for National Geographic News
It's no load of crap: Scientists have discovered the earliest evidence of humans in North America—in 14,300-year-old fossilized feces.
The discovery of the preserved scat fragments, known as coprolites, levels a major blow against the popular Clovis-first theory of how people first came to the Americas.
Since the summer of 2002, University of Oregon archaeologist Dennis Jenkins and his research team have uncovered about 700 coprolite samples from a group of bone-dry caves in the desert of central Oregon, including several from humans.
After repeated radiocarbon dating and DNA analyses, the scientists concluded that the oldest of the human-produced material was deposited at least a thousand years before the so-called Clovis culture, according to a paper appearing in this week's issue of the journal Science.
"Clearly Older Than Clovis"
The popular Clovis-first model (named for the New Mexico town where artifacts of a certain type were first found) holds that humans arrived in North America via the Bering land bridge that once connected Alaska to Asia. They then walked southward through an ice-free corridor during a period of glacial retreat.
For a long time, that model was king, ensconced in countless high school textbooks. But in the 1990s, an ancient settlement at Monte Verde, Chile, was found to be 14,500 years old.
Monte Verde posed a problem for the original theory, because the ice-free corridor hadn't formed by 14,500 years ago. Travelers must have arrived some other way and at an earlier date.
(Related: "Clovis People Not First Americans, Study Shows" [February 23, 2007].)
But Monte Verde remained an isolated case.
"People who don't like Monte Verde said, Well, it's only one site, and we need to replicate that," explained Don Grayson, professor of anthropology at the University of Washington.
"The importance of the find at Oregon's Paisley Caves is that it is that second site."
SOURCES AND RELATED WEB SITES