January 20, 2012

Extremely ancient introgression in Papuans

Melanesians
Neanderfollia mentions today[cat] new genetic research that has found unusual diversity in gene OAS1 among Papuans. They contend that this is caused by extremely old introgression that they estimate in more than three million years (more than the age of the genus Homo).

Abstract
Recent analysis of DNA extracted from two Eurasian forms of archaic human show that more genetic variants are shared with humans currently living in Eurasia than with anatomically modern humans in sub-Saharan Africa. While these genome-wide average measures of genetic similarity are consistent with the hypothesis of archaic admixture in Eurasia, analyses of individual loci exhibiting the signal of archaic introgression are needed to test alternative hypotheses and investigate the admixture process. Here, we provide a detailed sequence analysis of the innate immune gene, OAS1, a locus with a divergent Melanesian haplotype that is very similar to the Denisova sequence from the Altai region of Siberia. We re-sequenced a 7 kb region encompassing the OAS1 gene in 88 individuals from 6 Old World populations (San, Biaka, Mandenka, French Basque, Han Chinese, and Papua New Guineans) and discovered previously unknown and ancient genetic variation. The 5' region of this gene has unusual patterns of diversity, including 1) higher levels of nucleotide diversity in Papuans than in sub-Saharan Africans, 2) very deep ancestry with an estimated time to the most recent common ancestor of >3 million years, and 3) a basal branching pattern with Papuan individuals on either side of the rooted network. A global geographic survey of >1500 individuals showed that the divergent Papuan haplotype is nearly restricted to populations from eastern Indonesia and Melanesia. Polymorphic sites within this haplotype are shared with the draft Denisova genome over a span of ∼90 kb and are associated with an extended block of linkage disequilibrium, supporting the hypothesis that this haplotype introgressed from an archaic source that likely lived in Eurasia.

This is what I have been arguing since December 2010: "denisovan" admixture in Australasian and SE Asian aborigines stems from Homo erectus (diverged from our line at least 1.8 Ma ago) or even maybe a most distant cousin (maybe H. floresiensis, argued by some to be more archaic than H. erectus in key elements like the wrist or toes). 

Yet I am a bit skeptic of the age estimate, because, unless the H. floresiensis australopithecine hypothesis could be confirmed, the date is out of bounds for Humankind proper and creates many conceptual challenges, which are admittedly hard to swallow. While the "australopithecine hobbit" hypothesis would fit this scenario, it remains hard to swallow that the two genus would still be inter-fertile just a few dozen millennia ago and then again, why would archaic admixture come from this remote relative and not the much closer H. erectus, which we know lived in East Asia until rather recently. 

Finally I am in general very skeptic of age estimates as such and their ability to be able to inform more than they confuse. Normally I find them too recent but the opposite (too ancient) can also happen, I imagine. They are in any case just estimates: educated guesses and nothing else.


Update:

Got a copy of the paper (thanks again) and I would say that these two figures are of special interest:


Fig. 2 - Median joining network of OAS 1 haplotypes

Fig. 3 Geographic distribution of the deep lineage in A) Old World populations and B)
South East Asians and Oceanians.

I find particularly notable that the haplotype has been found at very low frequencies in South Asia and nowhere else West of Wallace Line. It can be backflow but may also be indicator about the possible location of the admixture event.

Certainly nothing seems to suggests in these or other maps (1, 2) of "Denisovan" admixture that the episode could have happened in Altai or nearby areas as some readers, stubborn proponents of obsolete migration models, have insisted on. Instead all the evidence suggests that the admixture episode happened in SE or otherwise Tropical Asia, whether deep in Indonesia or more towards the mainland is debatable indeed.


See also:

24 comments:

  1. WOW finally you got some images!

    It is very interesting that the ancient allele is found in India: maybe it was there were the admixture event happened, but don't you find odd that no East Asians have it?

    I don't think it was back-migration (otherwise, we would expect to see a very high % of Papuan ancestry in present-day Indians).

    The dates are crazy, but they're probably wrong... yet there's another possibility: maybe erectus mixed with other very ancient hominids or even australopitecines who lived in Asia and are the direct ancestors of Hobbits, and then the allele spread to modern humans from erectus.

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  2. Good analysis. I agree with Maju on all points.

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  3. "The dates are crazy, but they're probably wrong... yet there's another possibility: maybe erectus mixed with other very ancient hominids or even australopitecines who lived in Asia and are the direct ancestors of Hobbits, and then the allele spread to modern humans from erectus".

