Success in life depends on intelligence, which is measured by I.Q. tests. Intelligence is mostly a matter of heredity, as we know from studies of identical twins reared apart. Since I.Q. differences between individuals are mainly genetic, the same must be true for I.Q. differences between groups. So the I.Q. ranking of racial/ethnic groups — Ashkenazi Jews on top, followed by East Asians, whites in general, and then blacks — is fixed by nature, not culture. Social programs that seek to raise I.Q. are bound to be futile. Cognitive inequalities, being written in the genes, are here to stay, and so are the social inequalities that arise from them.
What I have just summarized, with only a hint of caricature, is the hereditarian view of intelligence. This is the view endorsed, for instance, by Richard J. Herrnstein and Charles Murray in “The Bell Curve” (1994), and by Arthur R. Jensen in “The g Factor” (1998). Although hereditarianism has been widely denounced as racism wrapped in pseudoscience, these books drew on a large body of research and were carefully reasoned. Critics often found it easier to impugn the authors’ motives than to refute their conclusions.
Richard E. Nisbett, a prominent cognitive psychologist who teaches at the University of Michigan, doesn’t shirk the hard work. In “Intelligence and How to Get It,” he offers a meticulous and eye-opening critique of hereditarianism. True to its self-helplike title, the book does contain a few tips on how to boost your child’s I.Q. — like exercising during pregnancy (mothers who work out tend to have bigger babies who grow up smarter, possibly because of greater brain size) [More likely because they are middle class]. But its real value lies in Nisbett’s forceful marshaling of the evidence, much of it recent, favoring what he calls “the new environmentalism,” which stresses the importance of nonhereditary factors in determining I.Q. So fascinating is this evidence — drawn from neuroscience and genetics, as well as from studies of educational interventions and parenting styles — that the author’s slightly academic prose style can be forgiven.
Intellectually, the I.Q. debate is a treacherous one. Concepts like heritability are so tricky that even experts stumble into fallacy. Moreover, the relevant data come mostly come from “natural experiments,” which can harbor subtle biases. When the evidence is ambiguous, it is all the easier for ideology to influence one’s scientific judgment. Liberals hope that social policy can redress life’s unfairness. Conservatives hold that natural inequality must be accepted as inevitable. When each side wants to believe certain scientific conclusions for extra-scientific reasons, skepticism is the better part of rigor.
Nisbett himself proceeds with due caution. He grants that I.Q. tests — which gauge both “fluid” intelligence (abstract reasoning skills) and “crystallized” intelligence (knowledge) — measure something real. They also measure something important: even within the same family, higher-I.Q. children go on to make more money than their less-bright siblings. [An important admission]
However, Nisbett bridles at the hereditarian claim that I.Q. is 75 to 85 percent heritable; the real figure, he thinks, is less than 50 percent [The most common estimation is two thirds so Nisbet is not being very original there. And even a 50% figure puts large contraints on what a person can achieve]. Estimates come from comparing the I.Q.’s of blood relatives — identical twins, fraternal twins, siblings — growing up in different adoptive families. But there is a snare here. As Nisbett observes, “adoptive families, like Tolstoy’s happy families, are all alike.” Not only are they more affluent than average, they also tend to give children lots of cognitive stimulation [I doubt those assertions. The point is one commonly made but I think the evidence for its effect is weak]. Thus data from them yield erroneously high estimates of I.Q. heritability. (Think: if we all grew up in exactly the same environment, I.Q. differences would appear to be 100 percent genetic.) This underscores an important point: there is no fixed value for heritability [A non sequitur. The value can be fixed even if it is hard to estimate]. The notion makes sense only relative to a population. Heritability of I.Q. is higher for upper-class families than for lower-class families, because lower-class families provide a wider range of cognitive environments, from terrible to pretty good. [An assertion only]
Even if genes play some role in determining I.Q. differences within a population, which Nisbett grants, that implies nothing about average differences between populations. The classic example is corn seed planted on two plots of land, one with rich soil and the other with poor soil. Within each plot, differences in the height of the corn plants are completely genetic. Yet the average difference between the two plots is entirely environmental. [True in theory but irrelevant in fact. There are studies going back many years where blacks and whites have sat in the same classrooms throughout their education but the IQ gap remains. And any claim that blacks are poorly fed is laughable. Their rate of obesity is higher than for whites]
Could the same logic explain the disparity in average I.Q. between Americans of European and of African descent? Nisbett thinks so. The racial I.Q. gap, he argues, is “purely environmental.” For one thing, it’s been shrinking: over the last 30 years, the measured I.Q. difference between black and white 12-year-olds has dropped from 15 points to 9.5 points. [Blacks mature faster so the IQ gap has long been smaller during childhood. The adult IQ gap remains the same] Among his more direct evidence, Nisbett cites impressive studies in population genetics. African-Americans have on average about 20 percent European genes, largely as a legacy of slavery. But the proportion of European genes ranges widely among individuals, from near zero to more than 80 percent. If the racial gap is mostly genetic, then blacks with more European genes ought to have higher I.Q.’s on average. In fact, they don’t. [But where do the white genes concerned come from? Mostly from the bottom of white society. "Race mixing" has been looked down on for most of America's history]
