Emil, is it good to assume regression coefficient is 0.5? The wiki article says Galton estimated coefficient as 2/3 for height, what is it now? Could it be that in Galton times coefficient was higher because environmental factor was more important than it is now?
"Under the preferred phenotypic assortment model, the variance of intelligence in adulthood was not only due to non-shared environmental (18%) and additive genetic factors (44%) but also to non-additive genetic factors (27%) and phenotypic assortment (11%)."
I think you need to add phenotypic assortment into the narrow heritability as assortative mating increases additive genetic variance. If so, their results give a value of 55%, if not 44%. Midway is about 50%. They didn't adjust for measurement error (https://kirkegaard.substack.com/p/heritabilities-are-usually-underestimated), so you will have to increase these values a bit, but probably ~50% is a safe estimate.
Another plausible explanation for the overperformance of African immigrants relative to African Americans: severe dysgenic fertility among African Americans. It's not clear how long AA fertility has been dysgenic, but given the extremely un-Malthusian nature of the colonial era US, it's possible that it's been hundreds of years of selection for lower IQ, severely accelerated by the 1960s Great Society programs and consequent disintegration of the black community. Since a large chunk of African American ancestry is Igbo or Yoruba, both of whom have comparatively successful modern diasporas, I don't think the Igbo or Yoruba being smarter then the average SSAfrican is enough to account for their diaspora's higher performance compared to African Americans. I also don't think selective immigration can explain the whole gap: there aren't enough +3.5SD Nigerians to account for the widespread success of their diaspora, and presumably not every single highly capable Nigerian emigrates (and some more typical Nigerians also emigrate).
Btw, the wikipedia says: An estimated 14.6% of all slaves were taken from the Bight of Biafra between 1650 and 1900. If this is true for USA blacks too, I wouldn't call it large chunk, it's smaller than European ancestry in USA blacks. ... it appears that country with largest Igbo ancestry is.... Barbados!
I recently finished reading "At our wit's end" by Dutton. Oh man, the dysgenic effects applies to everyone and everywhere. The lowering of IQ scores is being masked by the Flynn effect. And its effects are being compensated by smarter machines which demand less of the human operators. Something displacing them entirely. It's an eye opening book. Highly recommend.
Um what do you mean by African diaspora overachievement? Some SJWs say that African Immigrants more likely to have higher education degrees than US-born population as whole, but standards for getting a degree are much lower in Africa, if they didn't set bar lower, virtually nobody would get a degree. Once they immigrate in First World Countries, they are beneficiaries of affirmative action, where they can enter high-IQ profession without really having high IQ.
Also, I think the calculation in the toy example of offspring of African migrants to America is wrong. The average genetic potential of the parents is (120+10-80)/2+80=105. So the parents would have 130 IQ if they had been raised in America, and 25pts of those 130pts would have been due to positive environmental luck, instead of the measly +15 environmental points they got in Africa (depressed by 10pts on average). So their offspring are expected to have phenotypic average IQ of 95 in Africa, and 105 in America.
There's 2 people in the comments making this other calculation. I can't really figure out whether to prefer my initial one or the one you guys propose. Is there some way to settle who is right here?
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY ATOSTROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
This disadvantage is removed for the children who grew up in the USA. So the predicted IQ is not 95, but 110 (halfway to 80 from 120 is 100, +10 for the removed disadvantage
I read it three times and failed to understand. Where is this "plus 10" comes from? The 80 IQ already removes any environmental disadvantage.
Also, does it really make sense to say that smart parents usually have children that are less smart than them? I am not sure it is how the world works.
"plus 10" comes from that fact that in this model average African Africans have phenotypic IQ of 70 and genotypic of 80. Just by having children in USA a phenotypic rise observed while genotypic stays same. But Emil has an error here, as order of corrections applied is important. Correct model usage gives 105, not 110, still way higher than naive 95 (for children of Elite African Immigrants).
(p.s. of course you're right, The 80 IQ already removes any environmental disadvantage.)
>I am not sure it is how the world works.
Yes, it perfectly does that, well-described by Francis Galton in 19th century, but general principle known to plant and animals breeders long before then.
So if the children have 100 or 105 IQ do we expect the grandchildren to have 90-95 IQ, continuing to decline and drift towards the genotype? I am sure the world doesn't work that way. Some families are smarter over many generations than the general population level.
