First Americans may have crossed Atlantic 50,000 years ago

In a discovery sure to set off a firestorm of debate over human migration to the western hemisphere, archaeologists in South Carolina say they have uncovered evidence that people lived in eastern North America at least 50,000 years ago - far earlier than any previously known human presence.

If the results hold up, this could spur some significant rewriting of early human history. It adds to a growing body of evidence that human colonization of the Western Hemisphere is a more complicated - and much older - story than one involving simply a land bridge from Asia.

Cracks in that theory had already begun to appear in recent years. But the new evidence - in the form of stone tools buried deep in the South Carolina countryside - could be the most credible and provocative yet. Coupled with other finds, it promises to spur inquiry into the possibility the hemisphere's first humans may have come from Europe or Africa.

This could also put human migration to the Americas on the same time footing as human movement out of Africa and into Australia and Central Asia.

Lead archeologist Al Goodyear concedes that the findings of his group won't be accepted without debate. "I expect outright rejection of these results," he said in an interview. But he still asserts that the find is "the real deal."

The University of South Carolina archaeologist and his team uncovered what they interpret as simple stone tools in a layer of soil far below previous layers dated to about 16,000 years ago. "The geology and the [radiocarbon] dates are solid" for the layer in which the simple flake tools and coring tools were found.

The dating of the artifacts to some 50,000 years ago, announced at a press conference Wednesday at the university, comes at a period in North American archaeology when researchers are still smarting from bruising battles over evidence that humans arrived several thousand years earlier than the so-called Clovis culture, whose artifacts date to between 10,800 and 11,500 years ago.

"This is an interesting piece of information," says Tom Dillehay, an anthropologist at Vanderbilt University in Nashville. "It really needs to be compared against other available evidence. Even people with open minds will hesitate on 50,000 years."

Yet the South Carolina team's find is not alone in its antiquity - dates which begin to push the radiocarbon-dating techniques used to their limits. One site in Oklahoma has been dated to between 30,000 and 35,000 years ago. Brazilian and European archaeologists are working a site in Brazil that they say dates to 50,000 to 60,000 years ago. And a site in Chile has yielded artifacts dating to 33,000 years ago. In all cases, however, the evidence has been controversial.

Researchers interested in the origins of native Americans once held that the first Americans crossed a land bridge between Siberia and North America, then down into the "lower 48" through a corridor in the glaciers in the last ice age.

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