The pre-Columban migration of peoples to the North American continent occurred in three distinct waves, according to research published in scientific journal Nature, based on survey of Native American DNA.
Genetic data had previously suggested that only one major wave of migration explained the presence of the ancient Americans in the New World.
However, the majority of today’s “indigenous Americans” are the descendants of just one huge wave of immigrants who reached Alaska from Asia at least 15,000 years ago, when a land bridge linked the two continents.
"For years, it has been contentious whether the settlement of the Americas occurred by means of a single or multiple migrations from Siberia," said professor Andres Ruiz-Linares from University College London, a co-author of the study.
"But our research settles this debate: Native Americans do not stem from a single migration. Our study also begins to cast light on patterns of human dispersal within the Americas."
The second and third migrations apparently only influenced the certain populations in the Arctic, including Eskimo-Aleuts and the Chipewyans.
"There are at least three deep lineages in Native American populations," said another co-author of the study, David Reich, a professor of genetics at Harvard Medical School.
"The Asian lineage leading to First Americans is the most anciently diverged, whereas the Asian lineages that contributed some of the DNA to Eskimo-Aleut speakers and the Na-Dene-speaking Chipewyan from Canada are more closely related to present-day East Asian populations."
After their arrival on the North American continent, the people continued to migrate southward along the coast, with smaller groups periodically moving off on their own. Ultimately, these “migrants” eventually found themselves thousands of miles away in what is now South America as far as present-day Chile.
The new research appears to vindicate the theories of linguist Joseph Greenberg, who proposed in 1987 that most of the languages spoken by the native peoples of the Americas could be traced to the single tongue of the first settlers who arrived in Alaska from Siberia across the Bering Sea those uncounted centuries ago.
Greenberg, who died in 2001, called this ancient language Amerind.
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