The Americas were populated by both people crossing the bridge from Asia, and arriving on boats after the last ice age. (Photo : Wikimedia Commons)
They may be called Native Americans, but in reality they came from Asia. Of course that was a very long time ago, and a recent look into the origins of humans on Americas shows that Native Americans are actually the result of three distinct migrations from Siberia, not just one.
The migrations would have taken place between 5,000 and 15,000 years ago, says the study.
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The previously held theory is that it was a single Asian ancestral group that populated the Americas. Everyone from geneticists to linguists usually support this theory. The new findings change the way that scientists look at human migratory patterns, and builds upon a theory that was first proposed in 1986 by linguist Joseph Greenberg.
"This is part of the issue of how humans evolved and colonized the world," said human geneticist Andres Ruiz-Linares to the AFP.
The research was headed by David Reich at Harvard University Medical School, and compared more than 350,000 genetic markers between 52 Native American population group and 17 Siberian groups. They used archived genetic samples, and worked independently of any Native American group or tribe.
"This is monumental work," said anthropologist Tom Dillehay at Vanderbilt University, who studies the early settlement of North and South America but wasn't involved in the project. "What gives this great weight is the enormity of the database and the global approach."
The study concludes that the first wave of immigrants came over around 15,000 years ago, crossing the Beringia land bridge from Siberia to North America. The second and third waves of immigrants are believed to have come by boat, after the end of the last ice age and the Beringia bridge disappeared underwater.
"Speakers of Eskimo-Aleut languages from the Arctic inherit almost half their ancestry from a second stream of Asian gene flow, and the Na-Dene-speaking Chipewyan from Canada inherit roughly one-tenth of their ancestry from a third stream," said the study.
The most genetic diversity was found in the North, and the team proposes that these "First Americans" moved south and populated South America in a hunt for resources.