Archive for Friday, January 2, 2004

Ice Age find may yield migration clues

January 2, 2004

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— A people who may have been ancestors of the first Americans lived in Arctic Siberia, enduring one of the most unforgiving environments on Earth at the height of the Ice Age, according to researchers who discovered the oldest evidence yet of humans living near the frigid gateway to the New World.

Russian scientists uncovered a 30,000-year-old site where ancient hunters lived on the Yana River in Siberia, some 300 miles north of the Arctic Circle and not far from the Bering land bridge that then connected Asia with North America.

"Although a direct connection remains tenuous, the Yana ... site indicates that humans extended deep into the Arctic during colder (Ice Age) times," the authors wrote in a study appearing this week in the journal Science.

The researchers found stone tools, ivory weapons and the butchered bones of mammoths, bison, bear, lion and hare, all animals that would have been available to hunters during that Ice Age period.

Using a dating technique that measures the ratios of carbon, the researchers determined the artifacts were deposited at the site about 30,000 years before the present. That would be about twice as old as Monte Verde in Chile, the most ancient human life known in the American continents.

Donald K. Grayson, a paleoanthropologist at the University of Washington in Seattle, said the discovery was significant because it was so much earlier than any other proven evidence of people living in the frigid lands of Siberia that formed the gateway to the Americas.

"Until this site was reported, the earliest site in Bering land bridge area was dated at about 11,000 years ago," said Grayson. "Every other site that had been thought to have been early enough to have something to do with peopling of the New World has been shown not to be so."

At the time of the Yana occupation, much of the high latitudes on the Earth were in the grip of an ice age that sent glaciers creeping over much of what is now Europe, Canada and the northern United States.

But the Yana River area was ice free, a dry floodplain without glaciers. It was home to mammoth, horse, musk ox and other animals that provided food for the human hunters who braved Arctic blasts to live there.

"Abundant game means lots of food," Julie Brigham-Grette of the University of Massachusetts, Amherst, said in Science. "It was not stark tundra as one might imagine."

Some experts hope that the new discovery will provide important new clues about the ancient migration from Asia to the Americas.

Finding evidence of human habitation at the Yana site "makes it plausible that the first peopling of the Americas occurred prior to the last glacial maximum," Daniel Mann of the University of Alaska, Fairbanks, said in Science. The last glacial maximum was 20,000 to 25,000 years ago.

Grayson and others, however, said more evidence is needed before it becomes widely accepted that it was people from the Yana site who migrated to the New World.

The major problem, said Grayson, is that archaeological evidence for human dwellings in Siberia is still sparse. Also, there is a gap of thousands of years between the 30,000-year-old Yana site and other sites in Asia and the Americas.

There was no physical barrier to going to the Americas from Asia during that period. The Bering land bridge connected the two continents until about 11,000 years ago, when a rising sea level flooded the connection and created what is now called the Bering Strait between Russia and Alaska.

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