Variation in general intelligence and our evolutionary history

In a bit of “TMI”, I’m far more intellectually promiscuous than I am in my personal life. My primary focus on this blog, if I have one, is probably historical population genetics of the sort highlighted in David Reich’s Who We Are and How We Got Here. But I have plenty of other interests, from economic history to cognitive psychology. Like religion, I have precise and clear opinions about a topic like “intelligence.” Unlike many people with an interest in evolutionary genetics I have read psychometric work, am familiar with some of the empirical results, as well as being personally acquainted with people in the field of psychometrics.

A few days ago Nassim Nicholas Taleb opined on intelligence, and I was silent. Today some individuals who I know from within the field of cultural evolution, another one of my interests, discussed intelligence, and I was silent. I’ve said all I really have to say over 15 years, and it isn’t as if I reanalyze psychometric data sets. But, a question that Taleb acolytes (and presumably Taleb) have brought up is if intelligence is such an important heritable trait, why isn’t everyone much smarter?

Think of this as the second Von Neumann paradox. What I’m alluding to is the fact that we know for a fact that human biology is capable of producing a god-made-flesh. With all due respect to another Jew who lived 2,000 years earlier than him, I speak here of John Von Neumann. We know that he is possible because he was. So why are the likes of Von Neumann bright comets amongst the dust of the stars of the common man, rather than the norm?

First, consider the case of Von Neumann himself. He had one daughter and two grandchildren. That is, within two generations genetically there was less “Von Neumann” than there had been. Though his abilities were clearly mentat-like, from the perspective of evolution Von Neumann was not a many sigma individual. He was within the normal range. Close to the median, a bit below in fecundity and fitness.

Taking a step back and focusing on aggregate populations, the fact that intelligence seems to be a quantitative trait that is at least moderately heritable and normally distributed due to polygenic variation tells us some things evolutionarily already. In Principles of Population Genetics is noted that heritable quantitative traits are often those where directional selection is not occurring due to huge consistent fitness differentials within the population.

Breaking it down, if being very smart was much, much, better than being of average smarts, then everyone would become very smart up to the physiological limit and heritable genetic variation would be removed from the population. Characteristics with huge implications for fitness tend not to be heritable because natural selection quickly expunges the deleterious alleles. The reason that fingerprints are highly heritable is that the variation genetically is not much impacted by natural selection.

The fact that being very intelligent is not evolutionarily clearly “good” seems ridiculousness to many people who think about these things. That’s because if you think about these things, you are probably very good at thinking, and no one wants to think that what they are good at is not evolutionarily very important. The thinking man cannot comprehend that thinking is not the apotheosis of what it is to be a man (similarly, the thinking religious man sometimes confuses theological rumination with the heights of spirituality; reality is that man does not know god through analysis, man experiences god).

So let’s talk about another quantitative trait which is even more heritable than intelligence, and easier to measure: height. In most societies males, in particular, seem to be more attractive to females if they are taller. As a male who is a bit shorter than the American average, it is obvious that there is some penalty to this in social and potentially reproductive contexts. And yet there is normal variation in height, and some populations seem to be genetically smaller than others, such as the Pygmy peoples of the Congo rainforest. Why?

Though being a tall male seems in most circumstances to be better in terms of physical attractiveness than being a short male, circumstances vary, and being too tall increases one’s mortality and morbidity. Being larger is calorically expensive. Large people need to eat more because they have larger muscles. Selection for smaller size in many marginalized rainforest populations is indicative of the fact that in such calorically challenging environments (humans in rainforests have to work hard to obtain enough calories in a hunter-gatherer context), the fitness gain due to intrasexual competition is balanced by reduced fitness during times of ecological stress as well as individual correlated responses (very large males die more often than smaller males).

Additionally, for height I mentioned the sexual component: there does not seem to be a necessary association with higher reproductive fitness with being a tall woman. Though this is subject to taste and fashion, there is likely some antagonistic selection across the two sexes at work, where tall men are the fathers of taller daughters, whose reproductive fitness may actually be lower than smaller women. And vice versa, as short men may produce more fit short daughters (though again, this depends on ecological context and cultural preconditions).

Being very large impacts fitness through the genetic correlation of size with other characteristics. Very large males are subject to higher risk for sudden tears in their lungs, or suboptimal cardiac function. Humans select chickens to be very large in the breast for food, but these chickens can barely walk, and may not be able to reproduce without assistance. Evolution in a quantitative genetic sense may then be all about trade-offs.

