Who were the first Americans? Song and Nielsen are two of three corresponding authors of the paper.
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This other study suggests that ancestors of Australasians may also have crossed this land bridge but were replaced by the First Americans from North and South America.
The peopling of the Americas is a matter of great anthropological and archaeological interest.
Later migrations of Aleuts and Eskimos occurred approximately 9,000 and 4,000 years ago.
Scientists generally agree that modern human populations expanded out of Africa 45,000 to 60,000 years ago.
The exact process by which humanity introduced itself to the Americas has always been controversial.
“This finding was really surprising to us”, said study lead author Pontus Skoglund, a population geneticist at Harvard Medical School in Boston. “But there has always been this question of how statistically informative this morphology is, and to what extent this actually reflects population relationships”.
The researchers sampled a selection of 30 largely isolated native tribes living in Central and South America.
“The data presented here are consistent with a single initial migration of all Native Americans and with later gene flow from sources related to East Asians and, more distantly, Australo-Melanesians”.
“We’ve done a lot of sampling in East Asia and nobody looks like this”, Dr Skoglund says.
Their evidence, based on genetic analyses, suggests at least two quite distinct ancestries are evident in at least some Native American populations.
The migration route of Siberians into North America and the subsequent split into northern and southern Amerindian populations. But the “how” and “when” are confined to mystery.
And yet Reich says his data, like those And yet Reich says his data, like those of the Science team, clash with the classic Paleoamerican model, which postulates a major, more direct genetic contribution from Australo-Melanesians. But there were perhaps multiple pulses of people into the Americas, and they had slightly different proportions of this ancestry.
Crawford is an expert on genetic markers of Siberian human populations.
“Diversification of modern Native Americans happened in the Americas”, Nielsen says – “not because people came from all over the world into the Americas”. “That doesn’t leave time for a Beringian standstill. There could have been a little bit of a standstill, but nothing like 15,000 years”. That, this study found, was absent in populations farther south. Their descendants have later spread to the rest of the Americas. Right around this time, we see that the Native American population first began splitting up. And the two groups disagree about how it got there. But as simple as the finding seems to be, Rasmus says it is truly astonishing. The study doesn’t account for Inuit populations in the north because they arrived later, bringing a distinctive culture with them.
This genetic data “is a clock, that ticks”, said Nielsen, a computational biologist with UC-B’s Department of Integrative Biology.
These became the groups which anthropologists refer to as Amerindians (American Indians) and Athabascans (a native Alaskan people). Those Brazilian skeletons displaying Australasian features may provide a start point for just such an investigation. But do these individuals actually have any genetic affinity with Australians and Melanesians?
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Song added that the state-of-the-art statistical methods that his and Nielsen’s labs developed ‘are being made publicly available so that they can be used by others to study complex demographic histories of other populations.’. But different interpretations of those signals resulted in a few contrasting conclusions. “This finding just raises more questions we need to answer about American history”. This would have been at the height of the last Ice Age, and the earliest population would have probably remained in the north for as long as a thousand years before continuing the migration to regions in South America. “We have no support for all of these more fanciful theories”.
