Aside from being adorable, sea otters and Indo-Pacific bottlenose dolphins share an ecological feat: Both species use tools. Otters crack open snails with rocks, and dolphins carry cone-shaped sponges to protect their snouts while scavenging for rock dwelling fish.

Researchers have linked tool use in dolphins to a set of differences in mitochondrial DNA — which passes from mother to offspring — suggesting that tool-use behavior may be inherited. Biologist Katherine Ralls of the Smithsonian Institution in Washington, D.C., and her colleagues looked for a similar pattern in otters off the California coast. The team tracked diet (primarily abalone, crab, mussels, clams, urchins or snails) and tool use in the wild and analyzed DNA from 197 individual otters.

Otters that ate lots of hard-shelled snails — and used tools most frequently — rarely shared a common pattern in mitochondrial DNA, nor were they more closely related to other tool-users than any other otter in the population.

Unlike dolphins, sea otters may all be predisposed to using tools because their ancestors probably lived off mollusks, which required cracking open. However, modern otters only take up tools when their diet requires them, the researchers report March 21 in Biology Letters.

SAN FRANCISCO — When faced with simple math problems, people who get jittery about the subject may rely more heavily on certain brain circuitry than math-savvy people do. The different mental approach could help explain why people with math anxiety struggle on more complicated problems, researchers reported March 25 at the Cognitive Neuroscience Society’s annual meeting.

While in fMRI machines, adults with and without math anxiety evaluated whether simple arithmetic problems, such as 9+2=11, were correct or incorrect. Both groups had similar response times and accuracy on the problems, but brain scans turned up differences.

Specifically, in people who weren’t anxious about math, lower activation of the frontoparietal attention network was linked to better performance. That brain network is involved in working memory and problem solving. Math-anxious people showed no correlation between performance and frontoparietal network activity.

People who used the circuit less were probably getting ahead by automating simple arithmetic, said Hyesang Chang, a cognitive neuroscientist at the University of Chicago. Because math-anxious people showed more variable brain activity overall, Chang speculated that they might instead be using a variety of computationally demanding strategies. This scattershot approach works fine for simple math, she said, but might get maxed out when the math is more challenging.

Could fluorescence matter to a frog? Carlos Taboada wondered. They don’t have bedroom black lights, but their glow may still be about the night moves.

Taboada’s question is new to herpetology. No one had shown fluorescence in amphibians, or in any land vertebrate except parrots, until he and colleagues recently tested South American polka dot tree frogs. Under white light, male and female Hypsiboas punctatus frogs have translucent skin speckled with dark dots. But when the researchers spotlighted the frogs with an ultraviolet flashlight, the animals glowed blue-green. The intensity of the glow was “shocking,” says Taboada of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” in Buenos Aires.
And it is true fluorescence. Compounds in the frogs’ skin and lymph absorb the energy of shorter UV wavelengths and release it in longer wavelengths, the researchers report online March 13 in Proceedings of the National Academy of Sciences. But why bother, without a black bulb? Based on what he knows about a related tree frog’s vision, Taboada suggests that faint nocturnal light is enough to make the frogs more visible to their own kind. When twilight or moonlight reflects from their skin, the fluorescence accounts for 18 to 30 percent of light emanating from the frog, the researchers calculate.
Polka dot frogs, common in the Amazon Basin, have plenty to see in the tangled greenery where they breed. Males stake out multilevel territories in vast floating tangles of water hyacinths and other aquatic plants. When a territory holder spots a poaching male, frog grappling and wrestling ensues. Taboada can identify a distinctive short treble bleat “like the cry of a baby,” he says, indicating a frog fight.
Males discovering a female give a different call, which Taboada could not be coaxed to imitate over Skype. The polka dot frogs’ courtship is “complex and beautiful,” he says. For instance, a male has two kinds of secretion glands on the head and throat. During an embrace, he nudges and presses his alluring throat close to a female’s nose. If she breaks off the encounter, he goes back to clambering in rough figure eights among his hyacinths, patrolling for perhaps the blue-green ghost of another chance.

A stellar game of chicken between two young stars about 500 years ago has produced some fantastic celestial fireworks, new images released on April 7 by the European Southern Observatory reveal.

