New genetic review finds the ancestors of today’s Indigenous Americans most likely arrived near the end of the Last Glacial Maximum, no earlier than about 21,000 years ago. The paper evaluated three models—pre-LGM, during LGM, and post-LGM—and used ancient DNA to trace a split in a Siberia/Beringia population at ≈25,000 years ago. Genetic data and archaeological finds like White Sands footprints (≈23,000 years) leave open the possibility of earlier arrivals, but gaps in sampling and ethical, collaborative research practices mean future genomes could change the picture.
Genetic Review Suggests Ancestors Of Indigenous Americans Arrived Near Peak Of Last Ice Age — Likely No Earlier Than ~21,000 Years Ago
The ancestors of Indigenous peoples in the Americas may have arrived around 21,000 years ago. . | Credit: Alamy
New genetic analyses indicate that the population ancestral to today’s Indigenous peoples of the Americas most likely entered the continents near the coldest phase of the last ice age, arriving no earlier than about 21,000 years ago. While this timing aligns with a migration close to the end of the Last Glacial Maximum (LGM), researchers caution that earlier movements cannot yet be ruled out.
What the Study Reviewed
In a paper published online Sept. 23 in Current Opinion in Genetics & Development, Bethany Potter (Kansas Geological Survey) and Savannah Hay (University of Kansas) reviewed available ancient DNA and evaluated three major archaeological models for the peopling of the Americas: a pre-LGM entry (>25,000 years ago), an entry during the LGM (≈25,000–14,000 years ago), and a post-LGM arrival (<14,000 years ago) historically associated with the "Clovis First" interpretation.
Genetic Evidence And Key Findings
Genomic research in the Americas is still young but growing: since the first complete ancient Indigenous genome (from Greenland, ≈4,000 years old) was published in 2010, researchers have reported roughly 250 whole ancient genomes and genome-wide data from about 1,200 additional ancient individuals. These datasets point to a population living in or near Siberia/Beringia that split around the time of the LGM (≈25,000 years ago) into multiple lineages — including ancestral Native Americans, an ancient Beringian group, and one or more "ghost" lineages.
According to current models, the migrating group appears to have moved rapidly along the Pacific coast and may have split again by roughly 16,000 years ago into northern and southern Native American branches. Extrapolations from early sampled genomes, including the Anzick-1 child (≈12,800 years old), favor an initial migration no earlier than about 21,000 years ago.
Archaeology, White Sands, And Uncertainties
Archaeological evidence remains debated. Human footprints discovered at White Sands, New Mexico, have been dated to roughly 23,000 years ago; if those dates are correct, they imply an interior North American presence before the LGM. Indigenous communities in the region, including the Acoma Pueblo, recognize the footprints as ancestral traces. However, genetic data from both ancient and present-day Indigenous groups do not yet show a clear, substantial contribution from the White Sands individuals to most later populations. This could reflect incomplete sampling, a small genetic contribution, or the fact that descendants of the White Sands people have not yet been sampled.
Gaps In Data And Ethical Considerations
Important geographic gaps remain: for example, there are currently no published ancient genomes from the U.S. Great Plains. Potter and Hay emphasize that expanding geographic coverage is essential, but many researchers are proceeding cautiously to ensure that ancient DNA studies are ethical and collaborative with descendant communities. New ancient genomic data from under-sampled regions could change the timeline or reveal previously undetected migration events.
Conclusion
Neither the archaeological record nor the genetic evidence currently produces a single, definitive timeline for the initial peopling of the Americas. The balance of genetic evidence reviewed by Potter and Hay supports a founding migration near the end of the LGM (no earlier than ≈21,000 years ago), but additional genomic discoveries and careful, community-engaged research may refine or revise that timeline.
Help us improve.