Nisbett is similarly skeptical that genetics could account for the intellectual prowess of Ashkenazi Jews, whose average I.Q. measures somewhere between 110 and 115. As for the alleged I.Q. superiority of East Asians over American whites, that turns out to be an artifact of sloppy comparisons; when I.Q. tests are properly normed, Americans actually score slightly higher than East Asians. [I concede that some of the figures for Asian IQ may be poorly representative but the enormous rate of achievement among Asian Americans certainly shows that Asians who emigrate are superior. We are on much firmer ground with Jewish IQ because of Israeli army figures. There is no doubt of Ashkenazi superiority -- if Jewish achievements alone did not tell you that]
If I.Q. differences are indeed largely environmental, what might help eliminate group disparities? The most dramatic results come from adoption. When poor children are adopted by upper-middle-class families, they show an I.Q. gain of 12 to 16 points [For a while. In adulthood their differences are small. And the children chosen for adoption by such families are probably not representative either]. Upper-class parents talk to their children more than working-class parents do. And there are subtler differences. In poorer black families, for example, children are rarely asked “known-answer questions” — that is, questions where the parents already know the right answer. (“What color is the elephant, Billy?”) Consequently, as Nisbett observes, the children are nonplussed by such questions at school. (“If the teacher doesn’t know this, then I sure don’t.”)
The challenge is to find educational programs that are as effective as adoption in raising I.Q. So far, Nisbett observes, almost all school-age interventions have yielded disappointing results [An important and entirely true admission]. But some intensive early-childhood interventions have produced enduring I.Q. gains, at a cost of around $15,000 per child per year. [Small gains achieved at great effort are consistent with the environmental component of IQ]. Yet, by the author’s reckoning, it would cost less than $100 billion a year to extend such programs to the neediest third of America’s preschoolers. The gain to society would be incalculable. [More likely to be negligible -- on the balance of the evidence]
Still, there are limits even to Nisbett’s optimism. Social policy can get rid of ethnic I.Q. gaps, he thinks, but “the social-class gap” in I.Q. “is never going to be closed.” I would frame the matter a little differently. Even if I.Q. inequality is inevitable, it may eventually become irrelevant. Over the last century, for reasons that aren’t entirely clear, I.Q. scores around the world have been rising by three points a decade [That has now stopped and it did not affect the racial gap anyway]. Some of this rise, Nisbett argues, represents a real gain in intelligence. But beyond a certain threshold — an I.Q. of 115, say — there is no correlation between intelligence and creativity or genius [IQ has never correlated strongly with creativity -- largely because different sorts of creativity do not correlate with one-another]. As more of us are propelled above this threshold — and, if Nisbett is right, nearly all of us can be — the role of intelligence in determining success will come to be infinitesimal by comparison with such “moral” traits as conscientiousness and perseverance. [And law-abidingness?] Then we can start arguing about whether those are genetic.
Perhaps I should say a little more about the nutritional argument. It is briefly alluded to above but is very commonly mentioned in arguments of this sort.
There appear to be two adverse nutritional influences on IQ: Total calorie deprivation and micronutrient deprivation. The first is obviously irrelevant to American blacks so I will just note that the Dutch famine study showed it to have a eugenic effect if anything. It is mainly the children of smart people who survive a famine so the children concerned will on average tend to be brighter rather than dumber.
Micronutrient (vitamins and minerals) deficiency is more serious, though United Nations figures suggest that, even so, it accounts for only about 5 IQ points. If you give micronutrients to poor blacks in Africa, it does boost their average IQ by about that amount. The diet of poor blacks in Africa and the diet of American blacks are however quite different. Africans in Africa might see fried chicken only a few times in a lifetime. They mostly live on corn porridge ("mealie pap"). But critics nonetheless say that while African Americans eat plenty, they eat the "wrong" food: McDonalds for instance. But look at what is in a Big Mac meal: Meat, bread, salad and potatoes -- which adds up to a mainstream Western diet. Some contend that there is too much salt and fat in such meals but that the meals provide a good range of micronutrients can hardly be doubted.
So there are no grounds for saying that the cause of lower average IQ in blacks is nutritional. They are not "seed that fell on stony ground".
Posted by John Ray. For a daily critique of Leftist activities, see DISSECTING LEFTISM. For a daily survey of Australian politics, see AUSTRALIAN POLITICS Also, don't forget your daily roundup of pro-environment but anti-Greenie news and commentary at GREENIE WATCH . Email me (John Ray) here