Whether or not the stellar duo collided is unclear. But their close encounter sent hundreds of streamers of gas, dust and other young stars shooting into space like an exploding firecracker. Using the Atacama Large Millimeter/submillimeter Array in Chile, John Bally of the University of Colorado Boulder and colleagues made the first measurements of the velocities of carbon monoxide gas in the streamers. From the data, they identified the spot where the stars probably interacted and determined that the encounter ripped apart the stellar nursery in which the stars were born. Such a cataclysmic event flung nursery debris into space at speeds faster than 540,000 kilometers an hour.

The dueling stars were born in a stellar nursery called Orion Molecular Core 1, about 1,500 light-years from Earth behind the Orion Nebula. There, gas weighing 100 suns collapses under its own gravity, making the material dense enough for embryotic stars to take shape. Gravity can pull those stellar seeds toward each other, with some grazing or colliding with each other and violently erupting. In this case, the encounter produced a kick as powerful as the energy the sun emits over 10 million years.

This explosion may have initially released a burst of infrared light lasting years to decades. If so, such spars among young stars might explain mysterious infrared flashes observed in other galaxies, the scientists suggest.

Earth’s magnetic field helps eels go with the flow.

The Gulf Stream fast-tracks young European eels from their birthplace in the Sargasso Sea to the European rivers where they grow up. Eels can sense changes in Earth’s magnetic field to find those highways in a featureless expanse of ocean — even if it means swimming away from their ultimate destination at first, researchers report in the April 13 Current Biology.

European eels (Anguilla anguilla) mate and lay eggs in the salty waters of the Sargasso Sea, a seaweed-rich region in the North Atlantic Ocean. But the fish spend most of their adult lives living in freshwater rivers and estuaries in Europe and North Africa.
Exactly how eels make their journey from seawater to freshwater has baffled scientists for more than a century, says Nathan Putman, a biologist with the National Oceanic and Atmospheric Administration in Miami.

The critters are hard to track. “They’re elusive,” says study coauthor Lewis Naisbett-Jones, a biologist now at the University of North Carolina at Chapel Hill. “They migrate at night and at depth. The only reason we know they spawn in the Sargasso Sea is because that’s where the smallest larvae have been collected.”

Some other marine animals, like sea turtles and salmon, tune in to subtle changes in Earth’s magnetic field to help them migrate long distances. To test whether eels might have the same ability, Putman and his colleagues placed young European eels in a 3,000-liter tank of saltwater surrounded by copper wires. Running electric current through the wires simulated the magnetic field experienced at different places on Earth.
With no electric current, the eels didn’t swim in any particular direction. But when the magnetic field matched what eels would experience in the Sargasso Sea, the fish mostly swam to the southwest corner of their tank. That suggests the eels might use the magnetic field as a guide to help them move in a specific direction to leave their spawning grounds.

Swimming southwest from the Sargasso Sea seems counterintuitive for an eel trying to ultimately go northeast, Putman says. But computer simulations revealed that that particular bearing would push eels into the Gulf Stream, whisking them off to Europe. Catching a more circuitous ride on a current is probably more efficient for the eels than swimming directly across the North Atlantic, says Putman.

Magnetic fields could help eels stay the course, too. A magnetic field corresponding to a spot in the North Atlantic further along the eels’ route to Europe sent the eels in the tank heading northeast. That’s the direction they’d need to go to keep following the Gulf Stream to Europe.

The researchers did see a fair amount of variation in how strongly individual eels responded to magnetic fields. But that makes sense, says Julian Dodson, a biologist at Laval University in Quebec City who wasn’t part of the study. The Gulf Stream is such a powerful current that the eels could wriggle in a spread of directions to get swept up in its flow.

Now, the researchers are looking at whether adult eels use a similar magnetic map to get back to the Sargasso Sea. Adults follow a meandering return route that might take more than a year to complete, previous research suggests (SN Online: 10/5/16). But whether there’s some underlying force that guides them remains to be seen.

Lab coats aren’t typical garb for mass demonstrations, but they may be on full display April 22. That’s when thousands of scientists, science advocates and science-friendly citizens are expected to flood the streets in the March for Science. Billed by organizers as both a celebration of science and part of a movement to defend science’s vital role in society, the event will include rallies and demonstrations in Washington, D.C., and more than 400 other cities around the world.

“Unprecedented,” says sociologist Kelly Moore, an expert on the intersection of science and politics at Loyola University Chicago. “This is the first time in American history where scientists have taken to the streets to collectively protest the government’s misuse and rejection of scientific expertise.”