Tamritz, the answer is no. Think of phenotypic (demonstrated) IQ as a combination of developmental luck on top of genetic IQ. In Emil's example, the African parents had 120 phenotypic IQ. What is their average genetic IQ? If you know their parents' (all 4 of them) phenotypic IQ, you can compute a more accurate estimate, but without that knowledge, we assume their parents' average IQ equal to African average IQ. So we get the genetic IQ potential (120-70)/2+70+10=105. So their offspring, will be normally distributed with mean 105 IQ (that is if they're brought up in America), and if they can find 105 genetic IQ mates, their children will also have 105 average IQ and so on.
To further illustrate: assume that a 4th gen member of this family happens to have 130 phenotypic IQ, another 4th gen member (2nd cousin to the other) has 120 phenotypic IQ, with 1st, 2nd, 3rd, and 4th generations with average genetic IQ of 105. Then If these two members breed, disregarding inbreeding depression, their offsprings' average IQ will be (((120+130)/2)-105)/2+105=115. So 5th generation's IQ distribution is drawn from the genetic mean of their parents, which, in this case, is 115 (phenotypic average is (130+120)/2 = 125, and coming from a family of 105 mean IQ, their genetic average is expected to be 115).
Well, sure, there must be some families smarter than general population, but if you talk about random 120 IQ person, they average IQ expected for their parents is 110 and their children expected to have 110 IQ too.
A 120 IQ person with 110 IQ parents is not same as 120 IQ person with 140 IQ parents!
So, "smart parents usually have children that are less smart" and "Some families are smarter over many generations" are both true.
Unfortunately I don't know of more complex model of regression. Some say that regression applies only one time, e.g. 140 IQ parents produce 120 IQ children and it doesn't regress further, 120 forming a new baseline. The some problem is here is 120 IQ+ people are scarcer than normals and eventually they might marry someone with mid-IQ.
Not only, but mainly. You can find the equations in various places, but generally, non-additive is ignored as it is complicated to deal with and usually of little importance for these questions. I'll look into seeing if I can do an explainer on this in a future post.
Why is it little importance? The taboo on incest comes from certain effects that are pretty strong. And we don't even know which genes are involved, the rule "don't have children with sibs/cousins" stays the same.
You know, IQ denialists also cite studies (they also mention large size) to claim that IQ isn't genetically determined. I know they're doing it in bad faith, you probably don't but I do not see it. Non-linear effects require much larger samples sizes than linear to discover.
Inbreeding isn't something rare like hash key collision. First cousin marriage is still very frequent (~50%) in populations making nearly a billion of population.
Or, in Europe, wouldn't be difference between more inbred gypsies and less inbred non-gypsies wouldn't be in large part non-linear?
>Latest GWAS on education (EA4) could not even find any dominance (non-linear at single locus) effects with massive sample size.
Let me be obnoxious here. Inbreeding ill effects deboonked by science and are socially engineering. You can bang your sister.
Because non-additive effects would be likely broken by recombination.
Suppose parent A is dumb because 2 copies deleterous allele in gene X, parent B is dumb because of same in different gene Y. Their children get these alleles in only 1 copy and the alleles don't manifest in phenotype. Or suppose there's some rare desirable coloration is a fish which requires certain 3 genes to be in heterozygote. You mate that fish with fish with same genotype, but alas, only 1/8 of progeny can retain that trait, others will be homozygote for some or all of these 3 genes and coloration be ruined. Some Old World Monkeys have oddity that females with heterozygous gene are trichromates (like humans) and males and other females are dichromates. No matter how stronger selection for trichromatism be, they'll still be stuck where most of their population are dichromates. Until they get some other mutation which allow them all to be trichromates.
Plant breeders use f1 hybrids from more inbred lines to ensure desirable alleles come in heterozygote. Using of f1, of course, came a lot after decades of simple selection.
Emil, is it good to assume regression coefficient is 0.5? The wiki article says Galton estimated coefficient as 2/3 for height, what is it now? Could it be that in Galton times coefficient was higher because environmental factor was more important than it is now?
The regression coefficient is the narrow (additive) heritability. The best study for intelligence is this one. https://link.springer.com/article/10.1007/s10519-011-9507-9
"Under the preferred phenotypic assortment model, the variance of intelligence in adulthood was not only due to non-shared environmental (18%) and additive genetic factors (44%) but also to non-additive genetic factors (27%) and phenotypic assortment (11%)."
