Scientific dating of artifacts Dicrete chat room
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.
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.
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.
And although early studies arrived at some pretty errant dates, the technology has been refined and now, Bamforth notes, "it really works." But because the technology has only come into wide use in the past several years, many sites discovered and described earlier did not have the benefit of OLS dating.
So if no biological material was available for handy radiocarbon dating, researchers would have had no way to gauge exactly when an assemblage of tools was made.
The discovery is detailed in a new study, published online March 24 in .
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.
The presence of a settlement in the middle of North America by 15,500 years ago gives "ample time for Clovis to develop" and plenty of time for people to reach the South American sites in Monte Verde, Waters said.