a history of mental illness, but it’s easy for others to slip through the cracks. Even people the law does target can end up with guns — because states don’t have to report mental health records to the FBI’s national background-check system.
“You’ve got tons of records that would disqualify people from buying guns,” Swanson says, but they don’t necessarily make it into the system. Even if the United States had a perfect mental health care system and cured schizophrenia and bipolar disorder and depression, he says, the overall problem of gun violence would still exist. Mentally ill people just aren’t that violent toward others, Swanson noted in the Annals of Epidemiology in 2015. In fact, people with mental illness committed fewer than 5 percent of U.S. gun killings between 2001 and 2010, according to the CDC.
“People think that in order to fix gun violence, we need to fix the mental health care system,” Swanson says. That’s wrong, he argues. “It’s a diversion from talking about guns.”
Weak laws After Sandy Hook, San Bernardino and other high-profile mass shootings, people have been talking about what gun control laws, if any, actually work.
Unfortunately, there’s just not enough evidence to make strong conclusions about most laws, Hemenway says. In 2005, for example, a federal task force reviewed 51 studies of gun laws, mostly in the United States, and came up empty-handed. The task force couldn’t say whether any one of the laws made much of a difference. The efficacy of U.S. gun laws is hard to pin down for two main reasons, Hemenway says: Gun laws aren’t typically very strong, and studies tend to look at overall effects on violence.
One major study published in JAMA in 2000 analyzed suicide and homicide data from 1985 to 1997 to evaluate the impact of the Brady Act, a 1994 federal law that requires background checks for people buying guns.
Eighteen states and the District of Columbia already followed the law. So researchers compared suicide and homicide rates with those in the 32 states new to the law. If Brady curbed gun violence, those 32 states should see dips in deaths. That didn’t happen (with one exception: Gun suicides in those states dropped in people age 55 and older — by about 1 per 100,000 people).
“I don’t think anybody was really shocked,” Webster says. After all, Brady had a gaping hole: It didn’t require background checks for guns bought from private sellers (including those at gun shows). The loophole neutered Brady: People who didn’t want a background check could simply find a willing private seller. That’s just too easy, Webster says: It’s like letting people decide whether they want to go through the metal detector at the airport.
Like the Brady Act, the 1994 Federal Assault Weapons Ban didn’t seem to do much to prevent violence, criminologist Christopher Koper and colleagues concluded in a 2004 report to the U.S. Department of Justice. The law, which expired in 2004, imposed a 10-year ban on sales of military-style semiautomatic guns. These weapons fire one bullet per trigger squeeze and have features like threaded barrels (which can be used for screwing on silencers) or barrel mounts (for attaching bayonets). The 1994 law also banned most large-capacity magazines (storage devices that feed guns more than 10 rounds of ammo).
But like Brady, the ban came with a catch: It didn’t apply to weapons and magazines made before September 13, 1994. That’s a lot of exemptions. At the time, the United States had more than 1.5 million assault weapons and nearly 25 million guns with large-capacity magazines, reported Koper, of George Mason University in Fairfax, Va.
“The more complete the bans are, the better the effects seem to be,” Donohue says. Take Australia: In 1996, the country enacted strict laws and a gun buyback program after a mass shooting killed 35 people in Tasmania. The ban made certain long-barreled guns illegal (including semiautomatic rifles and pump-action shotguns — weapons that let people fire lots of rounds quickly), and the country bought back and destroyed more than 650,000 guns.
With the law, Donohue says, “Australia effectively ended the problem of mass shootings.”
And as economists Christine Neill and Andrew Leigh found, the law drastically cut down the number of gun suicides, too. Tough laws Eleven years after Australia launched its tough gun control legislation, Neill, of Wilfrid Laurier University in Canada, and Leigh, then at Australian National University in Canberra, announced that the law might actually be saving lives.
