Archaeologists have uncovered evidence at a remote rock shelter in the Oregon mountains that could significantly revise the timeline of human settlement in North America. The site, known as Rimrock Draw, may have been occupied by humans as early as 18,250 years ago, predating the long-held theory of human arrival via an ice-free corridor from Asia around 13,000 years ago.
If confirmed, these findings would position Rimrock Draw among the oldest known human occupation sites in North America, dating back to approximately four times the age of Egypt's Great Pyramid. The discovery adds to a growing body of evidence suggesting that early humans may have arrived on the continent much earlier, potentially traveling along the Pacific coastline before inland routes became accessible.
Researchers from the University of Oregon discovered two finely crafted orange agate stone tools beneath a layer of volcanic ash. This ash was identified as originating from an eruption of Mount St. Helens more than 15,000 years ago. Radiocarbon dating of extinct camel and bison tooth enamel found in conjunction with the tools yielded an age of approximately 18,250 years. The placement of the tools beneath this dated material suggests the site was occupied even earlier than the analyzed remains.
One of the discovered tools still bore traces of bison blood, indicating its use in butchering or processing the animal.
David Lewis, a professor of anthropology at Oregon State University and part of the research team, stated that the early date aligns with oral histories of local tribal nations, which include accounts of geological events like the Missoula floods that occurred between 18,000 and 15,000 years ago. He added that these histories also mention interactions with megafauna, which the Rimrock Draw findings suggest may have occurred.
Patrick O’Grady, a University of Oregon archaeologist overseeing a field school at the site, described the identification of 15,000-year-old volcanic ash as a shock, with the subsequent dating of 18,000-year-old enamel layers beneath the stone tools being even more startling.
While the findings have not yet undergone peer review, they have the potential to significantly alter the understanding of human migration into the Americas. The dating results were initially released in 2023 and recently gained wider attention through a YouTube video examining early human origins.
