mtDNA, Y-chromosomes, autosomal DNA

Imagine that we take men from population A, with a distinct set of Y-chromosomes, and have them father children with women from Population C. And their male descendants keep marrying women from population C: eventually we have a population (D) with all Y-chromosomes originating in population A while their mtDNA and autosomal DNA are all from population C.

Now we take women from population B, with a distinct set of mtDNA haplotypes. They marry guys from population D, and their descendants continue to do so for a long time: so we eventually end up with a population (E) all of whose Y-chromosomes come from population A, all mtDNA from population B, all autosomal DNA from population C.

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27 Responses to mtDNA, Y-chromosomes, autosomal DNA

  1. cargocultist says:

    “eventually we have a population (D) with all Y-chromosomes originating in population A while their mtDNA and autosomal DNA are all from population C.”

    What about the autosomal DNA the men from population A? Vanished?

    • RCB says:

      (1/2)^n

      • cargocultist says:

        I get that that the A-male genetic material in the autosomal DNA gets diluted. But it’s not so simple. The size of group A and C matter a lot and selection pressures (on specific genes) just a small amount proximally. What point is greg trying to make? Is it just an amusing example of what can happen?

        • cargocultist says:

          Oh, I see. The male descendants only marry just pure C-females again and again. Yes (1/2)^n is correct in this unnatural breeding example.

          • tautology123 says:

            Though where would the pure females be coming from? Suppose the A men killed all the C men. Then either there must be a separate source of pure C females such as the the decendants expanding into other pure C groups or the second generation would be half A allready and would stay so. Or am I missing something?

            • reiner Tor says:

              Population C could be large, and militarily weak, with beautiful blonde women, while Population A could be a strong nomadic tribe that lusts for blue eyed blondes, and takes slaves from it for several generations. Something like that happened to Ukrainians vs. Crimean Tatars, but the Tatars sold basically all slaves to Anatolia, so didn’t become autosomal Ukrainians at all. But at least it’s possible that something like that could have happened.

              Moreover, I think it’s not very likely that the men of Population A don’t marry A women at all. Selective infanticide might result in skewed sex ratios, but it’s not realistic to expect it to be fully effective. However, if children of poor nomads had a low life expectancy, and if the majority of wives or concubines of the aristocracy consisted of slave girls from population C, then over time the same thing could happen.

              The influx of males from this composite population into population B is easier to imagine, this has happened in Brazil, where white males kept marrying African (and to a smaller extent Amerind) women. However, there was a constant supply of Africans, so eventually the brown population still has some autosomal genes from Africa, but much less than would be expected based on mitochondrial DNA only.

  2. Abraham Lincoln says:

    What if the men of population D, as they were exclusively marrying C’s women, were undergoing strong selective pressure for the specific traits possessed by population A. Perhaps a unique behavioral profile, for instance.

    So male descendants of male Ds only would adhere to the standards of population A rather to the standards of their population C mothers.

    Some sort of Y-chromosome linked/influenced specific traits, where all are dominant over other the other chromosomes, and ultimately male Ds would be able to dilute their bloodline as much as they wanted but all of the males would possess the unique population A characteristics.

    (Please excuse for any incoherence.)

    Thoughts?

  3. M. M. says:

    can’t help it–steve sailer’s “merkel youth” comes to mind…

  4. jamesd127 says:

    I can see how everything except the Y chromosome gets swamped – we suppose population A is a tiny patriarchal patrilineal ruling minority, which has huge numbers of children among the conquered population, and all their male children inherit their privilege, till eventually no non privileged males exist.

    But the reverse is unlikely, indeed impossible. How does everything except the mitochondrial DNA get swamped?

  5. dearieme says:

    “And their male descendants keep marrying women from population C”: do you mean that A men never breed with A/C cross women? What happens to these women?

  6. Andrew says:

    Are we talking about Basques?

  7. ghazisiz says:

    Trying to think of an example. A=Portuguese; C=indigenous; D=Bandeirantes; B=European immigrants; E=elite Brazilians? A story like this could easily be made about the upper classes of Mexico. About the Yamnaya? Pygmies?

    Damned confusing for ancestry.com!

  8. IC says:

    Due to genetic recombination of autosome at meiosis, the conclusion for autosomal DNA is in question.

    Unless, it is introgression with increasing number of C women diluting A population.

  9. Tapas says:

    “Now we take women from population B, with a distinct set of mtDNA haplotypes. They marry guys from population D, and their descendants continue to do so for a long time: so we eventually end up with a population (E) all of whose Y-chromosomes come from population A, all mtDNA from population B, all autosomal DNA from population C. ”

    Here, female descendents are marrying “pure” males of D (reverse of the previous scenario), then shouldn’t the mtDNA be from C as well?

  10. AppSocRes says:

    Sounds a lot like the early genetic history of Ashkenazi Jews. Population A is male Jews from the classical diaspora who settle in Italy. Population C is local Italian women. Population B would be local women in Europe north of the Alps whom male Jewish immigrants from Italy marry after some genetic bottleneck. Hardy-Weinberg would manage things after that until cultural selection kicked in.

    • sprfls says:

      Not even close. Ashkenazi Jews are neither mostly Italian autosomally nor at all Germanic in their mtDNA.