So let’s go back to intelligence. What could be the trade-offs? First, there are now results presented at conferences that very high general intelligence may exhibit a correlation with some mental pathologies. Though unpublished, this aligns with some prior intuitions. Additionally, there is the issue where on some characteristics being “species-typical” increases reproductive fitness (an average size nose), while in other characteristics being at an extreme is more attractive (very curvy women with large eyes and small chins; secondary sexual characteristics). Within intelligence, one could argue that being too deviated from the norm might make socialization and pair-bonding difficult. Here is an anecdote about the genius Von Neumann:

Neumann married twice. He married Mariette Kövesi in 1930. When he proposed to her, he was incapable of expressing anything beyond “You and I might be able to have some fun together, seeing as how we both like to drink.”

Apparently having a very fast analytic mind which can engage in abstraction and conceptual manipulation does not mean that one can come up with anything better than that when it came to procuring a mate. And procuring a mate is one of the only “good” things from an evolutionary perspective.

The human mind is neither universally plastic, nor it is a prefabricated set of specialized modules. It is a mix of both. We clearly have some “pre-loaded” code, such as the ability to recognize faces intuitively and rapidly (which a small proportion of the population lacks). But other competencies develop over time, co-opting neurological architecture that grew organically for other purposes. In Reading in the Brain Stanislas Dehaene recounts how the region which specializes in the ability to recognize letter shapes is a preexistent visual-spatial module, probably developed for ecological adaptation to environments where recognition of various organic and inorganic objects was of fitness relevance (obviously now tied in to regions of the brain geared toward verbal comprehension). Dehaene even seems to suggest there may be a trade-off between various cognitive capacities when comparing individuals from urban developed societies and individuals from non-literate small-scale societies.

As human societies have specialized over the last 10,000 years a small number of people who naturally were on the end of a particular distribution in abstraction-and-analysis ability began to preferentially fill exotic niches that had previously not existed. From all we can tell the ancient polymath Archimedes was a Von Neumann for his age. Archimedes seems likely to have been of aristocratic background, and part of the class of leisured intellectuals. The fact that he had such innate talent and disposition, combined with his life circumstances, was simple happenstance.

Today we live in a different age. Specialization, and the post-industrial economy, put a premium on competencies associated only with individuals on the “right tail” of the IQ distribution. Similarly, our genetic background predisposes many of us to obesity because the modern environment is “obesogenic.” The reality is that obesity was not an issue for almost all of human history, so genetic variation (often behavioral/cognitive) that is associated with obesity today was not so associated with it in the past. There could be no selection against obesity when it wasn’t a trait within the population.

Just as the modern environment is potentially “obesogenic,” it is also potentially “intelligenic.” Here’s what I’m talking about, The Science Behind Making Your Child Smarter:

The research also lends insight into why many apps and training programs aimed at raising IQ fail to produce lasting effects, says Elliot Tucker-Drob, an associate professor of psychology at the University of Texas at Austin, and co-author of the study.

Raising IQ may require the kind of sustained involvement that comes with attending school, with all the practice and challenges it entails. “It’s not like you just go in for an hour of treatment a week. It’s a real lifestyle change,” he says

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To be a “nerd” is a lifestyle only possible in the modern information-rich environment. The Flynn effect is evidence that changing environments can shift the whole distribution. But just as with obesity or adult-onset diabetes risk, there is also heritable variation latent across the genome that seems to affect one’s response to the intelligenic environment.

Humans have large brains for our size. We are smarter than other primates. But evolutionary genetics today seems to be coming to the conclusion that it wasn’t a quantum jump, but gradual selection and change. Having a very low intellectual capacity was probably correlated with low fitness in the past (though small brains are calorically less greedy).

But, having a very high general intelligence does not seem to have resulted in that great of a gain in social or cultural status in comparison to being of normal intelligence. In fact, if the genetic correlation is such that it’s associated with some higher risk for mental instability, it could simply be that a form of stabilizating selection over time kept humans within the “normal range” because that was evolutionarily optimal. Be smart enough. But not too smart that you are weird.

