Sources of group differences

Plomin is and always has been careful not to talk about questions outside his immediate research, because they’d get him in trouble. He reaps more than enough trouble just doing his job.  So much so that he sometimes says ridiculous things just to avoid trouble, like saying that nobody knows what causes male-female differences. It is to laugh.  Yeah, we know that one.

What about inter-population differences in personality and intelligence?  Are they driven by mystic factors insusceptible to the scientific method, as Mr. T suggests? Of course not. Since they exist in populations going to the same schools, eating approximately the same food, watching similar TV – since they show up by age three – you can rule out a lot of causative factors.  Generally, anything that would fall into the shared-environment category doesn’t seem to explain it, just as it doesn’t explain within-pop differences.  In most developed countries anyhow: in some places factors like iodine deficiency play a role.

We could talk about structural racism, but since it does not exist, why bother? I’d rather talk about the aether.

Probably the causes of between-population differences are the same kind of  genetic factors that explain most variation between individuals in a population – systematic differences in the frequencies of many alleles of small effect.  Probably this explains the differences between populations that lived in different eras as well: with better recovery of ancient DNA, we might be able to detect historical trends.

Could genetic differences have an effect on the flavor of culture in different populations?  Well, even allowing for differences in intelligence: sure.  Identical twins like the same things, pick similar clothes,   read similar authors:  genetically different populations could and must have different tastes and preferences, on average.









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108 Responses to Sources of group differences

  1. Clearly put. It would be extraordinary if genetic factors applied everywhere, except in the comparison of different genetic groups.

  2. Henry Scrope says:

    You are wise to only post links on Twitter, looks like they have banned HBD Chick who never had a bad thing to say about anyone.

    • dearieme says:

      She’s a notorious pro-Hajnalist and therefore probably raped people when she was young. She was therefore quite properly unpersonned.

      • albatross says:

        She will be re-instated pending an FBI review of her high school yearbooks for inappropriate comments regarding sex and booze.

    • AppSocRes says:

      The suppression of HBDChick is the most disturbing and disgusting example yet of the prog censorship which has begun descending over the internet. HBDChick’s research was professional and unexceptional. She was extending areas of research that were already legitimate fields of inquiry when I first discovered historical demography back in grad school during the early 1970s.

      • Greying Wanderer says:

        the social media monopolies have outsourced their censorship to blue hairs cos they’re cheap and fanatical – they’ll eventually ban everyone but fellowette blue hairs

    • West Anon says:

      Her banning is valuable because it’s implicitly telling us what they’re doing, which is analyzing the so-called “social graph”.

      Everybody agrees it can’t be about the mostly harmless stuff hbdchick was actually writing about. Correct. Duh. That’s because this isn’t about what was written (which is still hard for machines to grasp), it’s about who was reading it — which machines totally get. The “social graph”.

      It’s like your favorite music/video/writing/shopping site telling you that people who read/like hbdchick also read/like … click whirr … HATE CRIMINAL DETECTED.

      Not coincidentally at all, analyzing audience instead of content is what made The Goolag all that money.

      Sorry, you’re not facing an easily defeated “stoopid” enemy.

      • J says:

        True. The machines analyze who reads what you write and which sites you visit. The Argentine dictatorship used the same method in my times: They searched the phone book of a leftist and they systematically “disappeared” every one in it. An so on in ever widening circles. The UBA (U of Buenos Aires) Math Dept. suspended activities because even the tea ladies had disappeared.

        • Jerome says:

          Scary. But at least Google isn’t throwing us out of helicopters. Yet.

          It seems like this should be a game that two (or more) can play. The systematic exclusion of a fairly popular set of ideas should open up opportunities for other players. But I’m not seeing it. Is this because technology is downstream of the universities?

  3. SMack says:

    “Probably this explains the differences between populations that lived in different eras as well…”

    Getting in early on a bet that the Sea Peoples were prone to adrenal tumors and sacked all those cities because a lighthouse keeper said the wrong thing at the wrong time.

  4. albatross says:

    The more free the society is, the more you’d expect innate differences in personality and interests to drive differences in outcomes.