      • gcochran9 says:

        They are mostly European autosomally, and that European fraction is mostly Italian.

        • sprfls says:

          I disagree. There is real Italian admixture in AJs, but on the order of ~10-30%, not ~40-60% as has been estimated previously. Believe I’ve written this here before, but I’ll gladly take another swing.

          It’s confusing to use “European” in this context, when many modern Europeans and Levantines descend large parts of their ancestry from a common population. So if AJs are mostly European, then so are Lebanese, Palestinians, Druze, etc…

          What I’m getting at is that in your model you would have to explain why a) other Jews and b) other eastern-Med related populations behave so similarly to AJs in a wide range of autosomal tests. Surely none of them have significant Italian admixture. So why?

          I believe a better, equally rough, model is to think of Jews as mostly a mixture of something like Bronze Age Levantines and something Aegean-related. More generally, a subset of the variation that formed in the eastern Med after the Bronze Age collapse. AJs are a subset of that subset that found themselves in Italy and acquired just enough admixture to make them slightly more European-shifted than their relatives.

          The other data you’ve used is mtDNA. Once again, the mtDNA in question are simply subsets of generic neolithic farmer mtDNA. Did you ever respond to this paper?

          Ancient DNA Analysis of 8000 B.C. Near Eastern Farmers Supports an Early Neolithic Pioneer Maritime Colonization of Mainland Europe through Cyprus and the Aegean Islands
          http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004401

          “Another interesting case are the Ashkenazi Jews, who display a frequency of haplogroup K similar to the PPNB sample together with low non-significant pairwise Fst values, which taken together suggests an ancient Near Eastern origin. This observation clearly contradicts the results of a recent study, where a detailed phylogeographical analysis of mtDNA lineages has suggested a predominantly European origin for the Ashkenazi communities [48]. According to that work the majority of the Ashkenazi mtDNA lineages can be assigned to three major founders within haplogroup K (31% of their total lineages): K1a1b1a, K1a9 and K2a2. The absence of characteristic mutations within the control region in the PPNB K-haplotypes allow discarding them as members of either sub-clades K1a1b1a or K2a2, both representing a 79% of total Ashkenazi K lineages. However, without a high-resolution typing of the mtDNA coding region it cannot be excluded that the PPNB K lineages belong to the third sub-cluster K1a9 (20% of Askhenazi K lineages). Moreover, in the light of the evidence presented here of a loss of lineages in the Near East since Neolithic times, the absence of Ashkenazi mtDNA founder clades in the Near East should not be taken as a definitive argument for its absence in the past.”

          • gcochran9 says:

            You’re wrong: I’m looking at an autosomal analysis. Talked about it some time ago. But the mtDNA fits that: none of the four big Ashkenazi mtDNA lineages come from the Middle East in historical times. We know for sure: the closest sister lineages are all southern European. And almost all of the next-biggest mtDNA lineages are European as well.

            Look, MtDNA mutates much rapidly than autosomal DNA: we can tell the difference between Middle Eastern lineages imported to Italy 2000 years ago and ones imported 8000 years ago with the Cardial culture/Anatolian farmers.

            There’s nothing to argue about.

            Now if you don’t like the answer – well, in the past I would have told you to go fuck yourself. But today, there are alternatives. If you want the Ashkenazi Jews to be wholly Jewish by ancestry ( instead of about half, which is the truth), you can replace their mtDNA with acceptable Middle Eastern lineages (three-parent kids) and, soon enough, start CRISPRing and replace all that European ancestry with appropriate raghead alleles. Or, if in search of true authenticity, dig up bodies from the siege of Masada and use their DNA. Make it so.

            Like the Kzin, you can make your dream of yourself come true.

            But how well has that worked for them?

            • sprfls says:

              As you wish: I won’t discuss further. Not sure how you got the idea that I’m somehow emotionally invested in this, but, for the record, I’d take guido genes over raghead genes any day.

              Don’t know about the Kzin, will have to look into that…

              • gcochran9 says:

                Well, it happens a lot: the articles I see range from mildly shading the evidence (using Flemings as a model for southern European admixture) to outright lying (Behar), even craziness (El-Haik).

                Behar, and a lot of others, want the Ashkenazi Jews to be something they’re not (pure Middle Eastern). As I understand it, El_Haik is A. dishonest, politically inclined to diss the Ashkenazim, somehow connected to being an Iraqi Jew in Israel, and B. incompetent. The first crowd is fairly successful: I don’t think the real facts are widely known. My Israeli readers can tell me if that’s the case.

                Although nobody knows, one can choose to believe that those Roman chicks in the Ashkenazi bloodline were effective clones of Gina Lollobrigida or Monica Bellucci.
                For those POWs from the Bar Kokhba revolt, resistance was futile.

                I may have misread you and if so apologize: but that PLOS paper has no chance.

  11. chrisdavies09 says:

    ‘East European’ R1a in South Asia? (Allegedly) ‘Eurasian’ haplogroup E in Africans? R1b in both?

  12. chrisdavies09 says:

    Could be Roma, Ashkenazi Jews, North Africans, Cape Colored, Cape Verdians, Madagascans, Carribean or Latin American populations?

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