Which environmental factors explain the black–white IQ gap?

Environmentalists don't seem to know.

Written by Noah Carl.

Every so often, and it does happen to be quite often, an academic article is published that equates the hereditarian hypothesis with racism. The latest example is a paper by Kevin Lala and Marcus Feldman, which just came out in the prestigious journal Proceedings of the National Academy of Sciences.

To illustrate what I’m talking about, let me share a few quotations. Lala and Feldman refer to “racist claims of ubiquitous genetic differences between socially defined races”. Such claims, they argue, “help to perpetuate racist ideas”. They state that Greg Cochran and Henry Harpending’s theory of Ashkenazi Jewish intelligence has “racist underpinnings”. Oh, and the paper itself is titled ‘Genes, culture, and scientific racism’.

According to Lala and Feldman, “there is no scientific evidence that supports the claims of Shockley, Jensen, Herrnstein, Murray, and other hereditarians that there are substantial genetic differences in intelligence between races”. So hereditarianism is not merely “racist”, but there is no scientific evidence that supports it – not a single piece, apparently.

Given how sweepingly Lala and Feldman dismiss hereditarianism, they must surely have a compelling alternative theory? They must have a large body of evidence that shows which specific environmental factor or factors explain racial IQ gaps? The problem is they don’t.¹

As you might have guessed, the authors begin by blaming racism. “Although phenotypic differences exist between socially defined races,” they write, “these are the product of different life experiences, including racism and discrimination”. However, they immediately switch to a much more elaborate theory, claiming that “inequitable niches” persist through “legacies of inherited norms and institutions, inherited wealth and power, inherited values and traditions, and inherited environments that vary in their amenities and opportunities”.

So racial gaps are caused by racism… But they’re also caused by norms, institutions, wealth, power, values, traditions and inherited environments that vary in their amenities and opportunities. This seems to be another way of saying, “Racial gaps are caused by the environment and it would be racist to suggest otherwise, but we don’t really know which aspects of the environment matter, so we’ll throw in the kitchen sink.”

Compelling evidence of environmental causation would be a study showing that racial IQ gaps disappear following such-and-such an intervention, or one showing that they’re absent in settings characterised by such-and-such a factor. No evidence of this kind is adduced by Lala and Feldman. In fact, the only paper they cite in support of their theory is one titled ‘Embedded racism: Inequitable niche construction as a neglected evolutionary process affecting health’. It does not mention IQ and presents no new data or analyses.²

Lala and Feldman’s style of argument is pretty much the default among environmentalists. They express supreme confidence in the falsity of hereditarianism, to the point of claiming the theory is so wrong it’s actually racist, but then fail to show that any specific environmental factors do explain racial IQ gaps.

When it comes to the black–white IQ gap in the US, we know that variables like income, wealth and socioeconomic status can’t explain more than a small part. There are several datasets, such as the NLSY (see p. 288) and Project Talent, where the gap is just as large in the top decile of parental SES as it is in the population as a whole. This means that when you have black and white Americans, all of whom were raised in wealthy families living in affluent neighbourhoods with access to good schools, the whites score about one standard deviation higher on IQ tests. In a recent study, Meng Hu found that Asian students whose parents didn’t finish high-school score higher on the SAT/ACT than black students whose parents completed a master’s degree.³

Racism as an explanation is no more promising. To begin with, there’s the pesky fact that some minority groups, notably East Asians and Ashkenazi Jews, score higher on IQ tests than the white majority. Why does racism cause blacks to score much lower than whites, while permitting other minority groups to score higher?

We can all agree that slavery and the holocaust qualify as two of the most racist acts in modern history. Indeed, it would be fair to say that blacks and Jews have faced more historical racism than other groups. Yet Ashkenazi Jews have an average IQ around 110, while blacks have an average IQ around 85. Even studies of holocaust survivors have found that they score no worse on tests of cognitive functioning than their counterparts who were not affected by the holocaust. If anti-black racism has such devastating effects on cognitive performance among blacks, why did the holocaust leave no discernible impact on cognitive performance among Jews?⁴

Furthermore, racism is not “some magic force that operates without a chain of causality,” as James Flynn noted. And yet, when we look at the variables through which it might plausibly operate, there is little evidence that blacks are severely hampered. For example, blacks have higher self-esteem than whites, lower rates of anxiety and similar rates of depression.

In a study published last year, Emil Kirkegaard reported direct evidence against the racism theory. Analysing variation in the black–white test score gap across more than 1,400 US counties, he found that the gap tends to be smaller where there are more whites and more Republicans – the exact opposite of what the racism theory predicts. He also found that the size of the gap is not significantly associated with a measure of “implicit racism”.

With neither SES nor racism likely to explain more than a small part of the gap, the only other obvious candidate is culture, specifically a black culture that stymies cognitive development. This is the avenue that Flynn, arguably the most sophisticated proponent of environmentalism, pursued toward the end of his career. Ironically, it landed him in a bit of hot water because even cultural explanations are seen as “blaming the victim”. (Many people care less about improving outcomes for blacks than they do about feeling morally righteous.)

One problem with the cultural theory is that it has always been rather vague. Which aspects of culture make a difference and how do you measure them? The most influential version of the theory is the one outlined by legendary economist Thomas Sowell. However, Nathan Cofnas recently penned a comprehensive rebuttal of Sowell’s arguments, which leaves relatively little in the theory to be salvaged. There may be some other version that could be made to work, but as of now the cultural theory looks rather implausible.

Returning to Lala and Feldman, their specific claims about the causes of racial IQ gaps are not merely speculative and unproven but inconsistent with a large amount of existing data. Meanwhile, their vaguer claims are borderline untestable. How exactly do you test whether gaps are caused by “inherited environments that vary in their amenities and opportunities”?

Environmentalists are very persistent in attacking hereditarianism and impugning the characters of its proponents. They are far less diligent in supplying evidence that environmentalism is actually true.

Noah Carl is Editor at Aporia.

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1. As far back as 1974, the philosopher Peter Urbach noted, “Environmentalist theories explaining observed group differences in average IQ have consistently lagged behind the facts and auxiliary hypotheses proposed to rescue these theories when their predictions have failed are all ad hoc.”

2. The authors do cite a few other works elsewhere in their article.

3. Lead exposure can’t explain more than a small fraction of the black–white IQ gap either, as racial differences in lead exposure are simply not large enough.

4. One could make a similar argument about the internment of Japanese Americans during World War II.