Regression to the Mean Means Regression to the Group Mean, Not to the Racial Mean

William Playfair Web writes:

It could be useful, if there are norms of reaction/ gene- environment interaction and/or dependence, but if additive heredity (Phenotype = Genotype + Environment), it’s largely not going to work unless heretibility is super high, which the evidence Robert has given has shown it’s not:
I have no problem with gentle Eugenics in theory, but in reality it may be fruitless.
Your group’s IQ would be barely above the previous mean in 2 generations – if one were to compensate for that, you’d have to continually make for only the upper portion of society that who want to breed, breed, consistently, so you’d end up diminishing your group’s population, severely.

The group regresses to the group mean is how I understand it. In other words, if you find a great big uninhabited island and put thousands of smart Blacks on there (average IQ = 120), what will happen is if you have two Black parents on that island with IQ’s of 145, their kids will tend to have IQ’s that crash back down towards that 120 mean, not the 85 mean for US Blacks as a whole. So the kids might have IQ’s of 132 instead of 145. That’s how it works. And yes, over time, you would end up with a bunch of really smart Black people on that island. I figure in 200-300 years, the Blacks on the island might still have 120 IQ’s.
Endless crashing back to the racial mean is irrational.
Look at the example above. What’s going on with US Blacks with average IQ’s of ~120? Well, what is going on with them probably is a higher frequency of whatever those smart genes are that increase IQ. Those same genes occur in the 85 IQ Black population, but unfortunately at a much lower frequency. They’re just not as common in that group.
After 200-300 years, no doubt those smart genes of those island Blacks would still be going on strong. Regression to the mean isn’t going to overrule those smart genes. And why would we expect this group to crash back down to 85 anyway? Look at their genetic profile. Look how different it is from the 85 IQ group. Why would they crash back down to 85 if they had such high frequency of those smart genes? It’s irrational.
The regression that will happen on the island though is that people with higher than 120 IQ’s will tend to have offspring that crash back down towards 120. My mother said regression to the mean has to happen “otherwise it would keep going up forever.” I don’t understand what she means by that, but apparently that is the logic behind regression to the mean.
For instance, you have some very tall people – 6’8 man and 6’4 woman. They have male kids. Well, their kids are going to crash back down towards the 5’11 mean for males in that society. They won’t go all the way to it. The boys might end up 6’2. I suppose my Mom makes sense though, in that very tall people have to crash back towards the mean because otherwise humans could keep getting taller and taller, and there are limits to human height due to the nature of our species. So now it is starting to make sense to me.

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0 thoughts on “Regression to the Mean Means Regression to the Group Mean, Not to the Racial Mean”

  1. ah…
    I think I just got your argument…
    this IS assuming selective mating (i.e. Island isolation)
    BUT, keep in mind,
    regression to the mean does incorporate the average of the parent’s IQ, not just one.

  2. The brain is the most metabolically expensive organ in the body. Takes 5% of body weight yet uses up 25% of your calories(if I’m not mistaken). It doesn’t make sense for nature to give you more brains then you need to survive. So in that sense, regression to the mean makes sense. More powerful brains would mean less calories for the rest of our organs.

  3. Obviously if the brain is so big and powerful as Tulio says, note when it’s cold or hot covering or uncovering vastly affects coolness, warmth, then of course stuff like nutrition and bad habits (doing drugs while pregnant,exposing kids to 2nd hand smoke) would vastly affect it.

        1. To Jason Y:
          Yep, and that’s one more strong reason why genetics as a source of inferority is exxagerated.
          Even the most hardcore hereditarians acknowledge that harsh environments (malnutrition; fetal, infant or child abuse (from drugs, alcohol, or physical violence) – or genetic misfires (down’s syndrome) have deleterious effects on IQ. Notorious HBD guy, Steve Sailer, advocates distributing micro-nutrients in poor countries.

          But being poor doesn’t mean one can’t succeed or even surpass the dominant culture – the children of Vietnamese immigrants in the US (at one time one of the poorest groups in the country) now graduate from college at higher rates than non-Hispanic whites.

