Scientists playing peekaboo with dark matter have entered a new stage of the game.
For the first time, physicists are snooping on some of the likeliest hiding places for hypothetical subatomic particles called axions, which could make up dark matter. So far, no traces of the particles have been found, scientists with the Axion Dark Matter Experiment, ADMX, report April 9 in Physical Review Letters. But the researchers have now shown that their equipment is sensitive enough to begin searching in earnest.
An ethereal substance that makes up much of the matter in the universe, dark matter is necessary to explain the motions of stars within galaxies, among other observations. Scientists don’t know what dark matter is, but axions, extremely lightweight particles that may permeate the cosmos, are one of the major contenders.
Most past searches for dark matter particles have focused on a different candidate particle, known as a weakly interacting massive particle, or WIMP. But those efforts have so far come up empty (SN: 11/12/16, p. 14). Now, the spotlight is on the underdog axions. “We have to make sure we are considering all the possibilities,” says theoretical physicist Matthew Buckley of Rutgers University in Piscataway, N.J., who was not involved with the new result. Axions, he says, are a plausible candidate for dark matter.
Axions would produce incredibly feeble signals, so pinning down evidence for the minuscule particles is no easy undertaking. But ADMX, located at the University of Washington in Seattle, is now up to the task, says ADMX member Aaron Chou, a physicist at Fermilab in Batavia, Ill. Previous experiments have searched for axions, but those efforts weren’t sensitive enough to have a good chance of detecting the particles.
“It’s an experimental tour de force; it’s amazing work,” says theoretical physicist Helen Quinn of SLAC National Accelerator Laboratory in Menlo Park, Calif., who was not involved with the research.
ADMX uses what is essentially a supersensitive radio, isolated from external sources of radio waves and cooled to temperatures near absolute zero (‒273.15° Celsius). Scientists use the apparatus to search for axions converting into radio waves in a strong magnetic field. If axions exist, they are expected to interact with photons, particles of light, from the magnetic field. In the process, they would produce radio waves at a frequency that depends on the axion’s mass, which is unknown. Like scanning the dial for a good oldies station, scientists will gradually change the frequency at which they search, trying to “listen in” on the axion signal.
While the new study came up empty, scientists scanned only a small range of frequencies, ruling out some possible masses for axions, from 2.66 to 2.81 microelectron volts. Those tiny masses are less than a billionth of an electron’s mass. In the future, ADMX will study other possible masses. “There’ll be a lot of excitement in the next few years,” Chou says. “A discovery could come at any time.”
Using the precise position and brightness of almost 1.7 billion stars, the Gaia spacecraft has created the most precise 3-D map of the Milky Way yet.
On April 25, the European Space Agency’s Gaia team released the spacecraft’s second batch of data, gathered from July 2014 to May 2016, used to create the map. The tally includes measurements of half a million quasars — the active black holes at the centers of distant galaxies — and 14,099 known solar system objects (mostly asteroids), observations of other nearby galaxies and the amount of dust in between Earth and 87 million stars (SN: 4/14/18, p. 27).The spacecraft also measures the distances and motions of stars by taking advantage of Earth’s motion around the sun, a technique called parallax. As Earth moves, stars appear to trace a small ellipse, whose size is related to the stars’ distance. Measuring the wavelengths of light the stars emit tells how fast they are moving toward or away from the sun. Combining Gaia’s measurements with earlier sky surveys let astronomers track stars’ motions.
Gaia launched in 2013, and released its first batch of data in September 2016 (SN: 10/15/16, p. 16). Those data included distances and motions of roughly 2 million stars; the new data up that number to 1.3 billion.
Knowing those distances will allow astronomers to decipher details about the Milky Way’s shape and history. Already the second data release suggests that the galaxy contains two distinct populations of stars that may have different origins. The stars’ chemistry and motions suggest that some could have originated in a different galaxy that the Milky Way cannibalized long ago.
“With Gaia, we can reconstruct the whole history of the Milky Way,” ESA science director Günther Hasinger said in a news conference April 25.
In Finland, 88 percent of people have a genetic variation that increases their risk for migraines. But in people of Nigerian descent, that number drops to 5 percent.
Coincidence? Maybe. But a new study suggests that, thousands of years ago, that particular genetic mutation increased in frequency in northern populations because it somehow made people better suited to handle cold temperatures. That change may have had the unfortunate consequence of raising the prevalence of these severe headaches in certain populations, researchers report May 3 in PLOS Genetics. The mutation is in a stretch of DNA that controls the behavior of TRPM8, a protein that responds to cold sensation. People with the older version of this DNA snippet seems less susceptible to migraines than people with the mutated version, previous studies have shown.