    There’s this paradoxically frustrating result here: The better you make your society, the more heredity matters. When everyone gets enough to eat and all their shots and goes to school, success becomes more heritable because you’ve flattened out a lot of environmental differences. When everyone has a lot of freedom and a lot of opportunity, the smart and driven people do a lot better than the dumb and lazy ones.

    • Garr says:

      Eccentric people did a lot better in 19th Century England than they do in early 21st Century USA, but I guess this just supports your point.

      • Zenit says:

        Eccentric people among the top 1% – 0,1%, you mean. I do not think that eccentric coal miner or farm laborer would do very well in 19th century England.

        • Greying Wanderer says:

        • Garr says:

          Eccentric low-status people in Dickens novels do okay in the sense of not feeling especially shitty about being weird. I guess I don’t know what you mean by “top 1%”. None of the interesting weird people of 19th Century England were very wealthy, were they?

          They didn’t cram all public spaces with bright mass-produced instructions on How To Be Flashily Normal back then — maybe that’s the main difference.

          • Jliw says:

            Your evidence is characters in Dickens novels?

            I think most of the eccentric people we know of were fairly wealthy, if not actually top 1%.

            • Garr says:

              Evidence of people’s attitudes toward other people, which is pretty much the point.

              When I say “eccentric” I don’t mean the sort of feature that might be expressed by emu-walking or the wearing of pythons around one’s neck. I refer to personality-configurations that, for example, lead people to spend a lot of time looking at the comments-pages of blogs such as this one and Slatestarcodex.

              Think, for example, of Casaubon in MIDDLEMARCH. Now, I’ve always thought that he was an admirable guy with an awesome project — a Key to All Mythologies! Of course, Dorothea, the young-woman-protagonist, ends up finding this man unsatisfactory — but he’s a recognizable 19th Century type with an accepted place in the scheme of things. Today the world is run by (or perhaps I should say “for”) people exactly like Dorothea — and so the Casaubons of our world haunt the comments-pages of blogs.

              • We are meant to understand that the marriage was unconsummated, so Dorothea had good reason to be discontented. For a real life recent Key to All Mythologies, you can try The Origins of the World’s Mythologies, by Harvard Sanskritist Michael Witzel.

        • Steven C. says:

          A working -class eccentric in 19th century western countries might have fewer friends, and employment difficulties, but wouldn’t receive much attention from the authorities; partly because they wouldn’t care, but mostly because they didn’t have the plentiful resources available to modern governments interested in micro-managing the general population. Most 19th century governments had their hands full with major crimes, smuggling and tax evasion and had little to spare for people who dressed oddly or owned exotic pets. The main sanctions would be shunning from the surrounding community, and complaints acted upon the the local Justice of the Peace. But modern society has the resources to send armed police officers to shut down lemonade stands run by children.

    • moscanarius says:

      Your last sentence doesn’t overlap completely with the previous two, but it’s equally worth of keeping in mind.

      Smart people make smart decisions because they are smart.

      Not-so-smart people make the right decisions because they follow sensible social norms.

      That is, if there are widespread sensible social norms. Otherwise…

  5. Jerome says:

    “Probably the causes of between-population differences are the same kind of genetic factors that explain most variation between individuals in a population – systematic differences in the frequencies of many alleles of small effect.”

    This isn’t anything I’ve studied carefully, but I would have thought that the driving factor would be the presence or absence of certain alleles, not their relative frequency. To make an exaggerated analogy, if all that mattered was relative frequencies within the same set of genes, once in a while a dog would have a litter of kittens.

    • gcochran9 says:

      There are only a few alleles that are common in one human population while vanishingly rare in others. So, phenotypic differences largely arise from differences in allele frequencies, not absolute presence or absence. There are exceptions: EDAR 370 is close to fixed in Northeast Asia, absent in Africa and rare in Europe.

      • magusjanus says:

        isnt it, i dont know, weird that EDAR370 is so prevalent in asia and basically absent elsewhere? what was it about asian environment that selected FOR it there, but AGAINST it elsewhere?

      • Jerome says:

        I’m having a hard time with this. You’re saying that the reason almost all world long distance running records are held by people from a few small villages in NE Africa is because they happen to have a somewhat higher concentration of a few of the same genes the other seven billion of us mix and match on a regular basis?