    The dates could be correct. It is possible that the Homo erectus population that made it out of Africa had accumulated a million years of diversity, or that there were several erectus migrations from Africa.

    "1) higher levels of nucleotide diversity in Papuans than in sub-Saharan Africans, 2) very deep ancestry with an estimated time to the most recent common ancestor of >3 million years, and 3) a basal branching pattern with Papuan individuals on either side of the rooted network".

    That certainly provides evidence for extensive admixture with SE Asian H. erectus for Melanesian populations, a possibility long denied by many. Whether it is the same as 'Denisova' or just similar remains to be discovered.

    "I don't think it was back-migration (otherwise, we would expect to see a very high % of Papuan ancestry in present-day Indians)".

    Back-migration is the more likely explanation. Y-DNA MNOPS and mt-DNA R both originated somewhere towards Wallacea. It seems extremely unlikely therefore that the admixture occurred in South Asia.

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  4. "I don't think it was back-migration (otherwise, we would expect to see a very high % of Papuan ancestry in present-day Indians)".

    How would you recognize it. Autosomal clustering analysis looks mostly useless for such extreme ages, when the very Eurasian (and Australasian) subpopulations were forming to begin with.

    As for haploid lineages, back-migration from Papua is not apparent (I'd say) but from somewhere in SE Asia (or Bengal) it is (mtDNA N and R, Y-DNA MNOPS mostly). It is very possible that these back-migrants carried tiny amounts of "Denisovan" blood, extremely hard to detect, has happens also with some SE Asians (and the French - let's not forget the French connection).

    So maybe we are all a bit "Denisovan" (i.e. erectus or maybe "hobbit") even if at near-homeopathic dilutions.

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  5. "I agree with Maju on all points".

    I am a bit surprised, admittedly, but glad about it anyhow. :)

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  6. "It is possible that the Homo erectus population that made it out of Africa had accumulated a million years of diversity"...

    And retained it as dominant and kept it in a sealed bottle of sort for when the Sapiens wave arrived. That happens when you don't believe in the bogeyman, I mean: drift.

    Not strictly impossible but statistically most unlikely.

    "... or that there were several erectus migrations from Africa".

    No evidence that I know of. You? Not only no evidence in Eurasia but also no evidence in Africa itself. There is no Homo sp. per all accounts before c. 2.5 or 2.3 Ma (Homo habilis, whose pertaining to the genus Homo is often questioned, then we'd go to 1.9 Ma), so, if the figures are correct, we are talking of an australopithecine lineage - and a quite deep one, even for this related genus (c. 4-1.8 Ma).

    It is certainly a very very long shot and genetic chronology lacks credibility in general so the least I'd expect is a lot of doubts, even from the proponents.

    "... a possibility long denied by many".

    Including you.

    "Whether it is the same as 'Denisova' or just similar remains to be discovered".

    It is already (read the abstract again):

    "Polymorphic sites within this haplotype are shared with the draft Denisova genome over a span of ∼90 kb and are associated with an extended block of linkage disequilibrium, supporting the hypothesis that this haplotype introgressed from an archaic source that likely lived in Eurasia".

    "It seems extremely unlikely therefore that the admixture occurred in South Asia".

    Not impossible at all either. The most parsimonious scenario is probably admixture in Indonesia with minor backflow but admixture at the wavefront of Sapiens expansion further inland is also very possible, if the wake of the wave was full of other people (an even bigger and pushy wave) who displaced them, leaving only Australasia and other remote islands for the wavefront survivors, who would also have been diluted somewhat anyhow.

    I'm in principle for the scenario of admixture in Indonesia (Java, Flores) but the other scenarios cannot be easily discarded either. We'd need to debate the very reconstructions of colonization of Eurasia and, if we could decide which models were more likely, then we might be able to discard something. All very ample and messy, so I pass - at least in this discussion.

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  7. "As for haploid lineages, back-migration from Papua is not apparent (I'd say) but from somewhere in SE Asia (or Bengal) it is (mtDNA N and R, Y-DNA MNOPS mostly)".

    The 'Denisova' genetic markers coincide strongly with mt-DNA haplogroups M27, M28, M29'Q and P. The 'erectus gene' makes it out into the Pacific in much the same proportions as do the above haplogroups. Very little of either, but varied, in Central Polynesia with progressively more of the gene and the haplogroups as we move west through Vanuatu/New Caledonia, the southern Solomons, northern Solomons to the Bismark Archipeligo and New Guinea. The distribution of Y-DNAs K and M also follows much the same pattern. So we have the gene and the haplogroups centred on New Guinea/Melanesia and moving both east and west (in the form of the related haplogroups Y-DNA MNOPS and mt-DNA R).