      1. Actually, ironically, I don’t think a lot of the poor should have kids, but is isn’t because of genetics. It’s because they’re just lousy people.
        Think about it.

        1. And what’s going to stop them, exactly? The fact we don’t WANT them to?
          Unless you’re willing to do something about it–i.e., start a Eugenic neutering program–they’ll breed MORE just because you don’t want them to! Like Mexicans and Moslems do in countries they invade.

      2. It’s definitely cultural,not genetic. But that’s good enough reason to ban them from having children,cause allowing them would be massive child abuse.
        I’d say a lot of it has to do with masculinity, which is in opposition sort of to what Robert was saying. Well, 2nd hand smoke exists cause these groups think smoking is manly, and they won’t stop not even around kids. And the women do it also and are exposed to the males’s smoking.
        No, not all masculinity is a good thing.

      3. “Actually, ironically, I don’t think a lot of the poor should have kids, but is isn’t because of genetics. It’s because they’re just lousy people.
        Think about it.”
        Because poor- typically low IQ and/or inefficient personality/behavior to gain wealth or interact with others decently, both of which can be linked to genetics – result not only in bad parenting but likely bad kids – I see it.
        “Yep, and that’s one more strong reason why genetics as a source of inferority is exxagerated.”
        No, it isn’t. I pointed that out because Birth defects is an environmental (pre-natal specifically) thing that can’t be redeemed. The point of a environmental hypothesis is for circumstances that CAN be recoverable.
        So no, that doesn’t refute genetics at all.

        1. Being macho and cool is from bad breeding? No, it’s more a cultural thing. Actually if wern’t for the fact Koreans had such a high IQ already, you’d probably see a lot of birth defects from them cause the men smoke like a burning building and the wives are often around the husband or maybe work in a smoke filled environment.
          I bet if Korean women smoked, though that’s not common due to the chauvanist culture, you’d probably see the Korean IQ come down.

        2. Phil is saying all these macho hyper-masculine cultures like the US poor white one (not meaning as insult) came from bad breeding. OK, that’s up for debate? Anyone got a comeback?
          Also the tough ghetto black one would be one with tons of 2nd hand smoke, drugs, all sorts of negative stuff to cause mild or severe birth defects.

        3. What I’m saying is that behaviors that lead to that are indeed genetic.
          Defects would be environmental consequences leading from that.
          What Robert describes as “Masculinity” would be specifically Extroversion or agressiveness.

          Also, don’t act like I never brought this up before. Also, why are you using the term culture as if genetics doesn’t contribute?
          Within a culture there would be a gradient of behavioral variations that go from least to most fit for the selection that culture gives.
          Theoretically, yes, a person that can adapt to one culture could adapt to another but not in the same way as some one actually breed from that first culture and would still likely maintain tendencies from the original.
          See the Jayman link.

      4. Now, back on birth defects, cases like pre-natal deformities are virtually as biological as genetics. Hell, environmental interference like that could actually ALTER genetics, being the DNA that it would pass down to it’s child.
        So basically innate biology is still the cause in that scenario.

      1. Oh, great, link to some idiot blogger as “proof” of your nonsense.
        This is typical of you people and why no one takes you seriously.

        1. Actually, as of currently only you and Jason don’t.
          Chinedu, question, if you find HBD so stupid ans consider me an idiot why do you always comeback?
          You’ve spoken before of how this was a waste of time for you and that only people without lives do this.
          Why do you always respond to me if you claimed to ignore me? Sure, I responded to you in that oil dispute but I haven’t summoned you here now.

        2. Racialist “sources” aren’t credible by any stretch of the imagination. Jayman is a notorious idiot amateur who has been debunked all over the Internet. To make matters worse, you’ve actually harangued me for not citing any evidence. Yet in all your posts you haven’t cited one piece of evidence that hasn’t been complete bullshit.

        3. Pot calling the Kettle Black.
          You haven’t link to a source or explain why Jayman has been discredited, along with the rest of my assertions.
          Second, the link wasn’t about “race”, it was about genetics and behavior.

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