New stone clues to ancient Americansy

GRANTS PASS, Ore. -- Stone tools and human DNA from ancient caves in Oregon offer new evidence of how some of the first Americans spread through the continent: Quite apart from the better-known Clovis culture, a separate group may have occupied the West.

Archaeologists said yesterday that, using multiple techniques, they have dated broken obsidian spear points from Paisley Caves to about 13,200 years ago, as old as much different stone tools from the Clovis culture found in the southeast and interior United States. Radiocarbon dating of human DNA from coprolites (ancient desiccated human feces) shows people lived in the caves as early as 14,300 years ago.

The dates indicate that the Clovis style of chipping stone was not the mother of Stone Age technology, as others have theorized, and that the two styles were developed independently by different groups, said Dennis Jenkins, an archaeologist with the University of Oregon's Museum of Natural and Cultural History, who led the excavations. That development may have happened in the Ice Age region of Beringia, where Siberia and Alaska were linked, before the two groups migrated south, he said.

The findings by an international team from the United States, Britain and Denmark were reported online yesterday in the journal Science.

The Clovis culture is named for elegantly chipped stone points found at a site uncovered in 1929 near Clovis, N.M. The bases are distinctly concave where they were tied to the wooden shafts of spears or throwing darts for hunting. The style found in Oregon is known as western stemmed projectile points for their thick bases and their discovery throughout the western United States.

"The big 'aha!' here, or the primary significance of this is that . . . we have demonstrated that these western stemmed tradition points are the same age as Clovis," Jenkins said. "There is no evidence of Clovis or any precursor to Clovis in the caves currently, and so that suggests that you've got here, at the exact same time, at least two technologies."

Until now, most western stemmed projectiles with accurate dating have been younger than Clovis artifacts, leading to theories the two technologies evolved from a single source. The new evidence directly goes against that idea. Jenkins said it appears more likely they evolved independently.