    "And retained it as dominant and kept it in a sealed bottle of sort for when the Sapiens wave arrived".

    That seems to be exactly the case for SE Asian Homo erectus. It changed very little over the long period between when it arrived in SE Asia and when H. sapiens arrived in SE Asia.

    "Polymorphic sites within this haplotype are shared with the draft Denisova genome over a span of ∼90 kb and are associated with an extended block of linkage disequilibrium"

    So we basically have one species of H. erectus stretching from the Altai to SE Asia. Via India or via Chinese H. erectus?

    "That happens when you don't believe in the bogeyman, I mean: drift. Not strictly impossible but statistically most unlikely".

    But certainly no more unlikely than that the 'Denisova' gene would remain in the erectus population all the way from the Altai to SE Asia. Surely drift should have produced two varieties at least at either end of the distribution.

    "No evidence that I know of. You? Not only no evidence in Eurasia but also no evidence in Africa itself".

    In a way there is evidence for two migrations. The Acheulean failed to move beyond the Movius Line to reach either SE Asia or the Altai, let alone East Asia. But perhaps it began in Africa and represents a second emergence. I've always assumed it was the technology that failed to reach the margins of the H. erectus geographic spread, but maybe the difference led to the formation of two subspecies of H. erectus: an eastern and a western one. The hand-axe reached South Asia so that places South Asia firmly into the western erectus population. The two subspecies would have been separated by the Himalayas all the way from the Hindu Kush to the Ganges/Brahmaputra Delta. The wide open grasslans of the Kazakh steppe also provided a barrier.

    "if the figures are correct, we are talking of an australopithecine lineage - and a quite deep one, even for this related genus (c. 4-1.8 Ma)".

    It is possible. Two erectus subspecies may have originated in different regions within Africa.

    "Including you".

    Maju. Read again my essay on Australia. I claimed exactly that people who made it to Australia/New Guinea had bred with SE Asian H. erectus. I have always claimed that 'modern humans' bred with 'ancient humans'. You have consistently disagreed with that idea.

    "The most parsimonious scenario is probably admixture in Indonesia with minor backflow"

    Considering the maps the part of Indonesia closest to New Guinea is the only realistic possibility. And Java was certainly home to SE Asian Homo erectus for a very long time.

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  8. "The 'Denisova' genetic markers coincide strongly with mt-DNA haplogroups M27, M28, M29'Q and P".

    First this is not "the 'Denisova' genetic markers" but just one item. What you just added after it is the lineages of Melanesians, Captain Obvious.

    The Denisovan genetic markers as a whole are distributed by a much larger area (links in main article).

    "Via India or via Chinese H. erectus?"

    China, I understand. Actually the Denisovans would be hybrids with Neanderthals, I estimate that 50-50, with maternal lineages from H. erectus.

    "Surely drift should have produced two varieties at least at either end of the distribution".

    Surely the facts say that you are wrong again. Maybe the allele was fixated at the H. erectus OoA or maybe it was retained in these two populations by chance. Wouldn't be the case, they would not have found it so it's like the anthropic principle: the leg that kicks its own ass (an ultimately pointless observation).

    "I have always claimed that 'modern humans' bred with 'ancient humans'".

    Maybe but you thought that they did in Siberia, not Java. And that's what I meant by "including you".

    "Considering the maps"...

    Consider ALL maps please. Links in main article (I'll add them now because I see that some have very short memory).

    This only indicates a revealing but very specific part of the Denisovan admixture and is not found equally among the various pops. that do show Denisovan admixture.

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  9. If the ancestor were Asian Homo Erectus, the most recent common ancestor ought to be roughly 1.9 million years. One of the easiest ways to reconcile a 3 million year date with a 1.9 million year date, without much tension with the data, given that the source is making a conversion from generations to years, could be as simple as inaccuracy regarding generation length in Homo Erectus, something about which we have very little data. If the conversion factor being used is 25 years, and the true generation length was closer to 16 years, which wouldn't be that huge of a jump for such a distant relative of modern humans (and is itself within the extreme of the modern human range) there would be no discrepency.

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  10. Sure but, well, the "molecular clock" being broken is a more consistent premise. I fail to see why anyone would say "is 3 million years" and not "a rough hunch is 3 million years, take or give 1.5 million". Even if the latter sentence is less precise and less pretentious, it is more accurate.

