Most archaeologists think the first Americans arrived by boat. Now, they’re beginning to prove it

"I had no idea what it meant," says Des Lauriers, now a professor at California State University (Cal State) in Northridge. Curiosity piqued, he returned for a test excavation and sent some shell and charcoal for radiocarbon dating. When Des Lauriers's adviser called with the results, he said, "You should probably sit down." The material dated from nearly 11,000 to more than 12,000 years ago—only a couple thousand years after the first people reached the Americas.

http://www.sciencemag.org/news/2017/08/most-archaeologists-think-first-americans-arrived-boat-now-they-re-beginning-prove-it

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