My cousin the Neanderthal

Discussion in 'Human Science' started by timojin, Oct 6, 2017.

  1. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Bells now accepts that the pure biology i posited is correct, not the little 'kink' she thought it was.

    Iceaura postulates that the sapien females were desired by the neanderthal males. I agree, they likely were.

    Indeed, we see before they became fully neanderthal, circa 220,000 KYA (proto-neanderthal) they were still breeding with proto-sapiens, as per Bells post showing proto-neanderthals mated with proto-sapiens, with the proto-sapien mtDNA overtaking and becoming the sole mtDNA in the proto-neanderthal tribes. But that was then. More recently, circa 60-40 KYA, when sapien invasion occurred, no such sapien mtDNA was incorporated into the neanderthal genome, and they remained with solely the proto-sapien mtDNA, since changed into the neanderthal mtDNA by further modification making it very much more distinguishable.

    It is this neanderthal mtDNA, the 'advanced' (more recent) mtDNA, that was not injected into the sapien lineage when the sapien tribes invaded the neanderthal tribal areas across Eurasia.

    Certainly when the proto-neanderthal and proto-sapien tribes looked more alike and lived in proximity, there was still some mating overlap. Apparently, the proto-sapiens females were sufficiently 'better' than the proto-neanderthal females, that that mtDNA became fixed in the neanderthal lineage (quite the woman).

    However, we've been talking about the full neanderthals, and how it came about that their mtDNA is not in the modern sapien lineage, and their Y-chromosome not in the modern sapien lineage (so far as we know - still waiting to find that anomalous one!)

    Biologically, there are two methods for those results: Neanderthal males mated with human females, but the male babies did not survive (leaving no trace of the neanderthal Y chromosome; and no trace of the neanderthal mtDNA); OR Sapien males mated with neanderthal females, but the female babies did not survive (leaving no Neanderthal Y chromosomes, and no trace of the mtDNA thereafter when the hybrid male grew up and mated)

    Of those two, I've suggested the latter is more likely, though it does require female infanticide. Likewise, the first scenario (espoused by Bells) requires either male infanticide or death of the male in-utero.

    Since female infanticide is a well-known sociological phenomena, it appears more probable to me than death of a male fetus when in-utero in a female sapien, but no death of the fetus when in-utero in the neanderthal female.

    Of course, it is possible that both 'mechanisms' were at play, though I suspect that future information will more likely support my scenario.
     
    Last edited: Oct 15, 2017
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  3. iceaura Valued Senior Member

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    Universal female infanticide on the continental scale and ubiquity and efficiency required is unknown in humans, or any mammal. Nothing remotely approaching that has ever existed in the historical or anthropological record of even a single tribe of humans for three generations, let alone the hundreds of tribes and thousands of years involved in culling Neandertal progeny in such a fashion.

    On the other hand, gender disparities in hybrid infertility of exactly the kind required are common, are found among many mammals and other kinds of living beings, and are suggested by the genetic evidence we have in this case. And of course that kind of factor would operate at any geographical scale and over any length of time automatically.

    Occam's Razor, remember?
     
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  5. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    so you say. any evidence that it is 'common' in mammals that the males die in-utero and the females survive?
     
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  7. iceaura Valued Senior Member

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    In inter-species mammalian hybrids, sure.
    Also common: that females are fertile to some degree and males are not, that one direction of hybrid is fertile and the other not or much less so, etc. Exactly what is required here.
    Look at horses and donkeys, for example. That's famous.

    Even a cursory netsearch will hand you what you need, lots of stuff like this: http://messybeast.com/genetics/hybrid-mammals.html
    Sound familiar?
     
    Last edited: Oct 16, 2017
  8. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Yes. But it is not what was 'invoked' by the articles referenced by Bells which were suggesting causation by anomalies on the Y chromosome, which instead 'invoked' some unknown causation.

    It could well have been present, as I indicated. And it could have been the other way too.

    More work needs to be done to determine whether there was sufficient disparity in those races to cause infertility/inviability in the male. The examples in nature from which that 'rule' was culled appear to involve far greater generational separation than the separation between sapiens and neanderthals. Time will tell, I suppose
     
  9. Gawdzilla Sama Registered Senior Member

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  10. iceaura Valued Senior Member

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    One way involves invoking the common and well established patterns of hybrid infertility in mammals, which all the evidence (though inadequate) matches perfectly. The other involves the assumption of cultural factors, voluntary behaviors, never seen on this planet on anything approaching the necessary intracultural consistency, cross-cultural scale, or evolutionary duration, in partial conflict with some of the limited evidence.

    Occam's Razor.
     
