Scientists have uncovered ancient stone tools and thousands of other artifacts dating back 15,500 years at an archaeological dig in Texas, suggesting that humans settled the continent 2,500 years earlier than previously believed.
The site, located in the Buttermilk Creek complex near Austin, is now the oldest settlement ever found in North America, scientists reported Thursday.
The findings could challenge conventional beliefs about who the first American inhabitants were, and when they settled there, the researchers said.
“We found Buttermilk Creek to be about 15,500 years ago — a few thousand years before Clovis,” said environmental sciences professor Steven Forman, referring to a site near Clovis, New Mexico, at which small number of artifacts were uncovered in the late 1930s.
For the current find, the scientists from the University of Illinois at Chicago and Texas A&M determined the age of the Buttermilk Creek artifacts using a variety of innovative optical dating methods.
They linked sediment and mineral samples to human artifacts and tools found in a single stratigraphic layer located below younger, previously dated Paleo-Indian Clovis-culture artifacts dating back some 13,000 years ago.
“We looked at the age structure of the sediment by many different ways and got the same answers,” Forman added.
“We also dated different mineral fractions as well, and we consistently got the same ages,” he said.
Carbon-14 dating couldn’t be used to date the pre-Clovis artifact layer because it did not contain any organic matter.
“It’s the first identification of pre-Clovis lithic technology (stone tool technology) in North America,” Forman said.
The Clovis people, whose tools were known for their distinctive “fluted” points, were once thought to be the original settlers of North America about 13,000 years ago, and the ancestors of all the indigenous cultures of North and South America.
This “Clovis First” model theorizes that the Clovis people came to the New World from Northeast Asia by crossing the Bering Land Bridge, which once connected Asia and North America. From there, it suggests that they spread out across the continent and eventually made their way down to South America.
However, scattered evidence over the past few years has hinted at several earlier cultures, although such evidence has often been disputed, in part, because so few artifacts have actually been recovered.
“There are a lot of problems with the Clovis first model,” said lead researcher Michael Waters of Texas A&M University, adding that evidence points to a culture earlier than Clovis.
“First off, there’s no Clovis technology anywhere in Northeast Asia. Second of all, fluted points in Alaska are made differently than those of the Clovis, and these actually date at two sites now 1,000 years younger than Clovis,” Dr. Waters said.
“And then, thirdly, there are six sites in South America that date to the same time period of Clovis… And these sites do not have Clovis artifacts at them.”
“These facts alone lead to the conclusion that Clovis couldn’t be the first Americans and that people had to have been here before Clovis,” he added.
“It’s basically time to abandon once and for all the Clovis first model and develop a new model for the peopling of the Americas.”
The findings are reported in the March 25 issue of Science.
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