And, as theorists from cultural evolution have observed, we are a “hive-mind” which leverages collective wisdom. Most of us don’t have to derive mathematical equations, we can use the formula provided to us. Though it’s useful to have a few people around who can invent statistics that the rest of us use…

37 thoughts on “Variation in general intelligence and our evolutionary history

  1. My attitude to optimal intelligence is that it’s like optimal beauty: doomed to be lost in the genetic shuffle in the next generation. All evolution can do is keep that balloon bumping on the ceiling as much as it can. Von Neumann was on the ceiling, and even if he married a female von Neumann, the random combination of those two low-entropy decks is unlikely to be lower entropy, and likely to be higher entropy.

    The paradox of intelligence is like the paradox of the sage grouse. In every generation of male sage grouse, most are losers who never pass their genes on, and yet every single one of those is the son of a long line of winners. Their fathers, grandfathers, and great grandfathers were all the prettiest male sage grouse you ever saw. What went wrong?

    If splendid peacock tails are reproductively advantageous, why aren’t they more splendid? The peacock replies “Jesus, lady, I’m doing my best, what do you want?”

  2. jim, i am not sure that the analogy with sexual selection works. our reproductive skew is not that high. also, the variation in health in these traits is probably due to variation in mutation if it’s heritable. there aren’t huge effect alleles segregating in the human population so probably not mutation load.

  3. If the daughters of tall men will tend to have lower fitness, it does make one wonder why women would start preferring tall men in the first place. The one explanation I’m familiar with is that having more “genetic load” will tend to make one shorter, as will being calorically deprived in development (also associated with reduced fitness). I’m guessing that some one has worked out a fuller model for how the factors will balance out in various environments (I don’t think Bergmann’s rule explains northern vs southern Europe, as Eskimos aren’t shaped like Swedes).

  4. the thinking religious man sometimes confuses theological rumination with the heights of spirituality; reality is that man does not know god through analysis, man experiences god).

    Easy enough to confuse the accelerate for the fire.

  5. Don’t discount the possibility that it’s simply not true that tall women are at a disadvantage. Although I couldn’t find the data now, I’ve seen studies that suggest women are paid more, promoted sooner, promoted further, date more and are less likely to remain unmarried, for every extra inch, just like men. The only difference is that it tops out at six feet for women, not getting worse, but getting no better for every inch after that. For men there is no such limit.

  6. Has there ever been a time and place where Von Neumann like intelligence would result in a significant selective advantage? Peasants and hunter-gatherers are already pretty good at what they do, and while more intelligence would certainly never hurt I don’t see Von Neumann’s level of intelligence as being all that big a plus for them. And these days high intelligence may even be a negative in reproductive terms. If Gregory Clark and Cochran & Harpending are to be believed, humans responded pretty quickly to even moderately strong selection for intelligence, when such selection existed. It just doesn’t seem to have existed all that often.

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  7. Touched upon but not explored is an idea that may explain much of these observations: “hive mind”…

    Perhaps human intelligence was not being selected at the individual level, but at kinship level within cooperative groups. For example, if one group has at a given moment in time, a very bright individual who reads the environmental signs that it would be best if they moved on to a better environment and is able to lead / cajole the group to better grounds, the group’s genes are better reproduced and represented in later generations in the larger pool. This group selection would allow lower intelligence alleles to remain in the pool as they are not actively selected against. Increases in brain size and intelligence would thus be a very slow process.

    Interestingly, the comment was made that the increase in brain size was slow. But I would argue the opposite. If we compare the rate of increase in cetacean compared to hominid species over evolutionary time, hominid increase looks truly rapid.

    Another comment made here was a reference to the EQ, encephalization quotient, the ratio of brain size to body size. This may not be as useful a measurement as is generally thought. A better one may be total neuron and synapse count. The smartest birds have denser neurons than mammals. It has always struck me as odd that we accept as proven that a larger body requires more brain to control it. Why should it? Aside the problem of having more muscle cells to control, the number of muscle groups and the degrees of freedom of articulation within a given phylogenetically related species group is largely unchanged.

  8. Is winning a Fields Medal really a significant selective advantage compared to, say, the ordinary (“ordinary”) professor of mathematics? Your typical university professor has their pick of sexual partners whether they’ve won an award or not.