    Also I reject to accept any MC estimate that does not state, to begin with, which Pan-Homo divergence age (or comparable reference) they use. Because much of the mess caused by molecularclockologists is because they use unbearably small Pan-Homo divergence estimates like 5 Ma, when the correct figure is at least 8 Ma.

    They better shut up than make such unlikely claims in my opinion.

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  11. "Maybe but you thought that they did in Siberia, not Java. And that's what I meant by 'including you'".

    Again you are wrong. I have always believed 'modern' humans bred with archaic regions in several regions, including both Siberia and Java.

    "This only indicates a revealing but very specific part of the Denisovan admixture and is not found equally among the various pops. that do show Denisovan admixture".

    Concentrated in New Guinea and northern Melanesia.

    "Actually the Denisovans would be hybrids with Neanderthals, I estimate that 50-50, with maternal lineages from H. erectus".

    That still gives us two H. erectus populations. And we know this is very much a possibility as many see two species: Homo erectus and Homo ergaster. This paper tends to support such a difference.

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  12. "Sure but, well, the 'molecular clock' being broken is a more consistent premise".

    Not 'broken', merely 'unreliable' and subject to distortions for various reasons.

    "If the ancestor were Asian Homo Erectus, the most recent common ancestor ought to be roughly 1.9 million years".

    Exactly.

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  13. Australian Aborigines have the same amount of "Denisovan" admixture than Melanesians per Reich 2011. Sigh!

    "This paper tends to support such a difference".

    In your dreams.

    "Not 'broken'"

    Broken clocks are most unreliable. However they do say the correct time twice a day.

    The whole premises have been challenged at least in Y-DNA. Whatever the case it's not possible to have all necessary assumptions (Pan-Homo divergence age, effective population size at each generation and in each location.

    While we can measure genetic change (number of mutations accumulated), at least in the simplest case: mtDNA, we can't reliably estimate chronologies from that: just that the ancestor came before the descendant and little more.

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  14. "In your dreams".

    Maju, it is impossible that the two genetic markers came from the same population. Even if you're correct in claiming one of the source populations is a hybrid with the other you have to be really crazy to believe it's possible to have a hybrid between two populations with exactly the same genetic makeup. The genes must originally have come from two separate populations, and if that separation goes back anything like 3,000,000 years (or even half that time) then we're looking at the western Homo ergaster and the eastern Homo erectus.

    "Australian Aborigines have the same amount of 'Denisovan' admixture than Melanesians per Reich 2011. Sigh!"

    The current paper contradicts that earlier one. Have another look at the most recent map. Not too much in Australia, and what is there quite possibly came in from New Guinea. The paper itself claims:

    "A global geographic survey of >1500 individuals showed that the divergent Papuan haplotype is nearly restricted to populations from eastern Indonesia and Melanesia".

    Note: not Australia. The haplotype makes up a lesser component of the population as you move east, west and south of Melanesia/New Guinea.

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  15. Terry: every day I find more impossible to follow your logic. So according to you Obama and his Kenyan cousin do not have the same Luo genetics overall but actually must be from branches that diverged 3 million years ago... Do you even think, let alone re-read what you write? It's totally absurd.

    "The current paper contradicts that earlier one. Have another look at the most recent map".

    They represent DIFFERENT things this map is a tiny subset (a single gene) of the other, which does represent TOTAL 'Denisovan' admixture as much as Reich et al. could discern it.

    Waste of time and pixelspace! Do your homework! At least know what you're talking about!

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  16. "every day I find more impossible to follow your logic".

    Probably because you have very strange ideas concerning practical genetics. For example:

    "So according to you Obama and his Kenyan cousin do not have the same Luo genetics overall but actually must be from branches that diverged 3 million years ago..."

    How on earth do you come to that conclusion? Anyway Obama does have admixture, with Europeans. But Europeans and Africans did not separate some 3 million years ago. However the paper suggests that Melanesians did mix with a population that had separated from 'modern humans' somewhere towards that length of time ago. This is the part of the paper you are desperate to avoid considering. Surely it can only be explained by an ancient diversification of some sort. The only possibility is the two 'species' of H. erectus. In other words most of us descend from H. ergaster but a small minority have H. erectus ancestry in part.

    "They represent DIFFERENT things this map is a tiny subset (a single gene) of the other, which does represent TOTAL 'Denisovan' admixture as much as Reich et al. could discern it".