        • gcochran9 says:

          Not by coincidence: there must have been selection for abilities that overlap with what you need in Olympic running. For example, tolerance of high altitudes could be helpful in maximizing oxygen supply. Maybe there were just payoffs in that area for being good at long-distance running.

          We know of cases in which a particular allele that contributes to some trait is local, not global, and makes a big difference. People (99% of them) in central Africa have a variant of the DARC chemokine receptor that is rare in non-African populations. It seems to completely prevent vivax malaria. But cases like this are not common.

          • Jerome says:

            OK, but look. You say, “not by coincidence”. But in fact, if they were selected, they first had to come together, precisely “by coincidence”. So if all the necessary ingredients are there in the rest of the world’s population, then they should come together fairly often, by coincidence, due to the vastly greater number of offspring. But they don’t. They’re the best, we’re the rest. You don’t think maybe they have some special sauce, like a hemoglobin modification, or something subtler, some obscure metabolic pathway, that means they start out ahead of us?

            • RCB says:

              A slight change in the means can lead to high over/under-representation in the tails of the distribution. A mean difference of a quarter SD in some phenotypic trait might be so small that it would be hard to notice that mean difference from every day interaction with people. It’s not until you look at olympians, say, that the difference becomes clear. Such a mean difference could just as easily be due to many small allele frequency differences, or a few big ones.

              Suppose I flip a coin with 50% chance of heads, 100 times. It’s pretty exceptional that I’ll get more than 70 heads – the probability is 1.6e-5. Now suppose you have just a slightly biased coin, with 55% chance of heads per flip. It seems like a very small bias, but the chance of flipping more than 70 heads is actually 47 times higher. “All the ingredients are there” in both cases, but they’re just more likely to show up in the latter.

    • crew says:

      Except that dogs have 78 chromosomes and cats have 38.

      Perhaps you meant a Chihauhau would have Great dane puppies?

  6. It is true that I liked Norwegian Carpenters’ Songs as soon as I heard them.

  7. AppSocRes says:

    “Could genetic differences have an effect on the flavor of culture in different populations?”

    Crimestop should kick in at this point, Professor Cochran. This is verging on doubleplusungoodthink.

    During a recent Cambridge dinner party, I admitted to thinking that there were systematic racial differences in average IQ, distribution of personality traits, and average internal time horizons and discounting rates. When pressed I admitted to concluding that members of different races might be be more compatible with different political, social, and cultural systems. At this point I was accused of racism! and had to admit that the definition of racist was limited to include only those holding these beliefs then I really was a racist. The rest is left to the reader’s imagination.

    • gcochran9 says:

      Was there a food fight?

    • Jim says:

      Obviously anybody who even admits the existence of races is a racist by the current use of the term.

    • biz says:

      Which Cambridge?

    • Jerome says:

      “the definition of racist was limited to include only those holding these beliefs”.

      It works the other way around. The term is carefully designed to include those who hold certain beliefs, and those who hack their neighbors up with machetes. The, if you hold the beliefs, you must hold a machete! Like motte and bailey, only for offense rather than defense.

      • I haven’t sen that comparison made. I imagine that’s because when you’re in the business of calling white people racist, you’ve got very little to gain by holding almost any white person in history up alongside a Rwandan in a mud hut hacking up his neighbor with a machete.

        Also, the latest fashionable definition of racism explicitly says only members of groups with “structural power” (or some term like that) can be racist, and then goes on to define “structural power” as something only white people can have. Or maybe the Japanese too, when convenient.

        But “…when convenient” is an unspoken caveat to everything those people say.

    • Steven C. says:

      I recently had a conversation with a leftist who didn’t support democracy in Hong Kong because the Chinese aren’t evolved enough for it! He seemed irritated when I mentioned that the Taiwanese seem to make it work.

  8. mapman says:

    Could genetic differences have an effect on the flavor of culture in different populations? Well, even allowing for differences in intelligence: sure.

