Discover的December 2016目录

→Luciana barely recalled when they first appeared — those painless, lavender bumps dappling her arms and legs. “Oh meu Deus, o que é isso?” (“Oh my God, what is this?”) thought the 40-year-old native of Goias, Brazil, while continuing to care for her family. Later on, an idea took root. Were the purple welts on her limbs connected to the flaming mass on her face? Almost reflexively, Luciana’s fingers brushed her nose, whose boggy, red flesh she sometimes draped with a scarf. This angry feature had puzzled Luciana’s American doctors for years. They initially blamed it on a terrible case of sinusitis. Then an ear, nose and throat surgeon sprayed local anesthetic, passed a scope and obtained tiny bites of tissue. The biopsies suggested Wegener’s granulomatosis, a rare autoimmune disease.…

It’s the soft part of a summer morning, when the sun is barely up and the day’s heat has not yet taken hold. A young rabbit ventures from a thicket of raspberries, nose quivering. Its movement does not go unnoticed. Some 20 feet away, one of two dogs sprawled belly-up on the grass opens her amber eyes. The other dog turns over slowly and looks in the direction of the raspberries. They roll to their feet, eyes now trained on the rabbit. The animal darts for the back gate. The dogs pursue. The female, smaller and more agile, swerves left and right like a cheetah, adjusting course with the rabbit. The bigger male dog thuds behind. They close in on the prey as a team. Without slowing, the rabbit squeezes…

The bone was no bigger than a coffee bean. It was a bit of pinky from a young girl that could have easily been missed among the thousands of bones dug up by archaeologists at the site each year. Yet the unassuming fossil made it out of Denisova Cave in Siberia’s Altai Mountains and into the Max Planck Institute’s ancient DNA laboratory in Leipzig, Germany, where in 2010 it yielded a complete genome of a previously unknown type of human. “No one had suspected such a population was out there,” says geneticist Matthias Meyer, who worked on the specimen. That partial finger bone was the first evidence of the Denisovans, a distinct branch of the Homo family tree, whose members mated with both Neanderthals and modern humans during the past…

Floss was in the hot seat this summer when news broke that it has no proven health benefits. The U.S. Department of Health and Human Services and the U.S. Department of Agriculture had recommended flossing in its 2015 Dietary Guidelines for Americans, a report issued every five years that must be based on scientific evidence. But when Associated Press journalists probed for the evidence, the government turned up emptyhanded and dropped flossing from its guidelines. In this Science Smackdown we ask: Does science support flossing? The Evidence Isn’t There Back in 2014, dozens of leading periodontists — dentists who focus on the tissues surrounding your chompers — hunkered down for several days to evaluate at-home techniques for cleaning plaque between teeth. Regarding floss, they considered findings from over 10 original…

Two cosmonauts stepped off a bus at the Baikonur Cosmodrome — the Soviet Cape Canaveral — ready to ride a 10-story Soyuz rocket into orbit. This launch complex in the heart of Kazakhstan had sent the first satellite, animal and human (Sputnik, Laika and Yuri Gagarin) into space. It was the spring of 1991, three decades after Gagarin’s historic flight, and Sergei Krikalev and Anatoly Artsebarsky were there to follow in his footsteps. But first, they kept up the tradition Gagarin had started back in 1961. The men marched to the right rear tire of the bus, unzipped their spacesuits and started urinating. Then, they headed for the launch pad. To the world, space travel had become routine. American astronauts had flown dozens of space shuttle missions, and Soviet cosmonauts…

→At 4:31 a.m. on Jan. 17, 1994, residents of Los Angeles were jolted awake by a 6.7-magnitude earthquake that killed more than 60 people, crumpled buildings and freeways, swallowed automobiles, ignited fires and caused a blackout. That last effect, plunging the city into darkness, prompted dozens of residents to call the city’s Griffith Observatory because of something weird they saw in the night sky: the Milky Way. “The lights of Los Angeles were out,” recalls E.C. Krupp, the longtime director of the observatory, “so the night sky was dark for a change. People were puzzled and wondered if there was a connection between the earthquake and the strange sky. We figured out they just weren’t used to seeing so many stars.” A global atlas of the night sky, published in…

