Mystery ancient human ancestor found in Australasian family tree
By Alice Klein
Who’s your daddy? An unknown hominin species that bred with early human ancestors when they migrated from Africa to Australasia has been identified through genome mapping of living humans.
The genome analysis also questions previous findings that modern humans populated Asia in two waves from their origin in Africa, finding instead a common origin for all populations in the Asia-Pacific region, dating back to a single out-of-Africa migration event.
Modern humans first left Africa about 60,000 years ago, with some heading west towards Europe, and others flowing east into the Asia-Pacific region.
Previous research looking at the genomes of people living today has revealed that the Asia-Pacific arrivals mated with two hominin species they found there – the Neanderthals and the Denisovans.
Mysterious ancestor But when Jaume Bertranpetit at Pompeu Fabra University in Spain and his colleagues analysed the genomes of living Indigenous Australians, Papuans, people from the Andaman Islands near India, and from mainland India, they found sections of DNA that did not match any previously identified hominin species.
These DNA sequences are not present in the genomes of living Europeans or east Asians, suggesting that the ancestors of these people met and bred with a mystery hominin in south Asia or the Pacific region, who left their genetic legacy in the area’s present-day populations.
The unidentified hominin may be Homo erectus or “upright man”, says Bertranpetit. H. erectus is believed to be the first hominin with a similar stature to today’s humans, and the first to leave Africa.
Ancient DNA needed Fossil records indicate that H. erectus was present in Asia between about 1.8 million and 33,000 years ago, so there could have been an overlap with humans towards the end of its existence.
“But we do not have any direct evidence,” says Bertranpetit. Confirmation would require a match between ancient DNA from H. erectus remains and DNA from current Australasian populations.
Unfortunately, none of the H. erectus fossils unearthed to date contain sufficient genomic data for this kind of comparison to be made, says Alan Cooper of the University of Adelaide, Australia. “Until we find a skeleton that is preserved well enough, we won’t be able to generate a whole genome like we’ve done with the Denisovans,” he says.
Many groups The Denisovan genome was derived from a well-preserved finger bone found in a cave in Siberia, but such findings are rare, especially in the hot climate of Asia. “We may never find another preserved hominin in Asia,” Cooper says.
Making the story even more complicated is the possibility that multiple unknown hominin species contributed to the mystery DNA snippets, says Cooper. “I wouldn’t be surprised – Asia is a bit of a nightmare in terms of the number of different groups that were running around at the same time,” he says.
Asia has turned out to have many more hominin forms than Europe, Cooper says.
“There is a tidal wave of studies coming out now on Australian and Asian genomes and they’re all concluding the same thing – there was a single out–of-Africa movement of modern humans,” says Cooper. “Europeans headed west, and everybody else headed east. And then within Asia, it became horribly complicated in terms of the movement, because there were several hominins floating around in that space – Denisovans, Neanderthals and now this third group.”
Genomic analysis of Andamanese provides insights into ancient human migration into Asia and adaptation
Mayukh Mondal, Ferran Casals, Tina Xu, Giovanni M Dall'Olio, Marc Pybus, Mihai G Netea, David Comas, Hafid Laayouni, Qibin Li, Partha P Majumder & Jaume Bertranpetit AffiliationsContributionsCorresponding authors Nature Genetics (2016) doi:10.1038/ng.3621 Received 31 December 2015 Accepted 17 June 2016 Published online 25 July 2016
To shed light on the peopling of South Asia and the origins of the morphological adaptations found there, we analyzed whole-genome sequences from 10 Andamanese individuals and compared them with sequences for 60 individuals from mainland Indian populations with different ethnic histories and with publicly available data from other populations. We show that all Asian and Pacific populations share a single origin and expansion out of Africa, contradicting an earlier proposal of two independent waves of migration1, 2, 3, 4. We also show that populations from South and Southeast Asia harbor a small proportion of ancestry from an unknown extinct hominin, and this ancestry is absent from Europeans and East Asians. The footprints of adaptive selection in the genomes of the Andamanese show that the characteristic distinctive phenotypes of this population (including very short stature) do not reflect an ancient African origin but instead result from strong natural selection on genes related to human body size.