Using a global database of human genetic information, evolutionary geneticist Aida Andres and her colleagues showed a correlation between the frequency of the mutation in a given population and that population’s latitude. It’s rare in Africa, for example, but fairly common across Europe.
Differences in temperature may have led to this variation, though scientists still aren’t sure exactly how the mutation affects TRPM8. Perhaps the mutation conferred some benefit to early humans who moved north from Africa, says Andres, of University College London. The connection to migraine appears to be a side effect.
The researchers acknowledge, however, that the science of migraines isn’t so simple. One variant can’t fully explain why these headaches are more common in certain populations. Migraine risk is “very complex,” Andres says. “It’s highly heritable, but other things impact it, too.” Plus, there’s still a lot to learn about TRPM8. “We don’t even really know how the entirely normal [protein], with no mutations, contributes to migraine,” says Greg Dussor, a neurobiologist at the University of Texas at Dallas who wasn’t part of the study.
Even the link between migraine and temperature is muddy: While cold temperatures can trigger migraines in some people, heat sets others off.
Choose wisely because in this fantasy you’ll transform into the creature and duel against one of your own. If you care about survival, go for the muscular, multispiked stag roaring at a rival. Never, ever pick the wingless male fig wasp. Way too dangerous.
This advice sounds exactly wrong. But that’s because many stereotypes of animal conflict get the real biology backward. All-out fighting to the death is the rule only for certain specialized creatures. Whether a species is bigger than a breadbox has little to do with lethal ferocity.
Many creatures that routinely kill their own kind would be terrifying, if they were larger than a jelly bean. Certain male fig wasps unable to leave the fruit they hatch in have become textbook examples, says Mark Briffa, who studies animal combat. Stranded for life in one fig, these males grow “big mouthparts like a pair of scissors,” he says, and “decapitate as many other males as they possibly can.” The last he-wasp crawling has no competition to mate with all the females in his own private fruit palace. In contrast, big mammals that inspire sports-team mascots mostly use antlers, horns and other outsize male weaponry for posing, feinting and strength testing. Duels to the death are rare.
“In the vast majority of cases, what we think of as fights are solved without any injuries at all,” says Briffa, of Plymouth University in England.
Evolution has produced a full rainbow of conflict styles, from the routine killers to animals that never touch an adversary. Working out how various species in that spectrum assess when it’s worth their while to go head-to-head has become a challenging research puzzle.“In the vast majority of cases, what we think of as fights are solved without any injuries at all,” says Briffa, of Plymouth University in England.
To untangle the rules of engagement, researchers are turning to animals that live large in small bodies but don’t have sports teams named after them. At least not yet. Deadliest matches It’s hard to imagine nematodes fighting at all. There’s little, if any, weaponry visible on the see-through, micronoodle body of the species called Steinernema longicaudum. Yet in Christine Griffin’s lab at Maynooth University in Ireland, a graduate student offered a rare hermaphrodite to a male as a possible mate. Instead of mating, the male went in for the kill. “We thought, well, poor hermaphrodite, she’s not used to mating, so maybe it’s just some kind of accident,” says Griffin, whose lab specializes in nematodes as pest control for insects. When the grad student, Kathryn O’Callaghan, offered females of another species, males killed some of those females too. When given a chance, males also readily killed each other. That’s how nematodes, in 2014, joined the list of kill-your-own-kind animals, Griffin says. Killing another nematode is an accomplishment for a skinny thread of an animal with just two thin, protruding prongs. The male S. longicaudum slays by repurposing his mating moves.
When he encounters a female of his own species, the male coils his tail around her and positions the prongs, known as spicules, to hold open the entrance to her reproductive tract. To kill, a male just coils his tail around another male, or a female of a different species, and squeezes extra hard. Pressure ruptures internal organs; sometimes spicules even punch a hole during the fatal embrace. The grip lasts from a few seconds to several minutes. Of those worms paralyzed by the attack, most are dead the next day.
Other nematodes live in labs around the world without murdering each other. So why does S. longicaudum, for one, lean toward extreme violence? Its lifestyle of colonizing the innards of an insect inclines it to kill, Griffin suggests. An insect larva is a prize one male worm can monopolize, not to mention the only place he can have sex.
These nematodes lurk in soil without reproducing or even feeding until they find a promising target, such as the pale fat larva of a black vine weevil. Nematodes wriggle in through any opening: the larva’s mouth, breathing pores, anus. If a male kills all rivals inside his new home, he becomes the nematode Adam for generations of offspring perhaps totaling in the hundreds of thousands, Griffin says. Territorial female slayers A defendable bonanza like a weevil larva, or a fig, has become a theme in the evolution of lethal fighting. Biologists have studied violence in certain male fig wasps for decades, but more recent research has revealed that some females kill each other too.
