Australasian signal in the DNA of Amerindians

BBack in 2015 (Skoglund P, Mallick S, Bortolini MC, et al. Genetic evidence for two founding populations of the Americas. Nature. 2015;525(7567):104–108. doi:10.1038/nature14895) an article showed that " 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 a ~12,600 year old Clovis genome, suggesting a more diverse set of founding populations of the Americas than previously accepted.".

This is quite a remarkable discovery, and the authors quickly clarified that "These results do not imply that an unmixed population related anciently to Australasians migrated to the Americas. While this is a formal possibility, an alternative model that we view as plausible is that the 'Population Y' (we use 'Population Y' after Ypykuéra, which means 'ancestor' in the Tupi language family spoken by the Suruí and Kartiana) that contributed Australian related ancestry to Amazonians was already mixed with a lineage related to First Americans at the time it reached Amazonia."

They concluded that "he genetic data allow us to say with confidence that Population Y ancestry arrived south of the ice sheets anciently: the fact that the geographically diverse Andamanese, Australian and New Guinean populations are all similarly related to this source suggests that the population is no longer extant, and the absence of long-range admixture linkage disequilibrium suggests that the population mixture did not occur in the last few thousand years."

Last year another study (Reconstructing the Deep Population History of Central and South America Posth C. et al., (2018) Cell, Vol 175:5 P1185-1197.E22, Nov. 15, 2018) looked into the peopling of America but didn't manage to find this Australasian signal in "ancient remains" that they analyzed:

"failure to find significant evidence of Australasian or Paleolithic East Asian affinities in any of the ancient Central and South American individuals raises the question of what ancient populations could have contributed the Population Y signal in Surui and other Amazonian groups and increases the previously small chance that this signal—despite the strong statistical evidence for it—was a false-positive."

But shortly after another paper was published in Science (Early human dispersals within the Americas, Moreno-Mayar et al., Science 07 Dec 2018: Vol. 362, Issue 6419, eaav2621 DOI: 10.1126/science.aav2621) that sequenced the DNA of ancient remains from all across America, Alaska to Patagonia and found that prior to the main migration into America, there was an earlier one, with Australasian traits:

"... there are genomic and archaeological hints of an earlier human presence. How these early groups are related or structured, particularly those with Australasian ancestry, remains unknown.... [there were] multiple independent, geographically uneven migrations into South America. One such migration provides clues of Late Pleistocene Australasian ancestry in South America, [which] contributed to present-day South American ancestry."

"... we find that the Amazonian Surui share a larger proportion of alleles with Australasian groups (represented by Papuans, Australians and Andaman Islanders), with respect to Mixe. Lagoa Santa yielded similar results to those obtained for the Surui. When compared to Mesoamerican groups (Mixe and Huichol), Lagoa Santa also shares a larger proportion of alleles with Australasian groups but not with other Eurasians."

Remarkably, these first wave individuals with Austronesian genes somehow reached South America without leaving any traces in North America: "[a populaton] that harbored an Australasian signal in the Late Pleistocene and reached South America, yet left no apparent traces in North America".

-- New, Sept. 4, 2019 --

I had originally written:

So the facial reconstruction of "Luzia", one of the 12,500 year-old Lagoa Santa crania (and almost lost in the fire that razed the Rio de Janeiro National Museum -fortunately the skull survived) which originally depicted her with an African look now has her looking more Asian:

One of Luzia's relatives - African look has gone. Source

Luzia before, more "African".

Reader feedback:

D. Parker wrote an e-mail to me with the following text:

your source: http://agencia.fapesp.br/the-new-face-of-luzia-and-the-lagoa-santa-people/29168/. Notice caption ^^^ does not say that that picture is Luzia.
The Brazilian researchers’ contribution to the study was fundamental. Among the 49 individuals from which fossil DNA was taken, seven skeletons dated to between 10,100 and 9,100 years ago came from Lapa do Santo, a rock shelter in Lagoa Santa. A new bust has replaced Luzia in the Brazilian scientific pantheon. Caroline Wilkinson, a forensic anthropologist at Liverpool John Moores University in the UK and a disciple of Neave, has produced a facial reconstruction of one of the individuals exhumed at Lapa do Santo. The reconstruction was based on a retrodeformed digital model of the skull.
Estudos genéticos dão nova cara ao Povo de Luzia Representação do fóssil humano mais fa...
Facial reconstruction of the People of Luzia by Caroline Wilkinson of Liverpool John Moores University in England, based on a retroformed digital skull model of the Lapa do Santo archaeological site. The skull used as a reference is from a young man, cataloged as Burial 26.
Also in regard to the Caroline Wilkinson reconstruction. None of the articles, not the one you sourced said the Caroline Wilkinson reconstruction. looks more Asian. The eye fold is not depicted Asian. None of the features are particularly Asian. The nose is not as flat as many Asians. It's true that the ancestors of Native are believed to be Asian but the reconstruction is intended to depict someone looking Native American and though they have Asian ancestry they dont always look exactly like,Asians. People have said it looks racially ambiguous or could even pass for a dark skinned European or Middle Eastern person, Nevertheless these reconstructions include speculation from the forensic artist
regards,
D. Parker

I thank Mr. Parker for his comments. And I promise to write a specific post on these Brazilian remains (the whole group).

See this post here:Lagoa Santa sites and remains: old and odd

.

My remark on the features of the reconstructed face still stands however. The overall impression of the original bust is that of an African, now it is more Eurasian, it does not look like the typical Amerindian people one sees -today- in South America which have distinct features.

-- end of comment--

So the question remains open: where did this signal come from? And why is it not present in North America or Asia? Below is a map from Skoglund's 2015 paper, and the white circles show this lack of Australasian DNA in those regions, and the red and yellow cicles indicate their presence in South America:

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