I think you need to add phenotypic assortment into the narrow heritability as assortative mating increases additive genetic variance. If so, their results give a value of 55%, if not 44%. Midway is about 50%. They didn't adjust for measurement error (https://kirkegaard.substack.com/p/heritabilities-are-usually-underestimated), so you will have to increase these values a bit, but probably ~50% is a safe estimate.
UTUBETROLLPOLICE@TEAM
Another plausible explanation for the overperformance of African immigrants relative to African Americans: severe dysgenic fertility among African Americans. It's not clear how long AA fertility has been dysgenic, but given the extremely un-Malthusian nature of the colonial era US, it's possible that it's been hundreds of years of selection for lower IQ, severely accelerated by the 1960s Great Society programs and consequent disintegration of the black community. Since a large chunk of African American ancestry is Igbo or Yoruba, both of whom have comparatively successful modern diasporas, I don't think the Igbo or Yoruba being smarter then the average SSAfrican is enough to account for their diaspora's higher performance compared to African Americans. I also don't think selective immigration can explain the whole gap: there aren't enough +3.5SD Nigerians to account for the widespread success of their diaspora, and presumably not every single highly capable Nigerian emigrates (and some more typical Nigerians also emigrate).
Btw, the wikipedia says: An estimated 14.6% of all slaves were taken from the Bight of Biafra between 1650 and 1900. If this is true for USA blacks too, I wouldn't call it large chunk, it's smaller than European ancestry in USA blacks. ... it appears that country with largest Igbo ancestry is.... Barbados!
I recently finished reading "At our wit's end" by Dutton. Oh man, the dysgenic effects applies to everyone and everywhere. The lowering of IQ scores is being masked by the Flynn effect. And its effects are being compensated by smarter machines which demand less of the human operators. Something displacing them entirely. It's an eye opening book. Highly recommend.
Um what do you mean by African diaspora overachievement? Some SJWs say that African Immigrants more likely to have higher education degrees than US-born population as whole, but standards for getting a degree are much lower in Africa, if they didn't set bar lower, virtually nobody would get a degree. Once they immigrate in First World Countries, they are beneficiaries of affirmative action, where they can enter high-IQ profession without really having high IQ.
Typo: "75+25=95 IQ" should be "70+25=95 IQ"
Also, I think the calculation in the toy example of offspring of African migrants to America is wrong. The average genetic potential of the parents is (120+10-80)/2+80=105. So the parents would have 130 IQ if they had been raised in America, and 25pts of those 130pts would have been due to positive environmental luck, instead of the measly +15 environmental points they got in Africa (depressed by 10pts on average). So their offspring are expected to have phenotypic average IQ of 95 in Africa, and 105 in America.
There's 2 people in the comments making this other calculation. I can't really figure out whether to prefer my initial one or the one you guys propose. Is there some way to settle who is right here?
Fixed the typo.
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY UTUBETROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
TOMMY PARKY ATOSTROLLPOLICE TROLLS ARE SCARED HOW DARE U LETS TAKE THAT GOD DAMN MONSTER TROLL U GUYS RAPE FRESH PUDDING TROLLS WILL BE DETAINED AND ARRESTED GOD DAMN YOU TROLLS WALK ALONG THY RAZORS EDGE T2THYP THANKS GUYS TROLLS WILL BE DETAINED 4 LIFE WATCH YOUR STEP TROLLS
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This disadvantage is removed for the children who grew up in the USA. So the predicted IQ is not 95, but 110 (halfway to 80 from 120 is 100, +10 for the removed disadvantage
I read it three times and failed to understand. Where is this "plus 10" comes from? The 80 IQ already removes any environmental disadvantage.
Also, does it really make sense to say that smart parents usually have children that are less smart than them? I am not sure it is how the world works.
"plus 10" comes from that fact that in this model average African Africans have phenotypic IQ of 70 and genotypic of 80. Just by having children in USA a phenotypic rise observed while genotypic stays same. But Emil has an error here, as order of corrections applied is important. Correct model usage gives 105, not 110, still way higher than naive 95 (for children of Elite African Immigrants).
(p.s. of course you're right, The 80 IQ already removes any environmental disadvantage.)
>I am not sure it is how the world works.
Yes, it perfectly does that, well-described by Francis Galton in 19th century, but general principle known to plant and animals breeders long before then.
