Researchers discovered the 14,000-year-old DNA in pieces of dried feces -- called coprolites -- unearthed in a cave in Oregon, according to a study published this week in the journal Science.With an ancient Chilean site being dated to 14,600 years old, even older remains may yet be found.
"This is the earliest direct evidence of a human presence in the Americas," Eske Willerslev, director of the University of Copenhagen's Center for Ancient Genetics and one of the study's authors, told the Boston Globe.
Until about a decade ago, scientists thought that the earliest humans in the Americas arrived via a land bridge from Asia around 13,000 years ago. That bridge, which was uncovered during the last ice age, disappeared when the climate warmed and sea level rose again.
The finding also lends weight to the theory that early North Americans might have accessed different parts of the continent via water routes -- taking boats down the Pacific coast -- because if humans arrived in North America during the ice age, overland routes through what is now Canada and the Northern United States would have been blocked by glaciers.
The researchers used two methods to analyze the DNA. Radiocarbon dating put its age at more than 14,000 years old, and an analysis of the mitochondrial DNA -- a part of the DNA that is passed through the maternal line -- suggested that the humans descended from people who came from Northeast Asia.
Human excrement itself doesn't contain any DNA, but it does contain DNA-holding flakes of tissue from the intestine.Hmm, I was unaware of the fact that there was a distinction between between excrement, shed gut issue and well anything else that exits via the anus. I had always applied the Seinfeld law of refuse (adjacent to refuse, is refuse) to excrement. Glad to have my mistaken assumption clarified.
via The News Hour and The Economist and Yahoo News