    Large part of culture is almost certain to be rooted in genes. Here is a careful, well-controlled experiment that strongly supports the idea:

    In brief: Young zebra finches learn songs from adult zebra finches. But when a colony is completely isolated from any tutors, in a few generations the birds converge on singing the wild type songs again.

    Think of the culture in the former French colony Haiti closely resembling that of its population’s ancestral West Africa. Or the culture of Liberia converging onto its African roots after a few generations.

    • Jim says:

      Of course in Liberia only a small part of the population ever consisted of descendants of former African-Americans.

    • J says:

      While you are scrutinizing inborn racial differences, Elvis has created a music to which we all dance, Hollywood cultural products (like cowboy movies) are bought everywhere, and even Hottentots wear blue-jeans. Humans, everywhere, – but not Judge Kavanaugh – drink whisky.

  9. Φορωνεύς says:

    I wonder if this would apply to language as well. Maybe the Han Chinese are a bit better at picking up on tones? We could test this with full blooded Chinese who weren’t exposed to Mandarin as infants. Maybe the Bushmen have an inborn ability/predilection to speak !Kung, or a Khoisan language. And this is to say nothing of possible anatomical/neurological differences, as they pertain to language, between phylogenetic/racial groups. Maybe groups are suited to their languages/languages are suited to their groups. Just like groups are suited to whatever form of social organization predominates in their societies. Just spitballing.

    Come to think of it, there’s already ample evidence for certain groups having a predilection for certain forms of social organization. People blame the Central African Republic being the national equivalent to a hole in the ground on French colonialism. But there wasn’t much going on there before the French showed up, was there? It takes a lot of education to deny the evidence of the senses. It’s crazy that rational observations like “Genetically different populations must have different tastes and preferences,” are so often denied in our society. Given that PhDs (and crossdressers having themselves spayed or castrated for that matter) don’t have kids, hopefully some of this group’s probable predilection for lunacy will diminish.

    • Boswald Bollocksworth says:

      There is apparently something to your suggestion about the Celestials:

      But old now, not sure how it held up under new methods.

    • Jim says:

      Tonal languages aren’t that uncommon and of course tonal variations are used in English to mark interrogative phrases. Classical Greek had a tonal accent as did probably Proto-Indo-European. The Khoisan languages are remarkable for their great abundance and variety of velar suction phonemes which are extremally rare in all the other languages of the world. On the other hand velar suction sounds are easily articulated by all humans. But aside from the Khoisan languages they are almost never used as phonemes. Just enunciated as funny noises.

    • ccscientist says:

      People speaking click languages like Bushmen have some unique tongue and mouth anatomy.

      • Jim says:

        Other than the Khoisan (Bushmen) languages the use of velar suction sounds as phonemes is very rare. But they are not hard to articulate, at least as isolated sounds. The Khoisan languages also have an enormous number of consonant phonemes. They are certainly phonologically very different from all non-Khoisan languages.

    • S3 says:

      I was reading Mark Twain’s “The Awful German Language”

      The Germans have another kind of parenthesis, which they make by splitting a verb in two and putting half of it at the beginning of an exciting chapter and the other half at the end of it. Can any one conceive of anything more confusing than that? These things are called “separable verbs.” The German grammar is blistered all over with separable verbs; and the wider the two portions of one of them are spread apart, the better the author of the crime is pleased with his performance. A favorite one is reiste ab — which means departed. Here is an example which I culled from a novel and reduced to English:

      “The trunks being now ready, he DE- after kissing his mother and sisters, and once more pressing to his bosom his adored Gretchen, who, dressed in simple white muslin, with a single tuberose in the ample folds of her rich brown hair, had tottered feebly down the stairs, still pale from the terror and excitement of the past evening, but longing to lay her poor aching head yet once again upon the breast of him whom she loved more dearly than life itself, PARTED.”

      It takes quite a bit of backward digit span to regularly handle constructs like this. Backward digit span is also needed for creativity (or so I am told).

    • Steven C. says:

      I’ve always wondered how tone-deaf members of tonal languages manage, or are tone-deaf people not completely tone-deaf?

  10. crew says:

    Perhaps they are all just a bunch of flockers!

