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Race and mental traits: Nicholas Wade’s third error
An octogenarian once invited me to his old, exclusive East Coast club to give a talk about neuroscience, my area of specialty. Afterwards, as we walked past oil portraits of old white men across the centuries, the octogenarian pulled me aside, lowered his voice and asked, “I was wondering if you could explain something. What is it about the brains of Chinese and Jews? They seem superior.” Evidently, as a member of one of those tribes (the former), he thought I might know the answer.
In May, the British science journalist Nicholas Wade published “A Troublesome Inheritance,” a book that, at its worst, reminds me of the octogenarian’s question. Throughout “A Troublesome Inheritance,” Wade argues that genetic inheritance, at the level of nations and races, has been shaped by local survival requirements with results that, in turn, shape the cultures in which we live. His interpretation of the genetic and evolutionary evidence has already been roundly criticized. As it turns out, his developmental biology has a few problems as well.
On the surface, his argument sounds a lot like past, discredited claims about the innate superiority of certain races over others. Wade, for his part, says he will have no truck with racism. “Racism and discrimination are wrong as a matter of principle, not of science,” he writes. He says he just wants to tell us the facts. The facts, in the case, are not so much the problem as Wade’s argumentation, which routinely goes much farther than science can justify and weaves a tale that will surely appeal to those who believe that the relative poverty and privilege of different peoples arises from irreparable, inborn differences in their genetic makeup.
First, let’s examine Wade’s many straw men. He argues against the claim that all the people of the world have essentially similar genetic makeup (a position not actually held by any credible geneticists or anthropologists) and argues that races, indeed, are groups delineated from one another by hard biological evidence. To bolster this claim, Wade cites a 2002 landmark study in Science magazine of fifty-two populations from around the world. That study employed a computer program called Structure, which uses differences in DNA to identify distinct groups of humans.
The problem is that Structure* was not intended to be used to prove that any grouping it found was, in fact, biological fact. Indeed, the boundaries between these groupings are so blurry that scientists have to tell the software how many groups to look for. Wade, instead, takes a procrustean approach, focusing on a run of the software that focused on five groups: Europe and central/south Asia; central/south/east Asia; Oceania; Africa; and the Americas. These boundaries roughly match continental geography, but some groups span multiple regions, and the boundaries shift when scientists ask the software for a different number of groups. Rather than running the analysis — which is meant to be agnostic — through a rigorous, scientific process, Wade cherrypicks results that justify his conclusions. What results is a tautology, in which any claims by the computer use Wade’s conclusion as a starting premise.
Worse for Wade’s argument, no matter how finely the software divides up the world population, individual people within a single group differ genetically from one other far more than two groups differ from one other. In the Science magazine study, 94.6% of the variation in genetic content was found within populations, with the remaining 5.4% accounting for differences between groups. Of all the gene variants studied, 93% were found in two or more geographic regions, while 47% were found on every continent. Genetically speaking, very little distinguishes Jews from Japanese, or Nigerians from Armenians.
In the second half of “A Troublesome Inheritance,” Wade completely abandons science for alluring, yet ultimately unsupported speculation. He asserts that (a) different nations reward success in different ways, (b) if success is defined as leaving more offspring, then genetic differences accumulate to make a nation distinctive, and (c) these distinctions shape a nation’s character and prosperity.
It takes breathtaking nerve to make such a chain of unsupported assertions. Wade’s a great storyteller, but to quote geneticist Michael Eisen, “unmoored from data and logic, one can make up an evolutionary explanation for anything.”
Wade asks why the Industrial Revolution took off in England but not in other countries. He asserts that the key difference is an inborn English tendency towards nonviolence and patience, which facilitated productive activities like standing in front of machines for many hours a day. As a biological mechanism, he suggests that the rich left more children on average than the poor, spreading their positive genetic traits downward throughout society. This speculation does not stand up well under scrutiny. The affluent have higher birth rates around the world, not just in jolly old England. And ask any Scotsman about the Highland Clearances of the 19th century. Whatever the cause of the Industrial Revolution’s timing, it is unlikely to have such a simple, genetically determined explanation.
A major problem with this line of speculation is Wade’s mistake of attributing the findings to genetics alone. Change in a nation’s character can occur in remarkably few generations. During the Meiji period from 1868 to 1912, Japan was transformed from a feudal society to one that was ruled by national law. Within a few more generations, Japanese customs became dominated by intense and elaborate courtesies that seem quite far from blood vengeance prevalent during the shogun period. Genetic selection can’t work fast enough to generate such a change. However, social evolution occurs as fast as ideas can move, so it is more logical to say that society changed before their genes could.
Interactions between an individual’s genome and his or her environment can have profound effects on developmental outcomes. In many developed countries, IQ scores have risen by several points per decade, a phenomenon called the Flynn effect. Its discoverer, James R. Flynn, reports that this change has been happening for many decades. For instance, in verbal and performance IQ, an average Danish 14-year-old in 1982 scored 20 points higher than the average person of the same age in his parents’ generation in 1952. The rapidity of the change suggests that some environmental factor, whether educational, nutritional, or other, has had substantial effects on brain development.
The effects of environment on genetic potential are seen most sharply in adoption studies. French children score twelve IQ points higher on average if they are adopted into middle-class homes than if they are adopted into working-class homes. If children are raised in poverty, the gap is as large as eighteen points.
Furthermore, we know that this large difference arises from environmental, not genetic influences. Environment can radically prune back a child’s genetic potential. For example, the heritability of IQ is nearly eliminated in children who are raised under conditions of poverty. Under these conditions, genes never get the chance to reach their potential. Even if there are genetically based average differences between nations, in individuals they are dwarfed by the effects of environment.
To me, a far more interesting question than the one posed by Wade in “A Troublesome Inheritance” is the question of why such speculations have attracted so much interest. The urge to find genetic roots for differences between ethnic groups is as longstanding as the history of genetics itself. Unsurprisingly enough, “A Troublesome Inheritance” has been endorsed by white supremacist and former Ku Klux Klan grand wizard David Duke, who has said, “the ideas for which I’ve been relentlessly villified are now becoming part of the mainstream because of the irrepressible movement of science and genetics.” It should be noted that Nicholas Wade is not directly responsible for how his work gets spun and coopted, by Duke or by anyone else. Still, Wade’s book seems to needlessly breathe new life racialist thinking of past decades and centuries, while discounting the more exciting, but different directions where the science has gone instead.
As it turns out, Chinese IQs are no different from those of white people. However, I didn’t say this to the octogenarian. I simply told him: “There are all kinds of Chinese people. In fact, some are real layabouts.” He looked incredulous, but I persisted. “If you were Chinese you’d know a few of them.”
*Originally, I wrote that STRUCTURE uses the k-means algorithm. Some population geneticists thought that I oversimplified what STRUCTURE does. Different clustering algorithms make different assumptions. STRUCTURE is indeed very similar to k-means, but with a particular error structure – binomial instead of gaussian. This is a fine technical detail compared with the principal point, which is that k is picked by the user, and does not emerge from the data automatically. To learn more, see this Twitter chain and this and this. Thanks to Graham Coop at UC Davis. Also, welcome to readers of Dienekes Pontikos, who has lots to say on this subject.