  9. Though his abilities were clearly mentat-like

    One of the big myths is that von Neumann was a great mental calculator — in fact he was not so at all, he simply memorized certain physical constants and algebraic techniques (there used to be a terrific bag of techniques back when the word “computer” referred to a human who calculated as a profession — look up “nomography” for example). This is because calculation is purely a matter of memorization and recall, and if von N. really was such a mental calculator then he could memorize text verbatim like Euler (who did have absolute recall) — and yet he had difficulty remembering people’s names. In terms of his proofs (e.g., in “Rings of Operators”, Parts I-IV), there is nothing at all to indicate any special faculty. There is a certain similarity in spirit between the way that von Neumann and Norbert Wiener thought. In their case, it has to do not with the originality of a certain construction, but of restricting the set of ideas in just the right manner, so that by taking combinations of them, the machinery (=formalism, language) itself would be powerful enough to smash open the problem. Wiener would, for example, translate any problem at all into a Wiener-Hopf problem, and then pull through by analytic tricks accumulated via memory. (A “baby example” of that — that I presume everyone here can follow — is the following simple problem involving random lengths: if a straight stick is cut up in three pieces at two points independently along its length, determine the probability that the three sticks can be made into the sides of a triangle [i.e., the sum of any two lengths must be larger than the third]. All you have to do, is to translate this into the language of (independent, continuous) random variables and uniform distributions — and then after everything had been completely translated, the problem simplifies almost to the solution via simple algebra.)

    Consequently their proofs are not elegant or efficient at all, even though once in a while it would be powerful enough to establish the first cracks in a problem. For example, G. D. Birkhoff, after reading von Neumann’s proof of the “mean” ergodic theorem, took just one week to prove his own (much better) version via “time averages”. Birkhoff’s proof was far more fundamental and difficult, than any single thing von Neumann did.

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  10. Not quite sure what is meant in the phrase, “very large males die more often than smaller males”.

    We all die precisely once so … That on average, very large (tall?) males have shorter lives than smaller (short?) males? That in an arbitrary situation, or any arbitrary life-threatening situation, a very large male is more likely to die than a smaller male?

    I suspect my first guess, but it’s just a guess, not even a hypothesis.

  11. Have you heard of the recent finding that children use the supposed “face-recognition module” to recognize Pokemon? I think the takeaway was that it isn’t a specialized face-recognition module after all, but a specialized module for distinguishing variations within a type. It’s used for distinguishing faces because that’s just a common cognitive task starting at birth. That may be a common pattern, and the brain may be less modular than supposed. I’m not a scientist though.

  12. marcel, yeah, shorter life expectancy. i guess i mean they have a higher death rate as adults. mostly cardiac. but tearing in lungs is pretty common apparently for tall thin males, though not lethal in a modern society.

  13. ” I’m far more intellectually promiscuous than I am in my personal life.”

    I am not totally sure that came out like you wanted it to. Does your wife read the blog?

  14. Since splitting from Pan, the brains in our lineage have tripled in size, with the result that humans are a lot smarter than chimps. I’m having difficulty even coming up with story in which this happened without any sort of selection for (heritable) intelligence.

  15. Since splitting from Pan, the brains in our lineage have tripled in size, with the result that humans are a lot smarter than chimps. I’m having difficulty even coming up with story in which this happened without any sort of selection for (heritable) intelligence.

    i think there was a lot of selection. but there is a difference btwn inter vs intra specific variation. encephalization plateaued around 100-200K BP for example. since then the changes are probably more subtle and more marginal re: fitness.

    (there may also be weird group-level dynamics)

  16. Mr. Khan, I don’t have anything to add, except to say that I found this piece to be both informative and entertaining. I don’t know whether you meant it to be or not (I suspect you did), but it was quite funny.

  17. “if intelligence is such an important heritable trait, why isn’t everyone much smarter?”

    Who says they aren’t? Modern humans are clearly far smarter than our primate ancestors a million years ago, and even looking back on a scale of thousands of years or even centuries, there seems to have been a massive rise in intelligence. We obviously have quantitative data on this going back about a century in the form of the Flynn effect. But aside from that, the bar for being a “genius” thousands of years ago seems to have been far lower. Just compare Aristotle with Newton, and it’s hard to argue that the former was anywhere near as smart as the latter. Now personally I think a lot of this is due to cultural changes (e.g. looking at Europe, there is a sudden jump in lucidity and logical reasoning in writing when you compare the late medieval age with the early modern period), but it seems weird to argue “if IQ is heritable, why aren’t people smarter?” when people are extraordinarily smart… Consider for example the fact that modern AI seems to be capable of replicating most animal behavior, or likely even primitive early humanoid behavior, but seems to be incredibly far from replicating the conversational and reasoning abilities of a modern human intellectual.

