Where did Native Americans come from?

September 6, 2015/BioValley BIOON/-Early research believed that today's Native Americans moved from the continental bridge in the Bering Strait, from Northeast Asia to North America and settled down 15,000 years ago. Therefore, the indigenous peoples of the Americas should have a single common ancestor. Some Native Americans and Arctic Ocean Native Americans can be traced back to more recent migratory waves. Palaeontological genomic analysis shows that the first human-American ancestors can be traced back to 12,600 years ago, while its mitochondrial genomic analysis shows that mitochondrial DNA may be traced back to 13,500 years ago. However, new research does not seem to support this theory.

A research article recently published in Nature by David Reich of Harvard Medical School in Massachusetts and colleagues pointed out that the origins of Native Americans are more diverse and complex than previously believed. The joint team analyzed genome-wide data from 63 individuals from 21 Native American populations in Central and South America, as well as 197 non-American populations worldwide. Because after Columbus discovered the American continent, Europeans and Africans entered the Americas, it was still difficult to find a genome that did not mix Europeans and Africans. Individuals in the 21 Native American populations designed for this study were selected, and were all individuals for whom no significant genetic characteristics were found. By comparing genomic data, they found evidence that the composition of the American ancestral population was more diverse than previously accepted.

The bone morphology of early Americans found now is very different from that of Asians, but it has some similarities with the bone formation of indigenous Australians. Based on this discovery, the World Customs Network may mean that compared with Eurasian people, Americans may be more likely to be descendants of Australian aborigines. Based on genome-wide data analysis, some Amazon Native Americans may not come from Asia, but may be descendants of indigenous people in Australia, New Guinea, Andaman Island and some islands in South Asia. For these Amazon Aborigines, their genomes are even more similar to those of Aboriginal Australians than to other Americans. The extent to which this genomic similarity varies among American populations, as it is lower among Native Americans in Central and North America, may mean that more diverse theories of Native American origin should be widely accepted.

When and how South American ancestors arrived in South America has always been an important issue of concern to anthropologists. Most early genetic studies showed that the earliest settlement of the Americas was a single ancestral population from Eurasia, but morphological research and genomic analysis questioned this. Current evidence further supports that the Native Americans originated from at least two ancestors, one was from Eurasian people from Northeast Asia, and the other was indigenous people from Australia and its surrounding areas. Regarding more detailed human migration, a more in-depth comparison of genomic data of people in different regions of the Americas is needed, which may gradually reveal the mystery of the origin of Native Americans in the future.

Genetic evidence for two founding populations of the Americas

Genetic studies have consistently indicated a single common origin of Native American groups from Central and South America1, 2, 3, 4. However, some morphological studies have suggested a more complex picture, whereby the northeast Asian affinities of present-day Native Americans contrast with a distinctive morphology seen in some of the earliest American skeletons, which share traits with present-day Australasians indigenous groups in Australia, Melanesia, and island Southeast Asia)5, 6, 7, 8. Here we analyse genome-wide data to show that some Amazonian Native Americans descend partly from a Native American founding population that carried ancestry more closely related to indigenous Australians, New Guineans and Andaman Islanders than to any present-day Eurasians or Native Americans. This signature is not present to the same extent, or at all, in present-day Northern and Central Americans or in a ~12,600-year-old Clovis-associated genome, suggesting a more diverse set of founding populations of the Americas than previously accepted.