Way Down South

I hear (tweets by Razib Khan ,  concerning Sankararaman’s talk at ASHG) that the Denisovans had substantially more genetic diversity than Neanderthals ( determined mainly by the variety seen in admixed segments). It makes sense that the Neanderthals should have low  diversity: at glacial maxima, they had to retreat into small refugia.  As John Hawks says, a northern population.  While the Denisovans could have spent the cold times in southeast Asia and Sundaland. The largest long-term population of modern humans outside Africa was in southern Asia during glacial maxima (judging from Bayesian skyline analysis of mtDNA) .

The high level of Denisovan admixture seen in Melanesians and Philippine Negritos may also argue for plenty of Denisovans in Sundaland.

We don’t know who was in India – but since it would have a big refugium, it probably wasn’t Neanderthals.

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27 Responses to Way Down South

  1. IC says:

    http://www.latimes.com/science/sciencenow/la-sci-sn-human-teeth-china-cave-20151014-story.html

    Some thing related. Old evolution theory was indeed just theory. What really happened was quite complicated. Beauty of science is willing to change with new evidence (very different from religion or ideology).

    • epoch2013 says:

      There have been papers about an aboriginal and onge signal in American Indians, which David Reich takes as evidence of two founding populations.

      http://genetics.med.harvard.edu/reich/Reich_Lab/Welcome_files/nature14895_Skoglund_2015.pdf

      “Among the outgroups, the most similar coefficients to Amazonian groups are found in Australasian populations: the Onge from the Andaman Islands in the Bay of Bengal (a so-called ‘Negrito’ group), New Guineans, Papuans and indigenous Australians (Supplementary Information section 2).”

      There also is an Onge signal in Ust-Ishim. Not very strong, but it looks as if it’s there if you look at the D-stats.

  2. Abraham Lincoln says:

    So was it Denisovans or is there just nothing left behind?

    • Presumably both. Bones simply don’t last very long in hot and humid climates. Not only do we have scant evidence for Denisovans in Southwest Asia we have scant evidence for any of the ancestors of great apes. Fossil evidence is very deceiving, Neanderthal population is over represented simply because they sometimes died in ideal bone preserving locations, cool limestone caves in Europe.

  3. Patrick Boyle says:

    Maybe I’m missing something but I don’t quite understand the timing of human evolution and the ice advances and retreats. The Out of Africa (OOA) hypothesis tells us that Anatomically Modern Humans (AMH) developed in the heart of Africa approximately while the Wurm and Riss glaciations were reaching their maxima in Europe. Then we are supposed to believe that these progeny of tropical apes decide to venture north into the worst of it.

    I would have thought that tropical hominoids might want to travel north during one of the interglacials. But if I’ve got the dates right the OOA theory claims that the Africans went north at a time of the glacial maxima. That seems wrong.

  4. sabracakeboo says:

    Australian Aborigines?

  5. Fourth doorman of the apocalypse says:

    The earliest unequivocally modern Humans in Southern China (80,000 YBP?)
    http://www.nature.com/nature/journal/vaop/ncurrent/full/nature15696.html

    • Rick says:

      How can they be sure these 80,000 year old “modern human” teeth in China aren’t Denisovan?

      All we have are their genomes from a mini bone fragments, right? I assume it’s that teeth are highly variable and it would be unlikely that they looked like modern humans instead of like Neanderthals?

  6. dearieme says:

    “We don’t know who was in India”: people with lots of arms?

  7. Big News from John Hawks regarding our Neanderthal ancestry! http://www.johnhawks.net/

    Scroll down to the tweets John Hawks has put on his weblog.

    “First ancient DNA from Ethiopia shows that today’s sub saharan african’s are at least .02 to .07% Neanderthal ancestry!”

    “What this means is everybody’s Neanderthal ancestry estimate just went up a half percent! If you thought you were 3% Neanderthal you are now 3.5%”

    If this is true then we no longer have to play let’s pretend we didn’t hybridize with the neanderthals and blend their intelligence enhancing alleles with those of anatomically modern humans. It was politically incorrect to hypothesis this when sub Saharan Africans were presumed to have no neanderthal admixture but now that they do we don’t have to whisper in back rooms about the amazing coincidence that right after a small population admixed with neanderthals the stone tools they were using became far more complex and that particular population exploded in size and spread all over the planet. (Yes that is too simple an explanation, yes this is an unproven hypothesis.)

    • Greying Wanderer says:

      lol, i didn’t realise everyone was just pretending

      • The last professional I am aware of that was professionally suicidal enough to broach the subject that 1)Neanderthals gave us some genes that benefitted us mentally and 2) these genes didn’t spread south of the Sahara was this fellow. article.https://en.wikipedia.org/wiki/Bruce_Lahn

        He had a very promising career in the United States up to the point of suggesting that Neanderthals bequeathed us some advantageous genes in the better brains department, but he would have been better served professionally if he had been caught getting frisky with either a live boy or a dead girl. He was shortly thereafter persuaded that going back to mainland China to work was in his best interest. That was way back yonder in 2005. Pretending that Neanderthals did not give us genes beneficial to our mental abilities probably isn’t the best way to put it. Fearing that you can’t make a living anymore in your chosen profession if you are as honest as Bruce Lahn was is a more accurate description.

