(CN) – Archaeologists combing through Cooper’s Ferry, a site in western Idaho containing some of the earliest evidence of human life, have discovered artifacts placing humans in the northwest region 16,500 years ago, according to a study released Thursday.
The study, published in Science, expands scientists’ understanding of how and when the first human settlements developed in the Americas.
Radiocarbon dating of archaeological findings at Cooper’s Ferry show that humans migrated to and occupied a region in what is now northwestern United States long before scientists previously believed.
A popular and long-standing scientific theory held that humans entered North America 14,800 years ago by crossing an ice-free land corridor linked to eastern Beringia, the land and maritime area between Russia and Canada.
The strip of land separated the Cordilleran and Laurentide ice sheets in what is now the Pacific Northwest.
But researchers, including lead author Loren Davis of Oregon State University, said in the study that findings support the growing hypothesis that the first inhabitants of the Americas landed on the shores of the Pacific coast.
“The Cooper’s Ferry site was initially occupied during a time that predates the opening of an ice-free corridor which supports the hypothesis that initial human migration into the Americas occurred via a Pacific coastal route,” the study said.
Researchers said in the study that human migration in this period likely occurred through a combination of boat transport and trekking south along frozen Pacific shorelines.
The study provides evidence of human settlements in the Pacific Northwest beginning between 16,560 to 15,280 years ago.
Artifacts discovered at the Cooper’s Ferry site – located in the Columbia River basin in Idaho – include unfluted and stemmed stone tools and sharp projectiles that could be attached to spears or arrows.
The artifacts predate the fluted, broad-based tools of the Clovis Paleoindian tradition of North America, the study said.
Clovis tools are distinctive, formed from chipped obsidian and other brittle stone and containing sharp edges that lead to concave grooves or “flutes.”
The tools, used mainly by the earliest Americans for hunting, have been discovered in the rib bones of extinct mammals such as saber-toothed tigers and mammoths, according to the Smithsonian Institute.
The age and design of the stone tools found at Cooper’s Ferry resemble artifacts found at archaeological sites of human settlements in northeastern Asia that existed in the late Pleistocene era.
“We interpret this temporal and technological affinity to signal a cultural connection with Upper Paleolithic northeastern Asia, which complements current evidence of shared genetic heritage between late Pleistocene peoples of northern Japan and North America,” the study said.