[Igor Antunov]

A new genetic analysis led by researchers at Harvard University has found a common ancestor shared by some Amazonians and the indigenous peoples of Australia and New Guinea, suggesting that the first Americans did not arrive in a single wave as believed.

According to Smithsonian.com, the prevailing theory is that a lone group of humans travelled over a land bridge connecting Eurasia and modern-day Alaska some 15,000 years ago. This new research, however, suggests that it is unlikely that all Native Americans descended from just one group, and that two different groups might have migrated from one continent to the other.

“Our results suggest this working model that we had is not correct,” study co-author and Harvard geneticist David Reich explained to the website. The findings, which were published in the latest edition of the journal Nature, suggest that “there’s another early population that founded modern Native American populations” – a group originating from Australasia, he added.

More: http://www.redorbit.com/news/science/11 ... ns-072315/

[ThirdTerm]

Researchers found that the Suruí, Karitiana and Xavante peoples in the Amazon are more closely related to indigenous populations in Australasia than any other modern group and they hypothesised that these ancient tribes travelled into the Americas via the Bering Land Bridge just like other native Siberians. Australasian DNA reached the Americas less than 9,000 years ago, much later than the first wave of humans’ migration across the Bering Land Bridge. It's unlikely that primitive tribes from Australasia could travel all the way to Siberia before crossing the Bering Land Bridge as there is no trace of their (Denisovan) DNA in North America and Russia. The ancestors of the Suruí, Karitiana and Xavante peoples could have crossed the Pacific Ocean to Latin America without taking circuitous routes via Siberia. There could have been numerous small islands between Australasia and Latin America 9,000 years ago, which enabled Australasians to cross an ocean by a series of shorter journeys (i.e. island hopping.)

Geneticists have found that Native American tribes living in the Amazon are most closely related to Aborigines from Australia, Papau New Guinea and the Andaman Islands, as shown in the image above, where warm colours show the greatest level of genetic affinity. White circles show populations with no genetic link.

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.
http://www.sciencemag.org/content/early ... ce.aab3884

[Smertios]

It's not a discovery. More like a confirmation through genetic analysis.

That link has been known at least since the early 1990s: http://www.nytimes.com/1999/10/26/science/an-ancient-skull-challenges-long-held-theories.html