August 30, 2019
Oregon State University
Stone tools and other
artifacts unearthed from an archeological dig at the Cooper's Ferry site in
western Idaho suggest that people lived in the area 16,000 years ago, more than
a thousand years earlier than scientists previously thought.
Stone tools and other
artifacts unearthed from an archeological dig at the Cooper's Ferry site in
western Idaho suggest that people lived in the area 16,000 years ago, more than
a thousand years earlier than scientists previously thought.
The artifacts would be
considered among the earliest evidence of people in North America.
The findings, published today
in Science, add weight to the hypothesis that initial human migration to
the Americas followed a Pacific coastal route rather than through the opening
of an inland ice-free corridor, said Loren Davis, a professor of anthropology
at Oregon State University and the study's lead author.
"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," Davis said.
"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."
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. Today the site is managed by the
U.S. Bureau of Land Management.
Davis first began studying
Cooper's Ferry as an archaeologist for the BLM in the 1990s. After joining the
Oregon State faculty, he partnered with the BLM to establish a summer
archaeological field school there, bringing undergraduate and graduate students
from Oregon State and elsewhere for eight weeks each summer from 2009 to 2018
to help with the research.
The site includes two dig
areas; the published findings are about artifacts found in area A. In the lower
part of that area, researchers uncovered several hundred artifacts, including
stone tools; charcoal; fire-cracked rock; and bone fragments likely from
medium- to large-bodied animals, Davis said. They also found evidence of a fire
hearth, a food processing station and other pits created as part of domestic
activities at the site.
Over the last two summers, the
team of students and researchers reached the lower layers of the site, which,
as expected, contained some of the oldest artifacts uncovered, Davis said. He
worked with a team of researchers at Oxford University, who were able to
successfully radiocarbon date a number of the animal bone fragments.
The results showed many
artifacts from the lowest layers are associated with dates in the range of
15,000 to 16,000 years old.
"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," Davis said.
"When I first saw that the lower archaeological layer contained
radiocarbon ages older than 14,000 years, I was stunned but skeptical 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 14,000-16,000 years old."
The dates from the oldest
artifacts challenge the long-held "Clovis First" theory of early
migration to the Americas, which suggested that people crossed from Siberia
into North America and traveled down through an opening in the ice sheet near
the present-day Dakotas. The ice-free corridor is hypothesized to have opened
as early as 14,800 years ago, well after the date of the oldest artifacts found
at Cooper's Ferry, Davis said.
"Now we have good
evidence that people were in Idaho before that corridor opened," he said.
"This evidence leads us to conclude that early peoples moved south of
continental ice sheets along the Pacific coast."
Davis's team also found tooth
fragments from an extinct form of horse known to have lived in North America at
the end of the last glacial period. These tooth fragments, along with the radiocarbon
dating, show that Cooper's Ferry is the oldest radiocarbon-dated site in North
America that includes artifacts associated with the bones of extinct animals,
Davis said.
The oldest artifacts uncovered
at Cooper's Ferry also are very similar in form to older artifacts found in
northeastern Asia, and particularly, Japan, Davis said. He is now collaborating
with Japanese researchers to do further comparisons of artifacts from Japan,
Russia and Cooper's Ferry. He is also awaiting carbon-dating information from
artifacts from a second dig location at the Cooper's Ferry site.
"We have 10 years' worth
of excavated artifacts and samples to analyze," Davis said. "We
anticipate we'll make other exciting discoveries as we continue to study the
artifacts and samples from our excavations."
Co-authors of the paper
include David Sisson, an archaeologist with the BLM; David Madsen of the
University of Texas at Austin; Lorena Becerra Valdivia and Thomas Higham of the
Oxford University radiocarbon accelerator unit; and other researchers in the
U.S., Japan and Canada. The research was funded in part by the Keystone
Archaeological Research Fund and the Bernice Peltier Huber Charitable Trust.
Story Source:
Materials provided by Oregon State University.
Original written by Michelle Klampe. Note: Content may be edited for style
and length.
Related Multimedia:
Journal Reference:
Loren G. Davis, et al. Late
Upper Paleolithic occupation at Cooper’s Ferry, Idaho, USA, ~16,000 years ago. Science,
Aug 30th, 2019 DOI: 10.1126/science.aax9830
Cite This Page:
Oregon State University.
"New artifacts suggest people arrived in North America earlier than
previously thought." ScienceDaily. ScienceDaily, 30 August 2019.
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