Fourteen-thousand-year-old feces from caves in Oregon is being held up
as the oldest evidence of human's presence in North America.
An international team says DNA recovered from an ancient latrine
pushes back the peopling of America by more than 1,000 years. It also
bolsters the theory that the first humans to reach North America
traveled down the B.C. coast while glaciers blanketed the rest of
Canada.
The team of European and U.S. archeologists re****ted online in the
journal Science Thursday that is has established "humans were present"
at the caves in south-central Oregon 14,300 years ago.
Fragments of human DNA recovered from the feces carry the genetic
signature of Native American subgroups that tie back to Siberia and
Asia, says the team led by Eske Willerslev, an expert on ancient DNA
at Denmark's University of Copenhagen.
Archeologists have speculated for years that people arrived in North
America long before the so-called Clovis people, who left behind
arrowheads and blades dating back 13,000 years. But evidence of the
early human presence has been elusive. The Oregon feces is being
widely described as by far the strongest yet.
"I think this probably nails it down," says Jonathan Driver,
archeologist and dean of graduate studies at Simon Fraser University.
He says the ancient human DNA is the next best thing to finding actual
human bones.
The DNA in the feces, combined with other telltale signs of pre-Clovis
humans, suggests hunters and gatherers were south of ice sheets "maybe
as early as 16,000 years ago," says Driver.
But not everyone is convinced the claims about the age of Oregon feces
will hold up.
Archeologist Michael Wilson, at Douglas College in New Westminster,
B.C., has nagging concerns that fecal samples may have been
contaminated. "The work is extremely encouraging, but I'm left with
the feeling that there could be pathways to contaminations that we
don't yet understand," says Wilson, who has been hunting for evidence
of early human activity for decades.
The 14 ancient coprolites were uncovered in the Paisley Caves in 2002
and 2003 by Dennis Jenkins and his team at the University of Oregon.
The dry sheltered caves have also yielded a trove of other artifacts -
baskets, rope, wooden pegs, manufactured threads, animal bones.
Based on the size, shape and colour, Jenkins concluded humans had left
the feces. He joined forces with Willerslev's team in Denmark, which
extracted the human mitochondrial DNA from six of the coprolites.
Three of the six also contain DNA believed to have come from red fox,
coyote or wolf - the researchers speculate that the early people
either ate the animals or animals urinated on the human feces.
Extensive testing was done to rule out contamination of the ancient
feces by the people at the Oregon dig, and the researchers in the
Copenhagen DNA lab. Two other labs in Europe verified their findings.
Some critics suggest animals may have actually produced the feces, and
the human DNA may have come from people later urinating in the caves.
But Jenkins and his colleagues rule that out, saying the feces contain
more human protein than expected from urine. The researchers also say
they found human hair in the feces.
"Any way you cut the poop, people and dogs would have to be at the
site within days of each other 14,000 years ago," Jenkins says in a
re****t in Science.
The Oregon discovery, if it stands up, would kill the theory that the
first people on the continent followed mammoths and other big game
animals down an ice-free corridor as the glaciers melted away and then
fanned out across North and South America over 200 to 300 years,
leaving behind distinct Clovis arrowheads and blades. Many
archeologists say the more plausible explanation is that Clovis
technology was devised after humans were already well established in
America - an idea sup****ted by ac***ulating evidence from the Pacific
Northwest, including a recent find by Wilson and his colleagues of
bison bone on an island off Wa****ngton coast that appears to have been
butchered by humans more than 13,000 years ago.
Driver expects the Oregon find will spur on the search for more
evidence. "If we devoted a little more time to the search on Vancouver
Island, it is certainly possible we'd find evidence for humans at a
very early age," says Driver.
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