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posted by martyb on Tuesday September 14, @04:04PM   Printer-friendly [Skip to comment(s)]
from the opposites-attract? dept.

Prehistoric humans rarely mated with their cousins:

At present-day, more than ten percent of all global marriages occur among first or second cousins. While cousin-marriages are common practice in some societies, unions between close relatives are discouraged in others. In a new study, researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the University of Chicago investigated how common close parental relatedness was in our ancestors.

The researchers re-analyzed previously published DNA data from ancient humans that lived during the last 45,000 years to find out how closely related their parents were. The results were surprising: Ancient humans rarely chose their cousins as mates. In a global dataset of 1,785 individuals only 54, that is, about three percent, show the typical signs of their parents being cousins. Those 54 did not cluster in space or time, showing that cousin matings were sporadic events in the studied ancient populations. Notably, even for hunter-gatherers who lived more than 10,000 years ago, unions between cousins were the exception.

To analyze such a large dataset, the researchers developed a new computational tool to screen ancient DNA for parental relatedness. It detects long stretches of DNA that are identical in the two DNA copies, one inherited from the mother and one from the father. The closer the parents are related, the longer and more abundant such identical segments are. For modern DNA data, computational methods can identify these stretches with ease. However, the quality of DNA from bones that are thousands of years old is, in most cases, too low to apply these methods. Thus, the new method fills the gaps in the ancient genomes by leveraging modern high-quality DNA data.

Journal Reference:
Harald Ringbauer, John Novembre, Matthias Steinrücken. Parental relatedness through time revealed by runs of homozygosity in ancient DNA [open], Nature Communications (DOI: 10.1038/s41467-021-25289-w)


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  • (Score: 3, Insightful) by Anonymous Coward on Tuesday September 14, @04:36PM (7 children)

    by Anonymous Coward on Tuesday September 14, @04:36PM (#1177753)

    At present-day, more than ten percent of all global marriages occur among first or second cousins.

    Well, if we didn't count Muslims or European royalty, that number would be a fraction of a percent.

    • (Score: 3, Insightful) by Anonymous Coward on Tuesday September 14, @04:54PM (3 children)

      by Anonymous Coward on Tuesday September 14, @04:54PM (#1177758)

      or Arkansans.

    • (Score: 0) by Anonymous Coward on Tuesday September 14, @05:20PM

      by Anonymous Coward on Tuesday September 14, @05:20PM (#1177763)

      Just goes to show those who marry their cousins are further along the evolutionary scale.

    • (Score: 2) by bzipitidoo on Tuesday September 14, @06:35PM (1 child)

      by bzipitidoo (4388) Subscriber Badge on Tuesday September 14, @06:35PM (#1177786) Journal

      Ancient Egyptian royalty was worse than the Habsburgs. Brother/sister marriages, and often their children did the same. Wouldn't surprise me if seeing the results of all that inbreeding inspired Biblical prohibitions against it.

      • (Score: 4, Interesting) by Immerman on Tuesday September 14, @08:11PM

        by Immerman (3985) on Tuesday September 14, @08:11PM (#1177832)

        I can think of a much more immediate reason. In fact it's the same reasons royalty so often engages in it - inbreeding concentrates family wealth. And nobody wants to worry about upwardly mobile peasants rocking the boat. They're much safer and more tractable when poor.

  • (Score: 2, Insightful) by Anonymous Coward on Tuesday September 14, @04:59PM

    by Anonymous Coward on Tuesday September 14, @04:59PM (#1177759)

    At present-day, more than ten percent of all global marriages occur among first or second cousins.

    In a global dataset of 1,785 individuals only 54, that is, about three percent, show the typical signs of their parents being cousins.

    So less than one third as prevalent, right? No, actually, because the 3% from the genetic study represents unions of first cousins only.

    So the figures actually seem compatible; absent more specific information about the current prevalence of first- vs. second-cousin marriage being lumped into that 10%, there's nothing to indicate any difference.

  • (Score: 0) by Anonymous Coward on Tuesday September 14, @05:43PM (3 children)

    by Anonymous Coward on Tuesday September 14, @05:43PM (#1177773)

    Did they control for feuds? It's hard to get over to the next cave to meet a non-related mate if you're likely going to get shot for some centuries-old complaint.

    • (Score: 3, Informative) by maxwell demon on Tuesday September 14, @05:52PM (2 children)

      by maxwell demon (1608) on Tuesday September 14, @05:52PM (#1177776) Journal

      Well, if you forcefully take your mates from the next tribe, it's probably not a cousin.

      --
      The Tao of math: The numbers you can count are not the real numbers.
      • (Score: 2) by crb3 on Tuesday September 14, @06:49PM (1 child)

        by crb3 (5919) on Tuesday September 14, @06:49PM (#1177793)

        Unless your tribe keeps doing that.

        • (Score: 1, Insightful) by Anonymous Coward on Tuesday September 14, @08:11PM

          by Anonymous Coward on Tuesday September 14, @08:11PM (#1177833)

          Or, better, your tribes take turns. One from you. Next, one from them. Eventually the two tribes are bound to have cousin-cousin mating.

  • (Score: 2) by inertnet on Tuesday September 14, @08:24PM

    by inertnet (4071) on Tuesday September 14, @08:24PM (#1177843)

    If you assume that the offspring was weaker on average, they would have less chance of survival. So per definition there must have been more than those 3 percent.

  • (Score: 2) by c0lo on Wednesday September 15, @12:28AM (4 children)

    by c0lo (156) Subscriber Badge on Wednesday September 15, @12:28AM (#1177904) Journal

    Hey, eds.
    If you "banned" politics into its special nexus because it "creates noise", it would only be fair to create an "Imperial/Metric" nexus, because you know posting stories of this nature is going to create even more useless noise.

    This is "story trolling", nobody expects anything good to come out of it. So, why are you doing it?

    =blame

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0
    • (Score: 2) by c0lo on Wednesday September 15, @12:30AM (1 child)

      by c0lo (156) Subscriber Badge on Wednesday September 15, @12:30AM (#1177905) Journal

      Wrong story, my apologies. I shall make the comment above in the story it belongs.

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0
      • (Score: 1, Touché) by Mockingbird on Wednesday September 15, @12:34AM

        by Mockingbird (15239) on Wednesday September 15, @12:34AM (#1177907)

        No, I think it fits. Cousins, Imperial measurements, incestuous rulers, it all fits together. Now where are the vi-emacs front page articles?

        --
        "It is a sin to kill a mockingbird" Atticus Finch
    • (Score: 0) by Anonymous Coward on Wednesday September 15, @01:34PM (1 child)

      by Anonymous Coward on Wednesday September 15, @01:34PM (#1177974)

      If you understand that it's trolling, why do you keep submitting political stories?

      • (Score: 2) by c0lo on Wednesday September 15, @02:23PM

        by c0lo (156) Subscriber Badge on Wednesday September 15, @02:23PM (#1177984) Journal

        Because very few are interested in STEM enough to comment on them and I get bored.
        Otherwise, the number of my science submissions far outweigh the ones in politics.

        --
        https://www.youtube.com/watch?v=aoFiw2jMy-0
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