GWAS scores & homozygosity

If we had good-enough average GWAS scores for a population, scores that worked for that population, we would still need to consider the extent of inbreeding. Whatever the average score is for the Saudis, lots of cousin marriage makes things worse.

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20 Responses to GWAS scores & homozygosity

  1. Daud Deden says:

    Mr. Charles Darwin.

  2. Smithie says:

    How quickly would the Saudi King be deposed, if he banned cousin marriage?

  3. William H. Stoddard says:

    If you have a deleterious recessive that’s present at a low to moderate frequency, clearly inbreeding is going to produce more homozygotes in whom the trait will be expressed; and that’s not good tor them, or their families. But does it result in more rapid elimination of the recessive gene from the population, all else being equal?

    • gcochran9 says:

      Close inbreeding decreases the equilibrium level of deleterious recessive. Not to zero, since mutations happen every generation, and it takes a long time to decrease that equilibrium level very much – thousands of years.

  4. dearieme says:

    I’ve recently read the diaries of a tank officer from WWII. He fell for his cousin; his parents strongly disapproved, saying that they didn’t want grandchildren who were “barmy”.

  5. Bad for IQ, but it works a treat to keep wealth under control of the family.

  6. Phille says:

    Intuitively, I would assume that inbreeding impedes purifying selection. After all, you can’t select for an undamaged gene if it doesn’t turn up in your families gene pool. Is that an actual effect that might explain certain observations?

  7. What is GWAS? Is GWAS the silly notion that the quantity of a trait in an individual is a linear combination of separate effects of genes? The very fact inbreeding decreases IQ shows this will never be “good” for IQ, and IQ denialists will use this to create bad image of IQ researchers.

    • catte says:

      as a matter of empirical fact, it is indeed true that a large fraction of the variation in IQ is due to a linear combination of separate genes. we know this from twin studies.

    • Eff says:

      Well, if IQ denialists would use that fact to create a bad image of IQ researchers, then they would be pretty stupid.

      It has been known for decades that the heritability of IQ is not entirely additive (narrow sense heritability). But a very significant portion of it is additive. More than half of the heritability is due to additive effects.

      Whether or not GWAS will be ‘good’ for IQ depends entirely on your definition of ‘good’. We can already predict with correlation ~0.3, which is already pretty impressive in my view. Let’s say, for the sake of argument, that 40% of the variance in IQ is due to genetic differences in the narrow sense (Not a particularly strong assumption). Then we would be able to create predictors with correlation ~0.6 with real IQ, based purely on DNA using only additive effects. Again, you might not think that’s ‘good’, but it’s a hell a lot better than what any sociologist could predict in a sample that is not genetically confounded (for example in an adoptive sample).

  8. JRM says:

    Homozygosity would seem to lower age at first marriage for women.

  9. jovien says:

    (I hope I have understood what has been said, without being absolutely sure)

    So, what is the best strategy for a species ?
    Inbreeding, or, on the opposite, large definition of the prohibition of incest, exogamy ?
    Inbreeding contributes to the elimination of bad recessing genes.
    But inbreeding depresses the qualities of bearers of genes excellent when heterozygotes.

    The answer would be found empirically. In our species, the strategy which prevails is probably the best one.
    And the non-inbreeding one has prevailed by far.
    Among the chimps, among our far ancestors Homo (that is the thesis which I read in a 2017 book, “Aux origines de la société humaine” (“Primeval Kinship” in English) by the French Canadian primatologist Bernard Chapais) and among most human societies, the “Arab way” being relatively marginal (by the way, one can maybe relate it to the marriage between siblings in Old Egypt (which some say occurred not only in the pharaonic families) and, more tentatively, to the uncle-niece marriage among past Zoroastrians of Iran : all in the same region).

    • dave chamberlin says:

      We can get more specific than what is the best strategy for a species, we can ask what is the best strategy for OUR species.

      I am very biased. I have had a great life because I am smart, but one has to look no farther than politics to realize that the mislead dumbshits are truly fucking up this world. My liberal friends get all idealistic and pissy about environmentalism, better media, better government, all the standard how we can make the world better angles.

      I avoid those conversations because they aren’t getting to the root of the problem. Nothing is going to get greatly improved when we live in a world that is ignorant because it is stupid. This here pale blue dot is a ship of fools that is going to flounder for a few more generations and then genetic engineering is going to present a way to make the average Joe smarter. When the dumbshits are able to give the next generation brain glasses then guess what happens. PRESTO CHANGO everything gets dramatically better fast. Oh there will be some serious kerfuffles, Someone like Trump’s porn baby will get his fool self put in charge and the smart bombs will do stupid things. But it will all sort out in the wash.

      How a billion people think cousin marriage is a good idea supports my cynicism about people in general.

      • William H. Stoddard says:

        You’re not cynical enough. Smart people will go wrong too, just in different ways. Ashkenazim are about as smart as any known human population, and they gave the world psychoanalysis and Marxism—and other things of the sort Orwell’s epigram about needing to be an intellectual to believe something so stupid applies to. For one thing, smart people are susceptible to believing that being brilliant at X means they’re equally brilliant at Y and Z. . . .

        • Jim says:

          Being highly intelligent is not necessarily combined with an interest in science or objective truth. Stalin was highly intelligent.

      • Spanky says:

        The biggest screw-ups I know have high IQ’s.
        My father, for instance, is a Mensa member, but is a total slave to his emotions and thinks there’s something to homeopathy. His brother has a Genetics PhD, but just got scammed by his “Russian girlfriend” who he met online, for $12,000. The examples go on and on.

        A high IQ does not correlate with intuition and common sense.

        • gcochran9 says:

          You may not know a statistical universe. Probably don’t.

          • dave chamberlin says:

            When you attempt to see things as a statistical universe (nice phrase) then it is real obvious that higher intelligence correlates incredibly well with a good life and prosperity. It might be a fact that your Uncle Joe is smart and talks to his shoes but it proves absolutely nothing. Nobody knows the future and futurists are full of shit. But it’s blindingly obvious genetics is progressing quickly and some country somewhere is going to start upping the IQ of it’s citizenry and the rest of the world will do a whole lot of hand wringing, fist shaking, foot stomping ect ect, but then when it really really works well, and it will, then everybody wiil either follow or get left behind.

  10. dave chamberlin says:

    Point well taken. I try to have a distant perspective on humanity. True revolutions are happening at an accelerating rate. The (shitty name) Great Leap Forward 45,000 years ago. The Agricultural revolution 10,000 years ago. The Industrial Revolution 1850. Brain Glasses for the Masses approximately two generations from now. Sure there are bumps, three steps forward, two steps back kind of things. Wars and tribulations galore, but big picture, distant perspective on humanity in the present, that is how it shapes up. The doomsday clock crap doesn’t interest me as being particularly probable.

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