The theory is based largely on the discovery in 1929 of distinctive stone tools, including sophisticated spear points, near Clovis, N.M. The same kinds of spear points were later identified at sites across North America. After radiocarbon dating was developed in 1949, scholars found that the age of these “Clovis sites” coincided with the appearance at the end of the last ice age of an ice-free corridor of tundra leading down from what is now Alberta and British Columbia to the American Midwest.
Over the years, hints surfaced that people might have been in the Americas earlier than the Clovis sites suggest, but the evidence was never solid enough to dislodge the consensus view. In the past five years, however, a number of discoveries have posed major challenges to the Clovis model. Taken together, they are turning our understanding of American prehistory on its head.
The first evidence to raise significant questions about the Clovis model emerged in the late 1970s, when the anthropologist Tom Dillehay came across a prehistoric campsite in southern Chile called Monte Verde. Radiocarbon dating of the site suggested that the first campfires were lighted there, all the way at the southern tip of South America, well before the first Clovis tools were made. Still, Professor Dillehay’s evidence wasn’t enough to persuade scholars to abandon the Clovis model.
But in 2008, that began to change. That year, researchers from the University of Oregon and the University of Copenhagen recovered human DNA from coprolites — preserved human feces — found in a dry cave in eastern Oregon. The coprolites had been deposited 14,000 years ago, suggesting that Professor Dillehay and others may have been right to place humans in the Americas before the Clovis people.
This discovery inspired other scholars to re-examine old finds with new techniques. In the 1970s, for instance, a farmer in Washington State found a mastodon rib with a bone shard lodged in it, as if the mastodon had been killed with a weapon. Since the mastodon remains predated the earliest Clovis sites by eight centuries, the nature of the finding was initially disputed. But in 2011, researchers led by the Texas A&M archaeologist Michael R. Waters announced that by analyzing the rib and the embedded fragment using scanning and modeling techniques, they had confirmed that the embedded bone was a spear point — strongly suggesting that humans in the Americas were hunting the animals with bone-tipped spears long before the end of the ice age.
The Clovis model suffered yet another blow last year when Professor Waters announced finding dozens of stone tools along a Texas creekbed. After using a technique that measures the last time the dirt around the stones was exposed to light, Professor Waters concluded, in a paper in Science, that the site was at least 15,000 years old — which would make it the earliest reliably dated site in the Americas.
FULL ARTICLE HERE: Who Arrived in the Americas First? – NYTimes.com.