    Cognitive mechanisms for human flocking dynamics

  11. Boswald Bollocksworth says:

    It’s noteworthy that this basic fact has to keep being said. I thought everyone read this and was convinced back in 2010, but I’m prone to projection. I do think headway is being made though, specifically thinking of Garret Jones work on population smart fractions and income per head, still can’t believe his book got published and reviewed.

    • I'll get the study name if you really want says:

      There’s also a much larger Californian study showing that such names aren’t associated with worse life outcomes when controlled for class.

  12. arch1 says:

    “We could talk about structural racism, but since it does not exist, why bother?”

    For any of you who agree with Greg, why are the studies showing lower callback rates for resumes with minority-associated names not convincing evidence of structural racism?

    • SMack says:

      Because those studies wrongly assume a name like Daquan carries no information beyond the applicant’s race.

    • gcochran9 says:

      There are also plenty of jobs that they’ll give to marginal black candidates over better white candidates. Government jobs (federal, state, local). Government contractors.

      Somehow structural racism doesn’t seem to hold back other recognizable racial groups. Even when their culture is very alien, even their native country was recently at war with us.

    • DataExplorer says:

      This 20 minute video deals with those callback studies directly:

    • Yudi says:

      I interpret such structural racism as being real, but also a response to the actual racial differences everyone quietly knows about. Since not everyone acts like stereotypes of their race, of course, it can hurt innocent people. In other words, the prejudices sit like an oil slick atop the deep water of real differences.

      • Young says:

        I think affirmative action is an example of structural racism.

      • albatross says:

        “Structural racism” always seems to me to be a kind of god-of-the-gaps theory. When there is actual evidence of discrimination, you can just call it discrimination or racism. When there’s a difference in outcomes that can’t be explained by any apparent discrimination or racism, then you label it “structural racism.”

        • Yudi says:

          That too.

          (I think the people who use this vocabulary, to the extent they are talking coherently about real things, intend for structural racism to mean discrimination without malice or awareness.)

    • Phille says:

      Because there is not a perfect correlation between credentials and job performance. So a member from a lower performing group regresses to a lower mean of job performance given the same credentials. Therefore, if you are interested in job performance, the same credentials are of different value, depending on the performance of the group to which the applicant belongs.

      Additionally, if you use some kind of threshold to decide whom to interview, groups with higher performance will have a fatter tail. Which means a higher percentage of these interviewees would get hired. Which makes it sensible to use a higher threshold for lower performing groups, to have a hiring process that is equally efficient.

      This sounds unfair, but it leads to people getting the jobs they are actually able to perform, i.e. it is the only meritocratic choice. And from the point of view of the companies, it is just statistically optimal decision making. (Of course I’m not implying that this is a consciously implemented strategy, more a wisdom (aka accurate stereotypes) of the crowd kinda thing.)

      • arch1 says:

        Thanks for laying this out Phille.
        The behavior you describe I think results in something like half of individuals identifiable as members of a lower-performing racial group being systematically underestimated, for reasons beyond their control, due to their race. As the rationale for this behavior is quite generally applicable, this presumably doesn’t happen only with hiring decisions, but rather in thousands of scenarios big and small throughout such a person’s life, many of them undetectably, and many others too late to fix because doors and minds have already closed. A sizeable fraction of such a person’s family, friends and neighbors are being similarly affected, with further blowback effects on the person herself. All of which is layered on top of good old animus-based discrimination.
        This doesn’t sound like nothing.

        • gcochran9 says:

          The problem is the lower average performance. Markets aren’t all-knowing, but if employers routinely underestimated how useful black employees were, one could immediately make money by hiring them. Arbitrage. If you look at the job distribution among blacks, it’s about what you would expect from the differences in IQ distributions. Actually, they do better ( in terms of employment status) than expected – due to racial favoritism and quotas. More doctors and lawyers. Linda Gottfredson has looked pretty hard at this.

          If other people systematically underestimate ( or overestimate) , while you don’t – profit!

          • arch1 says:

            Greg, it sounds like you’re providing reasons why (the conditions resulting in) structural racism exist. If so, that’s not a very good way of supporting your statement that it doesn’t exist.

            • Jim says:

              The point is that lower wages for blacks despite equal productivity would create a strong incentive to hire blacks. If white controlled firms refused to hire them black entrepreneurs would get a strong competitive advantage.