The Creepiest Behavior Watches you before interacting: 4.55 Touches you frequently during conversation: 4.24 Steers conversation toward sex: 4.16 Asks to take your picture: 4.11 Asks for personal details of family: 4.09 Opposite sex: 4.01 Appearance: 3.87 Never looks you in the eye: 3.74 Significantly older than you: 3.72 Shows little emotional expression: 3.62 Talks a lot about personal life: 3.41 Extremely thin: 3.18 Displays a lot of emotion: 3.15 Tall: 3.08 Has facial hair: 2.89 Dresses too formally for occasion: 2.64 Crosses arms: 2.61 The Creepiest Hobbies 25% of participants say collecting things (dolls, insects, bones, etc.) 8% say some variation of observing things (bird-watchers and photographers of children were most frequently listed) 8.6% say yes 59.4% say no 32% say they’re unsure…

When NASA’s Juno spacecraft arrived at Jupiter this summer, engineers did a victory dance — and not just because their mission would return the best Jovian data ever. They were also celebrating Juno’s solar panels — the biggest on any planetary probe — taking the mission farther than any other sun-powered spacecraft. Juno’s solar technology represents a giant leap in space exploration. Before its success, far-out craft used nuclear power. The Cassini mission to Saturn, the twin Voyagers’ trips beyond the solar system, Curiosity’s rove around the Martian surface, New Horizons’ pass by Pluto and Galileo’s close encounter with Jupiter were all brought to you by the radioactive element plutonium-238. NASA uses dense plutonium “pellets” for fuel. As the atoms decay, they release high-speed helium nuclei and then become smaller…

→On a sweaty October day in a dense, vine-laden forest near the town of Noh-Bec, Mexico, in the Yucatán Peninsula, a dozen American and Mexican conservation scientists bounce in the back of a truck headed down a narrow, rutted track of red mud. After a bone-jarring hour, the road widens. Teams of men haul logs from the forest and saw them into pieces, which they will later saw into lumber or carve into Popsicle sticks, feeding slash into furnaces to make charcoal. The truck stops, and the scientists climb down and file into a small, sunny clearing. Noh-Bec forester Pascual Blanco Reyes, the tour leader, shows the scientists some of the forest’s most pampered residents: stick-thin, 3-foot-tall mahogany saplings. Reyes and his colleagues planted them after cutting mahogany trees nearly…

“SPACE” IS CERTAINLY AN APT NICKNAME FOR OUR COSMOS, SINCE THERE’S A HECKUVA LOT OF IT OUT THERE. Between here and the moon, about a quarter-million miles away, there’s virtually nothing — just stray hydrogen, helium and the odd dust particle. On far grander scales, this barrenness becomes unimaginably vast. A desolate, virtually starless, 2.5 million light-year gulf — that’s nearly 15 quintillion miles — separates our home galaxy, the Milky Way, from its nearest sizable neighbor, the Andromeda Galaxy. Yet compared to cosmic scales, the Milky Way and Andromeda are right next door. Like neighbors awkwardly catching glances of each other through the windows, we can see Andromeda with the naked eye as a glowing smudge in its namesake constellation. The vast majority of the universe’s galaxies similarly huddle…

1 Of the 7,537 species of amphibians, 6,631 are frogs and toads. 2 Anura, the order of frogs, comprises 55 families including Ranidae, often referred to as “true frogs.” 3 With a name like “true frogs,” you might think ranids are a unified bunch. Think again: There are no definitive traits among family members, though most lack ribs, have teeth on their upper jaws and have horizontal pupils. 4 Ranids are found on every continent but Antarctica and in a wide range of habitats, from trees to deserts. 5 Wherever they roam, or hop, home is where the nest is — especially for tidy types such as the túngara frog, common in much of Central and South America. Like many other frogs, the túngara create foam nests for their eggs.…