Aug. 26th, 2014

brdgt: (Pollen death balls by iconomicon)
How a Weed, Once a Prehistoric Cavity Fighter
By RANJODH SINGH, The New York Times, August 18, 2014

Cyperus rotundus, commonly known as purple nutsedge or nutgrass, is considered one of the world’s worst invasive weeds. But new research suggests that prehistoric humans in what is now central Sudan may have gotten an unusual benefit from it.

Stephen Buckley, an archaeological chemist from the University of York in England, analyzed dental calculus — a form of hardened plaque — in fossilized teeth from people who lived thousands of years ago, in the pre-Mesolithic, Neolithic, and Meroitic periods.

In a paper published in the journal PLOS One, Dr. Buckley and his colleagues report that the teeth had remarkably few cavities and high levels of the chemical compounds found in purple nutsedge, suggesting that the plant may have protected against tooth decay.

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Tuberculosis Is Newer Than Thought, Study Says
By CARL ZIMMER, The New York Times, August 20, 2014

New research indicates that some seal species carried tuberculosis across the Atlantic Ocean.

After a remarkable analysis of bacterial DNA from 1,000-year-old mummies, scientists have proposed a new hypothesis for how tuberculosis arose and spread around the world.

The disease originated less than 6,000 years ago in Africa, they say, and took a surprising route to reach the New World: It was carried across the Atlantic by seals.

The new study, published Wednesday in the journal Nature, has already provoked strong reactions from other scientists.

“This is a landmark paper that challenges our previous ideas about the origins of tuberculosis,” said Terry Brown, a professor of biomolecular archaeology at the University of Manchester. “At the moment, I’m still in the astonished stage over this.”

But Helen Donoghue, an expert on ancient DNA at the University College London, rejected the idea that tuberculosis could have emerged so recently. “It just cannot be right,” she said, citing earlier fossil evidence of the disease.

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Neanderthals in Europe Died Out Thousands of Years Sooner Than Some Thought, Study Says
By KENNETH CHANG, The New York Times, August 20, 2014

Neanderthals, our heavy-browed relatives, spread out across Europe and Asia about 200,000 years ago. But when did they die out, giving way to modern humans?

A new analysis of Neanderthal sites from Spain to Russia provides the most definitive answer yet: about 40,000 years ago, at least in Europe. That is thousands of years earlier than some scientists have suggested, and it narrows the period that Neanderthals and modern humans overlapped in Europe.

“After that, we don’t think there are any Neanderthals on the continent anymore,” said Thomas Higham, the deputy director of the radiocarbon accelerator unit at the University of Oxford in England.

On the other hand, the dating also argues against the view that modern humans overwhelmed the Neanderthals as soon they arrived in Europe. While modern humans and Neanderthals do not appear to have intermingled in the same locales, the findings suggest they co-existed in neighboring regions for up to several thousand years.

The findings, reported Wednesday in the journal Nature, run counter to claims that pockets of Neanderthals persisted in Portugal, Spain and Gibraltar until just 30,000 years ago, even as modern humans spread outward.

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