The secret of Spirit Cave: Crossing from Asia, first Americans rushed into the unknown


Nearly 11,000 years ago, a man died in what is now Nevada. Wrapped in a rabbit-skin blanket and reed mats, he was buried in a place called Spirit Cave.

Now scientists have recovered and analyzed his DNA, along with that of 70 other ancient people whose remains were discovered throughout the Americas. The findings lend astonishing detail to a story once lost to prehistory: how and when humans spread across the Western Hemisphere.

The earliest known arrivals from Asia were already splitting into recognizably distinct groups, the research suggests. Some of these populations thrived, becoming the ancestors of indigenous peoples throughout the hemisphere.

But other groups died out entirely, leaving no trace save for what can be discerned in ancient DNA. Indeed, the new genetic research hints at many dramatic chapters in the peopling of the Americas that archaeology has yet to uncover.

“Now, this is the grist for archaeologists,” said Ben Potter of the University of Alaska, who was not involved in the new papers. “Holy cow, this is awesome.”

A photo provided by Linus Mørk, Magus Film shows Eske Willerslev, center, with members of the Fallon Paiute-Shoshone tribe in Nevada.

Earlier studies had indicated that people moved into the Americas at the end of the last ice age, traveling from Siberia to Alaska across a land bridge now under the Bering Sea. They spread southward, eventually reaching the tip of South America.

Until recently, geneticists could offer little insight into these vast migrations. Five years ago, just one ancient human genome had been recovered in the Western Hemisphere: that of a 4,000-year-old man discovered in Greenland.

The latest batch of analyses, published in three separate studies this week, marks a turnaround. In the past few years, researchers have recovered the genomes of 229 ancient people from teeth and bones discovered throughout the Americas.

One of them is a rare individual, only the second so-called Ancient Beringian whose DNA has ever been analyzed.

The first, described in January by Eske Willerslev, a geneticist at the University of Copenhagen, was a 11,500-year-old girl whose remains were found in eastern Alaska.

Artist impression’ provided by Nature.com, showing an Inuk to illustrate a study published in Nature in which Danish scientists carried out a DNA analysis on a tuft of human hair that has been buried in the Greenland permafrost for the last 4,000 years.

The second was discovered hundreds of miles away, in western Alaska, and lived 9,000 years ago, Willerslev and his colleagues reported Thursday in the journal Science.

The Ancient Beringians separated from the ancestors of living indigenous people in the Americas about 20,000 years ago. The new findings suggest they endured for several thousand years. Then they disappeared, leaving no known genetic trace in living people.

But another wave of migrants from Siberia did not stop in Alaska. They kept moving, eventually arriving south of the ice age glaciers. Then they split into two branches.

One group turned and headed north, following the retreating glaciers into Canada and back to Alaska. The other branch took a remarkable journey south.

The genetic data suggest that …read more

Source:: Nationalpost – News

      

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