    Yes. The 'total' denisovan subset may not be SE Asian in origin. Yet when I suggested such was possible you disagreed.

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  17. You said: "you have to be really crazy to believe it's possible to have a hybrid between two populations with exactly the same genetic makeup".

    Obama and his Kenyan cousin do have (almost) exactly the same genetic makeup (recombination still following the laws of probability).

    "But Europeans and Africans did not separate some 3 million years ago."

    Nor are either of them and H. erectus.

    "Surely it can only be explained by an ancient diversification of some sort".

    For which we lack evidence. Are you willing to trust more a molecular clock hunch than hard material evidence? I am not. That's the key of my thought: MC hunches are effectively pseudoscience and must be ignored or criticized as much as possible, exactly as you like to do with creationism and intelligent design (which I mostly ignore because they are just plain dumb).

    "In other words most of us descend from H. ergaster but a small minority have H. erectus ancestry in part".

    That's what I have been saying all this time. However H. erectus is not 3 million years old. 2 million at the most!

    "The 'total' denisovan subset may not be SE Asian in origin".

    It surely is. I doubt H. erectus or H. floresiensis ever reached Sahul.

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  18. "Obama and his Kenyan cousin do have (almost) exactly the same genetic makeup"

    Only to the extent that all humans 'have (almost) exactly the same genetic makeup'. Obama has a European side to his genetic makeup. He is a 'hybrid' in any meaningful use of the term.

    "Nor are either of them and H. erectus".

    Perhaps not, but both have H. erectus in their ancestry. And it turns out that some Melanesians carry genes that separated from the rest of our ancestors 2-3 million years ago. At such a time differential that can only be from a different H. erectus population to the one that all other humans descend from.

    "For which we lack evidence. Are you willing to trust more a molecular clock hunch than hard material evidence? [an ancient diversification of some sort]".

    Molecular clock has nothing to do with the matter. It could be 3 million, two million or even just one million. Irrelevant as to the actual figure. The only 'evidence' we need is the fact that the genetic makeup is different. As far as I'm aware no-one now living was present at the time to actually see what was happening. Are you proposing some other source of difference?

    "That's what I have been saying all this time. However H. erectus is not 3 million years old. 2 million at the most!"

    H. erectus as a species is only some 2 million years old, but H. erectus descends from a more ancient species. So the 3 million year date may be correct if there was population structure in the African H. erectus population before members moved out of Africa. I agree that the 3 million year figure could be wrong, but I wouldn't dismiss it out of hand. It could possibly be correct.

    "I doubt H. erectus or H. floresiensis ever reached Sahul".

    Again you're getting sidetracked. Both those species reached SE Asia, specifically Java and Flores respectively. The genes in question were obviously picked up there (less likely to be floresiensis in my opinion) and carried to Melanesia. In SE Asia the genes have been replaced by movement of Mongoloid populations from further north, a movement you deny has ever happened. The Polynesians are a product of exactly that mixture.

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  19. "Only to the extent that all humans 'have (almost) exactly the same genetic makeup'. Obama has a European side to his genetic makeup. He is a 'hybrid' in any meaningful use of the term".

    In their African side, I meant. These discussions are pointless because we take a whole week only to clarify a misunderstanding way too often.

    "And it turns out that some Melanesians carry genes that separated from the rest of our ancestors 2-3 million years ago".

    We do not know that for a fact. It's a molecular clock hunch and nothing else.

    And those genes are part of the Denisovan package anyhow, just that they are irregularly distributed. It's not something extra but part of the Denisovan heritage (which is likely to be H. erectus).

    "Molecular clock has nothing to do with the matter. It could be 3 million, two million or even just one million. Irrelevant as to the actual figure".

    You have been oddly insistent on the three million figure only to step back and abdicate from your claim so easily.

    "Are you proposing some other source of difference?"

    I think it's all H. erectus admixture. As in Asian H. erectus with choppers and flakes, you know (Sinanthropus, Javapitehcus... all that bunch).

    Not sure if it's "other" or "the same" in your mind, which is growingly opaque to my perception.

    "In SE Asia the genes have been replaced by movement of Mongoloid populations from further north, a movement you deny has ever happened".

    SE Asian Negritos other than Filipino ones also lack the "Denisovan" admixture. Instead more northernly SE Asians from South China and such (and probably even some Europeans and as we can see here the odd Indian as well) have some remnants of that admixture.

