When did humans first set foot on the American continents? A University of Kansas team has published a review in the journal Current Opinion in Genetics & Development that tests the three leading models for the peopling of the Americas against the genomic record: the evidence best fits a migration window of 14,000 to 20,000 years ago, with the lineage diversification of modern Indigenous ancestors starting no earlier than about 21,000 years ago.
The review was authored by Bethany Potter (Kansas Geological Survey), Savannah Hay, Archana Singh, and Jennifer Raff, all of the University of Kansas anthropology department, appearing in the journal's 2026 volume 101. The authors surveyed the published inventory of about 257 ancient American whole genomes plus 1,204 genome-wide datasets — the current genetic ledger of pre-contact Americas.
Researchers have long debated three scenarios: before the Last Glacial Maximum (more than 25,000 years ago), between 20,000 and 14,000 years ago, and after 14,000 years ago. Comparing each against the genomic record, the team found that the pre-25,000-year model shows no ancient population-split signal in the genomes — if people were in the Americas that early, they left no modern descendants, or their DNA simply hasn't been sequenced yet. The post-14,000-year model conflicts with the evidence, since key population splits happened well before the ice-free corridor opened. The best fit is the middle option: 14,000 to 20,000 years ago.
The review reconstructs a key timeline: about 15,000 years ago, a major branching event divided the ancient travelers into the northern and southern Indigenous lineages of the Americas; afterward, their descendants spread across both continents in multiple waves rather than a single migration. In other words, the ancestors of Indigenous peoples didn't arrive in one landing — they came in batches, along multiple routes.
The genetic window has narrowed, but the archaeological evidence still pushes back. The footprints at White Sands National Park in New Mexico date to about 23,000 years ago, Chiquihuite Cave to about 32,000, and California's Cerutti site to a claimed 130,000 years — all outside the genetic window. The authors concede gaps remain: the Great Plains has no published ancient genomes at all, and earlier migrations could be hiding in that blank spot; the archaeology and genetics of Chile's Monte Verde site (about 14,500 years old) are also not yet reconciled. The oldest American human genome remains Anzick-1 from Montana (about 12,800 years old, a Clovis-burial child).
The study also stresses that ancient genomics must proceed in ethical partnership with Indigenous descendant communities — after all, the people behind this DNA are the ancestors of today's Native peoples. As more ancient genomes are sequenced, the 14,000-to-20,000-year window may narrow further. The story of how humans reached the Americas is far from finished.