Archaeologists have proposed dates for the first people in the Americas that span more than 100,000 years, from roughly 130,000 years ago at the Cerutti site in California to about 14,200 years ago at Swan Point in Alaska. A review led from the University of Kansas lands on a far tighter window: 20,000 to 14,000 years ago, the stretch of time that covers the end of the Last Glacial Maximum and the retreat of the ice.
Bethany Potter of the Kansas Geological Survey and Savannah Hay of the University of Kansas are the lead authors, with equal contribution, and Archana Singh and Jennifer Raff are co-authors. The review appears in Current Opinion in Genetics & Development.
Three windows tested against ancient DNA
The authors sorted the competing archaeological claims into three models relative to the Last Glacial Maximum, which they date from about 25,000 to 14,000 years ago: arrival before the maximum, more than 25,000 years ago; arrival during it, 20,000 to 14,000 years ago; or arrival afterward, after 14,000 years ago. As Archaeology Magazine summarizes the result, they compared those models with DNA, archaeological and environmental evidence and concluded that arrival most likely fell between 20,000 and 14,000 years ago.
Genetics carries the weight. According to the review as relayed by La Brújula Verde, the window between 20,000 and 14,000 years ago has the most genetic support, and the review finds that lineage diversification does not appear before about 21,000 years ago.
The 15,000-year split and the missing early DNA
Northern and Southern Native American lineages had already split by about 15,000 years ago, a date that puts an upper bound on how late the founding group could have entered. Live Science gives a slightly older figure, about 16,000 years ago, for the same split, which it places after a group near Siberia or Beringia separated around 25,000 years ago and moved quickly along the Pacific coast.
For anything older than 25,000 years, no DNA evidence of comparable lineage splits has been identified. Archaeology News Online adds the reasoning behind that silence: a pre-maximum site would be expected to yield Neanderthal, Denisovan or unknown-lineage DNA in early American genomes, and the genomes sampled so far do not show the archaic mixing such a scenario would predict.
White Sands, Monte Verde and what the review leaves open
The question stays open. Footprints at White Sands, New Mexico, have been dated to about 23,000 years ago, which would sit before the 21,000-year diversification point. Live Science reports that the genetic data show the White Sands population contributed little to today’s Indigenous ancestry. Potter and Hay allow that DNA from the White Sands population may simply not have been found yet.
Evidence of human activity before 25,000 years ago may belong to groups that left few or no descendants, the authors say, and DNA from those earlier groups may simply not have been recovered. The caution rests on the numbers: about 257 whole ancient genomes from the Americas and genome-wide data from 1,204 more individuals, but none from the Great Plains and none older than the 12,800-year-old Anzick-1 child from Montana. Potter and Hay describe the dataset as having huge gaps. The least contested early sites, according to Archaeology News Online, are Monte Verde II in Chile at about 14,500 years ago, along with Paisley Caves and Page Ladson at similar ages. Humans were definitively in the Americas by about 13,500 years ago. For context, Wikipedia’s overview puts the Last Glacial Maximum at roughly 26,000 to 19,000 years ago, a slightly different bracket than the review’s, with Beringia exposed by lower sea levels and ice sheets blocking inland routes.
Ethics and who sets the questions
The authors tie further sampling to consent. Potter has said that paleogenomics research must be rooted in questions articulated by archaeologists and tribal historians, and the review stresses that expanding the genetic record has to be done ethically and collaboratively with descendant communities. Archaeology News Online notes that Indigenous knowledge, including oral histories, sits outside the archaeological evidence the review weighs. The same report records that the researchers say it is unclear whether the debate will be resolved, and that Great Plains genomes in particular are absent from the published record.
A pre-maximum migration stays alive in the review for one reason: ruling it in or out depends on linking an early site genetically to later Indigenous peoples, and the authors say that requires more data than exists now. They also point out that few early sites should be expected at all, since erosion and burial may have erased traces of small founding groups, who entered what the review describes as a continent with no other humans.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
More from Morning Overview
- The FBI told the rest of ShinyHunters to surrender after a 24-year-old was arrested
- Two passengers died at an Ohio toll plaza, and the NTSB now wants the cash lanes shut
- Long use of a common prostate pill is tied to a higher chance of glaucoma
- Ford is recalling 223,472 F-150 pickups because the fuel tank can leak or detach
