Radiocarbon dating stone tools
"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.
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.
And when biological material is scant or absent, making radiocarbon dating impossible, scientists can face greater challenges in establishing just how old objects really are—even though, as Bamforth says, it is becoming increasingly obvious that "people have to have been here way longer than radiocarbon dating could suggest." Nevertheless, pinning down a precise date is difficult.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.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.