Americas occupied 100,000 years earlier?

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April 28, 2017

The earliest date for human occupation of the Western Hemisphere has a long history of controversy. The finding of distinctive Clovis points in New Mexico in 1931, together with other evidence and the endorsement of Louis Leakey, and dated to around 12-13,000 years ago, was widely accepted. The Wisconsin glaciation, which began to recede around 18,000 years ago, created an ice barrier stretching from the Pacific to the Atlantic. As the climate warmed and the ice began receding, an ice free corridor opened along what is now the Mackenzie River in Canada. It was hypothesized theClovis people migrated from known settlements in Alaska down this corridor and into the present day United States.

Then in the 1980s and 1990s, the discovery of human activity at sites in Oregon, California and in the far south of Chile, and dated to 14,000 years ago and earlier, cast doubt on the Clovis hypothesis. About the same time it was revealed the “ice free corridor” was also free of any evidence of human activity. No stone tools, no charcoal from fires, no fossilized remains. It has been hypothesized the peoples who made it to Oregon, California and as far south as Chile, used boats to get around the melting ice covering the Aleutian Islands and then moved south along the Pacific Coast  in increments, from bays to river mouths. This was not a north to south exploring expedition but successive small groups over the course of many generations, leap frogging each other. This is sometimes called the “coastwise hypothesis”.

In an article in Nature  this week, scientists announce the finding of mastodon bones and the stones used to smash the bones and this activity is dated to 130,000 years ago. If the dating  is verified, human activity  in the Americas jumps back more than 100,000 years. It would also mean these occupiers were not of our species, Homo sapiens, for we had not yet emerged from Africa, but an earlier species, perhaps Homo erectus. This is a truly startling development, if the date of 130,000 years ago remains solid.

Dr Curtis Marean, Foundation Professor and assistant Director, Institute of Human Origins at Arizona State University, expressed skepticism concerning the dating methodology, saying “...u-series dating of bone using a diffusion model is experimental and not yet considered a reliable technique.  In my opinion this should not have been published without a second independent dating technique of the burial age.”

Read the full article in Nature.  Also, there is in this issue of Nature a video showing both the strong attacks and defense of the date claimed for this find.