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.
- Genetic evidence points to arrival between 14,000 and 20,000 years ago.
- White Sands footprints date to around 23,000 years ago.
- Researchers say the timing and location of early splits remain uncertain.
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For much of the last century, the “Clovis First” theory held that people first reached North America about 13,500 years ago. It was based on distinctive stone tools found at sites across the continent, though evidence of people living there earlier has since been reported.
Researchers study ancient human remains, living people’s DNA and archaeological sites to piece together when and how people moved into the Americas. The routes were shaped by vast ice sheets covering parts of the north, and the timing and paths of migration remain uncertain.
The debate matters because it concerns the deep history of Indigenous peoples in the Americas. Genetic evidence can reveal how populations are related, but it may not include groups that left no surviving descendants or whose DNA has not been sampled.