Just a thought

Denisovans apparently interbred with modern humans, with about 3–5% of the DNA of Melanesians and Aboriginal Australians and around 7–8% in Papuans deriving from Denisovans.
….
The Denisovans or Denisova hominins ( /dɪˈniːsəvə/ di-NEE-sə-və) are an extinct species

If the DNA lives on in such quantities then are they extinct?

After all, if the identifiable DNA of any one of us were present in such quantities in the population 10k (or 50k, whatever) years hence we’d describe that as a definite evolutionary win.

17 thoughts on “Just a thought”

  1. The Meissen Bison

    It would be an evolutionary win if those with this DNA were fitter, more successful or what have you than those without it.

    Otherwise it would surely be an evolutionary handicap to those having this DNA, wouldn’t it?

  2. If the DNA lives on in such quantities then are they extinct?

    https://en.wikipedia.org/wiki/Compilospecies
    “A compilospecies is a genetically aggressive species which acquires the heredities of a closely related sympatric species by means of hybridisation and comprehensive introgression. The target species may be incorporated to the point of despeciation, rendering it extinct.”

    https://en.wikipedia.org/wiki/Introgression
    “There is strong evidence for the introgression of Neanderthal genes[16] and Denisovan genes[17] into parts of the modern human gene pool.”

    So certain genes/DNA still around but species is gone.
    Dunno though. Biology memes evolve way faster than biological genes.

  3. “After all, if the identifiable DNA of any one of us were present in such quantities ”

    60% of human DNA is identical to DNA in a banana.

  4. @ Ottokring
    Surprisingly not: Ivan Denisovitch would, almost certainly, have traces of Neanderthal DNA along with almost all Europeans and Asians prior to the twentieth century and mass migration.
    Until recently it was widely accepted that Neanderthals had larger brains than “Homo sapiens sapiens” – this has now been challenged with the argument being that most Neanderthal skulls found were male skulls and that if you adjusted for the difference in size between male and female skulls the greater size of Neanderthal skulls was not statistically significant [for non-statisticians that means the average skull size *was* greater, even after you adjust for gender weightings, but not by enough to be certain *beyond reasonable doubt* that this was not due to random variation in the sample].
    That the majority of humans who have inherited some of the Neanderthal DNA have, on average, higher IQs than those without, does call into question the naming of “homo sapiens sapiens” – should Neanderthals be “homo sapiens sapientor”?

  5. “That the majority of humans who have inherited some of the Neanderthal DNA have, on average, higher IQs than those without …”: quelle délicatesse.

  6. @ The Meisson Bison:

    It would be an evolutionary win if those with this DNA were fitter, more successful or what have you than those without it.

    Denisovan genes are supposed to be what enable Tibetans and some Andean peoples the ability to live at high altitude.

    https://www.bbc.co.uk/news/science-environment-48107498#:~:text=Scientists%20have%20found%20evidence%20that,at%20high%20altitudes%20in%20Tibet.&text=The%20ancient%20ancestor%20seems%20to,published%20in%20the%20journal%20Nature.

  7. @Jonathan: it’s usually said that the genetic adaptation to altitude of the Tibetans is different from that of the Andeans. But not my field I must admit.

  8. @Dearieme It’s a bit of both, really.

    The people that crossed the Bering land bridge and entered the american continent took a while to get to the Andes.
    They may well have picked up the Denisovan high-altitude gene in Siberia, but for a couple millennia it really did not have much benefit as they moved south through the relative low altitudes down towards South America.
    So the gene mutated without any selective pressure to stay the same, and diverged from the “Denisovan” parent, but kept being expressed in the population as it still gave a minor advantage in low altitudes, and Stamina was a Thing back then.

    When they hit the Andes and there was once again a clear advantage to having that gene, the reverse happened, and the gene was specifically selected for, with the more efficient mutations rapidly spreading and stabilising, but moving the gene itself even further from the “Denisovan” parent.
    This alongside several other mutations unique to the Andeans that allows them to live happily where we’d end up gasping for every breath while freezing our arse off.

    So the Andean mutation does likely have a Denisovan origin, but it’s seen as a separate adaptation since it’s so far removed from the parent gene in both time and location.

  9. Ah, PJF.. What makes people think those artifacts must be “ours”?

    Both Neanderthals and Denisovans were able to make the move from Africa into the rest of the world. In fact our collective ancestors pulled the same trick several times..
    Our collective ancestors, as well as our nephews ( there’s a solid hint there was a third nephew around somewhere..), were tool-users. Every offspring from Homo Habilis on is…

    The Narrative is that only “we” crossed that land bridge, and that somehow magically our Denisovan nephews did not, even while the thing was right there in their “territory”, with us agressive bastards moving in and pushing them aside.

    Right….

    There’s simply not enough fossil evidence in the americas to make a scientific case, but a group of Denisovans looking for greener pastures and ending up on the american continent isn’t that far of a flight of fancy.
    Especially given that the older range of signs of habitation/tool use ( 33k years back ) sits right at the edge of when they are supposed to have gone “extinct”. As opposed to the “this was clearly us” wave around 14k years ago.

    And the simplicity of the putative tools in the article bugs me.. Could be there’s been a massive loss of knowledge during that older migration “over and south”, which didn’t happen during the later wave, but they lack the sophistication found in “sapiens” tools, even the early ones. They are much more like Neanderthal tools.

    Ah well… Patience and all that.. As DNA samples become available we’ll be able to piece together a much better “live” timeline from surviving bits than we can from haphazard and rare finds in the ground.

  10. @ PJF
    Thor Heyerdahl’s Kon-Tiki expedition demonstrated that it was possible to cross from South America to Polynesia by raft so it is practically certain that neolithic people could have crossed fro Polynesia to South America in the same era as they were crossing from south-east Asia to Polynesia and Australia. That would be a more plausible explanation of Denisovan genes in the Andean population as Denisovan genes are most common in Papua New Guinea, followed by Melanesia and totally or almost totally absent in north Asian and North American populations.

  11. @ Grikath
    I have yet to learn of evidence for Neanderthals and/or Denisovans living in Africa.
    The most popular theory seems to be that a favourable set of mutations occurred to hominims living in the Middle East (or one set in the Middle east, followed by a further set in Europe and/or southern Siberia), producing two race that were able to survive through a series of glacial and inter-glacial periods.

  12. I never said either subspecies lived in Africa… Our common ancestor did, spread out, and then a big fat ice age happened that separated the groups long enough for specialisation and speciation to happen.

    When things thawed out the three (four?) populations spread out and…well.. humped.. There’s evidence of Neanderthal/Denisovan crosses without us being involved, so they definitely did Walkabouts as well. We all found each other purty enough, it seems.

    I doubt that Neanderthals or Denisovans ever would have tried to “move back” to Africa. Except maybe for the inevitable oddball.
    We Were There Already.. Smarter(ish), definitely more agressive and adaptable, and better equipped.
    And for a cold-adapted people… Welll.. We have trouble enough in a hot summer.. For them it would have been worse.. Not exactly enticing..

    The Americas are another matter entirely.. No human population of any description/descent at all, and a lovely mountain range running north to south all the way down… Stranger things have happened..

  13. Birds share dinosaur DNA, but dinosaurs are extinct. Homo Sapiens share over 90% of their DNA with Chimps but can5 interbreed so aren’t the same species.

    so, yes, they’re extinct.

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