Some of the most interesting discoveries in archaeology come from sifting through ancient garbage dumps. Scientists working in Oregon have found one that has yielded what they say are the oldest human remains in the Americas and a puzzle about the earliest American tools.
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, because it's based on carbon dating of actual human "remains," 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.
"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," Jenkins says.
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?
"We have contemporaneous groups," Meltzer says. "They are doing different stylistic things on the landscape. What is the relationship? Dunno."
Writing in the journal Science, Jenkins and his group suggest 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.