https://www.sciencemag.org/news/2019/08/first-people-americas-came-sea-ancient-tools-unearthed-idaho-river-suggest
Ancient people apparently followed rivers more than 500 kilometers inland to Cooper's Ferry in western Idaho.
LOREN DAVIS
First people in the Americas came by sea, ancient tools unearthed by Idaho river suggest
By Lizzie WadeAug. 29, 2019 , 2:00 PM
About 16,000 years ago, on the banks of a river in western Idaho, people kindled fires, shaped stone blades and spearpoints, and butchered large mammals. All were routine activities in prehistory, but their legacy today is anything but. The charcoal and bone left at that ancient site, now called Cooper’s Ferry, are some 16,000 years old—the oldest radiocarbon-dated record of human presence in North America, according to work reported this week in Science.
The findings do more than add a few centuries to the timeline of people in the Americas. They also shore up a new picture of how humans first arrived, by showing that people lived at Cooper’s Ferry more than 1 millennium before melting glaciers opened an ice-free corridor through Canada about 14,800 years ago. That implies the first people in the Americas must have come by sea, moving rapidly down the Pacific coast and up rivers. The dates from Cooper’s Ferry “fit really nicely with the [coastal] model that we’re increasingly getting a consensus on from genetics and archaeology,” says Jennifer Raff, a geneticist at the University of Kansas in Lawrence who studies the peopling of the Americas.
The Clovis people, big game hunters who made characteristic stone tools dated to about 13,000 years ago, were once thought to have been the first to reach the Americas, presumably through the ice-free corridor. But a handful of earlier sites have persuaded many researchers that the coastal route is more likely. Archaeologists have questioned the signs of occupation at some putative pre-Clovis sites, but the stone tools and dating at Cooper’s Ferry pass the test with flying colors, says David Meltzer, an archaeologist at Southern Methodist University in Dallas, Texas. “It’s pre-Clovis. I’m convinced.”