    Of course, with recent shifts in mating dynamics, and particularly the rise of elective birth control, the selection forces are probably now tilted against intelligence.

  18. I’m suspicious of explanations that hand-wave that average intelligence is somehow optimal, with high intelligence implying some vague trade-off. It’s too pat, and it’s sometimes used to justify the idea that current genomes are somehow unimprovable, when they’re actually banged-up messes.

    The explanation you later bring up, that we’re simply living in an environment that is a poor match for evolutionary conditions, is more satisfying. For one thing, it’s obviously true. Today, it would be reproductively optimal to have a very large family (say 10 kids), and the fact that hardly anyone does that is obviously just because natural selection hasn’t had time to select for it. Intelligence is only fitness-negative because it causes people to burn time getting an education instead of popping out kids; if not for that, intelligence would be fitness-positive, by facilitating the earning of income to support a large family.

  19. Information richness could be the key maybe, to produce practical results with abstract reasoning you need reliable information, and that is much more likely to be the bottleneck than processing ability. In a small scale society what is there that’s fodder for fancy math? Which I guess is why science starts with astronomy – observable by everyone, tampered with by no one, repeats endlessly, amenable to calculation, plausibly having important effects worth knowing.

  20. (there may also be weird group-level dynamics)

    If you start subscription, will a subscriber get one free request for blogging subject with the subscription? If so, this is mine.

  21. It’s arguable that `intelligence’, like `race’, is only marginally
    meaningful; and that what von Neumann, or Schr\”odinger, or Newton or Ramanujan had wasn’t `intelligence’ at all. They were all extreme points on some very high-dimensional polyhedron; trying to
    order them linearly by `intelligence’ is a meaningless endeavor.

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  22. To what extent heritability from twin studied may reflect possibly common de novo dominant mutations (not necessarily with super severe deleterious effects on cognitive function, but still subject to purifying selection) ? Can one evaluate if the “left-side tail” contributed more to the heritability estimates than the “higher-end / right-side” tail of the distribution?

  23. Oh, and a couple more thoughts about reproductive disadvantages of extreme intelligence in the evolutionary past.
    Skilled administrators and accountants have been in demand in the societies soon after the invention of agriculture and literacy, but these jobs and their crowded locations must have been quite unhealthy. Priests and shamans might have contributed to demand to intelligence even sooner, and some of these occupations are also fairly unhealthy. But there wasn’t that much meritorcacy, more like hereditary occupations and dynasties, right? So outside of the immediate families of the priests or scribes, the demand for intelligence may have been lacking all the same? Just because the society has been structured in such a hereditary way?

    Another point along the same line of a larger-clan effects. If an extreme mental ability is by itself detrimental to reproductive success, then perhaps it may have positive effects for siblings and nephews of the ultra-smart person (the societal success / riches / influence rubs on the family members, right?)

    And a third one … along the same line of “clan effects” again. If a population group monopolizes an intellectual occupation for a historically long time, then wouldn’t such a group tend to develop Flynn-like trends towards increasing intelligence?

  24. I wonder whether the likes of Neumann were smart so “weird”, or just smart and weird, and that the smarts who are not weird are simply not salient to us culturally because that level of smarts is only useful on problems that the only the “weird” tend to be really interested in (where it is even still, not that useful in looked at in fitness terms).

    I can imagine there’s some level of correlation between extreme smart and weird, but I am rather a skeptic that a high correlation is not the “weird” doing themselves rather too much honor and indulging in a bit of self flattery.

  25. Many of the commenters seem to consider only “aspie-kind” of intelligence (e.g., the mathematical ability), while clearly it’s the social (even Macchiavellian) intelligence that has mattered most among our social species, and I think still does.

  26. I doubt that selective pressure has consistently favored increased intelligence. What would have happened if the entire population of Natufian settlements or the inhabitants of Uruk had been all Cavendish, Newton, and Von Newman?

    Somebody has to grow the food, repair the roofs and fix the plumbing to create a society in which someone like Cavendish can survive. I am not even sure that an aware population would elect a Cavendish over a more ordinary person. When the English spoke of someone of good breeding it probably was more than just an expression. Family trees of potential mates would be looked at with the care also bestowed on breeding cattle and horses. Somebody too odd, even if brilliant, might be a negative rather than a positive factor.