When a female Pegoscapus wasp, a bit longer than a poppy seed, chooses one particular pea-sized sac of flowers, a fig-to-be, she’s deciding her destiny. That sac is most likely her only chance at laying eggs, and will probably be the fruit she will die in, says evolutionary ecologist Charlotte Jandér of Harvard University.
Shortleaf fig trees (Ficus citrifolia) have “a delicate flowery smell,” Jandér says, but the blooms are hidden inside the little green-skinned sacs. To reach these inner riches and lay one egg per flower in as many flowers as she can, the wasp must push through a tight tunnel. The squeeze can take roughly half an hour and rip her wings and antennae. Reaching the inner cavity carpeted in whitish flowers, “there is plenty of space for one wasp to move around,” Jandér says. But more than one gets cramped, and conflicts get desperate.
In a Panamanian wasp species that Jandér has watched, females “can lock on to each other’s jaws for hours and push back and forth,” she says. In a Brazilian species, 31 females were found decapitated among 84 wasps, reported Jandér, Rodrigo A.S. Pereira of the University of São Paulo and colleagues in 2015. That was the first documented female-to-female killing in fig wasps.
Walk away From bellowing red deer stags to confrontational male stalk-eyed flies, many animal species have ways to back off rather than fight to the death. Searching for dynamics of less-than-deadly discord, Briffa studies sea anemones. And yes, anemones fight. Beadlet sea anemones (
Actinia equina
) release sperm and eggs into open seawater, so the animals don’t need to argue over mates. For a prime bit of tide pool rock, however, tensions rise.
Below a beadlet’s pinkish, swaying food-catcher tentacles are what often look like “little blue beads,” Briffa says. These are fighting tentacles, or acrorhagi. When combat looms, the anemone inflates them. “Imagine someone pulling out their bottom lip to make a funny face,” he says.
It’s no joke for an impertinent neighbor. Anemones, distant relatives of stinging jellies, carry harpoon-shooting, toxin-injecting capsules in the acrorhagi. Combatants rake stinger acrorhagi down each other’s soft flesh. “It almost looks like they’re punching each other,” Briffa says. “When one of the anemones decides it’s had enough and wants to quit the contest, it actually actively walks away.”
“Walk” is used loosely here, says Sarah Lane, a postdoc in Briffa’s lab, as she alternately arches her hand and flattens it in a measured trip across the Skype screen. “Like a cartoon caterpillar?” she says, trying to describe the gait. “A concertina?” When placed side by side in the lab for fighting tests, anemones concertina away or otherwise resolve the tension without any acrorhagi swipes about a third of the time. De-escalating makes sense considering that a full exchange “looks quite vicious,” Lane says. Strikes leave behind bluish fragments of acrorhagi full of stinging capsules, which kill tissue on the recipient. The attacker isn’t unscathed either; close-ups show open wounds where acrorhagi tissue was pulled out. An anemone “literally can’t hurt an opponent without ripping parts of itself off,” she says.
Injuries to an attacker from swiping, biting or other acts of aggression get overlooked in theorizing over how animals weigh the costs and benefits of dueling, Lane and Briffa argued in the April 2017 Animal Behaviour. The sea anemones may be an extreme example of self-harm from a strike, but they’re not the only one.
Humans can hurt themselves when they attack, and decision making around fighting has had some unintended consequences, Lane points out. In a bare-handed punch at somebody’s head, little bones in the hand crack — called boxer’s fractures — before the skull does. With the introduction of gloves around 1897, boxer’s fractures basically disappeared from match records, Lane says. Before gloves, however, records show no reported deaths in professional matches. Once gloves lessened the costs of delivering high-impact punches, deaths began appearing in the records.
Worth the fight? Sea anemones don’t have a brain or centralized nervous system, yet costs and benefits of fighting somehow still matter. The animals clearly pick their fights, escalating some blobby sting matches and creeping away from others.
Just how anemones choose, or how any animal chooses when to fight and when to back down, turns out to be a rich vein for research. Theorists have proposed versions of two basic approaches. One, called mutual assessment, “is sussing out when you’re weaker and giving up as soon as you know — that’s the smart way,” Briffa says. Yet the evidence Briffa has so far, he says with perhaps a touch of wistfulness, suggests anemones use “the dumb way of giving up.”
