Native Americans descended primarily from peoples who lived in East Asia and southern Siberia, who crossed into the Americas via a land connection between modern-day Russia and Alaska. But the story is more complex than a single walk across a bridge. Genetic and archaeological evidence now points to a long stopover in the land bridge region itself, multiple possible migration routes, and a timeline that keeps getting pushed further back as new discoveries emerge.
The Genetic Roots: East Asia and Siberia
DNA analysis shows that Native American ancestry draws from two major source populations. The larger contribution came from East Asian lineages. The other, making up roughly one-quarter to one-half of Native American ancestry, traces back to a population related to the Mal’ta-Buret’ culture of south-central Siberia, near Lake Baikal. This Siberian group had genetic ties to both East Asian and Western Eurasian populations, which explains why some early genetic studies incorrectly suggested a European connection to Native Americans.
By around 12,600 years ago, these two ancestral streams had already blended in the proportions found in Native Americans today. We know this from DNA extracted from the Anzick child, a boy buried in western Montana who remains one of the oldest human remains found in the Americas. His genome looks essentially like a mixture of East Asian and Mal’ta-related ancestry, with no additional sources needed to explain it.
The maternal side of the family tree tells a consistent story. The vast majority of Native American mitochondrial DNA (passed from mother to child) falls into just four major lineage groups, labeled A through D. Their genetic diversity is remarkably similar to one another, which strongly suggests they all arrived together as part of one founding population rather than in separate waves. Researchers estimate that the ancestral population began diverging from its Asian relatives somewhere between 25,000 and 40,000 years ago.
The Beringian Standstill
One of the most compelling ideas in the field is that the ancestors of Native Americans didn’t simply walk from Asia into the Americas in one continuous journey. Instead, they stopped in Beringia, the now-submerged landmass between Siberia and Alaska, and stayed there for thousands of years.
The logic comes from genetics. Native Americans carry specific mutations not found anywhere in Asia, meaning those mutations arose after the population had already separated from its Asian relatives but before it spread across the Americas. The only place that separation could have happened is Beringia. Evidence of humans at the Yana Rhinoceros Horn Site in northeastern Siberia, dated to 30,000 years ago, suggests this isolation in Beringia may have lasted as long as 15,000 years. During that time, the founding population developed its own distinct genetic identity, essentially becoming “proto-Native American” before anyone set foot south of the ice sheets.
The Land Bridge Itself
Beringia wasn’t a narrow bridge. At its maximum extent, it was a landmass roughly the size of the western United States, covered in grassland and tundra. Recent research published in PNAS pushed back the timeline for when it formed. The Bering Strait was flooded (meaning no land connection existed) from at least 46,000 years ago until roughly 36,000 years ago. Only then did falling sea levels during the approach to the Last Glacial Maximum expose the land bridge. It remained crossable through the peak of the ice age and finally flooded again between 13,000 and 11,000 years ago as glaciers melted and seas rose.
That gives a window of roughly 23,000 years during which people could have lived on or crossed this landmass on foot.
How They Moved South
Getting into Beringia was one thing. Getting past the massive ice sheets that covered most of Canada was another. Two routes have strong evidence behind them.
The first is an ice-free corridor that opened between two retreating glaciers in what is now western Canada. For decades, this was considered the primary route. But the corridor may not have been passable, or ecologically viable for human travel, until around 13,000 years ago, which is too late to explain the earliest sites further south.
The second route ran along the Pacific coast. Known as the “kelp highway” hypothesis, it proposes that people followed productive kelp forest ecosystems down the western coastline of the Americas, living off marine resources as they traveled. Archaeological sites on California’s Channel Islands show intensive use of marine resources tied to kelp ecosystems over the past 10,000 years, and dozens of coastal sites along South America’s Pacific shore preserve direct evidence of kelp harvesting stretching back nearly 8,000 years. Because sea levels were lower during the ice age, much of the coastline these early travelers would have used is now underwater, making direct evidence of the earliest coastal migration difficult to find. Still, the coastal route is now considered the more likely path for the first arrivals.
The Oldest Evidence in the Americas
The timeline for when people first arrived keeps getting older. For much of the 20th century, the consensus held that the Clovis people, known for their distinctive stone tools dated to about 13,000 years ago, were the first Americans. That consensus has collapsed.
The most striking evidence comes from White Sands National Park in New Mexico, where human footprints have been dated to between 23,000 and 21,000 years ago. Those dates were initially controversial because they relied on seeds from an aquatic plant that might have absorbed old carbon from the water, skewing the results. But a 2023 study using two independent methods (radiocarbon dating of terrestrial pollen from the same layers and a light-based technique for dating the surrounding sediment) confirmed the original ages. Humans were walking in what is now New Mexico during the Last Glacial Maximum, when ice sheets were at their peak.
In Canada’s Yukon Territory, Bluefish Caves preserves animal bones with unmistakable cut marks from stone tools, dated to around 24,000 years ago. This is currently the oldest confirmed evidence of human presence in North America and fits neatly with the idea that people were living in eastern Beringia before moving south.
In South America, the Monte Verde site in southern Chile shows evidence of human activity stretching back to at least 18,500 years ago, with a well-established occupation layer confirmed at around 14,500 years ago. The fact that people had reached the southern tip of South America by that date implies the initial entry into the Americas happened considerably earlier.
The European Origin Theory That Didn’t Hold Up
For a time, some researchers promoted the Solutrean hypothesis, which proposed that people from ice age Western Europe crossed the Atlantic and became the first Americans. The idea rested on superficial similarities between Clovis stone tools and those made by the Solutrean culture in France and Spain around 20,000 years ago. Genomic evidence has thoroughly refuted this. DNA from the earliest Americans shows no Western European ancestry. The Western Eurasian genetic signal in Native Americans traces specifically to the Mal’ta-Buret’ population of Siberia, not to anyone in Europe. The tool similarities appear to be coincidental.
Later Contact: Polynesians and South Americans
While the initial peopling of the Americas came from Asia, there is strong evidence for at least one later contact event across the Pacific. Genetic analysis of sweet potatoes, a plant domesticated in tropical America, reveals that Polynesian varieties trace their ancestry to a specific gene pool from the Peru-Ecuador region of South America rather than from Central America or the Caribbean. Polynesian languages use words for sweet potato (“kuumala” and its variants) that closely resemble Quechua terms (“kumara,” “cumar”) used by indigenous South Americans. Sweet potato specimens collected during Captain Cook’s first voyage to the Pacific in 1769 carry this South American genetic signature, confirming it predates European contact. The best estimate places this transfer around 1000 to 1100 A.D., likely the result of Polynesian voyagers reaching the coast of South America and bringing the plant back with them.
This contact was limited and left only faint traces in the DNA of a few Polynesian populations. It did not contribute to the founding of Native American populations, but it does show that the Pacific was not an impenetrable barrier even centuries before Columbus.