The earliest migration to the new land occurred in stages

Jul 13, 2012 07:00 GMT  ·  By

Following a series of complex genetic analyses, investigators determined that the first people to settle the American Continent did not arrive there at once, but rather in stages, spread out over many years.

Figuring this out was made possible by the advanced DNA analysis techniques scientists have access to today. The new research was based on investigating the whole genomes of Native Americans in South America and Canada.

One of the things that were made immediately clear was that both North and South America were populated by people who came from Siberia, across the Bering Sea, which may have not existed at the time. After arriving in what is now Alaska, the newcomers spread out.

However, the process occurred three times, say investigators at the Harvard Medical School (HMS) and the University College London (UCL). They say that the DNA of surviving natives indicates three different infusions of genes into the area's gene pool.

Before this study was released, experts were convinced that the Americas were populated by a single group of ancestors from Siberia, who arrived on the new lands some 15,000 years ago. What the new data suggest is that this large migration was followed by two others.

The first of these latter two was made up of individuals who are now considered the ancestors of Eskimos and Aleutians. The second group was made up of people who spoke Na-Dene, who are now the ancestors of racial groups constrained to North America.

Full details of how these lineages work appear in a paper published in the July 11 issue of the top scientific journal Nature. The research group was led by HMS investigator David Recih and UCL scientist, Dr. Andres Ruiz-Linares.

Interestingly, the migrations occurred during a rather narrow interval of time, when the great glaciers that blocked passage through Bering Strait had disappeared. This was also before the end of the last Ice, when rising waters submerged the land bridge between Alaska and Asia, called Beringia.

In addition to learning more about the history of human habitation on the American Continent, the new investigation also draws attention to an interesting connection between genetics and linguistics.

“It’s striking that we have this correspondence between the genetics and the linguistics,” concludes Dr. Ruiz-Linares.