        • Matt says:

          They was a pretty high profile paper out last year that showed Europeans inheriting Neanderthal variants that specifically relate to brain fat.

          Turns out these guys are still publishing and researching, funnily enough.

          • gcochran9 says:

            If it were the case that the difference in brain fat had any relationship to superior European intellectual performance (compared to sub-Saharan Africans, say) and some researcher discovered that relationship and tried to publish it, he’d be fired. Unless, perhaps, he buried that conclusion in the 156th page of the on-line supplement!

          • You miss my point purposely Matt. Plenty of work out there showing where Neanderthals genes have introgressed into modern populations. Nobody is coming right out and proclaiming hybridization with Neanderthals played a large role in anatomically modern humans getting smarter. It isn’t professionally advisable. Why? You know why Matt.

            If Neanderthal genes made us smarter and if their genes did not spread south of the Sahara then everybody better shut the fuck up about it IF they desire to make a living in academia or the related science fields, period.

            I don’t want it talked about in the main stream media either, it is too hurtful. Too many stupid hateful people out there. I am saying this on an obscure science blog, I would not want it peddled to all the boobs out there in TV land by talking heads. I am not a racist about people, there are all kinds in all groups, I am an idealist about science. The truth as revealed by science lasts, we and our silly beliefs don’t.

          • Matt says:

            I think on the whole probably not, and instead it would simply be “More research is needed” to find what other variants presumably in the minds of these people would “balance” it out. But there we are.

            • gcochran9 says:

              I know people who are convinced that they would be instantly fired for something of this sort, and their career ruined. People working at Harvard, for example – more than one. Why don’t you explain why they’re wrong? I’m sure they would be interested. I would be too.

              Still, there may be ways to get such info out. Suppose you had a reasonably complete list of which alleles gave small pluses or minuses to intelligence (additive effects), and published the frequencies of those alleles in different populations. One could easily add them up to see the net effects in different populations, but as long as you didn’t actually do that in your publication, only those interested would ever bother to look and see the net effect. Few people would, and nobody would listen to them if they did.

          • If neanderthal genes were equally distributed across all of humanity than it would now be taught to grade school kids that hybridizing with them gave us some of their genes that made us a little bit smarter and helped to make us what we are today. It is easily the best explanation as to why that small group of hybridized anatomically modern humans/ Neanderthals took off and conquered the world. But because some folks in the world don’t have the same percentage Neanderthal genes this idea is not only wrong but an evil and racist idea that needs to be repressed at all costs. Maybe I missed out on the science class that taught you can skew the facts to believe what you want to believe, or maybe I am just an evil racist up to no good. Funny i don’t feel evil, just sadly curious.

          • JayMan says:

            @gcochran9:

            “Still, there may be ways to get such info out. Suppose you had a reasonably complete list of which alleles gave small pluses or minuses to intelligence (additive effects), and published the frequencies of those alleles in different populations. One could easily add them up to see the net effects in different populations”

            I believe Davide Piffer has already done this:

            A review of intelligence GWAS hits: Their relationship to country IQ and the issue of spatial autocorrelation (ungated pdf here)

            • gcochran9 says:

              I would want a more complete list of variants before concluding much. Also, there are subtleties you need to address: if two populations have been separated for a really long time, the relevant alleles may not be quite the same in the two populations. If this matters, it would most likely apply to the Bushmen vs anyone Eurasian, because they’ve been separated for something like 200,000 years. And the problem with applying existing GWAS methods to Bushmen is that you need very large samples to find these small-effect alleles (hundreds of thousands and up) and there simply aren’t that many Bushmen in the world. We need more Bushmen, lots of them.

              Of course, an approach that worked for everyone other than Bushmen and/or Pygmies might be good enough for government work.

              The most likely result of such an approach would be to find a rank-ordering that was pretty much what you would have expected if you’d never heard of GWAS. The most interesting thing you might find would be if some group significantly underscored its apparent genetic potential, which would hint as some kind of environmental insult or deficiency, maybe something like iodine deficiency – which could then be fixed.

          • Anonymous says:

            “Bushmen vs anyone Eurasian, because they’ve been separated for something like 200,000 years.”

            It’s looking like more than that. As we get a hold of the extent of ancient “back migrations” to Africa, it is clear that everyone has more Neanderthal admixture, and the last common ‘modern human’ ancestor lived further in the past than can be told from modern genomes.

  8. Justin says:

    Glad to see you’re back

  9. Pingback: linkfest – 10/19/15 | hbd chick

  10. Cattle Guard says:

    Are the inhabitants of Sundaland called Mackams?

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