Stone tools and other artifacts unearthed from an archaeological excavation at Cooper’s Ferry, west of Idaho in the United States suggest that people lived in the area more than 16,000 years ago, which is more than a thousand years earlier than scientists previously thought.
Scientists say that these are examples of some of the first tools that prove the existence of people in Northern America.
The findings, published in Science, add weight to the hypothesis that the initial human migration to the Americas followed a Pacific coastal route rather than through the opening of an inner corridor without ice, explains Loren Davis, professor of Anthropology at Oregon State University and the lead author of the study.
Cooper’s Ferry is located along the Salmon River, which is a tributary of the largest Columbia River basin. The first people who moved south along the Pacific coast would have encountered the Columbia River as the first place under glaciers where they could easily walk and paddle to North America, says Davis.
Essentially, the Columbia River corridor was the first exit ramp on a Pacific coast migration route. The timing and position of the Cooper’s Ferry site are consistent and are more easily explained as a result of an early migration of the Pacific coast, Davis adds.
Incredible excavation results
Cooper’s Ferry is known by the Nez Perce people as an ancient town called Nipehe.
Today the place is managed by the United States Office of Land Administration.
Davis began studying Cooper’s Ferry as an archaeologist for the BLM in the 1990s.
After joining the Oregon State School, he partnered with the BLM to establish a summer archaeological field school there, bringing undergraduate and graduate students from the state for eight weeks each summer from 2009 to 2018 to help with the investigation.
The site comprises two excavation areas; the published findings are about artifacts found in area A. At the bottom of that section, researchers discovered several hundred artifacts, including stone tools, coal, fire-cracked rock, and bone fragments, probably of animals of medium to large size, says Davis.
They also found evidence of a chimney, a food processing station and other wells created as part of domestic activities.
During the last two summers, the team of students and researchers reached the lower layers that, as expected, contained some of the oldest artifacts uncovered, says Davis.
Working with a team of researchers from the University of Oxford, the scientists were able to successfully date several animal bone fragments by radiocarbon dating methods. The results showed that many artifacts from the lower layers are associated with dates in the range of 15,000 to 16,000 years.
The researchers argue that before obtaining the new radiocarbon dates, the oldest artifacts that had been mostly in the 13,000-year range, and the earliest evidence of people in the Americas had been dated just before the age of 14,000 at some other sites.
When Davis first saw that the lower archeological layer contained radiocarbon ages over 14,000 years old, he was stunned but skeptical and needed to see those numbers repeated over and over again just to make sure they were true. So, the researchers went on and published more radiocarbon dates, and the bottom layer was constantly dating between 14,000 to 16,000 years.
The dates of the oldest artifacts challenge the ancient ‘Clovis First’ theory of early migration to the Americas, which suggests that people crossed from Siberia to North America and traveled through an opening in the ice sheet near the Dakotas. The ice-free corridor is supposed to have been opened some 14,800 years ago, long after the date of the oldest artifacts found at Cooper’s Ferry, says Davis.
Researchers now say they have ample evidence that there were people living Idaho before that corridor opened. This evidence leads scientists to conclude that the first people moved south of the continental ice sheets, along the Pacific Coast.
But researchers also discovered tooth fragments of an extinct form of a horse that is known to have lived in North America at the end of the last glacial period.
These tooth fragments, along with radiocarbon dating, show that Cooper’s Ferry is the oldest site in North America that includes artifacts associated with the bones of extinct animals, the scientists added.
The oldest artifacts discovered at Cooper’s Ferry are also very similar in shape to the oldest artifacts found in Northeast Asia, and particularly in Japan, the researchers have revealed.
To understand the reason behind the similarity, scientists are collaborating with colleagues from Japan to understand the bigger picture.
Scientists are also waiting for the carbon dating results of the second set of items excavated at the site.