              • Jim says:

                In sports such as basketball where blacks are better than whites there doesn’t seem to be much “structural racism”. How long would a white owned sports franchise last if it refused to hire black athletes?

              • gcochran9 says:

                Well, there was a time when none of them did, so that kind of ‘structural racism’ is possible. But I don’t know of a good current example.

            • Greying Wanderer says:

              yes, anti-white structural racism has distorting side-effects

        • Toddy Cat says:

          There are doubtlessly some individual Black people that have been damaged by the sorts of things you point out – Blacks as a whole, no.

        • Low average IQ doesn’t affect individual performance directly; it merely affects susceptibility to undetectably subtle forms of racism.

          But perhaps there’s an as-yet undiscovered form of funding that will ameliorate these effects.

        • We also have good reason to suspect that Daquan got into college and through college with some assistance. Thus his degree may not signal what Roger’s or Alexa’s does. This doubtless harms some Daquans, but it helps others (who might not have even gotten to the desk otherwise) and is, on average, accurate.

          If that is a structural racism, it is not the employer who built that structure.

          • albatross says:

            ISTR a study looking at how likely professors were to want to take on graduate students that used male/female names (I think in biology–a field with a lot of high-performing women). Both male and female professors expected worse performance from a female than a male student. What wasn’t clear from that study was whether this was rational behavior from the professors (based on their experience).

        • Phille says:

          “The behavior you describe I think results in something like half of individuals identifiable as members of a lower-performing racial group being systematically underestimated, for reasons beyond their control, due to their race.”

          Half of ALL individuals are being systematically underestimated, no matter their race. The point is that on average underperforming groups are not underestimated if their credentials are somewhat discounted. It is the discounting that makes the estimate precise. If you would judge the credentials of underperforming groups exactly like you judged the same credentials for an overperforming group, you’d systematically overestimate the ability of the members of the underperforming group. Would that be better?

          To put it differently: An African American in the 99th percentile of African Americans will be underestimated exactly to the same degree as a white American in the 99th percentile of white Americans. On the group level there is no injustice. (At least not necessarily, of course there might still be additional bias, the reason I don’t really believe that is arbitrage, as Greg has pointed out.)

          The way to make your point is that ALL members of an underperforming group are underestimated if compared to a member of an overperforming group with exactly the same ability. Does it sound weird to you that this can be true and there is still no injustice on the group level? Well, that is the magic of the Simpson paradox.

          The only way to ameliorate this without introducing injustice on the group level would be better credentials, i.e. credentials that correlate more tightly with job performance. In reality this happens after the hiring process, because job performance correlates pretty strongly with future job performance.

    • Jim says:

      Compare the performance of ethnic Chinese with Malays in Indonesia. The ethnic Chinese do far better economically despite plenty of anti-Chinese “racism”. In one episode of anti-Chinese violence a few decades an estimated 100,000 were slaughtered. Now there’s “structural racism” for you.

    • SlushFundPuppie says:

      “studies showing lower callback rates for resumes with minority-associated names”


      Jewish militiamen assisting the state send fake job applications with ghetto names to white owned businesses to use as a pretext to have their assets confiscated.

      Two lawsuits filed last week by federal regulators suggest that if employers act unilaterally to exclude all job applicants who have criminal records, … they could be opening themselves up to charges of race discrimination.

      • Toddy Cat says:

        “why are the studies showing lower callback rates for resumes with minority-associated names not convincing evidence of structural racism?”

        I wonder how many of there “studies” actually replicated?

    • Steven C. says:

      Is it structural racism, or structural classism? Does Billy-Bob have a better shot at an office position than LaShonda?

  13. David Chamberlin says:

    “Could genetic differences have an effect on the flavor of culture in different populations?”