Critics attacked. One petitioned Neill’s university to reprimand her. Then they came for Leigh’s e-mails. He had to hand over any that mentioned firearms or guns. Had there been anything improper — any whiff that the researchers were biased — Neill believes gun advocates would have pounced.
Neill and Leigh, now an Australian politician, had uncovered telling changes in different regions’ suicide rates between 1990–1995 and 1998–2003. “Firearms suicides fell most in Tasmania, by a long shot,” Neill says, almost 70 percent, the team later reported in 2010 in the American Law and Economics Review.
Australia’s law, called the National Firearms Agreement, or NFA, applied to all of the country’s states and territories, but some had more guns than others. Tasmania, for example, had the most guns bought back, Neill says: 7,302 guns per 100,000 people. More guns bought back meant bigger drops in suicide rates, she says. Instead, the United States goes for smaller laws, fashioned mostly state-by-state. Still, some may be effective. Blocking domestic violence offenders’ access to guns seems to cut down on homicides, for example. From 1982 to 2002, states with restraining order laws that bar offenders from buying guns had rates of intimate partner homicide that were 10 percent lower than in states lacking the laws, researchers reported in 2006 in Evaluation Review.It’s a stark result, and suggests that tough laws can have big impacts. Australia “did an outright ban and something akin to a confiscation of guns,” Webster says. “That’s never going to happen in the United States.”
In 2010, Webster and colleagues reported similar results at the city level. He and colleagues tracked intimate partner homicides from 1979 to 2003 in 46 U.S. cities. Those that made it hard for people with domestic violence restraining orders to get guns had 19 percent fewer intimate partner homicides compared with cities with less stringent laws, the team reported in Injury Prevention.
“These are pretty consistent findings,” Webster says. Those state policies seem to be working.
Conclusions about other, more well-known laws, such as “right-to-carry,” are less convincing. Such laws, which allow people to carry concealed handguns in public, could offer people a means of defense. Or they could make it easier for people in an argument to whip out a gun. “The findings are all over the map,” Hemenway says. A report from the National Research Council in 2005 found no causal link between right-to-carry laws and crime. It also concluded that people do use guns to protect themselves (say, by threatening or shooting an attacker) but how often is hard to say. Estimates vary from 100,000 to 2.5 million times per year in the United States.
Economist Mark Gius of Quinnipiac University in Hamden, Conn., estimated that restricting people’s right to carry boosts a state’s murder rate by 10 percent, he reported in 2014 in Applied Economics Letters.
Donohue’s 2014 results lean a different way. The Stanford researcher updated the NRC analysis with more than a decade of new data and found that laws letting people carry concealed weapons boost violent crime — a bit. Based on data from 1979 to 2012, his statistical modeling showed that a state with a right-to-carry law would experience 8 percent more aggravated assaults than a state without such a law, for example.
“More and more evidence is amassing that these laws are harmful,” Donohue says, but he concedes that there’s still uncertainty. “I’m not quite ready to say that we’ve nailed it down.”
Less uncertainty would require more analyses and more data. But in this field, even that doesn’t guarantee consensus.
“The problem is that there are many ways to slice the data,” Donohue says. “Almost nothing is as clear as the advocates make it — on both sides.”
Shaken-but-not-stirred remnants of Earth’s earliest years still exist nearly 4.6 billion years later.
Researchers traced the shadowy footprints of an isotope that hasn’t existed for over 4.5 billion years to much younger lava rocks from the Pacific and Atlantic oceans. That suggests that reservoirs of the ancient mantle may be hidden deep inside the planet, geochemist Hanika Rizo and colleagues report May 13 in Science.
