The first Americans arrived in the present day United States more than a thousand years earlier than previous thought, according to a new study.
Experts suggest that people lived in the area as much as 16,500 years ago, a whole millennium before previously thought.
They made the conclusion after stone tools and other artefacts were unearthed at an archaeological dig at the Cooper’s Ferry site in Idaho.
The artefacts are considered among the earliest evidence of people in North America.
The findings add weight to the theory that human migration to mainland America followed a Pacific coastal route.
Previous research suggests people first arrived in Alaska from East Asia around 20,000 years ago across the Bering Strait, a land like submerged in the last ice age.
Early migration of humans came through Alaska, and the first people to arrive actually came from three different genetic groups.
One group, the Ancient Beringians, stayed in the region for thousands of years after arriving, before being replaced entirely or interbreeding with Native Americans.
Another group, the descendants of the Native Americans, then split into two groups – one conquered Northern America while the second ventured to Southern America.
The first Americans arrived in the present day United States more than a thousand years earlier than previous thought, according to a new study. This map depicts a possible Pacific coastal migration route for early Americans.
Cooper’s Ferry, located at the confluence of Rock Creek and the lower Salmon River, is known by the Nez Perce Tribe as an ancient village site named Nipéhe.
The site includes two dig areas, A and B, and the published findings are about artefacts found in area A.
In the lower part of that area, researchers uncovered several hundred artefacts, including stone tools, charcoal, fire-cracked rocks and bone fragments likely from medium to large-bodied animals.
They also found evidence of a fire hearth, an area for food preparation and other pits created as part of domestic activities at the site.
Study lead author Professor Loren Davis, of Oregon State University, said: ‘The Cooper’s Ferry site is located along the Salmon River, which is a tributary of the larger Columbia River basin.
‘Early peoples moving south along the Pacific coast would have encountered the Columbia River as the first place below the glaciers where they could easily walk and paddle in to North America.
‘Essentially, the Columbia River corridor was the first off-ramp of a Pacific coast migration route.
‘The timing and position of the Cooper’s Ferry site is consistent with and most easily explained as the result of an early Pacific coastal migration.’
Experts suggest that people lived in the area 16,000 years ago, a whole millennium before previously thought. They made the conclusion after stone tools and other artefacts were unearthed at an archaeological dig at the Cooper’s Ferry site in Idaho (pictured)
Professor Davis first began studying Cooper’s Ferry as an archaeologist in the 1990s.
Over the last two summers, a team of students and researchers reached the lower layers of the site, which contained some of the oldest artefacts uncovered.
Professor Davis worked with a team of researchers from Oxford University, who were able to successfully radiocarbon date a number of the animal bone fragments.
The results showed many of the artefacts from the lowest layers are associated with dates in the range of 15,000 to 16,500 years old.
Professor Davis said: ‘Prior to getting these radiocarbon ages, the oldest things we’d found dated mostly in the 13,000-year range, and the earliest evidence of people in the Americas had been dated to just before 14,000 years old in a handful of other sites.
‘When I first saw that the lower archaeological layer contained radiocarbon ages older than 14,000 years, I was stunned but sceptical and needed to see those numbers repeated over and over just to be sure they’re right.
‘So we ran more radiocarbon dates, and the lower layer consistently dated between 14,000 to 16,000 years old.’
WHEN DID NORTHERN AND SOUTHERN NATIVES SPLIT?
While the Ancient Beringians split from all other Native Americans around 20,000 years ago, the Northern and Southern groups diverged later on.
Based on previous research, this suggests they must have already been on the American continent south of the glacial ice when they diverged.
The divide probably occurred after their ancestors had passed through the Laurentide and Cordilleran ice sheets.
These are two vast glaciers that covered what is now Canada and parts of the northern United States, but began to thaw around this time.
The ice sheet isolated southbound travellers from the Ancient Beringians in Alaska, who were eventually replaced or absorbed by other Native American populations.
Although modern populations in Alaska and northern Canada belong to the Northern Native American branch, the new analysis shows that these derive from a later ‘back’ migration north, long after the initial migration events.
The dates from the oldest artefacts challenge the long-held ‘Clovis First’ theory of early migration to the Americas, which suggested that people crossed from Siberia into North America and travelled down through an opening in the ice sheet near the present-day Dakotas.
The ice-free corridor is believed to have opened as early as 14,800 years ago, well after the date of the oldest artefacts found at Cooper’s Ferry.
Professor Davis added: ‘Now we have good evidence that people were in Idaho before that corridor opened.
‘This evidence leads us to conclude that early peoples moved south of continental ice sheets along the Pacific coast.’
Researchers also found tooth fragments at Copper’s Ferry from an extinct form of horse known to have lived in North America at the end of the last glacial period.
Professor Davis said that the tooth fragments, along with the radiocarbon dating, show that Cooper’s Ferry is the oldest radiocarbon-dated site in North America that includes artefacts associated with the bones of extinct animals.
He said that the oldest artefacts found at Cooper’s Ferry also are very similar in form to older artefacts found in north eastern Asia, particularly Japan.
The dates from the oldest artefacts challenge the long-held ‘Clovis First’ theory of early migration to the Americas, A distinctive DNA type associated with the Clovis culture found in Chile, Brazil and Belize dates it to between 11,000 and 9,000 years ago
Professor Davis is now collaborating with Japanese researchers to do further comparisons of artefacts from Japan, Russia and Cooper’s Ferry.
He is also awaiting carbon-dating information from further finds from a second dig location at the Cooper’s Ferry site.
Professor Davis added: ‘We have 10 years’ worth of excavated artefacts and samples to analyse.
‘We anticipate we’ll make other exciting discoveries as we continue to study the artefacts and samples from our excavations.’
The full findings were published in the journal Science.
Cooper’s Ferry (pictured), located at the confluence of Rock Creek and the lower Salmon River, is known by the Nez Perce Tribe as an ancient village site named Nipéhe. The site includes two dig areas, A and B, and the published findings are about artefacts found in area A
WHO WERE THE ANCIENT BERINGIANS?
A single, ancestral Native American population first emerged as a separate group around 36,000 years ago in northeast Asia.
Constant contact with Asian populations continued until around 25,000 years ago, when the gene flow between the two groups ceased.
This cessation was probably caused by brutal changes in the climate, which isolated the Native American ancestors.
At this point the group likely began crossing to Alaska via an ancient land bridge spanning the Bering Strait which was submerged at the end of the last Ice Age.
Then, about 20,000 years ago, that group split into two lineages – the Ancient Beringians and the ancestors of all other Native Americans.
The Beringians continued to breed with their Native American cousins at least until the Upward Sun River girl was born in Alaska around 8,500 years later.