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Science

How Musk Ox Make It Through Arctic Nights and Never-Ending Days

In the distant reaches of northeastern Greenland, musk oxen amble across the tundra, grazing as they go. As Arctic creatures, they need to gather enough energy to make it through cold, dark winters. So when the bright summers come, they eat as if their lives depend on it — as in fact they do.Their lives are so extreme, scientists have wondered: Do they have circadian clocks?Most creatures on the planet live in lock step with the planet’s daily cycle of light and dark. There’s a time of day for eating, a time of day for sleeping, a time for digestion and so on. Scientists think 24-hour internal clocks help maximize an organism’s survival by keeping it from, for instance, wasting energy foraging at times of day when food may be hard to find. Evolution clearly favored this approach — circa...

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Science

These Hummingbirds Take Extreme Naps. Some May Even Hibernate.

Indeed, they found that birds that used torpor only briefly could lose as much as 15 percent of their body weight. Birds who took a longer break, on the order of 12 hours, lost only 2 percent. Birds that reached lower temperatures lost a smaller percentage, too.Some species, like the sparkling violetear, descended to a set temperature (in this case, roughly 46 degrees Fahrenheit) regardless of the ambient temperature. Others, like the black metaltail, seemed to be tracking the air and got very cold. One metaltail hovered around 38 degrees Fahrenheit, scoring the lowest recorded temperature of any hummingbird, to the researchers’ knowledge.In fact, the metaltail, the black-breasted hillstar and the bronze-tailed comet, which are related species, all entered colder, longer bouts of torpor...

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How the Aging Immune System Makes Older People Vulnerable to Covid-19

A second waveSeveral days after the innate immune response begins, the body begins a second wave of attacks against the viral invader. This adaptive immune system response is more targeted than the first, methodically destroying cells infected by this specific virus.But in older bodies, the adaptive response not only takes longer to get into gear, it arrives to find a scene of inflammatory pandemonium, said Amber Mueller, a postdoctoral researcher at Harvard Medical School who co-authored a paper published in May about Covid-19 and aging. Think of firefighters coming to put out a house fire, she said.The Coronavirus Outbreak ›Frequently Asked QuestionsUpdated September 4, 2020What are the symptoms of coronavirus?In the beginning, the coronavirus seemed like it was primarily a respirator...

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How a Fruit in Your Garden Gets Its Shiny Blue Color

Big, leafy viburnum bushes have lined yards in the United States and Europe for decades — their domes of blossoms have an understated attractiveness. But once the flowers of the Viburnum tinus plant fade, the shrub makes something unusual: shiny, brilliantly blue fruit.Scientists had noticed that pigments related to those in blueberries exist in viburnum fruit, and assumed that this must be the source of their odd hue. Blue fruit, after all, is rare. But researchers reported last week in Current Biology that viburnum’s blue is actually created by layers of molecules arranged under the surface of the skin, a form of what scientists call structural color. By means still unknown, the plant’s cells create thin slabs of fat arranged in a stack, like the flakes of puff pastry, and their pecul...

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