Earth formed about 4.6 billion to 4.5 billion years ago as planetary bodies collided, disintegrating and melting to accrete into one mass like a hot, rocky lint ball. Geologists have assumed that any relics of this bumpy beginning were mixed beyond recognition. Instead, Rizo’s team found a surprise: Some modern flood basalts have unusually high concentrations of tungsten-182. That’s significant because that isotope forms only from radioactive decay of hafnium-182. And hafnium-182 only existed during Earth’s first 50 million years. “These isotopes had to be created early,” says Rizo, of the University of Quebec in Montreal. It is “spectacular” that some of Earth’s earliest materials may still be preserved, says Matthias Willbold, a geochemist at the University of Manchester in England. “We may have to revise our view of the Earth’s internal structure.”
Rizo and colleagues measured the tungsten-182 in flood basalts from two locations: Canada’s Baffin Bay, part of the 60-million-year-old North Atlantic Igneous Province, and near the Solomon Islands, part of the 120-million-year-old Ontong Java Plateau in the Pacific Ocean. “Flood basalts are not normal eruptions,” Rizo says. “They are capable of tapping into the deep mantle.” Her team found that levels of tungsten-182 in the lavas varied, suggesting that the deep sources of these younger rocks were different pieces of Earth’s oldest material, each with their own isotopic signature and history. These results also show that the ancient remnants have somehow escaped being mixed by convection currents.
Geophysicists have identified two large “blobs” in the deep mantle, called large low-shear velocity provinces. Those blobs “could be candidates” for the remnants of the ancient mantle, Rizo says.
What builds up can also tear down, a new study of bacteria suggests.
Bacteria build biofilms, communities of the microorganisms encased in a protective goo that shields the microbes from antibiotics and immune system attacks. But the very enzymes bacteria use to construct that shield can also destroy some of its molecules and strip away the protection, researchers report May 20 in Science Advances.
“We’re weaponizing the bacteria against themselves,” says P. Lynne Howell, a structural microbiologist at the Hospital for Sick Children in Toronto. Howell and colleagues studied Pseudomonas aeruginosa bacteria, which can cause pneumonia and other infections and is particularly problematic for people with the lung disease cystic fibrosis. The researchers discovered that two enzymes, PelAh and PslGh, which the bacteria use to build two different sugar polymers, can degrade those same polymers. That delete function, supplied by parts of the enzymes known as glycoside hydrolase domains, normally helps correct mistakes or prevents buildup of the sugar chains inside bacterial cells, Howell says.
In laboratory tests, synthetic versions of the glycoside hydrolase domains applied to P. aeruginosa cultures stopped the bacteria from forming new biofilms and melted existing ones. Stripping away sugar polymers did not kill the bacteria but did make them more vulnerable to antibiotics and immune cells. Human lung cells grown in dishes containing the enzymes suffered no harm, suggesting the enzymes wouldn’t damage human tissues.
Animal tests are needed to determine whether the enzymes are safe and can fight biofilm infections in the body, Howell says. Similar enzymes from other bacteria and fungi may also fight biofilm infections caused by those organisms, she says.
Giant pandas have better ears than people — and polar bears. Pandas can hear surprisingly high frequencies, conservation biologist Megan Owen of the San Diego Zoo and colleagues report in the April Global Ecology and Conservation.
The scientists played a range of tones for five zoo pandas trained to nose a target in response to sound. Training, which took three to six months for each animal, demanded serious focus and patience, says Owen, who called the effort “a lot to ask of a bear.”
Both males and females heard into the range of a “silent” ultrasonic dog whistle. Polar bears, the only other bears scientists have tested, are less sensitive to sounds at or above 14 kilohertz. Researchers still don’t know why pandas have ultrasonic hearing. The bears are a vocal bunch, but their chirps and other calls have never been recorded at ultrasonic levels, Owen says. Great hearing may be a holdover from the bears’ ancient past.
Even if you’ve never lived in rattlesnake territory, you know what the sound of a snake’s rattle means: Beware! A shake of its rattle is an effective way for a snake to communicate to a potential predator that an attack could result in a venomous bite.
