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. Last Updated: 07/27/2016

Prehistoric Find Fuels Debate Over First Americans

Most people probably wouldn't have noticed it, but farmer Harold Conover in 1988 happened to see a stone spear point in the sand on a logging road near his farm in Carson, Virginia.

That chance discovery triggered a decadelong excavation that eventually might resolve the ongoing, often bitter controversy over when humans first migrated to North America.

The spear point itself wasn't unusually old, but it led archeologists Joseph and Lynn McAvoy to a prehistoric campsite that might be as many as 17,000 years old - or 5,500 years older than the so-called Clovis sites thought to be the oldest on this continent.

The findings indicate that humans have lived in North America much longer than researchers previously believed and hint that their origins might be different from what had been believed.

Other archeologists have made similar claims for a number of sites in both North and South America, some apparently dating as far back as 35,000 years. But the dating of those sites, as well as the validity of the artifacts found there, are questionable.

But data presented last month by Joseph McAvoy and a team of archeologists at the Society for American Archeology meeting in Philadelphia seem to have firmly established the age of the Virginia site, called Cactus Hill.

"This one looks real," McAvoy said, and others agree. "This is probably some of the oldest material in North America, if not the entire New World," said Dennis Stanford of the Smithsonian's National Museum of Natural History.

The Cactus Hill site is one of several that are overturning the long-reigning theory of how humans first came to the Americas. Archeologists had assumed that the first inhabitants walked across the Bering Strait to Alaska when ice covered its surface about 12,000 years ago.

Those first migrants quickly moved south, expanding their presence throughout the continent within as few as 500 years. That population is termed "Clovis" because the first remnants of its existence - fluted spear points and other tools - were discovered at a site near Clovis, New Mexico. The distinctive Clovis spear points have since been found throughout the continent and, recently, in northeastern Asia as well, affirming the origin of these nomadic hunters.

But the story has been growing more complicated. Some archeologists have identified other sites, such as the Meadowcroft rock shelter in Pennsylvania and the Topper site along the Savannah River in Georgia, that appear to be pre-Clovis. But their dates have not been authenticated to everyone's satisfaction.

Others have found evidence that other populations might have migrated to the continent as well. Recent studies suggest that a seafaring population worked its way down the Pacific coast, establishing villages and fishing grounds on land that is now submerged. Some archeologists believe that the process occurred along the Atlantic coast as well.

But the dates of such events are questionable, and that is why the Cactus Hill site has assumed such importance. The McAvoys and their colleagues have produced dating evidence that might well be irrefutable, thanks in part to Conover's discovery. Skeptics scoffed at Joseph McAvoy's claim that the Cactus Hill spear points were possibly 17,000 years old. Stung, McAvoy organized a team of at least 10 specialists and spent the last three years "challenging the conclusions" of his original report.

Soil scientist James Baker of Virginia Tech University, for example, used a technique called luminescent dating to show that the sand at the site had not been disturbed over the millenniums, suggesting that perturbation of the site by water or burrowing animals had not occurred.

"To me, the evidence is irrefutable," McAvoy said.