Life › Human evolution › Homo sapiens
Peopling of the Americas
by c. 23,000–15,000 years ago (debated)· Event· Human ancestors & us
DebatedScientists disagree about when, how or why.
The first people reached the Americas from northeast Asia during or after the last ice age; exactly when is hotly debated.
See it on the Life map →What happened
They came from Siberia across Beringia, the land bridge exposed when sea levels fell. Genetics suggests their ancestors split from East Asians about 25,000–20,000 years ago, perhaps pausing in Beringia. They spread south along the Pacific coast, probably partly by boat, and later through an ice-free inland corridor. Monte Verde in Chile shows people far south by about 14,500 years ago, and the Clovis culture, with its fluted spear points, spread about 13,000 years ago.
Why it matters
It completed the settlement of every continent but Antarctica and founded the Indigenous peoples of two continents, whose later civilizations appear on the Curious History map.
The evidence (fossils, genes, rocks)
Sites such as Monte Verde (Chile), Paisley Caves (Oregon) and Cooper's Ferry (Idaho), with radiocarbon dates; ancient and modern DNA tie Native Americans to Siberian and East Asian ancestors.
Still debated
When people first arrived (before or after the ice-age peak), which routes they used, and whether the earliest arrivals, like the White Sands walkers, left descendants.
Inside this (1)
Connections (4)
▸Out of Africa: Homo sapiens spreads worldwide eventually led to Peopling of the AmericasStrong evidence
The connection
The Out of Africa expansion carried people across Asia by about 60,000–45,000 years ago. Some reached the far northeast; by about 32,000 years ago people lived at Yana, above the Arctic Circle in Siberia. Their descendants, mixing with an East Asian population, became the ancestors of Native Americans and crossed into the Americas, the last continents settled before Antarctica.
When and how
Northeast Asia and Beringia, roughly 30,000–15,000 years ago, well after the main Out of Africa dispersal of about 70,000–50,000 years ago.
How sure are we?
Ancient genomes, such as the 24,000-year-old Mal'ta boy from Siberia, show Native Americans descend from a mix of ancient North Eurasians and East Asians.
Debates and open questions
Exactly where the ancestral population lived during the ice-age peak, possibly in Beringia (the 'standstill' idea), and when it split from East Asians.
▸Pleistocene ice ages opened the Bering land bridge for Peopling of the AmericasWell established
The connection
At ice-age peaks, so much water was locked in ice sheets that sea level fell about 120 meters, exposing Beringia, a land bridge up to about 1,000 km wide between Siberia and Alaska. People could walk across. But the same ice sheets blocked the way south, so travelers likely followed the Pacific coast until an inland corridor opened.
When and how
Beringia, roughly 30,000–11,000 years ago; the coast route ice-free from perhaps 17,000–16,000 years ago; the inland corridor from about 14,000–13,000 years ago.
The evidence
Drowned land mapped under the Bering Sea, pollen and plant remains from Beringia, and dates showing when the ice-free corridor could support life.
Debates and open questions
Whether people crossed before the ice maximum, when the coast route opened, and whether early coastal sites now lie under the risen sea, explaining gaps in the evidence.
▸White Sands footprints (New Mexico) may push back the date of Peopling of the AmericasDebated
The connection
Most well-dated sites placed the first Americans at about 16,000–14,000 years ago. If White Sands' footprints are 23,000–21,000 years old, people were already in what is now New Mexico, south of the ice sheets, about 7,000 years earlier. That would mean they arrived before the ice-age peak blocked the inland route.
When and how
White Sands National Park, New Mexico; published in Science in 2021 by Matthew Bennett, David Bustos, Jeffrey Pigati, Kathleen Springer and colleagues; follow-up dating in 2023.
How sure are we?
Three dating methods (seeds, pollen and quartz luminescence) agree on about 23,000–21,000 years, and the footprints are clearly human.
Debates and open questions
Critics ask whether the seeds and pollen were washed in from older layers or skewed by old carbon in the water; no tools have been found; how people got there is unknown.
▸Peopling of the Americas may have helped cause Ice-age megafauna extinctionsDebated
The connection
In 1967 Paul Martin proposed that hunters spreading through the Americas killed off the big animals: his 'overkill' idea. About 13,000–11,000 years ago, soon after Clovis hunters with distinctive fluted spear points appeared, mammoths, mastodons, ground sloths, horses and camels vanished. Many researchers now think hunting added pressure to animals already stressed by climate.
When and how
North and South America, about 13,000–11,000 years ago; Clovis sites such as Murray Springs and Naco in Arizona, where mammoths were butchered.
How sure are we?
Spear points found with mammoth and mastodon bones at roughly 15–20 Clovis kill sites; radiocarbon dates show the extinctions closely follow human spread.
Debates and open questions
Why so few kill sites exist if hunting was decisive, and how people present thousands of years earlier, as at White Sands, fit the overkill story.