For more than a century, scientists have posited how that rattle might have evolved. The rattle is composed of segments of keratin (the same stuff that makes up human hair), and specialized muscles in a snake’s tail vibrate those segments rapidly to create the rattling sound. The rattlesnake’s rattle is a trait that evolved only once in the past and is now found in only two closely related genera of snakes that live in North and South America. But plenty of other species of snakes also vibrate their tails as a warning to potential predators.
Bradley Allf and colleagues at the University of North Carolina in Chapel Hill think that the tail vibration and the evolution of the rattle might be connected. They gathered 155 snakes of 56 species — 38 species from the Viperidae family, which includes rattlesnakes, and 18 species from the largest snake family, Colubridae — from museums, zoos and private collectors. Working with captive snakes let them control conditions, such as temperature, that can affect tail vibration. With each snake, one of the researchers tried to get it to behave defensively by waving a stuffed animal in front of it. The team videotaped the snakes as they vibrated their tails, or not.
The researchers plotted the snakes’ tail vibration duration and rate against how closely related a species was to rattlesnakes. One group of snakes that lives in the Americas was taken out of the analysis because its tail vibrations were so similar to those of rattlesnakes; it appears that these species are mimicking the dangerous snakes that live near them (not a bad strategy for survival). Among the rest of the snakes analyzed, those that were more closely related had tail behavior that was more similar to that of rattlesnakes.
“Our results suggest that tail vibration by rattleless ancestors of rattlesnakes may have served as the signal precursor to rattlesnake rattling behavior,” the researchers write in the October issue of the American Naturalist. “If ancestral tail vibration was a reliable cue to predators that a bite was imminent, then this behavior could have become elaborated as a defensive signal.”
Allf and his colleagues propose a couple of ways that this could have happened. Perhaps snakes that made noise with their tails were better at startling predators, and this may have prompted such noise-making tail features to spread and eventually become refined into what is now a rattle. Or maybe snakes that shook their tails longer and faster developed calluses of keratin. If these calluses provided better warning, that may have somehow evolved into a rattle.
“Thus, the rattlesnake rattle might have evolved via elaboration of a simple behavior,” they conclude.
The first time Jessica Cantlon met Kumang at the Seneca Park Zoo, the matriarch orangutan regurgitated her previous meal right into Cantlon’s face. “I was retching,” Cantlon recalls. “It was so gross.” But Cantlon was there to kick off a series of behavioral experiments, and her students, who would be working with Kumang regularly, were watching. “Does anyone have any towels?” she remembers asking, knowing she had to keep her cool.
Cantlon’s deliberate nature and whatever-it-takes attitude have served her well. As a cognitive neuroscientist at the University of Rochester in New York, she investigates numerical thinking with some of the most unpredictable and often difficult study subjects: nonhuman primates, including orangutans, baboons and rhesus macaques, and — most remarkably — children as young as age 3. Both groups participate in cognitive tests that require them, for example, to track relative quantities as researchers sequentially add items to cups and to distinguish between quantities of assorted dots on touch screens. The kids also go into the functional MRI scanner where, in a feat impressive to parents everywhere, they lie completely still for 20 to 30 minutes so Cantlon and colleagues can get pictures of their brains. “She takes steps carefully, and she thinks very hard about where she is going,” says Daniel Ansari, a developmental cognitive neuroscientist at the University of Western Ontario in London, Canada, who is familiar with Cantlon’s work. “She goes for the big questions and big methodological challenges.”
The central question in Cantlon’s research is: How do humans understand numbers and where does that understanding come from? Sub-questions include: What are the most primitive mathematical concepts? What concepts do humans and other primates share? Are these shared concepts the foundation for fancier forms of mathematical reasoning? In addressing these questions, Cantlon draws on a wide range of methods. “Very few people can combine work on cognitive skills — studies from the point of view of behavior — with imaging work in very young children, and very few people do that same combination in nonhuman primates,” says Elissa Newport, who chaired the brain and cognitive sciences department at Rochester for more than a decade and now leads the Center for Brain Plasticity and Recovery at Georgetown University.