Animals resort to this “dumb” option, called self-assessment, when they can’t compare their opponent’s odds of winning with their own. Maybe they fight in shadowy, murky places. Maybe they don’t have the neural capacity for that kind of comparison. For whatever reason, they’re stuck with “keep going until you can’t keep going anymore,” he says. Never mind if the fight is hopeless from the beginning.
The odds of fighting “smart” look better for the animals that Patrick Green of Duke University studies. Those creatures have a brainlike ganglion and come close to fighting with superpowers. He’s working with, of course, mantis shrimp.
The high-powered smashers among these small crustaceans flick out a club that can accelerate as fast as a bullet shooting out of a .22 caliber pistol. When the clubs wham a tasty snail, the bounce back creates a low-pressure zone that vaporizes water. “I always feel weird saying this because it seems just goofy, but that does release heat equivalent to the surface of the sun,” Green says. But only for a fraction of a microsecond.
When smasher mantis shrimp — male or female — fight each other, they don’t supernova rivals into oblivion. The reality, arguably stranger, is that they superpunch each other. But the blows land on an area that can withstand the force: the telson, a bumpy shield covering the rump (SN: 7/11/15, p. 13).
In Caribbean rock mantis shrimp (Neogonodactylus bredini), the battle is often over after just one to five blows too fast for the human eye to see. With combatants of equal size, the winner is not the animal that lands the most forceful blow, but the one that gets in the most punches. Then, with no visible gore, one dueler just gives up. Now Green and Sheila Patek, also of Duke, propose that telson sparring, as they call it,
permits genuine mutual assessment, the smart way of losing a fight
. It’s difficult to figure out what lurks in the neural circuits of an arthropod, but the researchers presented multiple lines of evidence in the Jan. 31
Proceedings of the Royal Society B.
One strong clue came from matches Green staged between mantis shrimp of different sizes. He didn’t see a trend of smaller ones pointlessly pounding telsons as the lightweights fought bigger animals. Those bigger animals were going to win anyway, and it seemed as if the smaller ones got it, suggesting something more than self-assessment is going on, Green and Patek propose.
Researchers think they have seen mutual assessment in other animals too, among wrestling male New Zealand giraffe weevils (SN: 10/4/14, p. 4) and male jumping spiders that flip up banded legs in “Goal!” position to intimidate rivals. Analyzing assessment gets tricky. Game theorists have weighed in, but there’s debate over what kind of biological evidence truly distinguishes one form of assessment from another. And research in new directions is bringing more biological realism to the discussion of conflicts. Human scientists, dazzled by the sights and sounds that our own sensory world emphasizes, may be underestimating chemical cues. Among crawfish, “part of their fight is squirting urine in one another’s faces,” Briffa says.
Paradoxically peaceful Many of the scariest-looking weapons end up causing little bodily harm. Some are specialized for combat that’s more strategic than gory. Other weapons look so scary they hardly ever get used.
Among the tools for odd but not life-threatening combat are the horns of the male Asian rhinoceros beetles studied by Erin McCullough, now at the University of Western Australia in Perth. Male Trypoxylus dichotomus compete furiously with each other and grow forked horns on their heads that stretch nearly two-thirds the beetle’s body length. The horns are surprisingly lightweight, but look cumbersome. “Like a Styrofoam leg sticking out of your forehead,” she says. She watched the beetles in action on a muggy summer night lurking around ash trees at a university in Taiwan. Hardly blending in with the students, she decked out in leather gloves and a head lamp, making sure her shirts had the collars pulled way up. “You shouldn’t wear mosquito repellant when you’re working with insects,” she says.
The scene was “really messy and chaotic,” she recalls. Beetles flying out of the dark fought to dominate cracks in ash tree bark that oozed sap and attracted females. A dominant beetle would grip the bark and use his horn to flick incoming challengers off the branch left and right — until he was usurped. Getting thrown off the limb doesn’t kill losers; often they buzz right back for another try.
Yet evolutionarily speaking, a male prevented from mating might as well be dead, so the tactic was consequential. Males with longer horns are better at flicking off other males, but longer horns are more likely to snap, McCullough concluded. A broken horn doesn’t grow back, so the extravagant tool needs to be a pry bar of the right length, lightness and strength. Pristine horns on male beetles just starting their fighting careers have about four times the strength the horns need to resist cracking, about the safety factor that engineers build into bridges but less than the standard for elevator cables, she says.
Horns or antlers on male mammals often can kill, yet fatal fights may be rare. One of his favorite studies from decades-old literature, says Douglas Emlen of the University of Montana in Missoula, looked at about 1,308 sparring matches between male caribou in Alaska. With all this glaring, snorting and rushing, only six matches escalated into violent, bloody fights.