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"The Denisovan genome was derived from a well-preserved finger bone found in a cave in Siberia"
Note: Siberia ~ Tibetia ~ cold cave DNA remains?
"We also show that populations from South and Southeast Asia harbor a small proportion of ancestry from an unknown extinct hominin, and this ancestry is absent from Europeans and East Asians."
Ok so far, I guess.
"The footprints of adaptive selection in the genomes of the Andamanese show that the characteristic distinctive phenotypes of this population (including very short stature) do not reflect an ancient African origin but instead result from strong natural selection on genes related to human body size."
Wrong interpretation. They assume that presence of unique body size genes in Andamans indicates dwarfing from tall body THERE. That assumption is unproven and unlikely, but expected, since the article was written by Open Sky people.
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What about Africans? SMH! --- Quote: “harbor a small proportion of ancestry from an unknown extinct hominin, and this ancestry is absent from Europeans and East Asians. The footprints of adaptive selection in the genomes of the Andamanese show that the characteristic distinctive phenotypes of this population (including very short stature) do not reflect an ancient African origin but instead result from strong natural selection on genes related to human body size.
“
-------------------- Without data you are just another person with an opinion - Deming Posts: 12143 | From: When you have eliminated the impossible, whatever remains, however improbable | Registered: Jun 2007
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It's always a good feeling to know you're ahead of the game. I already spoke on this (distinctive phenotypes in this region) a month ago here, here and here. I bet at least some of this genetic material is pre-Toba OOA.
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Lol! Europeans and their trickery and lies. Tsk! Tsk! . Anyone get what they are saying in this statement?
------------ Our results do NOT indicate whether the introgression is derived from the SAME hominin in ALL populations, but in the case of the Andamanese (Supplementary Fig. 22) we have shown that it comes from a new unknown hominin population, which likely separated very early in the hominin tree. Also, we have shown that the hominin admix¬ture in these populations can cause a bias in D-statistic calcula¬tion that can be erroneously interpreted as a first OOA migration. Finally, the distinctive morphology of the Andamanese probably has originated from strong adaptive selection, as demonstrated by the excess of genes under selection related to height and body
We found that Andamanese, mainland Indian and Papuan popula¬tions carried ~2–3% FEWER African alleles THAN Europeans (Fig. 2a) or East Asians (Fig. 2b), as was also the case for Aboriginal Australians (similar yet higher proportion of unshared alleles). We performed extensive simulations to show that this reduction in the proportion of African alleles in Andamanese could not be explained by the low effec¬tive population size of Andamanese; thus, the reduction is not caused by private variants resulting from specific mutations in the Andamanese genome (no-admixture model; Supplementary Table 5), by later admixture between European or Asian and African populations (that is, the reduction cannot be due to a ‘back-to-Africa’ event; Supplementary Table 5 and Supplementary Note) or by admixture with the modern humans from the initial OOA event settling in Eurasia. In contrast, the reduction in the proportion of African alleles in Andamanese ****COULD*** be caused by admixture with a population that diverged from modern humans at least 300,000 years ago (Supplementary Fig. 15). In fact, an
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Objective We investigated whether Andamanese share more derived alleles with Africans or with other Asian populations. Although these results (Supplementary Figure 6) are redundant with TreeMix (Supplementary Note 9) and MSMC analysis (Supplementary Note 10), this analysis is motivated by two factors. 1) To test the hypothesis that Andamanese could have originated from an African Pygmy-related population {DD: They did}, thus having a different African background than other modern humans {False paradigm, all other modern humans have Pygmy ancestry as well}. If this is true, we would expect a different amount of derived allele sharing between Andamanese and African populations as compared to other OOA populations. 2) We found an unknown hominin introgression in Andamanese (see below), it was necessary to check if every tree (suggested by TreeMix and MSMC) could be confirmed by Dstat.
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