Some 15,500 years ago early nomadic North Americans had already set up camp near Buttermilk Creek in central Texas's hill country, where they left behind impressive array of stone tools and artifacts.
Such an old habitation predates the widespread toolmaking tradition known as Clovis, which spread across the continent some 12,800 to 13,100 years ago and was once thought to mark the first wave of settlers in the Americas. The find is "unequivocal proof for pre-Clovis occupation of America," said Steven Forman, of the Department of Earth and Environmental Sciences at the University of Illinois at Chicago.
The area where the tools were found, northwest of Austin, must have been an appealing campsite for millennia, because it bears a record of nearly continuous occupation from 15,500 years ago. The discovery is detailed in a new study, published online March 24 in Science.
When the makers of these tools were using the site (from 15,500 to 13,200 years ago), the region would have been slightly cooler than it is today, probably by an average of about 5 to 6 degrees Celsius—"rather amiable at that time period," Lee Nordt, of Baylor University's Department of Geology and co-author of the new study, said in a press briefing on Wednesday. But the resources in the area were likely plentiful, added Michael Waters, of the Center for the Study of the First Americans at Texas A&M University in College Station and co-author of the new study. With the rich hill country around them, "it's not surprising people came back time and time again."
The people who left the tools and fragments described in the study were likely hunter–gatherers, passing through the site from time to time over thousands of years. "This was a mobile tool kit—something that was easily transported," Waters said.
The prevalence of Clovis style tools—epitomized by fine, fluted (grooved) stone points—across the continent had suggested to many archaeologists for decades that the groups who made these tools must have comprised the first wave of settlement in the Americas. This arrival would have placed the initial migration from northeastern Asia over the Bering Land Bridge and through the Arctic corridor that opened between ice sheets at some 15,000 years ago.
This latest tool evidence, however, suggests that people were already making and discarding stone tools about 15,500 years ago, which would mean that the migration likely occurred even earlier. "You'd have to get to central Texas, and that would probably take a little while," Waters said.
Waters argues that their find of 15,528 artifacts (made from chert, a flint-like rock), which span the 2,400 years before the accepted emergence of Clovis technology 13,100 years ago, is the nail in coffin of the theory that Clovis toolmakers were the first inhabitants of the New World, the so-called Clovis-first model. "This is almost like a baseball bat to the side of the head to the archaeological community to wake up," he said.
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