Some scientists have expressed concern that marching coats science in a partisan sheen; others say that cat is long out of the bag. Keeping science nonpartisan is a laudable goal, but scientists are human beings who work and live in societies — and have opinions as scientists and citizens when it comes to the use, or perceived misuse, of science.

Typically when scientists get involved with a political issue, it’s as an expert sharing knowledge that can aid in creating informed policy. There are standard venues for this: Professional societies review evidence and make statements about a particular issue, researchers publish findings or consensus statements in reports or journals, and sometimes scientists testify before Congress.

In extreme circumstances, though, scientists have embraced other forms of activism. To broadly categorize, there are:

Celebrity voices
In 1938, amid the rise of fascism and use of false scientific claims to support the racism embedded in Nazism, prominent German-American anthropologist Franz Boas released his “Scientists Manifesto.” Signed by nearly 1,300 scientists, including three Nobel laureates, the manifesto denounced the unscientific tenets of Nazism and condemned fascist attacks on scientific freedom.
Fear of war of a different sort prompted Albert Einstein, Bertrand Russell and nine other scientists to compose a manifesto in 1955 calling for nuclear disarmament. The Russell-Einstein Manifesto led to the first Pugwash Conference on Science and World Affairs, which sought “a world free of nuclear weapons and other weapons of mass destruction.”
Wildlife biologist Rachel Carson eloquently synthesized research on the effects of pesticides in her wildly popular book Silent Spring, published in 1962 (she would later testify before Congress). Despite attacks from industry and some in government, Carson’s work helped launch the modern environmental movement, paving the way for the establishment of the Environmental Protection Agency.

Advocacy groups
In the 1930s, chapters of the American Association of Scientific Workers (based loosely on a similar British organization) formed in various cities including Philadelphia, Boston and Chicago. Despite broad goals — promoting science for the benefit of society, stressing public science education, taking a moral stand against government and industry misuse of science — infighting and members’ opposing views limited the group’s effectiveness.

In the decades since, other broadly focused groups — for example, Science for the People (born out of a group started in 1969 by physicists frustrated by their professional society’s lack of action against the Vietnam War), the Union of Concerned Scientists, the American Association for the Advancement of Science — have picked up the banner, speaking out, circulating petitions and more. Single-issue groups such as the Environmental Defense Fund and the Council for Responsible Genetics have proliferated as well.

Protest marchers
Many scientists have traded pocket protectors for placards, hitting the streets as concerned scientist-citizens. Academic scientists frequently joined university students in rallies against the Vietnam War in the 1960s and early ’70s. Linus Pauling famously protested nuclear testing in a march outside the White House in 1962 (he was in town for a dinner with the Kennedys honoring Nobel laureates). Carl Sagan was one of hundreds arrested for protesting nuclear testing at a Nevada site in 1987. And plenty of scientist-citizens joined the inaugural Women’s March on Washington in January and the annual People’s Climate March (the 2017 one is scheduled for April 29, just a week after the March for Science).

But the March for Science feels different, say the science historians. Transforming concern into sign-toting, pavement-pounding, slogan-shouting activism is motivated by a collective — and growing — sense of outrage that the federal government is undermining, ignoring, even discarding and stifling science. That’s hitting many scientists not just in their livelihoods, but in the very fabric of their DNA. “Part of [President] Trump’s message is that science is not going to be thought of as part of a collective good that’s essential for decision making in a democracy,” Moore says. “We have not seen this outright rejection of science by the state.”

That rejection has come in many forms, says David Kaiser, a science historian at MIT. “It’s a cluster of issues: cutbacks in basic research across many domains, the censure and censorship regarding data collected by the government or the ability of government scientists to speak, and a range of threats to academic freedom and the research process generally.”

It’s a sign of the times, too, says Al Teich, a science policy expert at George Washington University in Washington, D.C. President Reagan, for example, slashed science in his budget in 1981. But many more people today are aware of science’s role in society, says Teich, the former director for science and policy programs at AAAS. This awareness may be fueling the upcoming march. “The number of people engaged and the range of scientists involved is not something that I’ve ever seen before.”

Measuring the impact of any of these efforts is difficult. They aren’t controlled laboratory experiments, after all. But one thing this march may do is spawn a new form of activism, says Moore: more scientists running for political office.

Mooching roommates are an ancient problem. Certain species of beetles evolved to live with and leech off social insects such as ants and termites as long ago as the mid-Cretaceous, two new beetle fossils suggest. The finds date the behavior, called social parasitism, to almost 50 million years earlier than previously thought.

