Post updated, 11/17/13
4/14/13 1/19/13, see below!
It is already known that educational attainment and income are highly heritable. However, finding specific genes linked to cognitive and behavioral traits has been difficult. This is primarily because most traits arise not from a few genes with large effects, but from many genes with small effects (and from many genes with effects similar to those of other genes). Hence, figuring out what alleles are linked to what behaviors against the backdrop of the tens of thousands of genes in the genome—and the many more variants of such—is by no means an easy task.
None the less, a few such links have been identified, which I talked about in my earlier post about free will. A recent paper was released that took a look at genes that play a role in education attainment. This study looked at three genes involved in the production and control of dopamine, one of the brain’s “reward” hormones.
They did this by looking the Add Health study, a national longitudinal study of adolescents, done in four waves. This is the same study that much maligned evolutionary psychologist Satoshi Kanazawa relied on to make his infamous blog post about the physical attractiveness of Black women—which landed him in so much hot water (more on that soon). Wave 3 of the study however included a DNA sample of the participants. From this, the researchers were able to make links between genes and the behavior and outcomes of the study participants.
You’re probably now thinking what I was thinking when I first read this: since the Add Health study contained participants of various races, a genetic analysis could be used to identify genes that impact behavior that differs between the races.
And it seems that they have done just that. They found that the three dopamine genes they examined, the dopamine transporter gene (DAT1), the dopamine D2 receptor gene (DRD2), and the dopamine D4 receptor gene (DRD4), had small but reliable effects on educational attainment, such that those with a higher “dopamine index” tended to attain less education.
Presumably, this is because those with higher “dopamine indices” (based on having more of certain alleles of these three genes) are more much impulsive/novelty seeking, and in general derive much less satisfaction from things that don’t offer immediate rewards.
But what’s much more interesting is that they found significant differences in the prevalence of the alleles of theses genes between the White and the Black subjects, with Blacks having tending to have higher dopamine indices. The differences are small, but solid.
This finding, as significant as it seems, is but one of many pieces of evidence demonstrating genes that affect behavior that differ in prevalence between racial groups. Here are just a few others:
- Researchers have found a correlation between a serotonin transporter gene (5-HTTLPR) and whether a society is individualistic or collectivist; Anglo countries are on one end of the distribution while East Asian countries are on the other.
- The “Warrior Gene”, monoamine oxidase A (MAO-A): This gene is known to be associated with a host of anti-social behaviors, and varies considerably around the word. Certain variants of this gene were found to be quite prevalent among the Maori of New Zealand, a people with a reputation for fierceness and who today have significantly higher rates of violence than White New Zealanders.
- Genes for myopia, a condition which is known to be associated with increased intelligence (there is a reason that wearing glasses makes one look more intelligent). The prevalence of myopia varies greatly around the world, being higher in European and Asian countries, reaching as high as 80% in Singapore. Singapore also has an average IQ of 108!
- The aforementioned DRD4 gene, which Greg Cochran and Henry Harpending discuss (along with many other genes that vary among different populations) in The 10,000 Year Explosion (pg 112):
the 7R (for 7-repeat) allele of the DRD4 (dopamine receptor D4) gene. It is associated with Attention-Deficit/Hyperactivity Disorder (ADHD), a behavioral syndrome best characterized by actions that annoy elementary school teachers: restless-impulsive behavior, inattention, distractibility, and the like. The polymorphism is found at varying but significant levels in many parts of the world, but is almost totally absent from East Asia. Interestingly, alleles derived from the 7R allele are fairly common in China, even though the 7R alleles themselves are extremely rare there. It is possible that individuals bearing these alleles were selected against because of cultural patterns in China. The Japanese say that the nail that sticks out is hammered down, but in China it may have been pulled out and thrown away.
- About that DRD4 gene, the presence of longer copies of the gene are found to vary across the world, and is found to increase as migratory distance from Africa increases.
- Edit, 11/17/13: The gene TAS2R16, certain variants of which render the individual highly sensitive to bitter flavors. All of those variants are only found in Africa! (Paper here, paywalled.)
- Edit: Additionally, a new study (Aug, 2012) also using the Add Health data found that the 2-repeat version of the aforementioned warrior gene, MAO-A, is significantly associated with antisocial behavior and the likelihood of criminality in Black males. This allele is found in 5% of Black males, but is very rare (0.1%) in White males.