    Certainly the avantguard bunch who crossed into Australasia carried more of that admixture but that's also quite true of those who did not cross and remained in Wallacea and parts of Philippines.

    It's a Wallace Line issue, not a Mongoloid vs. Australoid one. And it's not a purely B&W issue because the levels of admixture are extremely low everywhere and there are remnants in mainland Eurasia (Cambodia, China, France and now India as well have ringed positive in my notebook at very low levels).

    We are all probably a bit H. erectus, even if at near-homeopatic doses. All with Eurasian ancestry, I mean. People with 0% or near 0% Eurasian ancestry are probably lacking even the slightest trace of this admixture event.

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  20. "Only to the extent that all humans 'have (almost) exactly the same genetic makeup'. Obama has a European side to his genetic makeup. He is a 'hybrid' in any meaningful use of the term".

    In their African side, I meant. These discussions are pointless because we take a whole week only to clarify a misunderstanding way too often.

    "And it turns out that some Melanesians carry genes that separated from the rest of our ancestors 2-3 million years ago".

    We do not know that for a fact. It's a molecular clock hunch and nothing else.

    And those genes are part of the Denisovan package anyhow, just that they are irregularly distributed. It's not something extra but part of the Denisovan heritage (which is likely to be H. erectus).

    "Molecular clock has nothing to do with the matter. It could be 3 million, two million or even just one million. Irrelevant as to the actual figure".

    You have been oddly insistent on the three million figure only to step back and abdicate from your claim so easily.

    "Are you proposing some other source of difference?"

    I think it's all H. erectus admixture. As in Asian H. erectus with choppers and flakes, you know (Sinanthropus, Javapitehcus... all that bunch).

    Not sure if it's "other" or "the same" in your mind, which is growingly opaque to my perception.

    "In SE Asia the genes have been replaced by movement of Mongoloid populations from further north, a movement you deny has ever happened".

    SE Asian Negritos other than Filipino ones also lack the "Denisovan" admixture. Instead more northernly SE Asians from South China and such (and probably even some Europeans and as we can see here the odd Indian as well) have some remnants of that admixture.

    Certainly the avantguard bunch who crossed into Australasia carried more of that admixture but that's also quite true of those who did not cross and remained in Wallacea and parts of Philippines.

    It's a Wallace Line issue, not a Mongoloid vs. Australoid one. And it's not a purely B&W issue because the levels of admixture are extremely low everywhere and there are remnants in mainland Eurasia (Cambodia, China, France and now India as well have ringed positive in my notebook at very low levels).

    We are all probably a bit H. erectus, even if at near-homeopatic doses. All with Eurasian ancestry, I mean. People with 0% or near 0% Eurasian ancestry are probably lacking even the slightest trace of this admixture event.

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  21. "I think it's all H. erectus admixture. As in Asian H. erectus with choppers and flakes, you know (Sinanthropus, Javapitehcus... all that bunch)".

    And those H. erectus split from the branch that gave rise to western H. erectus (in the form of Neanderthals and moderns) up to 3 million years ago. We have to have admixture of two anciently diverged H. erectus population. Why can you not see that? Just because it doesn't fit your belief?

    "SE Asian Negritos other than Filipino ones also lack the 'Denisovan' admixture".

    Not surprising. They've long been thought to be the product of the earliest southward movement. Their haplogroups are mainly East Asian, not Melanesian or Australian.

    "It's a Wallace Line issue, not a Mongoloid vs. Australoid one".

    The Mongoloids are later arrivals to SE Asia, as I've long been trying to peruade you.

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  22. "And those H. erectus split from the branch that gave rise to western H. erectus (in the form of Neanderthals and moderns) up to 3 million years ago".

    No. The evidence only suggests 2 million years ago.

    Don't waste my time.

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  23. "No. The evidence only suggests 2 million years ago".

    The actual date is not really the main point. The main conclusion is that Papuans have some genes from a different H. erectus than the one that gave rise to the rest of us. Presumably that difference goes back to the difference between H. erectus and H. ergaster.

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  24. "The main conclusion is that Papuans have some genes from a different H. erectus than the one that gave rise to the rest of us".

    False. That's nowhere but in your imagination. The only possible conclusion is that the Erectus (Denisovan) genes suffered drift/founder effects as any other human fraction of the genome AFTER the hybridization episode.

    Anyhow, the populations sharing this particular allele are about the same for which the generic Denisovan admixture has been detected previously, just that here we see a small specific fraction of that admixture and not the whole.

    You just don't seem to understand it but it is as I say for sure.

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