Ants and termites are eusocial — they live in communal groups, sharing labor and collectively raising their young. The freeloading beetles turn that social nature to their advantage. They snack on their hosts’ larvae and use their tunnels for protection, while giving nothing in return.

Previous fossils have suggested that this social parasitism has been going on for about 52 million years. But the new finds push that date way back. The specimens, preserved in 99-million-year-old Burmese amber, would have evolved relatively shortly after eusociality is thought to have popped up.

One beetle, Mesosymbion compactus, was reported in Nature Communications in December 2016. A different group of researchers described the other, Cretotrichopsenius burmiticus, in Current Biology on April 13. Both species have shielded heads and teardrop-shaped bodies, similar to modern termite-mound trespassers. Those adaptations aren’t just for looks. Like a roommate who’s found his leftovers filched one too many times, termites frequently turn against their pilfering housemates.

A hard look at experimental setups may start to explain dueling predictions on whether ocean acidification will boost, or choke, vital marine nitrogen fixers. So far, the new look trends toward choking.

As people release more and more carbon dioxide into the air, the ocean takes up the gas and edges closer toward acidity. In these shifting waters, marine microbes called Trichodesmium could falter in adding nitrogen, a critical input for marine food webs, says Dalin Shi of Xiamen University in China. And the problem could be exacerbated in acidifying seas where iron is scarce — for instance, in wide swaths of tropical and subtropical waters such as the southern Atlantic and Pacific oceans, Shi and colleagues report April 27 in Science.
The question of how Trichodesmium cyanobacteria are reacting to the changing ocean makes a big difference in predicting how other marine life, from whales to mere specks of floating plankton, will react, too. Nitrogen, essential to life for such basic processes as building DNA and proteins, makes up much of Earth’s atmosphere. Yet most living things can’t do any chemistry with the atmospheric form, two nitrogen atoms fiercely triple-bonded to each other. Trichodesmium microbes, however, can crack those bonds and transform nitrogen into more usable forms. These cyanobacteria may account for up to half of the nitrogen fixed in the ocean.

Lab research in the past 10 years generally suggested that increasing CO2 encouraged the photosynthetic Trichodesmium to grow more abundantly and supply more usable nitrogen. The rates varied, however. But when Shi and colleagues tried their version of the experiment, they found a decrease in nitrogen fixation, not an increase. “I was very excited, and I was really puzzled,” says Shi, who published the results in 2012.

After a string of detailed lab work, from culturing lab microbes to sampling wild cyanobacteria, he and colleagues propose an explanation for the contradictions. For one thing, much of the previous lab work used a recipe for artificial seawater that permitted contamination by toxic metals and forms of nitrogen, the researchers concluded. These unwanted additions introduced unexplained variety to the results.

Also, Shi and collaborators demonstrated that rising CO2 alone can stimulate the microbes’ growth but that the watery slide toward ocean acidity can depress the microbes’ ability to fix nitrogen. And if the cyanobacteria are growing in water short on iron, an essential nutrient for them, the slowdown in nitrogen fixation can overwhelm any positive growth effects from extra CO2.

The paper could be a big help in resolving the contradictions among experiments, says oceanographer Douglas Capone of the University of Southern California in Los Angeles.

Orly Levitan, an author of what may have been the first study of acidification boosting nitrogen fixation, says she would consider changing her seawater recipe based on the new paper if she were to revisit this work. Yet Levitan, who studies plankton at Rutgers University in New Brunswick, N.J., cautions against extrapolating too far. A look at wild Trichodesmium suggests that the cyanobacteria may have unexpected ways of compensating in iron-starved waters, enhancing the capture of minerals from dust settling out of the air, for instance. It’s too early, she says, to close discussion on what will happen in the complexities of the real ocean.

Oxygen on comets might not date all the way back to the birth of the solar system.

