Discover的March 2018目录

As kids who grew up skiing in the mountains of Montana, my brother and I were always on guard for those pesky and elusive snow snakes. The little rascals were masters at hiding beneath the chopped-up powder, lying in wait to snag your ski edge and knock you off balance. They weren’t actual snakes, of course. But I was more than happy to shift blame onto these imaginary creatures that had nabbed my metal edges and sent me tumbling. For the daughter of a ski racing coach, that dose of humor helped curb the frustration of keeping Dad’s long list of things to do in your head as you carved, and slid, down a run. The fictional snow snakes were a way for a kid to push through something difficult.…

YOU’VE HEARD IT FOR YEARS: When you get antibiotics, finish the prescription even if you feel better. Otherwise, the bug might develop antibiotic resistance — a growing problem that’s making infections harder to treat. But a recent commentary in The BMJ argues that advice needs updating; stopping the meds might be better. In Science Smackdown, we invite experts to debate both sides of the issue. The Claim TIME TO CHANGE THE MESSAGE It’s been known for decades that stopping antibiotics early doesn’t cause resistance, says Martin Llewelyn, author of The BMJ paper and an infectious diseases professor at Brighton and Sussex Medical School in the U.K. For most of the bacteria posing threats today, it’s just the opposite: Longer exposure to antibiotics increases the risk they’ll develop a resistance. To…

It’s a hazy Sunday morning in early July as Levi Jamison pulls to the side of the road in central New Mexico. He grabs a camera, clipboard and thick canvas insect net from the blue Volkswagen van that is his traveling home and office, and begins to hike along an irrigation ditch just east of the Rio Grande. A seemingly unending thicket of tall, shrubby tamarisk trees parallels the ditch. He stops just a few feet in, picks a tree at random, and sweeps the net over the dusty-green leaves exactly five times. Then, he peers into the canvas, quickly counting a mass of tiny Diorhabda beetles already crawling up the fabric to escape. He scribbles the number — “160,” he says — and the GPS coordinates in his notes.…

PUT A RING ON IT PUT A RING ON IT It’s no Saturn, but one day Mars may have rings of its own. Researchers predict that gravitational forces will tear the tiny moon Phobos apart as it spirals closer to the Red Planet. From this violent end, a serene set of rings (albeit darker and less spectacular than Saturn’s) could emerge as soon as 25 million years from now. Read about how this will happen, starting on page 58.…

SENSING A MATCH Perched on a branch in Australia, a male feather-horned beetle, Rhipicera femorata, searches for companionship. A 2015 paper suggests that during the beetle’s mating season, sight and hearing don’t come into play when a male is looking for a partner. Instead, the aptly named insect uses chemical receptors on its large, bushy antennae to sense the mating pheromones of nearby females, which have fewer receptors.…

ANTHROPOLOGIST CAMERON SMITH usually digs into the past, but these days, he does a lot of forward thinking. The Portland State University professor spends his spare time and money designing and building a spacesuit. He wants to make one with a price that’s about 1 percent of a comparable NASA getup, which costs roughly $70,000. This year, he’ll put his life on the line to test his design by piloting a hot air balloon by himself to about 50,000 feet, far above the altitude of commercial jetliners. Smith’s designs have attracted the attention of SpaceX, but the 51-year-old isn’t interested in profits. He’s committed to making his spacesuit plans freely available online. Discover joined Smith at his downtown Portland condoand- workshop to learn more about what drives this explorer. Q…

More than a thousand years ago, the Vikings arrived on the world stage as swiftly as their longships cut through the waves. They raided and traded, conquered and colonized. They left their mark on four continents — not just at archaeological sites, but also in the flora and fauna, the languages and local populations. The Viking Age did not last long — it’s generally defined as beginning in the late eighth century and ending in most areas by the early 12th century — but the explorers still capture our imagination today. “The Vikings epitomized the freedom and strength we like in our heroes,” says Judith Jesch, professor of Viking studies at the University of Nottingham. “They were enterprising and bold; they were certainly violent, but so was everyone else at…

One day in April 2014, Mathilde Tissier noticed her hamsters were acting a little odd. The Cricetus cricetus in her lab at the University of Strasbourg in France, once happily subsisting on a corn-based diet, were now banging their feeder against the cage, their tongues swollen and black, and had begun to eat their pups alive. As Tissier reported in the Proceedings of the Royal Society B in January 2017, she suddenly had cannibal hamsters on her hands. “I was shocked,” says Tissier, a conservation biologist. “I thought I did something wrong.” Searching for an explanation, Tissier teased out a thread that wove through America’s past. Some of the symptoms she saw in both the mothers and surviving pups resembled those of a debilitating disease called pellagra. The illness affected…

THE TRANSANTARCTIC MOUNTAINS SPLIT our planet’s southernmost continent into east and west, at times rising more than 14,000 feet high. Today, it’s a barren landscape of inhospitable rock and ice. But for the scientists who hike and camp this rocky spine, it’s also a portal to another Earth. Park University paleobotanist Patty Ryberg and her colleagues are uncovering the fossilized remains of a lush forest that thrived in the Antarctic Circle some 260 million years ago during the Permian period. One type of tree, called glossopterids, dominated much of a supercontinent. Then they vanished in a geological instant. The glossopterids didn’t die alone. About 90 percent of life on Earth was snuffed out in our planet’s biggest known extinction, called the Great Dying. What killed everything? Scientists have long debated…

Thanks to humans, our planet is facing its sixth great extinction. As their habitats dwindle or are destroyed altogether, many plants and animals are disappearing. That’s not much fun to think about. So, with that in mind, writer Ceri Levy sought out legendary illustrator Ralph Steadman. Among his many accolades, the British artist co-invented gonzo journalism — where the storyteller becomes the story — as an illustrator for the various works of lifelong friend Hunter S. Thompson, including Fear and Loathing in Las Vegas. Levy asked Steadman to draw one particular endangered bird for an art exhibition. He agreed. But Steadman couldn’t stop at just one; he’s now drawn hundreds of endangered species. The pair have published three books together, including their latest, Critical Critters, excerpted here. Steadman starts the…

Jupiter’s four faint and dusty rings probably formed by a different mechanism — and more recently — than Saturn’s, but its moons still play a vital role. Amalthea and Thebe are the likely sources of the material in Jupiter’s outer two “gossamer” rings. Thebe orbits within the outer gossamer ring, while Amalthea lies near the outer edge of the inner gossamer ring. Metis and Adrastea, two other small moons, orbit near the outer edge of Jupiter’s main ring, and are the sources of the dust grains making up the main and innermost halo rings. Some forces work against the rings, keeping them relatively thin. Electromagnetic forces, a phenomenon called plasma drag, and even pressure from sunlight (called the Poynting-Robertson effect) continually remove the micronsized particles from the rings. But particles…