Apr 3 2008, 2:27 PM EST
EUREKALERT
Contact: Jim Barlow
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DNA from dried human excrement recovered from Oregon's Paisley Caves is the oldest found yet in the New World -- dating to 14,300 years ago, some 1,200 years before Clovis culture -- and provides apparent genetic ties to Siberia or Asia, according to an international team of 13 scientists.
Among the researchers is Dennis L. Jenkins, a senior archaeologist with the University of Oregons Museum of Natural and Cultural History, whose summer field expeditions over two summers uncovered a variety of artifacts in caves that had caught the scientific attention of the UOs Luther Cressman in the 1930s.
The Paisley Caves are located in the Summer Lake basin near Paisley, about 220 miles southeast of Eugene on the eastern side of the Cascade Range. The series of eight caves are westward-facing, wave-cut shelters on the highest shoreline of pluvial Lake Chewaucan, which rose and fell in periods of greater precipitation during the Pleistocene.
The teams extensively documented analyses on mitochondrial DNA -- genetic material passed on maternally -- removed from long-dried feces, known as coprolites, were published online April 3 in Science Express ahead of regular publication in the journal Science.
The Paisley Cave material represents, to the best of my knowledge, the oldest human DNA obtained from the Americas, said Eske Willerslev, director of the Centre for Ancient Genetics at Denmarks University of Copenhagen. Other pre-Clovis sites have been claimed, but no human DNA has been obtained, mostly because no human organic material had been recovered.
Willerslev visited the UO in 2004 to obtain samples for DNA analyses after word spread among archaeologists and anthropologists about Jenkins discoveries. A Danish team, led by Willerslev, examined 14 coprolites -- initially using multiplex polymerase chain reaction to rapidly amplify DNA and a minisequencing assay that were found by Jenkins and colleagues during summer field work in 2002 and 2003.
A lengthy analysis, including the collection of DNA samples from 55 UO students, supervisors, and site visitors and 12 Danish DNA researchers, was done to screen for modern DNA contamination. From that analysis, six coprolites containing the ancient DNA were radiocarbon dated using accelerator mass spectrometry and calendar calibrated to between 1,300 and 14,300 years ago.
Of these, half date from the early arrival time, Jenkins said. All six coprolites containing ancient DNA underwent additional testing at two independent labs. Three of the six also contained DNA similar to red fox, coyote or wolf. The researchers suggest that these early Americans ate the animals or that the animals urinated on the human feces during times of non-human habitation.
The DNA testing indicated that the feces belonged to Native Americans in haplogroups A2 and B2, haplogroup
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