Ancient residents of four caves in south-central Oregon may deserve bragging rights as the earliest known Americans. New finds in the caves unveil a population that reached the New World around the same time or shortly before the famed Clovis hunters who roamed the Great Plains and Southeast at the end of the Ice Age.
Regardless of who first set foot in North America after crossing a land bridge from Asia, populations practicing at least two spear-making styles colonized the New World, say archaeologist Dennis Jenkins of the University of Oregon in Eugene and his colleagues.
Excavations at Oregon’s Paisley Caves find that four distinctively shaped stone spearheads — representing a toolmaking style called the Western Stemmed Tradition — date to between 14,000 and 13,000 years ago, Jenkins and his colleagues report in the July 13 Science.
Weaponry from Clovis hunters, long-thought to be the first Americans, spread westward from the Southeast between about 13,500 and 13,000 years ago, whereas the Western Stemmed Tradition arose in the far western United States and moved eastward over several thousand years, the researchers suggest.
“We seem to have two different toolmaking traditions that coexisted in North America and did not blend for hundreds of years,” Jenkins says.
Some investigators have held that Clovis-style implements were precursors of Western Stemmed points. In support of that scenario, a Wyoming site previously yielded Clovis points in deposits below Western Stemmed points, a clear sign of Clovis seniority.
But Western Stemmed points at the Paisley Caves are at least as old as 13,000- to 12,800-year-old Clovis points that have been found elsewhere in Oregon, Jenkins says. Makers of Western Stemmed artifacts developed their own style in the Far West before traveling east to Wyoming and other areas already inhabited by Clovis hunters, he suggests.
Western Stemmed points previously recovered at two Nevada sites and one Idaho location probably also date to Clovis times, although better radiocarbon evidence is needed, Jenkins says.
At the Paisley Caves, Jenkins’ team obtained 121 new radiocarbon dates, in addition to 69 previous radiocarbon dates, for sagebrush twigs, dried feces and animal bones unearthed above and below stone artifacts. An independent lab identified human DNA in dried feces from the Oregon caves that dated to at least 13,000 years ago.
The team found that human DNA from the Paisley Caves contained signatures known to be common among Siberians and many Native Americans, indicating an Asian homeland for early New World colonists.
Evolutionary geneticist Hendrik Poinar of McMaster University in Hamilton, Ontario, suspected that DNA from later Native Americans might have seeped through soil and into ancient feces at the Paisley Caves. Several soil samples in the new study contained human DNA, raising the possibility that genetic material from later Paisley Caves visitors contaminated older, buried feces at the sites, Poinar says.
Still, radiocarbon measures obtained by Jenkins’ team provide “reliable ages that put Western Stemmed points contemporaneous with Clovis points,” comments anthropologist David Meltzer of Southern Methodist University in Dallas.
Early New World settlers practiced several different toolmaking traditions, including one at a roughly 14,000-year-old Chilean site, remarks archaeologist James Adovasio of Mercyhurst College in Erie, Pa.
“The emerging picture is of multiple movements from Asia into the Americas by populations with multiple tool traditions,” Adovasio says.
It’s too early to say whether Western Stemmed points were the product of one population of New World settlers and Clovis spear points the handiwork of another population, or if different groups of colonists contributed to each toolmaking style, Meltzer cautions.
Source: Science News/ Bruce Bower / photo Credit: Jim Barlow