- Edit: Also see the gene ASPM, which is associated with brain growth. Alleles of this gene vary in different human populations, a new variant being more common in the Middle East (37%-52% incidence) and Europe (38-50% incidence) than in East Asia (0-25%). The prevalence follows the spread of writing.
Also, from the above link, note the Visual Word Form Area (VWFA) of the brain. This region appears to be heavily involved in recognizing written words and language, apparently performing no other functions. Westerners, who rely on an alphabetic script, process their sound-based symbols only in the VWFA, whereas Chinese, who have a logographic script, use more brain regions to decode their language.
Edit, 4/17/13: As well, quite damningly, racial differences in behavior are evident right after birth. See this movie documenting experiments done by Dan Freedman on newborn babies of different races. Also see Greg Cochran’s discussion, here and here.
A staunch critic might (correctly) point out that our knowledge of how behavior is derived from these genes is incomplete at best, and hence (incorrectly) conclude that it’s hasty to conclude that we have proved concrete innate behavioral differences thanks to genetic differences. They might point to the oxytocin receptor gene, where the same alleles leads to different behavior for Koreans than it does for Americans, presumably confounding research linking genes and behavior. That study is used to demonstrate the importance of “culture” in determining behavioral differences between groups.
Of course, the problem with that line of reasoning—which is used to support the importance of culture in the above example—is that the OXTR gene cited doesn’t just operate in different cultures between Koreans and Americans, but in different genomes as well. It shouldn’t be horrendously surprising that the same alleles have different effects in different groups, thanks to the mediation of other genes that differ between those groups.
But effects such as these do make it difficult to draw straight comparisons between genetic differences between groups and behavioral differences between those groups, as inferred by the behaviors these genes appear to be associated with. (Some “low-activity” MAO-A genes are common among East Asians, for example.)
But this criticism completely misses the point. We know of genes that are linked to behavior and intelligence, and we know that those genes differ in prevalence between racial groups. Hence, unless the rest of the genome operates in such a way to cancel out the effect of the genes we have isolated (which is essentially impossible), then some of the behavioral and cognitive differences between groups must be due to genetic differences. There is no way every group is going to be dealt a different hand of cards and have those cards all work to operate the same basic way. It simply could not have happened. Ergo, demonstrating these genetic differences and their links to behavioral differences are a proof-of-concept of heritable behavioral/cognitive differences between racial groups, as Half Sigma noted. And if these differences could have something to do with heredity, why can’t other differences?
(Sure, convergent evolution does produce between-group similarities despite different genes doing the trick. The genes that give East Asians light skin are different from the ones that give Europeans light skin, for example. But it’ll be an absurd notion to think that every gene involved with intelligence and behavior is going to end up working roughly the same way in every different racial group.)
These data disprove the “environment-only” hypothesis for group differences. And with that out of the way, we should be able to move forward with explanations that involve heredity to some degree. However, these facts (in addition to all the other mountains of evidence for HBD, such as the recent discovery of endemic genetic variants that are yet more proof that Lewontin’s Fallcy is just that), are very damaging to the approved narrative that “were all the same”. We’re at the edge of that volcano that Charles Murray mentioned in his interview with Harald Eia for the Norwegian documentary Brainwash. Yet, despite such research being published for years, all the books published, and all the discussion in the “blogosphere”, talk about group differences is still verboten. Academics who talk about about racial differences still face “Watsoning”. Eia’s warning at the end of the video is part of the reason why.
In short, it’s because people are stupid.
Most people will take knowledge of group-wide differences, which mostly apply to averages, to mean that they apply in all cases. Most people are too dumb to consider the nuances of statistics, and instead rely on heuristics of the type “if the fruit is ripe, it’s sweet; if it’s green, it’s sour”, even though those are only statistically true. Upon hearing of the lower average IQ and higher average criminality of Blacks, many Whites will assume that all Blacks are uneducatable thugs, despite the fact that criminals make up a minority of Blacks. This is why people object to stereotypes. While stereotypes are generally valid empirical generalizations, people have a tendency to apply them sweepingly, and that’s where we run into trouble.
In any case, sooner or later, someone is going to write a book compiling all of this direct, genetic evidence for racial differences (over and beyond what Cochran and Harpending have already written), or publicize this knowledge through some medium that will get widespread attention. No doubt that will make a big splash, and then we will have to talk about this reality.