New findings from the Paisley Caves in Oregon suggest that a stone tool technology known as Western Stemmed projectile points overlapped with—rather than followed—the technology of the Clovis culture.
The Clovis culture, defined by its distinctive broad, fluted projectile points, is believed to have arrived in North American about 13,500 years ago. Many researchers had believed that Western Stemmed projectile points evolved directly from Clovis technology.
But Dennis Jenkins from the University of Oregon in Eugene, along with colleagues from around the world, have unearthed examples of Western Stemmed projectile points in the Paisley Caves that date back approximately 14,000 years, preceding or overlapping with Clovis technology.
These new findings, in the context of other fossils recovered from the caves, imply that a separate human population with their own unique technology may have occupied the far western region of what is now the United States while the Clovis culture developed on the Plains and in the Southeast.
“It suggests that we may have here in the Western United States a tradition that is at least as old as Clovis, and quite possibly older,” said Jenkins. “We seem to have two different traditions co-existing in the United States that did not blend for a period of hundreds of years.”
The findings appear in the 13 July issue of the journal Science.
“The last few years have seen great improvements—almost a revolution—in our understanding of the early colonization of the Americas,” said Brooks Hanson, deputy editor for the physical sciences at the journal. “This has been brought about by many new archaeological finds… improved dating methods… and genomics data, both on extant populations and ancient DNA recovered from fossils. These collectively have indicated that the colonization history was more complex and complicated—and I think interesting—than we had thought earlier.”
“The discoveries at Paisley Caves have been particularly important in understanding this early history,” he said. “Not only is it a rich site, but the caves also combine all three of the important pieces of evidence together: really interesting artifacts, human material that provides ancient DNA, and now a rich chronological record.”
Jenkins and the other researchers discovered four Western Stemmed projectile points in the Paisley Caves, two of which lay in soil deposits that are at least Clovis or pre-Clovis in age. Evidence of this technology is not uncommon in the western United States, but no other Western Stemmed projectile points have been reliably dated to such an old age.
The researchers also used radiocarbon dating to estimate the ages of 121 different samples of fossilized plants, dried human feces, and bone collagen found in the caves. Their analysis of the feces revealed human DNA that belongs to haplogroup A—an ancient genome that made its way to the Americas from Asia—that was also dated to pre-Clovis times.
“The radiocarbon dating is extremely tight,” Jenkins said during an 11 July press teleconference. “We have demonstrated that these Western Stemmed projectile points are the same age as Clovis. There is no evidence of Clovis or any precursor to Clovis in the caves currently, so that suggests that we’ve got—at the exact same time—at least two technologies.”
Read the abstract, “Clovis Age Western Stemmed Projectile Points and Human Coprolites at the Paisley Caves,” by Dennis Jenkins et al.
Listen to a related Science Podcast discussing the research.