The caribou fit one of the paradoxical phases of the evolution of animal weaponry that Emlen studies. Usually evolution doesn’t favor extremes in teeth, horns or other such fighting body parts. Certain forms of sexual rivalry, however, can escape such stabilizing forces and expand extravagantly in a body-part arms race. There are common patterns to such arms races, he says, including some cheating.
Among the conditions that favor an arms race are rivalries playing out in one-on-one duels, he says. Imagine a magnificently endowed dung beetle in a tunnel, a female in the depths behind him, as he fends off rivals one by one for her attention. Growing bigger and bigger horns for an arms race becomes biologically expensive. Eventually, only an animal with the best nutrition, genes and luck can spare the resources to grow a truly commanding horn. At that point, horn size honestly signals a male that can overpower just about all rivals. Only if he confronts another supermale will he need to fight all out. The rest of the time, the signal value of his prodigious weaponry keeps the peace with barely a bump or a bruise.
Yet this is “a very unstable situation,” Emlen says. “It creates incentives for males to cheat.” Or maybe the word is “innovate.” He found that big-horned male dung beetles defending their tunnels could be outmaneuvered by small rivals who dug bypass tunnels around the guard zone and mated with the supposedly defended female. Beetle horns may not be the best analogy for human nuclear arsenals, but, Emlen notes, the innovations of cyberattacks have certainly bypassed hugely expensive national defense systems.
At the far extreme of animal rivalries are some species that blur the meaning of fights. Some butterflies, such as the speckled wood butterfly, “fight” without physical contact. Males compete for a little sunlit dapple on the forest floor by flying furious circles around each other until one gives up and scrams. No gore, but probably really exhausting.
Pity the protons: Those little particles are under a lot of pressure. Protons’ innards are squeezed harder than any other substance we have measured, a new study finds.
“It’s really the highest pressure we have ever seen,” says physicist Volker Burkert, a coauthor of the study, published in the May 17 Nature. Protons break the pressure record set by neutron stars, the incredibly dense dead stars that can form when a massive star explodes and its core collapses, squeezing more mass than the sun’s into a remnant the size of a city. The pressure in the proton’s center averages a million trillion trillion times the strength of Earth’s atmospheric pressure, report Burkert and colleagues, from Thomas Jefferson National Accelerator Facility in Newport News, Va. That’s around 10 times the pressure found inside a neutron star. Previously, scientists had theoretically predicted that such pressures might occur inside protons, but the new result is the first experimental proton pressure gauge.
In proton research, the particle’s internal pressure distribution has been a largely unexplored frontier, even though pressure is one of the proton’s fundamental properties. “It’s as important as electric charge or mass,” says physicist Peter Schweitzer of the University of Connecticut in Storrs, but was unknown until now.
Protons are made up of smaller particles including quarks, which are electrically charged, and gluons, which transmit the strong nuclear force that holds protons together (SN: 4/29/17, p. 22). In the center of this ball of particles, Burkert and colleagues report, an intense pressure pushes outward. But this record-breaking outward force is kept in check by an inward pressure from the outer regions of the particle.
This pressure pattern parallels what happens in much larger objects: “In some sense, it’s looking like a star,” says physicist Oleg Teryaev of the Joint Institute for Nuclear Research in Dubna, Russia. Stars also have pressures that push outward in their centers, which counteract the inward pull of gravity. Protons are held together by the strong force, just as stars are held together by gravity. But the tiny protons are a different beast. So “it’s natural, but it’s not completely trivial” that the two objects would have similarities pressure-wise, Teryaev says. To quantify the proton’s squeeze, the researchers used data from a particle detector known as CLAS, short for the Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer, located at Jefferson Lab. In experiments with CLAS, scientists shot electrons at liquid hydrogen, a plentiful source of protons, and watched what happened as electrons interacted with the protons’ constituents and ricocheted away. The new measurement is based on data from 2015 that was analyzed for the first time using a technique that could tease out the proton’s pressure.
The experiment, however, studied the quarks in protons, but not gluons, because the energy of the electrons — 6 billion electron volts — was not enough for the electrons to fully probe the protons. To make their pressure estimate, the researchers assumed that the gluons’ pressure contribution was the same as the quarks’, which is in line with some theoretical predictions.
Future particle accelerators, such as the planned Electron-Ion Collider, would allow for gauging the gluons’ contribution to provide a better estimate of the crushing pressure protons endure.
Green blood is weird enough. But now the first genealogical tree tracing green blood in New Guinea’s Prasinohaema lizards is suggesting something even odder.
