Dating the first Americans

New study challenges theories of earlier human arrival in Americas.

For years, there have been claims that humans settled in the Americas well back in the Ice Age, perhaps even as early as 40,000 years ago – even some Neanderthals. The latter have long been dismissed from the stage, but the claims for earlier settlement before the commonly accepted 15,000 to 20,000-year date still circulate. Now a research team at the University of Wyoming has applied carefully argued simulation to the problem.

Todd Surovell and his colleagues point out that proof that people settled south of the great ice sheets must be based on significant numbers of humanly manufactured tools and meticulously dated contexts. They claim that such evidence does not exist earlier than about 14,200 years ago in Beringia (the Bering Land Bridge region) and 13,000 in the temperate latitudes of North America.

The team developed a simulation that combined the depositional history of the occurrence, its occupational history, and what they call a disturbance model – evidence for disturbance of the context. They modeled actual artifact dispersal rates as a function of depth and maximum dispersal rate.

Their model, which uses an accumulation rate of 0.1mm annually, and is based on 500 artifacts being placed on the ground surface at the time, was applied to a series of North American multicomponent sites that contain Palaeolithic occupations. Five sites came from eastern Beringia (Alaska). These date to before 13,000 years ago and are unambiguously stratified. The sites south of the ice sheets lack large artifact samples, or display evidence that the relevant tools shifted in the deposits, a phenomenon identified by retrofitting fragments of different stone fragments

The new simulation confirms that the earliest North American settlement is currently between 14,200 and 13,000 in Alaska, while there is no definite evidence for human settlement south of the ice sheets before 13,000 years ago. Given the small amount of evidence to hand, these conclusions are about as definite as one can get. This leaves aside the issue of the White Sands find in New Mexico, dated to 23,000 years ago, as published in issue 5 of Archaeology Worldwide magazine – but there are only footprints and no tools there, so far.

Want more in-depth archaeology? Get Archaeology Worldwide magazine today (special offer applied). See issue 5 for our cover-story on the White Sands research.

Image: The Hell Gap archaeological site in eastern Wyoming is one of the sites included in the new study that supports the hypothesis that humans first arrived in the Americas by at least 14,200 years ago in Beringia, and by about 13,000 years ago in the temperate latitudes of North America.

Credit: Todd Surovell