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Does a common ancestor become less relevant with distance?

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  • #16
    Originally posted by dna View Post
    Actually, it is the opposite. John I Lackland PlantagenĂȘt (Jean sans Terre) is listed there with 856773 descendants (as of today). That means the bulk of Charlemagne descendants are through King John.

    There is a limit of generations that can be displayed through a single query by guest users of the roglo database.

    W. (Mr.)

    P.S.
    If you know about people who could be added to that database, the researches behind roglo would be extremely happy to add them.
    Interesting. I'm fairly certain a couple of my ancestors are known descendants of John Lackland, so I probably would know a number of people who aren't on the list yet, but I guess I'd need to become a member of roglo to find out?

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    • #17
      Originally posted by Adam Nisbett View Post
      Interesting. I'm fairly certain a couple of my ancestors are known descendants of John Lackland, so I probably would know a number of people who aren't on the list yet, but I guess I'd need to become a member of roglo to find out?
      If they are the 19th century or earlier ancestors, they might be already in the database.

      If you know the ancestry line, you can just keep following it in roglo from John Lackland. I think everybody before the 19th century is public, afterwards it depends.

      W. (Mr.)

      P.S.
      If you have documents supporting the ancestry (or such documents exist and are available in some library), I think you would enjoy working with roglo.

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      • #18
        Originally posted by Adam Nisbett View Post
        I think this person either is assuming an enormous pedigree collapse or is not taking into account the exponential nature of ancestry.
        First, pedigree collapse is enormous. For most of human history, most people were born, married, reproduced, and died within a single small community--a wandering tribe, a small village, etc. After the rise of nation-states, this immobility was often enforced by the government: Serfdom survived in Central-Eastern Europe until the middle of the 19th century. And even within a single community, social stratification was the rule, not the exception: A nobleman could not marry a serf (lest he become a serf himself), a Jewish merchant could not marry a Catholic serf (both religious authorities would object), etc.

        Second, DNA ancestry is (at most) linear rather than exponential, due to the observed "chunkiness" of chromosome recombination. In other words--even if we falsely imagine that my ancestors could roam the world at will--the increment in ancestor count from my 21st to my 22nd generation back is about the same as the ancestor count increment from my 20th to my 21st generation. This reference asserts:
        ---
        Your number of genetic ancestors eventually settles down to growing linearly back over the generations, at least over the time-scale here, with your number of ancestors in generation k being roughly 2*(22+33*(k-1)).
        ---

        I must re-emphasize that this latter calculation is based only on the observed behavior of chromosome recombination itself--it does not take into account the massive pedigree collapse that has been true for most of human history.
        Last edited by lgmayka; 10 July 2015, 09:23 PM.

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        • #19
          Originally posted by dna View Post
          Oh, that argument

          Whoever the original author was, she or he did not take into account pedigree collapse
          http://en.wikipedia.org/wiki/Pedigree_collapse
          http://www.isogg.org/wiki/Pedigree_collapse
          http://www.familytreedna.com/learn/a...any-ancestors/

          W. (Mr.)
          Good links that you provided.

          Additional, one can not look over the impact to Pedigrees impacted by genocide, war, epidemics, and natural disasters.

          Largest number of deaths by genocides:
          https://en.wikipedia.org/wiki/List_o..._by_death_toll

          Largest number of deaths by war:
          https://en.wikipedia.org/wiki/List_o..._by_death_toll

          Largest number of deaths by epidemics:
          https://en.wikipedia.org/wiki/List_of_epidemics

          Largest number of deaths by natural disasters
          https://en.wikipedia.org/wiki/List_o..._by_death_toll

          A lot of reasons, for a lot of DNA to be no longer existing on this earth. Whole related families eliminated due to some type of catastrophic event.

          I find it very amazing what my ancestors went through for this R-U152 to be typing on this wonderful Saturday morning in Florida.

          Comment


          • #20
            Originally posted by lgmayka View Post
            First, pedigree collapse is enormous. For most of human history, most people were born, married, reproduced, and died within a single small community--a wandering tribe, a small village, etc. After the rise of nation-states, this immobility was often enforced by the government: Serfdom survived in Central-Eastern Europe until the middle of the 19th century. And even within a single community, social stratification was the rule, not the exception: A nobleman could not marry a serf (lest he become a serf himself), a Jewish merchant could not marry a Catholic serf (both religious authorities would object), etc.

            Second, DNA ancestry is (at most) linear rather than exponential, due to the observed "chunkiness" of chromosome recombination. In other words--even if we falsely imagine that my ancestors could roam the world at will--the increment in ancestor count from my 21st to my 22nd generation back is about the same as the ancestor count increment from my 20th to my 21st generation. This reference asserts:
            ---
            Your number of genetic ancestors eventually settles down to growing linearly back over the generations, at least over the time-scale here, with your number of ancestors in generation k being roughly 2*(22+33*(k-1)).
            ---

            I must re-emphasize that this latter calculation is based only on the observed behavior of chromosome recombination itself--it does not take into account the massive pedigree collapse that has been true for most of human history.
            I agree that DNA ancestry has much greater collapse than one's actual pedigree. Though I tend to think it likely that a large portion of Europeans have ancestry from Charlemagne, I think it also likely that very few if any have bits of DNA from him (other than possibly Y-DNA if he has any direct male line descendants)

            I also agree that for any random person of that distance it is likely their DNA is restricted to a small community by social pressures, however I think those same social pressures likely magnified the spread of DNA for someone like Charlemagne. Because royalty only married each other, they would intermarry with neighboring regions for political reasons. Rulers of various European countries were often more closely related to each other than to their populace. Nearly all European countries have rulers at some point in their history with ancestry from Charlemagne. And then when you factor the filter down effect of DNA through social status by illegitimate children, I think with time, much of the lower social tiers pick up royal lines (though illegitimately born, it's still the biological pedigree) Also with families of multiple children, you would often see a portion of them not able to maintain the social status of their parents and drift down over generations. (ie not all princes become king) Hence why I do think it's likely that a large portion of European population likely has at least one line to Charlemagne if all facts could be known.

            Comment


            • #21
              Originally posted by Adam Nisbett View Post
              I agree that DNA ancestry has much greater collapse than one's actual pedigree. Though I tend to think it likely that a large portion of Europeans have ancestry from Charlemagne, I think it also likely that very few if any have bits of DNA from him (other than possibly Y-DNA if he has any direct male line descendants)

              I also agree that for any random person of that distance it is likely their DNA is restricted to a small community by social pressures, however I think those same social pressures likely magnified the spread of DNA for someone like Charlemagne. Because royalty only married each other, they would intermarry with neighboring regions for political reasons. Rulers of various European countries were often more closely related to each other than to their populace. Nearly all European countries have rulers at some point in their history with ancestry from Charlemagne. And then when you factor the filter down effect of DNA through social status by illegitimate children, I think with time, much of the lower social tiers pick up royal lines (though illegitimately born, it's still the biological pedigree) Also with families of multiple children, you would often see a portion of them not able to maintain the social status of their parents and drift down over generations. (ie not all princes become king) Hence why I do think it's likely that a large portion of European population likely has at least one line to Charlemagne if all facts could be known.
              https://en.wikipedia.org/wiki/Droit_du_seigneur

              Comment

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