    When I visit my sister who lives outside Puerto Vallarta in Mexico I can’t discuss with her why Latin and South America are going down the toilet because of increased violence as narco terrorism just gets worse and worse. She’s a die hard liberal who thinks all the blame falls on the the United States because we are the primary consumers of all the drugs that the narcos produce or ship. Political conversations are retarded, people just look to confirm what they already believe. I would immediately be branded a horrible racist if I was to talk about shifted bell shaped curves of intelligence and what they mean in different parts of the world. Like Plomin I have to STFU in certain company about certain subjects. I sure my sister understands she was born into a bright family where everybody grew up to go on their merry way being skilled professionals. I will never have a conversation with my sister about shifted bell shaped curves of human intelligence in different regions of the world and how that directly limits the opportunity to live the good life. I would be cut off and harshly dismissed before I could start talking about how crucial it is for a productive modern society to have a sizable percentage of the population with high IQ’s and how quickly that percentage decreases when average IQ in the general population shifts just a few points.

    My sister has a point that if we didn’t consume umpteen billion dollars in illegal drugs every year than the Narcos in the region of Sinaloa Mexico where she lives wouldn’t be tearing the place up. But I have a point too but all the graphs in the world that clearly show a high correlation between prosperity of a nation and average IQ won’t make a difference to my sister. I’m a racist and there isn’t point in discussing it further. My liberal friends and family were born into bright families, and have moved through life keeping as much as possible to that elite circle. I can’t talk to them about this touchy subject whatsoever. When the percentage of the population with an IQ above 130 drops fifteen fold when a nations average IQ drops from 100 to 85 than then where does the professional class of that dumb nation come from? What choices does some poor soul born dumb and without opportunities have besides crime to get ahead? Mexico and the Mexican people don’t deserve the drug cartels destroying their wonderful country but all the wishes of idealistic liberals everywhere won’t change the underlying mathematics of the bell shaped curve of human intelligence.

    • Jim says:

      Yes, the result of a shift from an average IQ of 100 to 85 are dramatic. For a population with an average IQ of 100 about 25% would have IQ’s above 110 and be suitable for professional or quasi-professional occupations. With an average IQ of 85 only about 5% would have IQ’s over 110.

    • Jim says:

      It’s also a “double whammy” effect. Just as the high-cognitive end of the population collapses the low-cognitive end of the population who are dysfunctional in an advanced modern economy shoots up.

    • Ursiform says:

      There are countries with lower average IQs than Mexico that aren’t “going down the toilet because of increased violence as narco terrorism just gets worse and worse.” The lack of a market for drugs would clear up narco terrorism. Yes, Mexico would still have problems without narco terrorists. But it wouldn’t spontaneously generate narco terrorists. Seems to me that your arguments about bell curves are pretty much irrelevant to the problem of narco terrorism. So I guess I have some sympathy for you sister on this one.

      • David Chamberlin says:

        You make some good points. i have puzzled over what in the hell is going on in Latin and Central America. See this Wiki article on murder rates around the world.
        It’s surprising just how high the murder rate is in the Americas as compared to Africa and the middle east. Many many factors are going into why the murder rate in the Americas is so high and if I misled by saying it is only due to low IQ people with no opportunity to get ahead other than crime than I am glad to be corrected, but it sure is part of it. All the Mexican people want is for the gringos to stop buying illegal drugs so that they can have their country back the way it was. Parts of Mexico, Brazil, Venezuela, and multiple other places in Central America are war zones and looking at the trends over time they are only getting worse.

        • Toddy Cat says:

          “All the Mexican people want is for the gringos to stop buying illegal drugs”

          Yet another reason to build the wall…

          • David Chamberlin says:

            the wall won’t stop the drugs from coming in

            • Jim says:

              A lot of the drugs come over the border in small planes.

              • Toddy Cat says:

                Using “Wall” in a figurative sense here, to mean tight border enforcement. That includes airspace, of course.

              • Jim says:

                It would definitely take a significant air defense system to stop the incoming drug planes.

            • Reducing them would help. Increasing the cost should reduce the behavior.

              Will that matter enough? Don’t know.

              • albatross says:

                Is there data anywhere on whether the intensity of enforcement efforts correlates with street price of drugs? Short of the Singaporan solution (limit both supply and demand via the judicious use of hangmens’ ropes), it looks pretty damned hard to have a big effect.

                My guess is that it is much easier to get to zero/negative net illegal immigration than to double the street price of drugs.

