The first known people to settle America can now be divided into at least two cultures, the Clovis and the recently discovered "Western Stemmed" tradition, according to new research.
Researchers excavating an Oregon cave, found traces and unique tools made by a second people, who lived more than 13,200 years ago. The discovery, described in the latest issue of Science, strengthens the idea that that people moved into the Americas in several waves of migrations, not just one.
"From our results, it is likely that we have at least two independent migration events to the lower 48 states," co-author Eske Willerslev of the University of Copenhagen's Center for GeoGenetics told Discovery News. "Additionally, we previously showed by sequencing the first ancient human genome (that of a 4,000-year-old paleoeskimo) that there have been at least two independent migrations into the Arctic parts of North America, so as I see it, it's likely we have at least around four migration events."
Willerslev added that three of these groups came from Asia, but the origins of the Clovis culture remain a mystery. What's now clear is that the newly discovered Western Stemmed culture was present at least 13,200 years ago, during or even before the Clovis culture in western North America.
The Clovis culture is defined by its "points," used for hunting. Lead author Dennis Jenkins explained that Clovis points are generally large "and have one or more distinctive flute flakes removed from the base so that a channel runs from the base up the blade roughly half way or slightly more to the tip."
Western Stemmed points, on the other hand, "are narrower, sometimes thicker, and thinned by percussion and pressure flakes from the edges to the midline." They were used as dart and thrusting spear tips, while Clovis points are generally assumed to be lance points.
The researchers aren't certain why these technologies diverged, probably long ago, from a common weapon-making tradition in Siberia or Asia. Since the early Americans only used one or the other method, the technologies suggest that the Clovis culture may have arisen in the Southeastern United States and moved west, while the Western Stemmed tradition began, perhaps earlier, in the West and moved east.
Jenkins, an archaeologist at the University of Oregon's Museum of Natural and Cultural History, and his team analyzed Western Stemmed points from Paisley Caves, located about 220 miles southeast of Eugene, Oregon. The researchers also studied dried human feces, bones, sagebrush twigs and other artifacts excavated from well-stratified layers of silt in the ancient caves.
Based on the analysis, it's believed that the people who lived at the same time as the Clovis were "broad range foragers, taking large game whenever possible, but also well adapted to a desert mosaic plant community similar, but not identical to, that of the northern Great Basin today," Jenkins shared.
If the oldest fossilized feces found in the caves (dating to 14,300 years ago) belonged to the Western Stemmed occupations, then the individuals hunted now-extinct horses, camels and elephants, in addition to deer, elk, mountain sheep, bison, waterfowl, rabbits and other animals.
In a separate paper published in Nature this week, David Reich, a Harvard Medical School geneticist, and his team found that Native Americans descend from at least three streams of Asian gene flow. Most come from a single ancestral population, but the Eskimo-Aleut language speakers from the Arctic and the Na-Dene-speaking Chipewyan from Canada inherit some of their ancestry from different streams.
The way that these people entered the Americas might also have varied.
For decades, researchers have speculated that a temporary land bridge existed between Russia and Alaska. Evidence is also mounting for a "kelp highway" from Japan to Kamchatka, along the south coast of Beringia and Alaska, then southward down the Northwest Coast to California.
As to how people first wound up in Oregon, Jenkins said, "It is possible they represent a migration down the Pacific Coast followed by a migration inland."