At Oregon’s Paisley Caves, archaeologists have dated fossilized human feces to 14,300 years ago. The Meadowcroft Rockshelter in Pennsylvania, which Adovasio began excavating in the 1970s, has a human history that may stretch back at least 16,000 years. Beneath the Clovis layers along the shores of Buttermilk Creek in Texas, researchers have found thousands of stone tool fragments dating back 15,500 years. At a site called Arroyo Seco 2 in the Pampas grasslands of Argentina, archaeologists have found 14,000-year-old butchered animal bones.
As researchers validate these finds, studies are chipping away at the story many of us read in textbooks. For one, the idea of a single pioneering population may have been a mistake. “It’s probably more like a dripping faucet where people are coming in at different times, from different directions,” Dillehay says.
Most archaeologists would now agree that there were widely scattered, small but culturally diverse groups of people living in the Americas at least one or two millennia before the emergence of Clovis spear points. That estimate, then, placing people in the Americas roughly 15,000 years ago, is among the most conservative.
As the Clovis-first model has fallen out of favor, even bolder chronologies have emerged. For example, one group of scientists has made a case that they have uncovered evidence of humans butchering megafauna 130,000 years ago at what is now called the Cerutti mastodon site in Southern California—though many archaeologists have contested that argument. In an article for Science, Braje, Dillehay, and a few other colleagues wrote that the collapse of the Clovis-first paradigm “has opened a Pandora’s box of alternative scenarios for the peopling of the Americas, with some scholars and members of the general public quick to accept implausible claims based on limited and equivocal evidence.” They cited the Cerutti mastodon site as one such example.
Genetics, meanwhile, has brought a daunting deluge of new findings, which also shed light on how and when entire lineages of people moved across continents. Genetic markers from the DNA of a child buried in what is now Alaska around 11,500 years ago, for instance, recently revealed that she shared equal DNA with all Indigenous populations in the Americas. The authors concluded she was likely descended from a population that stayed in Beringia, instead of spreading through the lower continents.
The basic story some geneticists have gleaned from this and other finds is that a so-called Beringian population would have diverged from Siberian populations around 36,000 years ago. About 25,000 years ago, the Beringians became isolated, and a new genetic population emerged, one that scientists have confirmed relates to contemporary Native American people, splitting into two main lineages around 17,000 years ago.
