After 32 generations (~800 years) you have more genealogical ancestors than there are base pairs in human DNA. There literally isn’t enough resolution to store a “record” of each of your ancestors, even if you inherited exactly 1 base pair from each ancestor.

Additional complications make it an even shorter timeline. After about 8 generations, you share no more DNA with your ancestors than you do with a random stranger.

Politically this should be more well known. Of course, racists and fascists rely on “blood quantum” arguments to justify racial or ethnic oppression. But they don’t invent this idea of strict genetic identity. It’s latent in the population.

Leftists should more frequently call out genetic tests like 23andMe as inherently racist because it’s based in race science nonsense. It may not be as obvious as Nazis invoking aryan genes or whatever; but it’s still just as incorrect when your aunt at Thanksgiving talks about how she discovered she’s 2% Choctaw or whatever

pickle-liz

  • UlyssesT [he/him]
    ·
    3 hours ago

    "Genetic immortality" is a massive cope from breeder fetishists for this and many other reasons, another one of which is that the offspring of such narcissists owe fucking nothing especially to people they may never meet as time goes on.

  • edge [he/him]
    ·
    edit-2
    6 hours ago

    The keyword is each. You still have DNA from many of them. Plus DNA based ancestry works with key genes. A male has his father's Y chromosome, who has his father's Y chromosome, who has his father's Y chromosome and so on. The same goes for mitochondrial DNA through the maternal line. There are mutations of course, but those actually allow you to paint an (imperfect) timeline and create groupings (haplogroups). Men from Europe have more similar Y chromosomes to each other than to men from elsewhere.

    Obviously none of that justifies racial or ethnic oppression nor indicates any significant differences between peoples, but it does allow for those trivial (as in, interesting bits of information that aren't all too useful otherwise) but imperfect groupings.

    I don't know how the exact percentages are determined and I'm sure there is something closer to race science bullshit in there, but it's mixed with actual science. It's pretty simple to see for example that my mitochondrial DNA aligns more with people from Iberia while my Y chromosome is much more like men from England. Thus I am half Portuguese half English(-descended American). But it means absolutely nothing other indicating who my parents are. That of course tells you nothing about my intellectual or physical abilities or any predispositions despite what fascists claim.

    • CleverOleg [he/him]
      ·
      5 hours ago

      but those actually allow you to paint an (imperfect) timeline and create groupings (haplogroups)

      measurehead

    • quarrk [he/him]
      hexagon
      ·
      5 hours ago

      Not an expert but

      In the first place, mitochondrial dna are shared among many people, for the basic fact that it is passed matrilineally. This allows us to prove the existence of the so-called Mitochondrial Eve, to whom all humans alive today are related.

      Second, the mitochondrial dna encodes basically the production of ATP. Not genes that would be used to express any apparent difference between people.

      Third, the number of base pairs in mitochondrial dna is very small, tens of thousands, compared to the 3.1 billion base pairs in nuclear dna.

    • Belly_Beanis [he/him]
      ·
      4 hours ago

      In North America, you a certain percentage of your ethnicity must be Native American in order to qualify for recognition by the government to receive tribal benefits. I think it's a minimum of 1/12th. in the US (not 100% positive on the exact number). This is called the "blood quantum."

      If you don't meet the minimum, regardless of how or where you were raised, or what you look like, or what languages you speak, you are automatically disqualified from stuff like scholarships, reparations, and official membership to a federally recognized tribe. This was put in place in the early 1900s by white people with no discussion about how Native Americans establish heritage or tribal membership.

      A lot of racism in the US still lingers around this concept where a person is or isn't part of an ethnicity based on their blood quantum, rather than their lived experiences. Someone who is 1/4th. black, for example, may have their concerns dismissed because "they're not really black." That is until it becomes convenient for the racist to go by the "one drop rule," which is when a person has any non-white heritage, they are no longer considered white (even if it's something like 1/100th. black).

      • combat_brandonism [they/them]
        ·
        2 hours ago

        I think it's a minimum of 1/12th.

        Depends on the tribe/nation, which is the insidious part of blood quantum. It's a genocidal tool developed by settlers but implemented and enforced by comprador governments themselves.

  • Wheaties [she/her]
    ·
    5 hours ago

    Really highlights just how ass-backwards Richard Dawkins is when he suggests DNA is the begging and the end, the only thing that actually matters

      • Wheaties [she/her]
        ·
        11 minutes ago

        Perhaps I'm misremembering, but I'm pretty sure he describes everything about life as just a means for DNA to propagate itself. As if DNA isn't merely a component in a larger, more complex and complicated system, but as the reason for the whole thing.

  • Barx [none/use name]
    ·
    6 hours ago

    Don't discount inbreeding tho. Not just cousins or whatever, but villages and groups of villages. Peoplehave gotten increasingly mobile over time of course but the reason there are groups of folks that look a bit different from one another is that we split off for a little while and became semi-isolated.

    PS this isn't race theory, just genetics and a recognition of human variation. We are all modern humans and overall the same, our differences are very minor. One example would be lactose tolerance (which is the less common thing for humans to have than lactose intolerance) which has popped up a few times in human genetic history but did not spread out over the whole population in a couple thousand years.

    • Xavienth@lemmygrad.ml
      ·
      5 hours ago

      Yeah, the post says at 32 generations (800 years) there's more ancestors than base pairs, but at 37 generations, there's more ancestors than humans that have ever existed.

      • MaoTheLawn [any, any]
        ·
        4 hours ago

        37 generations doesn't take us back to pre-human times, does it? Or is that not what you're saying?

        • Xavienth@lemmygrad.ml
          ·
          4 hours ago

          No it's like 900 years. So the fact that 900 years back, you should have over 100 billion ancestors indicates a lot of inbreeding. And to be clear, not necessarily familial inbreeding (though ofc that too), but just like, being distantly related too.

  • Bobson_Dugnutt [he/him]
    ·
    7 hours ago

    Just you wait until some wacko invents homeopathic genetics to refute this. The blood has memory!

  • blobjim [he/him]
    ·
    7 hours ago

    Most people wouldn't consider 800 years to be their ancestry. 3 generations is the typical.

    • glans [it/its]
      ·
      6 hours ago

      that's totally false. people feel all kinds of ways about things done hundreds, even thousands of years ago.

      lots of people will tell you about their "line" being "traced" back to such n such. most prominently all royalty everywhere but lots of normal people have stories.

    • quarrk [he/him]
      hexagon
      ·
      edit-2
      7 hours ago

      800 years is just the hard cap, the theoretical maximum. In reality, not all 3 billion base pairs are relevant to distinguishing humans from each other. Much of the genome is just basic biology shit, which is why the human genome overlaps 70% with bananas, 96% with chimpanzees, etc.

      This 800-year rule also ignores the fact that there were not 4 billion people on earth in 1250 AD. There is a lot of… ahem… crossover within our lineage.

      The point is that the way many people think about identity is rooted in a wrong understanding of genetics. The whole point of these genetic tests is to discover a supposed “true” identity that is ostensibly encoded in one’s DNA. Closely related with this belief is a strictly biological view of race and ethnicity.

    • thirtymilliondeadfish [she/her]
      ·
      7 hours ago

      this feels pretty culturally disconnected/nuclear-family-brained tbh

      I mean, same, but I wouldn't want to project that onto others. Feels like conflating these new age physiognomy peddlers' bullshit with actual connection to place and people