The earliest evidence yet of human DNA in North America has been found -- in fossilised faeces, known as coprolites.
Scientists have announced the discovery of DNA of the oldest known North American humans, challenging previous migration perceptions. Photo: Paisley Caves, Oregon. Credit: University of Oregon.
Dennis Jenkins, of the University of Oregon, wrote in the journal Science that, since 2002, he and his team had found about 700 coprolite samples in caves in the north-western US state of Oregon.
Jenkins said the samples were found amidst a variety of other artefacts.
"We found a little pit in the bottom of a cave," he said, "It was full of camel, horse and mountain sheep bones, and in there we found a human coprolite."
The find dates the extracted DNA to around 14,300 years ago, which challenges the customary theory (known as the Clovis theory) that the earliest American humans entered the continent via the Bering land bridge that once connected Alaska to Asia. The theory, named after the New Mexico town where remains were found) contends that humans gradually moved south, taking advantage of a ice-free period.
The Oregon find, which links with previous finds, shows that humans arrived in the Americas prior to the establishment of the Bering land bridge.
University of California scholar David Smith, who was not involved in the study, told Science journal, "If this doesn't convince what's left of the 'Clovis first' people, it should."
"The importance of the find at Oregon's Paisley Caves is that it is that second site," said Don Grayson, professor of anthropology at the University of Washington to the National Geographic.
"It's clearly older than Clovis," Grayson said.
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