These skinks have been lumped into one genus just because of blood color, says biologist Christopher Austin of Louisiana State University in Baton Rouge. Yet they don’t all turn out to be close relatives. Green blood looks as if it arose four separate times in the island’s lizards, he and colleagues propose May 16 in Science Advances. These lizards do have crimson red blood cells, but that color is overwhelmed by extreme buildups of a green pigment called biliverdin at levels that could kill other animals. Biliverdin forms as the oxygen-carrying hemoglobin molecules break down in dead red blood cells. In humans, biliverdin is converted into the bile that, in excess, causes yellow jaundice. An excess of the biliverdin itself can cause green jaundice. In one case study, levels reaching nearly 50 micromoles of biliverdin per liter of blood were deadly in humans. Yet Austin has found lizards thriving with 714 to 1,020 micromoles per liter (SN: 8/20/16, p. 4).
To figure out how such a peculiar trait evolved, he and colleagues compared segments of DNA and reconstructed the evolutionary history of green-blooded lizards and some close relatives. The greens did not emerge as a single cluster, but were scattered among the reds. The most probable explanation is that green blood, though rare, evolved independently multiple times, he says. The team is now working out the full sequences of lizards’ DNA building blocks and hoping to spot clearer evolutionary clues, such as particular mutations that helped red turn green. He hopes this research eventually will yield insights into human bile disorders. High but harmless biliverdin hasn’t turned up in the blood of other reptiles, or in mammal and bird blood. Older papers, however, argue for high circulating biliverdin in some sculpins and other fishes in at least two more families, two frogs and insects such as tobacco hornworm caterpillars. Whether the pigment offers any advantage is still a mystery. When Austin started studying lizards, he wondered if green blood would deter predators. “I tested the hypothesis by eating a few lizards myself and also feeding lizards to native birds and snakes,” he says. “No ill effects.” Now he’s musing that biliverdin might discourage blood parasites such as malaria pathogens.
And the taste of a green-blooded lizard? “Like bad sushi,” he says.
The Elephant Man, novelist Pearl S. Buck and Phoebus, god of the sun, all find their way into science writer Carl Zimmer’s latest book. In She Has Her Mother’s Laugh, Zimmer uses famous moments in history — and Greek mythology — to explain genetics and how researchers have come to understand heredity and try to manipulate it.
Zimmer walks through centuries of exploration, settling into stories of scientists who tried to use simplistic notions of heredity to improve the human race. While investigating inheritance, Francis Galton, who coined the term “eugenics,” noticed that notable men had notable sons. He suggested in 1865 that England’s well-being depended on a national breeding program to produce more talented people. His hereditary utopia would make a terrifying episode of TV’s Black Mirror. Galton’s work launched later efforts in the United States to erase undesirable characteristics through sterilization laws and mental capacity checks of immigrants. Eugenics also fed the Nazis’ notion of a superior race. Zimmer doesn’t shy away from the harmful impact of such research and describes the science that showed the flaws in such discriminatory thinking. With more than 550 pages, the book covers a lot of ground, from discoveries of inherited diseases like phenylketonuria to mosaics, individuals whose cells are not all genetically identical. In places, Zimmer uses the private lives of public figures to introduce advances in genetics. With so many examples, it’s hard to grasp why he included certain stories. Some parts drag a bit, others zing. We’re all familiar with Joseph Merrick, the Elephant Man. How researchers came to understand why he was deformed is fascinating. In the early 2000s, scientists discovered that several people with the same disease, now called Proteus syndrome, had mutations in the AKT1 gene important to controlling cell growth. There is current work on a drug to block the gene’s actions. Too late for Merrick, but the work offers hope for people today with the disease.
For some readers, the parts of the book that cover recent research history may feel like familiar walks down memory lane, with added context and details. Zimmer takes us back to research on Neandertals interbreeding with ancient humans (SN: 6/5/10, p. 5), Pima Indians and their high rates of type 2 diabetes, and CRISPR, the prized gene-editing tool (SN: 9/3/16, p. 22). Zimmer describes following CRISPR research as a reporter, witnessing “the beginning of something enormous.”
The book ends with cautionary tales about past attempts to toy with nature to fix environmental problems that turned into ecological disasters. Zimmer also points out future risks of gene manipulation that scientists and ethicists have just begun to consider. The next chapter on heredity, he notes, has as many warning signs as opportunities.
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LEESBURG, Va. — Astronomers watching the 2017 solar eclipse from the ground and from the air witnessed new, tantalizing features of the sun’s outer atmosphere.