As a graduate student, Cantlon determined that neuroimaging studies would add an independent source of data to the cognitive questions under exploration in Elizabeth Brannon’s lab at Duke University. So she identified collaborators and taught herself functional MRI. “By the time she graduated, she had something like four dissertations’ worth of work,” says Brannon, now of the University of Pennsylvania.
In the years since, Cantlon has identified a type of “protocounting” in baboons; they can keep tabs on approximate quantities of peanuts as researchers increase those quantities (SN Online: 5/17/15). In her most attention-grabbing work, Cantlon studied activity in the brains of children while they watched Sesame Street clips that dealt with number concepts — an unexpected success that proved everyday, relatively unaltered stimuli can yield meaningful data. An ongoing study in Cantlon’s lab seeks to find out how monkeys, U.S. kids and adults, and the Tsimané people of Bolivia, who have little formal education, distinguish between quantities. Do they determine the number of dots presented on the computer screen or do they rely on a proxy such as the total area covered by the dots? The work explores how the brain understands everyday concepts, but it could also inform strategies in math education. “If we understand the fundamental nature of the human brain and mind, that might give us a better insight into how to communicate number concepts to kids,” Cantlon says.
Growing up outside of Chicago, Cantlon enjoyed digging deep into a topic and becoming an expert. She and a friend turned themselves into ice skating superfans one summer, reading up on the Olympic skaters and checking videos out of the local library. In another project, Cantlon decided to learn everything possible about the price of gold. When she moved to a school where she could no longer take Latin, she taught and tested herself. Despite the fact that neither of her parents went to college, no one ever questioned that Cantlon would go. She studied anthropology as an undergraduate at Indiana University in Bloomington. “I was interested in the question of where we come from,” Cantlon says. “I was interested in studying people.” During college, she went on an archaeological dig in Belize and studied lemurs in Madagascar. For a year after graduation, she observed mountain gorillas in Rwanda, detailing their behavior every 10 minutes. “What they were thinking was something that was constantly on my mind,” she says. “‘How are we similar? Are you thinking what I’m thinking?’” Though she might have succeeded in any number of careers, she wanted exploration to be a big part of her life: “I don’t think doing a less exotic type of work would have been as satisfying.”
Today, Cantlon, who at age 40 recently earned tenure, doesn’t spend much time in the field. And even in the lab, she leaves much of the data collection to her graduate students and research assistants. “At this point, we are a well-oiled system,” she says, referring to the brain scan studies on kids. To make the kids comfortable, Cantlon’s team does trial runs in a mock scanner, describing it as a spaceship and providing “walkie-talkies” for any necessary communication. To keep them interested, the researchers treat it as a team activity and offer a ton of positive reinforcement, with prizes including Lego sets and a volcano-making kit. The kids receive pictures of their brains, which typically interest the parents most. The older of Cantlon’s two daughters, a 5-year-old extrovert named Cloe, has participated in behavioral tests and will no doubt be excited for her first brain scan.
The Sesame Street study was in part inspired by a paper by Uri Hasson, a neuroscientist at Princeton University who imaged the brains of volunteers while they watched The Good, the Bad and the Ugly. To better understand brain development, Cantlon wanted to see how brain activity compared in kids and adults exposed to math in a natural way. Of particular interest was a region called the intraparietal sulcus, or IPS, thought to play a role in symbolic number processing. The results, reported in PLOS Biology in 2013, showed that kids with IPS activity more closely resembling adults’ activity performed better on mathematical aptitude tests.
“It was the clearest, cleanest — did not have to come out this way — result,” Cantlon says.
Cantlon is notable for her diverse set of tools, says Steve Piantadosi, a computational neuroscientist and colleague at Rochester. “But she has something which is even more powerful than that. If you have different hypotheses and you want to come up with the perfect experiment that distinguishes them, that is something she is very good at thinking about. She is a great combination of critical and creative.”
