A map showing the proposed spread of languages back and forth over Beringia (Image: Sicoli & Holt/PLOSOne)
Anthropologists have long believed that the indigenous peoples of the Americas migrated over from Asia between 15,000 and 40,000 years ago by crossing over "Beringia," a strip of land that used to connect the two continents before being submerged into the Bering Sea.
Now a new study published this week in PLOSOne is lending support to an interesting twist on that theory — humans might have lived on Beringia for as long as 10,000 years before splitting up, with some groups moving east to the New World and others going back west to Siberia. And the evidence comes from the languages spoken on either side of the Bering Sea.
The study comes from a pair of linguists, Mark Sicoli and Gary Holton, who used computation models borrowed from evolutionary biology to examine the relationships between the North American Na-Dene family of languages (like Western Apache and Tlingit) and the Siberian Yeneseian family (Ket and Kott). By comparing dozens of different features of the languages — like their grammar and sound structure — the researchers found that the two groups were indeed related.
But they went beyond just showing the languages were connected. They were able to construct a family tree of the 40 languages they were comparing, which showed the historical relations between them. Their evidence strongly supported the idea that the Na-Dene languages and the Yeneseian ones evolved from a common tongue. In other words, the ancestors of today's Aboriginal peoples didn't just bring a language across the Bering land bridge. Instead, the inhabitants of the land bridge fanned both east and west, spreading their language in both North America and Asia.
This new linguistic evidence dovetails with geological evidence announced a few weeks ago that suggests that Beringia was likely home to a wooded ecosystem around the time that early migrants lived there — making it a much more hospitable environment to live in than glacial Alaska. It also lines up with DNA evidence for a "Beringian Standstill," Sicoli and Holton write, "before both a rapid early coastal migration into North America and back-migrations from Beringia into Asia."
"Growing up, I'd look at maps showing migrations to the Americas, and they'd always just show arrows going in one direction: straight across from Asia to North America," Sicoli told Smithsonianmag.com. "What we see now is something more complicated, because some of those arrows go back to Siberia, and it wasn't a non-stop trip."