CUTTING EDGE: These chunks of chert might not be as elegant as a Clovis-style spear head, but they show some primitive markings of similar technology--and were made 15,500 to 13,200 years ago, some time before Clovis emerged. Image: Michael Waters
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.
Uprooting the Clovis-first model
Extracting and describing these thousands of small stone tools has been slow going. The research team has been working in the pre-Clovis layers of the site since 2006, uncovering the artifacts, which were scattered in a layer of clay just 20 centimeters thick.
Douglas Bamforth, a professor of anthropology at the University of Colorado at Boulder who was not involved in the new research, calls the work "beautiful excavation and beautiful analysis."
The Buttermilk Creek site is not the first evidence of pre-Clovis habitation of the Americas. Several sites, including two in Wisconsin as well as one in Pennsylvania and one in Oregon, had already offered up a handful of stone tools that predated Clovis. These have offered up many fewer artifacts, and the dating of some pieces has drawn scrutiny over the years.
The striking discovery of 14,100- to 14,600-year-old stone tools at a site in Monte Verde, Chile, raised questions about just how quickly the new settlers could have arrived so far south so quickly. These early people might have used the two continents' west coast as a pathway to settlement but, as Waters noted, it would mean those early explorers would have been "paddling as fast as they could to get down to the southern tip of South America," passing up a lot of awfully nice places on the North American coast along the way—such as the Columbia River, San Francisco Bay and San Diego, "where I would have stopped," Waters said, half jokingly.
Researchers have also yet to find strong technological links between Clovis technology and same-period stone tools in northeastern Asia. "There are a lot of problems with the Clovis-first model," Waters said, adding that it is "time to abandon [it] once and for all."
Some of the pre-Clovis tools found at the Buttermilk Creek site, such as "bladelets," do show similarities with bifacial (two-sided) techniques found in Asia, suggesting a deeper history. But, as Waters pointed out, known tools from that period in Siberia and northeastern Asia are relatively scant.
Given the previous finds in Wisconsin, Chile and other sites, John Shea, an associate professor of anthropology at Stony Brook University in New York State, notes that "it's been pretty clear" that humans were living in the Americas long before the Clovis tradition emerged.
Likewise, Bamforth was not surprised by the discovery of the new evidence. "I think it's kind of been waiting to be found," he says of a substantial pre-Clovis site.