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Detectives sometimes investigate people by looking through their garbage. Archaeologists often work the same way, studying people of the past by sifting through ancient garbage dumps. Scientists working in Oregon found one that yielded what they say are the oldest human remains in the Americas, and also a puzzle about the earliest American tools. NPR's Christopher Joyce reports on the people of Paisley Cave.
CHRISTOPHER JOYCE, BYLINE: Early Americans used Oregon's Paisley Caves for, among other things, a toilet. Little did they know that scientists would be picking through what they left behind. The scientists extracted DNA from dried-up feces in the cave, known politely as coprolites. And they've got something more - four projectile points, flaked from stone and presumably used for weapons. They're broken. Their makers probably trashed them.
And the scientists now have reliable dates for all this stuff. Some of the coprolites appear to be 14,500 years old. They say it's the oldest direct evidence of people in America. That's because it's based on carbon dating of actual human remains, so to speak. Carbon dating is the gold standard for dating ancient cultures.
And those stone points? They tell a new story, too. Dennis Jenkins of the University of Oregon says the shape of the points looks quite different from other stone points from around that time.
DENNIS JENKINS: It looks like you've got a separate group of people on the landscape, and these people are making different kinds of arrowheads or spear points.
JOYCE: The stone points from Paisley Caves are called western stemmed. Jenkins says they appear to be as old or older than Clovis points, which were thought to be the first in the Americas.
Archaeologist David Meltzer at Southern Methodist University says finding a different group with a different technology is surprising. But the next question is: Who came first? The Western Stem people or the Clovis? Were they related?
DAVID MELTZER: We have contemporaneous groups. They're doing different stylistic things on the landscape. What is the relationship? Don't know.
JOYCE: Writing in the journal Science, Jenkins suggests that whether the two groups were genetically related or not, one probably moved to the interior of the continent and used the Clovis technology. And the other stayed in the West and developed its own tool kit, as well as the continent's oldest known toilet.
Christopher Joyce, NPR News.