Instead, interactions between water, particles streaming from the sun and grains of sand or rust on the comet’s surface could generate the gas. Those interactions could explain the surprising abundance of O2 detected in the fuzzy envelope of gas around comet 67P/Churyumov-Gerasimenko in 2015 (SN: 11/28/15, p. 6), researchers report May 8 in Nature Communications. Such reactions might also reveal how oxygen forms in other regions of space.
“Molecular oxygen is very hard to find out there in the universe,” says Caltech chemical engineer Konstantinos Giapis. When the Rosetta spacecraft detected oxygen around comet 67P, astronomers argued it must be primordial, trapped in water ice as the comet formed roughly 4.6 billion years ago. Intrigued by the result, Giapis and Caltech colleague Yunxi Yao wanted to see if an alternative way to create O2 existed. Drawing on their work with fast-moving charged particles and materials such as silicon, they performed experiments that showed that charged water particles could slam into rust or sand grains and generate O2.

Something similar could happen on comet 67P, they suggest. As the sun evaporates water from the comet’s surface, ultraviolet light could strip an electron from the water, giving it a positive charge. Then, fast-moving particles in the solar wind could shoot the ionized water back toward the comet’s surface, where it could collide with rust or sand particles. Atoms of oxygen from the water could pair with atoms of oxygen from the rust or sand, creating O2.

The idea is plausible, says Paul Goldsmith, an astrophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. He helped discover O2 in the Orion nebula and says the reaction might happen in places where young stars are forming and in other regions of space.

Rosetta mission scientist Kathrin Altwegg of the University of Bern in Switzerland calls the result interesting, but is skeptical it can explain comet 67P’s oxygen abundance. As the comet gets closer to the sun, a protective bubble develops around 67P, data from the mission showed; that bubble would prevent solar wind particles or other ionized particles from reaching the comet’s surface, Altwegg says. Also, the ratio of oxygen to un-ionized water also stays constant over time. It should be more variable if this chemical reaction were generating oxygen on the comet, she says.

Goldsmith, however, suggests researchers keep an open mind and design missions with instruments to test whether this newly detected reaction does, in fact, generate oxygen in space.

For black adults, moving out of a racially segregated neighborhood is linked to a drop in blood pressure, according to a new study. The finding adds to growing evidence of an association between a lack of resources in many predominately black neighborhoods and adverse health conditions among their residents, such as diabetes and obesity.

Systolic blood pressure — the pressure in blood vessels when the heart beats — of black adults who left their highly segregated communities decreased just over 1 millimeter of mercury on average, researchers report online May 15 in JAMA Internal Medicine. This decline, though small, could reduce the overall incidence of heart failure and coronary heart disease.
“It’s the social conditions, not the segregation itself, that’s driving the relationship between segregation and blood pressure,” says Thomas LaVeist, a medical sociologist at George Washington University in Washington, D.C., who was not involved with the study. “Maybe hypertension is not so much a matter of being genetically predisposed.” That’s important, LaVeist adds, because it means that racial health disparity “can be fixed. It’s not necessarily contained in our DNA; it’s contained in the social DNA.”

Racial segregation can impact a neighborhood’s school quality, employment opportunities or even whether there is a full-service grocery store nearby. Social policies that improve residents’ access to education, employment and fresh foods can “have spillover effects in health,” says Kiarri Kershaw, an epidemiologist at Northwestern University Feinberg School of Medicine in Chicago.

Kershaw and colleagues examined data from a study of how cardiovascular disease progresses in healthy adults, aged 18 to 30, who were recruited from four locations: Chicago, Minneapolis, Oakland, Calif., and Birmingham, Ala. The researchers specifically looked at blood pressure readings for 2,280 black participants, recorded at six points over 25 years, and noted their addresses at the time of each reading. A neighborhood’s designation of high, medium or low racial segregation was based on the percentage of black residents in the neighborhood compared with the larger metropolitan area or county, Kershaw says.

At the start of the study in the mid-1980s, 1,861 participants were living in highly segregated neighborhoods. A temporary move to a less segregated neighborhood, the researchers found, was associated with a 1 millimeter of mercury drop in blood pressure on average.

If the change of address was permanent — as it was for 243 participants — the impact was greater. On average, blood pressure dropped close to 6 millimeters of mercury for those who moved to low-segregation neighborhoods, and nearly 4 millimeters for a move to a medium-segregation neighborhood.
A 2015 study in the Journal of the American Heart Association estimates that a decrease in systolic blood pressure of 1 millimeter of mercury could result in several thousand fewer cases of heart failure, stroke and coronary heart disease annually in the U.S. population of black adults aged 45 to 64, Kershaw says.

Along with other research on racial segregation and health, the findings suggest that policies that improve housing conditions, educational resources and employment opportunities “will have implications for the health of individuals,” LaVeist says. “Social policy is health policy.”