So if the children have 100 or 105 IQ do we expect the grandchildren to have 90-95 IQ, continuing to decline and drift towards the genotype? I am sure the world doesn't work that way. Some families are smarter over many generations than the general population level.
Tamritz, the answer is no. Think of phenotypic (demonstrated) IQ as a combination of developmental luck on top of genetic IQ. In Emil's example, the African parents had 120 phenotypic IQ. What is their average genetic IQ? If you know their parents' (all 4 of them) phenotypic IQ, you can compute a more accurate estimate, but without that knowledge, we assume their parents' average IQ equal to African average IQ. So we get the genetic IQ potential (120-70)/2+70+10=105. So their offspring, will be normally distributed with mean 105 IQ (that is if they're brought up in America), and if they can find 105 genetic IQ mates, their children will also have 105 average IQ and so on.
To further illustrate: assume that a 4th gen member of this family happens to have 130 phenotypic IQ, another 4th gen member (2nd cousin to the other) has 120 phenotypic IQ, with 1st, 2nd, 3rd, and 4th generations with average genetic IQ of 105. Then If these two members breed, disregarding inbreeding depression, their offsprings' average IQ will be (((120+130)/2)-105)/2+105=115. So 5th generation's IQ distribution is drawn from the genetic mean of their parents, which, in this case, is 115 (phenotypic average is (130+120)/2 = 125, and coming from a family of 105 mean IQ, their genetic average is expected to be 115).
Well, sure, there must be some families smarter than general population, but if you talk about random 120 IQ person, they average IQ expected for their parents is 110 and their children expected to have 110 IQ too.
A 120 IQ person with 110 IQ parents is not same as 120 IQ person with 140 IQ parents!
So, "smart parents usually have children that are less smart" and "Some families are smarter over many generations" are both true.
Unfortunately I don't know of more complex model of regression. Some say that regression applies only one time, e.g. 140 IQ parents produce 120 IQ children and it doesn't regress further, 120 forming a new baseline. The some problem is here is 120 IQ+ people are scarcer than normals and eventually they might marry someone with mid-IQ.
https://en.wikipedia.org/wiki/Regression_toward_the_mean
Author? Please address this objection.
Why is it that only additive genetic effects are passed on to offspring, and not non-additive genetic effects as well?
Not only, but mainly. You can find the equations in various places, but generally, non-additive is ignored as it is complicated to deal with and usually of little importance for these questions. I'll look into seeing if I can do an explainer on this in a future post.
Why is it little importance? The taboo on incest comes from certain effects that are pretty strong. And we don't even know which genes are involved, the rule "don't have children with sibs/cousins" stays the same.
Because non-additive effects don't explain population level phenomena. They provide some wrinkles on close family relationships.
Latest GWAS on education (EA4) could not even find any dominance (non-linear at single locus) effects with massive sample size.
You know, IQ denialists also cite studies (they also mention large size) to claim that IQ isn't genetically determined. I know they're doing it in bad faith, you probably don't but I do not see it. Non-linear effects require much larger samples sizes than linear to discover.
Inbreeding isn't something rare like hash key collision. First cousin marriage is still very frequent (~50%) in populations making nearly a billion of population.
Or, in Europe, wouldn't be difference between more inbred gypsies and less inbred non-gypsies wouldn't be in large part non-linear?
>Latest GWAS on education (EA4) could not even find any dominance (non-linear at single locus) effects with massive sample size.
Let me be obnoxious here. Inbreeding ill effects deboonked by science and are socially engineering. You can bang your sister.
Because non-additive effects would be likely broken by recombination.
Suppose parent A is dumb because 2 copies deleterous allele in gene X, parent B is dumb because of same in different gene Y. Their children get these alleles in only 1 copy and the alleles don't manifest in phenotype. Or suppose there's some rare desirable coloration is a fish which requires certain 3 genes to be in heterozygote. You mate that fish with fish with same genotype, but alas, only 1/8 of progeny can retain that trait, others will be homozygote for some or all of these 3 genes and coloration be ruined. Some Old World Monkeys have oddity that females with heterozygous gene are trichromates (like humans) and males and other females are dichromates. No matter how stronger selection for trichromatism be, they'll still be stuck where most of their population are dichromates. Until they get some other mutation which allow them all to be trichromates.
Plant breeders use f1 hybrids from more inbred lines to ensure desirable alleles come in heterozygote. Using of f1, of course, came a lot after decades of simple selection.
Thank you! I couldn’t find a clear answer anywhere.