To add another methodological approach, Cantlon next plans to collaborate with Piantadosi to develop computational models that explain the operations the brain performs as it counts or compares quantities. She would also like to add data analyses from wild primates into the mix. When researchers talk about the evolution of a primitive number sense, they often speak about foraging activity — identifying areas of the forest with more food, for example. But Cantlon wonders whether social interactions also require some basic understanding of quantities.
As for a recent question from a colleague about what risky project she’ll pursue now that she has tenure, Cantlon says nothing in particular comes to mind: “I feel like we’ve been doing the crazy things all along.”
ORLANDO, Fla. — New evidence from separate labs supports the controversial idea that an overlooked and unexpected Culex mosquito might spread Zika virus.
The southern house mosquito, Culex quinquefasciatus, is common in the Americas. Constância Ayres, working with Brazil’s Oswaldo Cruz Foundation in Recife, previously surprised Zika researchers with the disturbing proposal that this mosquito might be a stealth spreader of Zika. But two U.S. research groups tested the basic idea and couldn’t get the virus to infect the species. Now, preliminary results from Ayres’ and two other research groups are renewing the discussion. The data, shared September 26 at the International Congress of Entomology, suggest that Zika can build up in the house mosquito’s salivary glands — a key step in being able to transmit disease. Basic insect physiology is only part of the puzzle, though. Even if the mosquitoes prove competent at passing along Zika, there remain questions of whether their tastes, behavior and ecology will lead them to actually do so.
In the current outbreak, the World Health Organization has focused on mosquitoes in a different genus, Aedes, particularly Ae. aegypti, as the main disease vector. But Ayres had announced months ago the discovery of the virus in Brazil’s free-flying house mosquitoes (SN Online: 7/28/16).
At the congress, Ayres’ foundation colleague Duschinka Guedes reported that captive mosquitoes fed Zika-tainted blood had virus growing in their own guts and salivary glands within days. The virus doesn’t spread every time a mosquito slurping contaminated blood gets virus smeared on its mouthparts, though. To move from the mosquito to what it bites, viruses have to infect the insect midgut, then travel to the salivary glands and build up enough of a population for an infective dose drooling into the next victim. When Guedes offered the infected mosquitoes a special card to bite, they left telltale virus in the salivary traces, a sign of what they could do when biting — and infecting — a real animal.
Researchers from China and Canada who were not originally on the symposium program also stepped up to share their results, some of which are unpublished. Some tasks are still in early stages, but both labs showed Zika virus building up in some kind of Culex mosquitoes.
At the Beijing Institute of Microbiology and Epidemiology, Tong-Yan Zhao found the virus peaking in the house mosquitoes eight days after their first contaminated drink. As a test of the infectious powers of the mosquitoes, researchers let the Zika-carrying insects bite baby lab mice. Later, the virus showed up in the brains of eight out of nine lab mice. The results were reported September 7 in Emerging Microbes & Infections. From Brock University in St. Catharines, Canada, Fiona Hunter has found signs that 11 out of 50 wild-caught Culex pipiens pipiens mosquitoes picked up the virus somewhere on their bodies. So far, she has completely analyzed one mosquito and reports that the virus was indeed in its saliva.
These positive results contradict Culex tests at the University of Texas Medical Branch in Galveston. Those tests, with U.S. mosquitoes, found no evidence that C. quinquefasciatus can pick up and pass along a Zika infection, says study coauthor Scott Weaver. Stephen Higgs of Kansas State University in Manhattan and his colleagues got similar results. “We’re pretty good at infecting mosquitoes,” Higgs says, so he muses over whether certain virus strains won’t infect mosquitoes from particular places.
The main risk from Culex at the moment is distraction, warned Roger Nasci of North Shore Mosquito Abatement District in Northfield, Ill. After the talks, he rose from the audience to say that Ae. aegypti is a known enemy and limited resources should not be diverted from fighting it.
