Published on April 5, 2008

The oldest human DNA in The New World

April 3, 2008 — Dennis Jenkins, an archeologist from the University of Oregon, along with other researchers, have recovered mitochondrial DNA from human excrements found in the Paisley Caves located in the Summer Lake Basin north of Paisley in south-central Oregon.

Mitochondrial DNA (mtDNA), the DNA present in the mitochondria (a membrane-enclosed organelle found in cells) is passed from mother to offspring and there is usually no change in the process.

Because of this and because the mutation rate of mtDNA is higher than that of nuclear DNA (found in cells' nucleus), which acts like a marker, mtDNA is a powerful tool for tracking ancestry through females and has been used in this role to backtrack the ancestry of many species for hundreds of generations.

The analysis of the mtDNA enabled the researchers to establish that the material is 14,300 years old, some 1,200 years older than the Clovis culture which appeared at the end of the last glacial period.

The DNA testing of the fossilized excrements or coprolites (from kopros, 'dung' and lithos, 'stone') indicates that the feces belonged to Native Americans in haplogroups A2 and B2, common in Siberia and East Asia. A haplogroup is a group with similar patterned DNA which shares a common ancestor.

Besides the coprolites, the researchers found manufactured threads of sinew and plant fibers, hides, basketry, cordage, rope, wooden pegs, animal bones and a couple of projectile point fragments.

Jenkins, who directs the Northern Great Basin Archaeological Field School, said in an interview that "To find these threads was just incredible. We found a little pit in the bottom of a cave. It was full of camel, horse and mountain sheep bones, and in there we found a human coprolite.
We radiocarbon-dated the camel and mountain sheep bones, as well as the coprolite, to 14,300 years ago. Had the human coprolites at the Paisley Caves not been analyzed for DNA and subjected to rigorous dating methodology, the pre-Clovis age of the artifacts recovered with the mega faunal remains could not have been conclusively proven.
In other words, the pre-Clovis-aged component of this site could very well have been missed or dismissed by archaeologists.”