Three teams have recently presented their first science results from the Great American Eclipse. Combined, the findings could help disentangle lingering solar puzzles, such as how bursts of plasma leave the sun, why the outer atmosphere, the solar corona, is so well organized and what is the nature of the corona’s magnetic field. While thousands of eclipse watchers gathered across the country last August armed with special glasses and cameras, solar physicists Adalbert Ding and Shadia Habbal and their colleagues set up a specially designed spectrometer in Mitchell, Ore. (That was one of four sites from which their team monitored the eclipse.) The team had used an earlier version of the instrument, which takes in specific wavelengths of light that can trace different coronal temperatures, to watch a solar eclipse in March 2015 from Svalbard, Norway. In both 2015 and 2017, the scientists observed evidence of relatively cool blobs of gas embedded in hot plasma in the outer corona. (The sun’s surface simmers at about 6000° Celsius, but its corona roasts at millions of degrees — and no one knows why.) Ding, of the Institute for Optics and Atomic Physics in Berlin, and Habbal, of the University of Hawaii in Honolulu, measured wavelengths of light emitted by atoms and charged particles called ions in the corona, as a proxy for the plasma’s heat. To the researchers’ astonishment, they saw blobs of plasma during both eclipses that had maintained temperatures as low as 20,000° C embedded within material in the corona that was as hot as 3.7 million degrees Celsius, Ding said at the Triennial Earth-Sun Summit on May 23. “We were very surprised,” Ding says. He thinks the cooler material may be trapped within plasma bubbles and can’t get out. “The stunning thing is that they survive.” The team also measured solar material’s Doppler shift, or the change in wavelength as the material moved toward or away from Earth. The shifts suggested that the scientists had caught a huge bubble of plasma erupting off the sun’s surface and fleeing out into space in 2015 (SN Online: 6/16/17). At the time, they thought seeing such an explosion, called a coronal mass ejection, was just luck.
If so, their luck held for the 2017 eclipse. The researchers haven’t finished processing all of their data yet, but preliminary results showed uncharged hydrogen and helium atoms fleeing the sun as far out as 3.5 solar radii from the edge of the sun’s bright disk, at speeds of about 600 kilometers per second.
In another talk at the meeting, solar physicist Amir Caspi of the Southwest Research Institute in Boulder, Colo., presented results from a different vantage point: a WB-57F aircraft flying at about 15 kilometers in altitude.
Caspi’s team was trying to see signs of magnetic waves called Alfvén waves rippling through the outer corona. Simulations of the plasma in the corona “lead you to this Velcro-looking thing, a tangled snarled mess,” Caspi said. “In fact, that’s not what we see.” Alfvén waves could smooth out the snarls, which could help explain why the material there is so neatly organized (SN Online: 8/17/17). What’s more, the waves may contribute to the mysterious coronal heating. So Caspi’s colleagues flew telescopes on a pair of NASA’s high-altitude aircraft during the eclipse to look for these waves. The results were mixed, Caspi admits, in part because the telescopes were not designed for this type of science. NASA originally commissioned them to monitor shuttle launches for issues after the space shuttle Columbia disaster in 2003 (SN: 2/8/03, p. 83).
“Our mission was the first attempt to use them for astronomy,” Caspi says.
The telescopes saw some motion in the corona that could have been waves — or could have been jitter from the planes’ motion. “They’re tantalizing, they’re definitely not random,” Caspi said. “But we don’t know yet whether this is an artifact of the corrections we had to make, or if this is really on the sun.”
The team also captured an image of the corona in infrared wavelengths, which the researchers think is the first image of its kind. Eventually, such infrared measurements could help scientists measure the corona’s magnetic field, which governs most of the corona’s behavior but has never been measured directly (SN Online: 8/16/17).
In another experiment, solar physicist Jenna Samra of Harvard University and her colleagues were on the lookout for certain infrared wavelengths in the corona that were expected to be bright enough to see from the ground.
The team measured five wavelengths, one of which had never been seen before, the team reports in the April 1 Astrophysical Journal Letters. Solar physicist and study coauthor Philip Judge of the High Altitude Observatory in Boulder had predicted in 1998 that those wavelengths, which are especially sensitive to the magnetic field, should be visible in the corona. The results can help plan future observations with the Daniel K. Inouye Solar Telescope, currently under construction in Maui, Hawaii.
Judge and other team members observed the eclipse from Casper, Wyo., and saw some of the same wavelengths (SN Online: 8/21/17), although water in Earth’s atmosphere absorbed some of the light.
