Ancient DNA challenges theories about when humans first reached North America

A review of existing genetic and archaeological evidence suggests humans reached the Americas between 14,000 and 20,000 years ago, with arrival before 15,000 years ago considered likely. The findings challenge the older “Clovis First” theory, which placed the first arrival at about 13,500 years ago, and help explain why evidence for early migration remains debated.

Researchers from the University of Kansas considered evidence including 23,000-year-old footprints at White Sands, New Mexico, which may predate the timeline supported by available genetic data. Their review found ancestral lineages diverging around 21,000 years ago and northern and southern Native American populations splitting roughly 15,500 years ago, likely south of the ice sheets. The authors said the timing and locations remain uncertain; earlier populations may have left no surviving descendants or may not yet be represented in genetic samples.