Thousands of years before European colonizers arrived in the New World, Native Americans had established nations across the continent. But even Native Americans migrated across the Bering Land Bridge from elsewhere. On Wednesday, new research presented in Nature reviews the story of ancient Americans coming from Eurasia, where the 10,000-year-old remains of an Ice Age man reveal a never-before-discovered people — the ancestors of Native Americans.
These people have been named the “Ancient North Siberians,” after the location of the site near Russia’s Kolyma River, where the 10,000-year-old body was discovered in 2001. DNA from the body revealed that he is “the closest old world relative of ancestral Native Americans among ancient humans studied so far,” the paper’s first author, Martin Sikora, Ph.D., of the Lundbeck Foundation GeoGenetics Center, tells Inverse.
In the study, the team of international co-authors describe the DNA of 34 ancient genomes in total, including that from a pair of 31,000-year-old milk teeth found nearby along the Yana River at the Yana Rhinoceros Horn Site. This DNA revealed an even older, related people, though they were not Native Americans’ “direct ancestors,” says Sikora. Together, the evidence fills in gaps in our understanding of the ancestors of Native Americans and their journey across the Bering Land Bridge during the Ice Age.
Southern Methodist University professor and co-author David Meltzer, Ph.D., tells Inverse that the new work “fills in the details of what is proving to be a far more complicated picture” compared to the previous assumption that the ancient people who traveled across the Bering Strait into America were generally a “single entity.”
Who Were These People?
By recent accounts, modern humans started leaving Africa up to 120,000 years ago, but the exact date is up for debate. But it’s fairly well established that by 40,000 years ago, different groups of humans had started to spread across Eurasia, eventually venturing very far north and east. “It’s not terribly surprising that, at 30,000 years ago, we’ve got a group that’s in far northern what’s now Russia,” says Meltzer.
Because they were isolated for many generations, these groups developed distinct genetic signatures that we can still trace today.
“What we’ve done with the new Yana genome [the milk teeth] is we’ve been able to show that that genetics signal, a portion of which is in Native Americans today, reaches back to 31,000-plus years ago — in one of the most remote places on Earth,” says Meltzer.
“This population, through kind of a circuitous route, portions of its genome end up crossing the Bering Land Bridge 20,000, 15,000 years later and making it all the way to Tierra del Fuego.”
Life on the Steppe
Life for the Ancient North Siberians on the Arctic steppe was not easy, but it wasn’t unlivable. The last ice age (technically a glaciation period that continues today) began 2.6 million years ago and was in an “interstadial” — a warm period between cold periods — 31,000 years ago.
“You wouldn’t want to be there 10,000 years after those guys were there,” says Meltzer. The warm period “is probably the reason they are there — because it would have been possible to be there.”
The relatively mild conditions of the steppe at the time meant it was “more rich in plant diversity than today and dominated by various grasses” but not trees, says Sikora. Animals included mammoths, woolly rhino, horses, bison, wolves and lions, which the Yana people hunted, as the rich archeological record suggests.
“It would be cold, but not, you know, brutally cold that they couldn’t survive,” says Meltzer.
Coming to America
There’s a lot of debate surrounding the moment when ancient peoples trekked over the Bering Land Bridge, if at all. So much, in fact, that Meltzer is currently revising his 2010 book, First Peoples in a New World, which he says is “woefully out of date” because of the wealth of new information about those early humans.
While some scientists have recently cast doubt on the idea that humans could have walked over the Bering Land Bridge 15,000 years ago, Meltzer is not swayed by this argument. While Beringia — the name given to the land bridge, which is now thought to be submerged — wasn’t the most hospitable of places, he suspects the southern coast offered sufficient “micro-refuges” for travelers heading east.
Besides, he points out, “humans have a remarkable capability and ability to adapt to challenging environments.”
Multiple subsets of ancient populations are thought to have landed in what is now Alaska, spreading out over North America through a variety of routes. The remains of the Ancient North Siberians confirm one of their starting points, though there may be many others. What is becoming clearer, for now, is who the ancestors of present-day Native Americans actually were.
“These were not folks who were, in any sense, huddled together in some marginal environment with their teeth chattering, watching animals walk by and wishing they could really just kill one and eat it,” says Meltzer. “They were doing okay.”
Northeastern Siberia has been inhabited by humans for more than 40,000 years but its deep population history remains poorly understood. Here we investigate the late Pleistocene population history of northeastern Siberia through analyses of 34 newly recovered ancient genomes that date to between 31,000 and 600 years ago. We document complex population dynamics during this period, including at least three major migration events: an initial peopling by a previously unknown Palaeolithic population of ‘Ancient North Siberians’ who are distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian-related peoples, which gave rise to ‘Ancient Palaeo-Siberians’ who are closely related to contemporary communities from far-northeastern Siberia (such as the Koryaks), as well as Native Americans; and a Holocene migration of other East Asian-related peoples, who we name ‘Neo-Siberians’, and from whom many contemporary Siberians are descended. Each of these population expansions largely replaced the earlier inhabitants, and ultimately generated the mosaic genetic make-up of contemporary peoples who inhabit a vast area across northern Eurasia and the Americas.