Genetic evidence from ancient American whole genomes points to an initial human migration into the American continents no earlier than 21,000 years ago, placing the ancestors of today’s Indigenous peoples at the height of the last ice age, according to a genomic review published in September 2026.
Genomic Data Places Initial Migration at 21,000 Years Ago
A review published online Sept. 23 in Current Opinion in Genetics & Development examines decades of archaeological discoveries alongside a rapidly expanding record of ancient human DNA to test three primary migration models. Archaeologists have argued for more than a century over whether human arrival in the Americas predated, coincided with, or followed the coldest peak of the last ice age, known as the Last Glacial Maximum.
Singh and Jennifer Raff. The authors compared scenarios of human entry before 25,000 years ago, during the glacial maximum between 25,000 and 14,000 years ago, and after 14,000 years ago under the traditional Clovis First theory. Based on the available genetic evidence, the researchers concluded that the group giving rise to modern Indigenous populations arrived no earlier than about 21,000 years ago.
Two Hundred Fifty-Seven Whole Genomes Map the Beringian Standstill
Scientists have published approximately 257 whole genomes from ancient individuals in the Americas, supplemented by genome-wide data from another 1,204 ancient people. Genetic records for ancient populations have grown substantially over the past 16 years. By comparing these genetic datasets, researchers can reconstruct population lineages that extend far beyond the physical samples themselves.
Between approximately 25,000 and 20,000 years ago, ancient populations carrying Siberian and East Asian ancestry contributed to a group ancestral to Indigenous Americans. This population spent thousands of years in relative isolation during an interval known as the Beringian Standstill. During the glacial maximum, these groups split into ancient Native Americans, ancient Beringians, and one or more unmapped ghost
lineages.
The White Sands Footprint Discrepancy and Missing Regional DNA
Human footprints discovered at White Sands National Park in New Mexico have been dated to between 21,000 and 23,000 years ago using ancient pollen, sediment measurements, and radiocarbon dates. Despite the clarity provided by genomic family trees, physical evidence from certain archaeological sites complicates the timeline. However, genetic data from contemporary and ancient Indigenous populations indicates that the White Sands population did not make a major genetic contribution to the ancestors of today’s Native Americans.
Researchers suggest several explanations for this gap. The White Sands inhabitants may belong to an unsampled lineage, or their descendants might carry a low proportion of genetic ancestry that has not yet been isolated in the available samples.
Independent Archaeological Perspectives on the Genomic Review
Ben Potter, an archaeologist at the University of Alaska Fairbanks who was not connected to the study, told Gizmodo that he found the paper’s interpretation of the archaeological data less convincing than its genetic findings, noting that many of his colleagues favor a post-Last Glacial Maximum model between 16,000 and 14,000 years ago.