Archivo: Science

It’s only a tiny change. At some point early in the pandemic, one of the 30,000 letters in the genome of SARS-CoV-2 changed from an A to a G. Today, that mutation, at position 23,403, has spread around the world. It is found in the vast majority of newly sequenced viruses and has become the center of a burning scientific question: Has the mutation become so common because it helps the virus spread faster? Or is it just coincidence?

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In a biological beating of swords into plowshares, researchers have converted a bacterial toxin into a genome editing tool that, for the first time, can make precise changes to DNA in mitochondria, the cell’s power plants. The tool, which worked in lab experiments with human cells, could open the door to new studies of—and one day therapies for—dozens of hard-to-treat diseases caused by mutations in mitochondrial DNA (mtDNA). These rare conditions, which include Leber hereditary optic neuropathy and lethal infantile cardiomyopathy, collectively affect about one in 4000 people. Until now, research on these illnesses has been stymied in part because there was no way of reproducing the mutations in strains of mice.

Crouching as she wound her way through a pinched underground corridor, a young woman grasped a torch in one hand, soot blackening the craggy ceiling above her. Guided by stacks of stones deeper and deeper in the darkness of the cave, she finally spied her prize: a blood-red vein of rock in the fire-lit wall. It would be 10,000 years before another pair of eyes saw it again.

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Myths about horses and gender abound. Many equestrians, for example, say they prefer “predictable” geldings over “moody” mares, despite no real difference in their behavior while ridden. Now, a new study suggests our biased views of horses may have ancient origins. Based on ancient DNA from hundreds of horse skeletons, researchers suggest Bronze Age Eurasians overwhelmingly preferred male horses—preferences that may shed light on the earliest days of horse husbandry.

The landscape—more than 300 turquoise-blue pozas scattered across 800 square kilometers, among marshes and majestic mountains—wasn’t the only draw. The waters, whose chemistry resembled that of Earth’s ancient seas, teemed with microbes; unusual bacterial mats and formations called stromatolites carpeted the shallows.

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NASA’s newest Mars rover, Perseverance, is going back in time to the bottom of a vanished lake. If all goes well, in February 2021 it will land in Jezero crater and pop the dust covers off its camera lenses. Towering in front of it, in all likelihood, will be a 60-meter cliff of mudstone: the edge of a fossilized river delta. These lithified martian sediments could hold answers to urgent questions about the earliest days of Earth’s chilly, parched neighbor: How did this pintsize planet, so distant from a faint young Sun, support liquid water on its surface? How much water was there, and how long did it persist? And did Mars ever spawn life?

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It is the world’s most common farm animal as well as humanity’s largest single source of animal protein. Some 24 billion strong, it outnumbers all other birds by an order of magnitude. Yet for 2 centuries, biologists have struggled to explain how the chicken became the chicken.

For ages, the shadow of a volcano has hung over the fall of the Roman Republic. Ancient historians told of the Sun’s mysterious disappearance after Julius Caesar’s murder in 44 B.C.E., which was followed by bouts of cold and crop failures. Now, a team of scientists and historians has discovered that one of the largest known eruptions in history struck in 43 B.C.E.—potentially contributing to 2 years of weird weather and famine as the republic dissolved and the empire took shape.

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Every summer, as the days get long, Anastassia Makarieva leaves her lab in St. Petersburg for a vacation in the vast forests of northern Russia. The nuclear physicist camps on the shores of the White Sea, amid spruce and pine, and kayaks along the region’s wide rivers, taking notes on nature and the weather. “The forests are a big part of my inner life,” she says. In the 25 years she has made her annual pilgrimage north, they have become a big part of her professional life, too.

Planets are forming around young stars far faster than scientists expected, arising in a cosmic eye blink of less than half a million years, according to a new study. That finding could inform models of planet formation and help resolve a problem plaguing astronomers since 2018, when data indicated that planetary nurseries contained far too little material to actually create planets.