    I suppose that is changing now that society is becoming so complex that the need for odd-ball brilliance is accepted and we try to engineer our children in that direction.

  27. A. Karhumaa: “while clearly it’s the social (even Macchiavellian) intelligence that has mattered most among our social species,”

    I think there is a paradox here: social (“Machiavelian”) intelligence is much more useful to the individual than to society (because many of this social manipulation is very close to a zero-sum game: what a good used cars salesman do is to convince people to by from him instead of from other salesman); in contrast, the schizoid/aspie-kind of intelligence (the intelligence of the asocial nerd) is much more useful to society than to the individual (the positive externalities of inventing or discovering something are sometimes enormous, because good ideas are then copied by not-so bright people)

  28. IQ is obviously heritable and does have evolutionary advantage as is evident from the dominance of humankind over other forms of life. Does a higher IQ within human races (whatever race might mean) lead to the dominance of one race over the other is a different sort of question. Whites dominated blacks, browns and yellows though the Chinese and Japanese are supposed to have a higher IQ. And we know all about the Ashkenazi IQ which seems not to have helped in domination at all.
    The broader question is I think what benefit analysis of intelligence by ethnicity confers. If the percentage of blacks with an IQ of 120 is smaller than that of whites, what policy prescriptions follow? If a higher IQ population is a eugenic goal then obviously it does not rule out mating between whites and blacks when their IQs are similar. On the other hand, if the elimination of lower IQ is a eugenic goal it would mean restricting procreation among low IQ blacks and whites alike. In my opinion research in this field can have no practical outcomes.

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  29. IQ is heritability + environment. Personal success, however you measure that, is IQ + industriousness, or conscientiousness, or you could call it ‘application’. People need more than just raw cognitive ability, they need to want to succeed in some field of endeavour enough to work hard at it.

    In societies with a lot of environmental insults that disproportionately affect children badly (malnutrition, lead, childhood diseases, parasites, chronic diarrhea due to poor public hygiene, and no doubt some others), heritability of intelligence is only about 50%, because those environmental insults adversely impact cognitive ability. If you eliminate most of the environmental insults, it rises to 70-80%. Plus you need to think of all of the possible reasons for the Flynn effect, which seems now to have topped out in the most highly developed, wealthy countries but is still happening in countries that are still developing.

    By dominance, you seem to mean military dominance. A lot of factors played a part in that. If you had been around in E/SE Asia and the Pacific in 1942, the Japanese would certainly have had your attention. They had Australia terrified, although at that distance the Japanese supply lines were stretched to breaking point and there was a major rift between the Japanese army and navy about whether or not to invade Australia; they bombed Darwin extensively, and could have invaded northern Australia easily if they had managed to take Port Moresby in Papua New Guinea and secured their supply lines, and that was a close run thing by combined American and Australian military with close support bases against starving Japanese troops suffering tropical diseases. It was their lack of resources to replace lost material, particularly aircraft carriers and trained pilots, and the industrial might of the USA once it was fully geared to the war effort, that led to them being defeated in the Pacific, but a very large number of very courageous US Marines, naval personnel and airmen died in the process. American industry had been cranking out new ships and planes at an amazing rate that the Japanese didn’t have anywhere near the resources to match.

    The reasons enabling the European humiliation of China in the 19th Century have been well documented, and China in the first 70 or so years of the 20th Century was a mess. It is obviously emerging strongly from that now. I first traveled extensively in China in 1982, and since then it has been transformed unrecognizably.

    If you adopt a criterion of personal achievement, rather than military dominance (which is a ridiculous criterion to apply to Ashkenazim, just on effective population size alone), then it’s very hard to argue that Ashkenazim have not been disproportionately successful, particularly in intellectual endeavours, in very many fields.

    Take a look at any Chinese diaspora community and it is obvious that they are disproportionately commercially successful compared to the locals. In my field of civil engineering, take a look at the big, commercially successful international heavy engineering contractors, and you will see that Japanese companies are disproportionately successful. The Japanese automobile industry is still dominant. Chinese overseas investment is becoming so large that it has a lot of people very worried about ‘dominance’. Do you think South Korea has not risen very rapidly to economic success? Ever heard of Samsung?