Samra, however, observed the eclipse from a plane, a Gulfstream V aircraft at an altitude of 14.3 kilometers. “It was a one-of-a-kind experience. I wouldn’t trade it,” she says. “But in the moment it was terrifying, honestly.”
Fusion may have a dark side. A shadowy hypothetical process called “dark fusion” could be occurring throughout the cosmos, a new study suggests.
The standard type of fusion occurs when two atomic nuclei unite to form a new element, releasing energy in the process. “This is why the sun shines,” says physicist Sam McDermott of Fermilab in Batavia, Ill. A similar process — dark fusion — could occur with particles of dark matter, McDermott suggests in a paper published in the June 1 Physical Review Letters. If the idea is correct, the proposed phenomenon may help physicists resolve a puzzle related to dark matter — a poorly understood substance believed to bulk up the mass of galaxies. Without dark matter, scientists can’t explain how galaxies’ stars move the way they do. But some of the quirks of how dark matter is distributed within galaxy centers remain a mystery.
Dark matter is thought to be composed of reclusive particles that don’t interact much with ordinary matter — the stuff that makes up stars, planets and living creatures. That introverted nature is what makes the enigmatic particles so hard to detect. But dark matter may not be totally antisocial (SN: 3/3/18, p. 8). “Why wouldn’t the dark matter particles interact with each other? There’s really no good reason to say they wouldn’t,” says physicist Manoj Kaplinghat of the University of California, Irvine.
Scientists have suggested that dark matter particles might ricochet off one another. But the new study goes a step further, proposing that pairs of dark matter particles could fuse, forming other unknown types of dark matter particles in the process.
Such dark fusion could help explain why dark matter near the centers of galaxies is more evenly distributed than expected. In computer simulations of galaxy formation, the density of dark matter rises sharply toward a cusp in the center of a galaxy. But in reality, galaxies have a core evenly filled with dark matter. Those simulations assume dark matter particles don’t interact with one another. But dark fusion could change how the particles behave, giving them energy that would provide the oomph necessary to escape entrapment in a galaxy’s dense cusp, thereby producing an evenly filled core.
“You can kick [particles] around through this interaction, so that’s kind of cool,” says physicist Annika Peter of the Ohio State University in Columbus. But, she says, dark fusion might end up kicking the particles out of the galaxy entirely, which wouldn’t mesh with expectations: The particles could escape the halo of dark matter that scientists believe surrounds each galaxy.
For now, if fusion does have an alter ego, scientists remain in the dark.
Tropical cyclones don’t move as fast as they used to.
The fierce, swirling storms move 10 percent slower, on average, than they did nearly 70 years ago, a new study finds. Such lingering storms can potentially cause more damage by dumping even more rainfall on land beneath them.
Atmospheric scientist James Kossin examined changes in how quickly tropical cyclones, known as hurricanes in the Atlantic Ocean, moved across the planet from 1949 to 2016. Storms slowed at different rates depending on the region, with the biggest changes seen in the Northern Hemisphere, Kossin reports in the June 7 Nature. Over that same time period, the average temperature of Earth’s surface rose by about half a degree Celsius. Scientists already predict that average wind speeds will increase in tropical cyclones as ocean waters warm due to global warming (SN: 6/27/15, p. 9). The new study suggests that climate change is also altering how quickly these tropical cyclones travel across land or water.
The effect was even more pronounced as storms moved over land, with those originating in the western North Pacific, such as near Japan, slowing by 30 percent. Storms coming in from the North Atlantic – such as 2017’s Hurricane Harvey — are moving 20 percent slower over land, says Kossin, of the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information in Madison, Wis. The new study makes an important link between the atmospheric effects of global warming to its effects on tropical cyclones, says atmospheric scientist Christina Patricola of the Lawrence Berkeley National Laboratory in California, who also wrote a commentary that accompanies the new paper. “Tropical cyclones tend to move along with larger-scale [atmospheric] circulation around them,” she says. “Kossin perceptively hypothesized that this overall slowdown would also affect tropical cyclones.”
It’s not clear whether the slowdown will continue into the future, or how it might vary regionally, Patricola says. Most previous work has focused on how climate change will affect the wind speeds of storms rather than how quickly they travel, known as the translation speed. “But in order to have the best information for building resilience to storms, we need to understand these other characteristics,” she says.
The cyclone slowdown is consistent with a weakening in atmospheric circulation in the tropical parts of the planet, a result of global warming, Kossin found. Global warming is also expected to increase how much water vapor the atmosphere can hold, which means storms could accumulate more moisture before releasing it in rainfall.
Slow-moving Hurricane Harvey, which dumped record levels of rain while lingering for days over southern Texas, could be a harbinger of things to come.