      • Jim says:

        Supposing that say all these drugs were legalized in the US and the narcotics business in Mexico collapsed what would be the effect on the Mexican economy?

        • Jim says:

          Does anyone have any idea what percent of the Mexican economy the narcotics business is?

          • DataExplorer says:

            I have no idea. But you are giving the money to the wrong people. And in so doing, encouraging the worst kind if behaviour. Its amuch worse dygenic process than welfare dependency.

            • albatross says:

              One natural experiment we could look at: a few years back, the US started cracking down on sale of sudafed to prevent people cooking meth. My understanding is that this decreased the amount of meth cooked here and increased the smuggling of meth from Mexico. It would be interesting to see if that corresponded with an increase in crime in Mexico.

              Similarly, marijuana decriminalization/legalization might give us some additional natural experiments.

              The problem is path dependency. Just like organized crime networks that got rich on prohibition didn’t go away when we ended prohibition, I’d expect that the narco gangs won’t go away just because drug money is no longer available. (They may eventually fade away, but not all at once–there are a lot of men who’ve been doing drug gang stuff their whole lives, and probably have no idea how to live any other way. They’ll be looking for other ways to make money using their skills of violence and terror and bribing police and judges.)

          • David Chamberlin says:

            I can’t give a good economic answer. In those parts of the country where the cartels are the strongest the people live in fear, real estate prices are way down, and the tourism business, crucial to parts of Mexico, has gone away. Would you open a business in a place run by gangsters? They don’t just stick to the drug business, they shake down all businesses and greatly repress economic growth. The police are a joke, law and order is nonexistent, and there is a constant war between cartel factions when the head honchos like Chapo Guzman are removed.

      • albatross says:

        I think there’s a hell of a lot of path dependency and culture behind that stuff, along with the narcos. Probably also some genetics that don’t have anything to do with IQ. Latin America is an extremely violent place–most of the cities in the world with really high murder rates are in Latin America.

        I kind-of wonder if countries like El Salvador suffer from a variant of the resource curse. It’s hard to do anything in El Salvador that makes as much money as helping move drugs north to the US, so guess where the super-ambitious people go? (And the ambitious people who aren’t up for a life of crime and murder just head to the US themselves.)

    • Warren Notes says:

      I believe most people don’t have any idea what the practical (even face-to-face) results of IQ variation are. I gave IQ tests for several years, and as a consequence, I almost automatically consider the probable IQ of someone I’m talking with, especially with the most easily observable aspect, Verbal IQ / Vocabulary. But for most people, talking with the lawn guy, if he is anything less than a standard deviation below average, is the same thing as talking to the Professor next door. Another part of the problem is that elites have no idea how the other half thinks. Having little to no real exposure to residents of the left side of the bell curve, they assume that they don’t differ dramatically from their own colleagues. I know, I know – how in the hell can they think that after going all the way through school? It’s because they were self-segregating there, as well, and they also didn’t pay as much attention to anything other than obsessing about the opposite sex – or same sex, in the case of the rainbow people. There also is the “Mike Tyson effect” (my label) – in which someone seems to be speaking intelligently at times, but there is something about it that makes you suspect it’s a kind of well-practiced parlor trick – sort of cognitive version of slight-of-hand. When you add the rocket fuel of political biases to these factors, your wrong assumptions become invulnerable.

      • gcochran9 says:

        I always thought it was fairly easy to get an approximate idea how smart people were, but yes, most people are poor at this. Talking fellow students, I’d known almost every one of them since we were six: surely that’s enough observational info? But most people don’t really remember their own lives very well.

      • albatross says:

        I suspect that a major factor in the demand for illegal immigrant labor in the US is that the kind of person in the US who wants a bottom-tier unskilled job is usually either 16 or is screwed-up somehow–dumb as a stick, crazy, addicted to something, incredibly lazy, recently released from prison, etc. A just-across-the-border Salvadoran who wants the job is probably of normal intelligence (lower average than US whites, but higher than US blacks) and just had shitty choices. And working conditions at even really lousy jobs in the US are probably easy if your previous work experience was third-world subsistence farming with minimal technology in some indio village in El Salvador or Guatemala.

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