    Last edited: Oct 17, 2017
  11. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    One way involves invoking patterns of hybrid infertility from separate species hybridization (such as donkey/horse with different chromosome numbers), extrapolated to same species for close affinity (as per proto-neanderthal/prot-sapien breeding of the male proto-neanderthal with female proto-sapien resulting in the proto-sapien mtDNA becoming the offspring mtDNA) [hybrid vigor?], in which infertility was not present in the offspring (the female proto-sapien/proto-neanderthal hybrid offspring became dominant)

    The other way involves known patterns of social behavior (female infanticide) with likely a hybrid vigor component (neanderthal/sapien hybrid male offspring becomes dominant via hybrid vigor, and takes more female mates than average).

    It's possible both mechanisms were at play, of course, based on our incomplete information as of yet. I rather like the idea of a hybrid male taking a large harem and spreading the neanderthal genes he has (but without passing the mtDNA) widely, as a strong possibility, because large harems with a dominant male is also a known social phenomena.
     
    Last edited: Oct 18, 2017
  12. iceaura Valued Senior Member

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    You are talking about neandertal and sapiens, not "proto" anything. And hybrid vigor does not plausibly account for the complete culling of entire categories of crosses on a continental scale - gender disparities in hybrid infertility, as is frequently observed among mammals, does.
    The data point more to neandertal males doing that, than hybrids (they would be expected to vary more, with consequent loss of neandertal genetics, and they would also be expected to more likely bypass the hybrid infertility with female neandertals)
    There is no known pattern of female infanticide on the requisite geographical, cross-cultural, and temporal scale. Nothing like that has ever been seen on this planet.

    None of that is impossible. It's just not the way to bet, given the data so far.

    btw: In Science magazine recently, an analysis of Neandertal skeletons from the likely crossbreeding era indicates that Neandertals probably took longer to achieve adult brain size than sapiens do - their larger brains seem to have involved longer childhoods and learning intervals, as one would expect from a species apparently more reliant on brain capacity and functioning.
     
    Last edited: Oct 18, 2017
  13. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Neanderthal separated from sapien circa 400 kya. at that stage, and until circa 250 kya, I refer to them as 'proto-neanderthal'. the other lineage i refer to as 'proto-sapien'. They both continued to evolve/develop, until circa 50 kya, they were fully neanderthal and fully sapien (with the sapien invasion of eurasia about that time). It is the recent neanderthal for which we have the bulk of the genetic evidence. You can't just 'smear' all those generations into one category of 'neanderthal' and get a reasonable assessment.

    You assert that 'culling of entire categories on the requisite geographical, cross-cultural and temporal scale' is not likely but it really doesn't take that. If a few sapien males had offspring with neanderthal females, and the male offspring became a dominant member of the sapien tribe, they would spread their inherited neanderthal dna far and wide if they took many mates. That is what less-civilized tribes do. Dominant males take many mates. Look at biblical accounts (David/Solomon) with many thousands of mates for one man. Look at Genghis Kahn. If that one man were a sapien/neanderthal hybrid, from a sapien father and neanderthal mother, showing hybrid vigor and becoming dominant, it is quite plausible that a few such males (over the course of a few thousand years) could spread the neanderthal genome far and wide into the sapien gene pool, without injecting the neanderthal mtDNA. You seem to think such a scenario is implausible. I find it highly probable.

    But then again, perhaps both scenarios were at play.
     
  14. iceaura Valued Senior Member

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    So as I pointed out, the entire crossbreeding discussion involves neandertals and sapiens, not "proto" anything. The "proto" stages are not involved.
    They don't all do that. They don't kill all their foreign female progeny - especially not the foreign female progeny of dominant males. They don't maintain tribal breeding isolation after single encounters. They don't succeed in preventing outbreeding by non-dominant males, and they don't succeed in preventing outbreeding by females dominant or otherwise. They don't keep harem wives as isolated slaves. They don't maintain such customs inviolate for thousands of years.

    More to the point: There was no single "sapiens tribe". There were hundreds of them, spread over four continents, encountering neandertals in regions thousands of miles apart and at times thousands of years apart, living alongside them for hundreds or even thousands of years.
    Not primitive tribesmen, either one. Had they been, they would have had no such plethora of mates. And even they didn't kill all their foreign daughters, or prevent their fellow tribesmen (and women) from outbreeding.
    It's just much less likely than hybrid infertility. It's also less likely than direct bigger-brained, bigger-bodied, better adapted, neandertal male dominance and gene-spreading, which would account for all the stuff you need universal female infanticide on the entire Eurasian continent after every outbreeding event over the centuries to explain.
     
  15. iceaura Valued Senior Member

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    Last edited: Nov 10, 2017

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