George Peck, who runs mosquito control for Clackamas County in Oregon, isn’t convinced that the high virus concentrations dosing the test mosquitoes are realistic. Yet he’s watching the issue because like much of northern North America, Clackamas doesn’t have the Ae. aegypti vector to worry about. But it does have plenty of Culex mosquitoes.
Using nasal cartilage cells to repair joints is nothing to sniff at.
It has worked in goats. Now, in the first human trial, researchers at the University of Basel in Switzerland have grown cells called chondrocytes, taken from the noses of 10 patients with damaged knee joints, into cartilage grafts. These repair patches were then surgically implanted into the patients’ knee joints.
Two years after surgery, nine patients have seen improvements in knee function, quality of life and pain. (One patient dropped out of the trial because of additional athletic injuries.) MRI scans showed that the grafts looked like normal hyaline cartilage, the hard-to-replicate material that coats the tips of bones, the team reports in the Oct. 22 Lancet. Tests in more people are needed to determine whether the technique is ready for prime time.
Mothers who don’t eat enough during pregnancy could give birth to babies with long-lasting heart problems. The results from a new study in primates add to accumulating evidence that a mother’s nutrition has more bearing on her child’s health than previously thought.
“We pass more biological milestones during development than we will ever pass again in our entire lives,” says Peter Nathanielsz, coauthor of the study published November 6 in the Journal of Physiology. And during those critical nine months, calorie intake at the extremes — too many or too few — appears to have a lifelong influence on newborn weight, future metabolism and chronic health problems (SN: 1/23/16, p. 22). One landmark epidemiological investigation found that people born in the Dutch Hunger Winter during World War II suffered from an elevated risk of heart disease and other health concerns, with some risks even affecting two generations. But studies of human populations are complicated. It’s hard to account for the role of stress, behavior or environmental exposures. So Nathanielsz, of the University of Wyoming in Laramie, and colleagues from the University of Texas Health Science Center at San Antonio studied baboons, close genetic relatives to humans.
Sixteen pregnant baboons were fed their normal amount of chow, while 16 others received 30 percent less during pregnancy, a reduction researchers characterize as “moderate.” All other living conditions were the same. The researchers then compared offspring of the well-fed mothers with the offspring of undernourished mothers.
Infants of the underfed mothers were born small but nonetheless caught up in body weight to the offspring of the well-fed mothers by young adulthood. However, those whose mothers were underfed had more fibrous, abnormally shaped heart muscle, the researchers report. A normal heart is roughly an upside-down pyramid, but underfed offspring had more rounded and less muscular hearts. Evidence showed that these less-muscled hearts were not as efficient at pumping blood, with an average output about 20 percent lower.
Offspring undernourished in the womb also had hearts that appeared to age faster. By age five, the human equivalent of almost 25, many of their heart functions more closely resembled those of hearts of primates about three times as old.
Such experiments can show cause and effect — something that human studies can’t do, says Susan Ozanne, a developmental endocrinologist at the University of Cambridge. As a result, they provide strong evidence about the effects of maternal nutrition. “What this shows us is that certainly maternal diet has an effect on a child’s cardiac health long-term,” she says. Studies in rodents have produced similar findings, but “when you validate those in multiple species, it shows you you’re looking at a fundamentally conserved mechanism.” The next step, she says, is to learn whether diet and exercise after birth can make up for poor nutrition during development. Doctors also don’t know whether there is a window of time during childhood for intervention, or a longer period to counteract any effects, she says.
Much attention on maternal nutrition has focused on the obesity epidemic, Nathanielsz says, but undernutrition remains a public health challenge throughout the world, even in developed countries. The U.S. Department of Agriculture estimates that approximately 13 percent of American households in 2015 reported food insecurity, or uncertainty about having enough money for food. “The number of people with food insecurity is very high,” Nathanielsz says. “It would be sad if we discounted this problem.”