    SubSaharan Africa is beset by environmental insults of all kinds, more than any other continent. It will be of interest to see what happens when those are progressively overcome. Even so, sSA communities are not uniform by any means. The Igbo of Nigeria produce a disproportionate number of very smart people who are very successful, once they migrate into an environment where they can apply their abilities fully.

    None of this is about eugenics. If there is a good reason to analyse mean IQ by population, it is so that environmental insults to cognitive ability can be identified and progressively eliminated. What would happen in India if public hygiene could be massively improved with modern plumbing? I guess we’ll find out in Bangladesh, where government efforts to improve public hygiene have been pretty spectacularly successful in driving down childhood mortality.

    I’m bored with this subject, bored by Taleb, and bored by people who think that it is not a useful field for research.

  30. RB Singh: You wondered what practical benefit might flow from IQ studies of different ethnicities. One benefit could be legal. We could stop punishing organizations for not employing or graduating people in ratios corresponding to their percentages in the population under the notion that any ‘disparate impact’is due to racism rather than different group characteristics.

  31. Talking about success gets us on to some definition questions. The post mainly talks about it in Darwinian fitness terms. I’d guess intelligence is probably maximised in relevance for individual scientific success in our societies, where there’s a fair amount of public and private investment wealth about to fund careers as a scientist whatever your background (though I’d say even then, single biggest factor or threshold factor rather than sufficient). On individual economic success, or even group level scientific or economic success it seems a bit less obviously influential (even if still the single largest factor).

    On the side of group economic success in the very long term, and taking China (as that’s sort of where the conversation led) for an example, it’s known that Chinese tend to have fairly relatively high IQ scores and this looks reasonable to go back in time, and also had a fairly strong intellectual and technical economy for their time, between at least 0-1500 AD. But less clear to me this IQ had much to do with the economic and so intellectual success of the culture relative to other factors.

    Namely: In good times, being able to sustain a relatively large integrated empire or people through being fairly ethnically and religiously homogenous and isolated from much of the world on rich farmland, with just enough pressure from the steppe groups to prevent too much infighting. Then in bad times, relative to the world’s leading edge, being isolated from ideas and the competitive pressures that force positive innovation, and the fragility of having one big state.

    There’s an argument China’s elite were captured by the landlord class which dominated examinations and were able to push a vision of a stable, conservative state with an idealised agrarian basis with low land tax levels (and hence low government revenue) and limited trade and merchant class. Just when other states in the West were (so goes the story) using a shift to a trade and manufacturing fuelled economy with higher tax to fund more capable and stronger states with constitutionally defined limits, and that this is all because competitive pressures forced European states to do this.

    Of course, there’s also a question about whether this agrarian bias relates to China’s 18th century demographic doubling – http://visualizingeconomics.com/blog/2007/12/09/comparing-population-growth-china-india-africa-latin-america-western-europe-united-states. For all that it has did absolutely nothing for GDP per capita – https://i.imgur.com/lRitoeZ.png – which was looks more morose under the Qing than India under the Mughals!

  32. Matt, suggest maximised in ‘successful life outcomes’ by a whole range of measures (Hong Kong and Macau have among the world’s highest life expectancies, even higher than Japan). China shows a lot of variation in mean IQ by province, and regional – south east tends to be smarter than north (haven’t figured out why – not necessarily what you would expect). Smart people now migrate to those cities where they perceive they have the best opportunities, so Shanghai and Shenzhen a lot higher than other parts of the country, but this is largely a modern trend (?). Hong Kong has benefited in the past due to smart people getting out of e.g. Shanghai and Guandong to HK after the communists won the civil war, but that is no longer salient and HK is now falling behind Shanghai and Shenzhen in innovation. Ageing population could be a factor, particularly pronounced in HK, plus small pool of human capital with pop. of only 7 million and sky high cost of infrastructure. Probably won’t matter much longer term as the whole Pearl River Delta region is being integrated into a megalopolis.

    Projecting back in time, need to be mindful of environmental insults that prevent children from reaching their genetic potential. For large majority of population in China, likely to include poor nutrition, disease and, in the south esp., parasites. Qing – endemic corruption; has a really big effect. Xi Jinping has been brutal in putting down corruption for very good reasons, and he has a proven track record of fighting corruption since at least 1986 – he knows what it does to economy.

    Just things to bear in mind.

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