Ancient DNA Study Reshapes Timeline of Human Arrival in North America

Recent analysis of ancient DNA, combined with archaeological evidence, is refining the understanding of when humans first migrated into North America. The study, published in Current Opinion in Genetics & Development, indicates that human arrival likely occurred between 14,000 and 20,000 years ago, with an arrival before 15,000 years ago considered probable.

This timeline challenges the long-standing "Clovis First" theory, which posited that the first humans arrived in North America approximately 13,500 years ago. However, subsequent archaeological findings have increasingly suggested an earlier human presence on the continent.

Researchers Bethany Potter and Savannah Hay of the University of Kansas reviewed existing genetic and archaeological data. This included evidence from 23,000-year-old human footprints discovered at White Sands National Park in New Mexico, which suggest human inhabitation potentially predates the timeline supported by current genetic data.

"Genomic data show us that the dynamics of the peopling of the Americas were quite different — at one point, a small group of people must have entered the American continents completely devoid of other humans," the researchers stated. By comparing genetic data from ancient human remains in Asia and the Americas, the study explored shared ancestry to understand how early Indigenous populations diverged into distinct groups.

The study suggests that some ancestral lineages split around 21,000 years ago. Furthermore, it highlights evidence indicating that ancestral Native American populations separated into northern and southern groups approximately 15,500 years ago, likely south of the extensive ice sheets that once covered much of the continent. This implies that their ancestors had already arrived in the Americas before this divergence occurred.

While the new findings offer a more refined timeline, the researchers acknowledge that uncertainties remain regarding the precise timing and geographical locations of these key divergence events. The study also notes the possibility that early populations may have belonged to lineages for which no surviving descendants or genetic samples have yet been found.

Ancient DNA has been instrumental in other recent archaeological discoveries, including the identification of ancient sheep pox virus DNA in a 1,000-year-old English manuscript and ancient smallpox DNA found in centuries-old mummies in Chile, providing the first genetic evidence of the disease in that region of South America.