Field of Science

Should scientists study differences in intelligence?

Celebrating Darwin 200, this week Nature has a great issue with lots of articles about evolution and things related. Among them are two articles debating whether science and society benefit from research on race and gender differences in intelligence. Should scientists do such research at all?

What do you think? Given that many consider it politically incorrect to say that men are more intelligent than women, or white people are more intelligent than black people, should research into the matter be undertaken in the first place?

Steven Rose, professor emeritus in neuroscience at the Open University, UK, argues that neither science nor society benefits by exploring differences in intelligence in terms of race and gender. My first instinct was to ask "why the hell not?", but after reading what he has to say, I was actually somewhat won over by his argument. Which goes like this.

According to Rose, three criteria must be be met for research to have any merit:
  1. The questions it asks must be well-founded,
  2. the questions asked must be answerable with the theoretical and technical tools available, and
  3. any answers the research arrives at must either contribute to scientific understanding, offer new technological prospects, or aid sound public policy-making.

To the first criterion his answer is that there is so much difficulty defining intelligence that the question of intelligence differences doesn't really make much sense. He doesn't believe there is any general intelligence factor, g, this hypothesized measure of an underlying heritable intelligence, and if so it really does not make sense to ask what the differences are based on genetic differences.
However, except to a small band of dedicated psychometricians, it seems obvious that to try to capture the many forms of socially expressed intelligent behaviour in a single coefficient — and to rank an entire population in a linear mode, like soldiers on parade lined up by height — excludes most richly intelligent human activities. Social intelligence, emotional intelligence, the intelligent hands of the craftsman or the intelligent intuition of the scientist all elude the 'g' straightjacket.
Secondly, Rose asserts that we don't have the theoretical tools to study differences in intelligence. All attempts to make culture-free IQ tests have failed, he says.

His third criterion puts the final nail in the coffin by noting that there are no examples of such research that is not used to justify a social hierarchy in which white males continue to occupy the premier positions in society.

To summarize, there is no point in doing research on intelligence differences between races or genders, because it isn't even clear what intelligence, or IQ, is, and if it is definable, we certainly can't measure it, and if we could, then people would again use it to justify their own superiority.

Personally, as a scientist, I can't care all that much how the results of research will be used in society. If people are dumb enough that they would take results indicating that Asians have higher IQ than white people to justify that Asians should have any kind of advantage over whites, then so be it. I find it very hard to believe that anyone would today suggest that policies should be made to such effect. On the contrary, I would sooner expect the opposite - that groups that would be disfavored by nature would get some sort of benefit by law.

Rose's first two criteria are what made me think for a while that perhaps he had something going for his disdain. Genetically there is less difference between negroid, mongoloid, and caucasoid that there are between various African ethnic groups. Then, assuming that IQ is genetically based (as opposed to purely environmentally based), does it make sense to suppose that we can find any differences between non-African groups at all?

And, is it even possible to measure g?

I think that the biggest error committed by scientists and laymen alike is thinking of the good ways we can put our minds to use as 'intelligence'. This is clearly wrong, as when intelligence is equated with IQ. From Wikipedia:
Intelligence (also called intellect) is an umbrella term used to describe a property of the mind that encompasses many related abilities, such as the capacities to reason, to plan, to solve problems, to think abstractly, to comprehend ideas, to use language, and to learn.
Daniel Goleman, author of Emotional Intelligence: Why It Can Matter More Than IQ (1996), talks of seven kinds of intelligence that do not correlate within a single person. That is to say, being very good at logic does not mean that one is very good at thinking abstractly, for example. However, I have experienced many people expressing that intelligence is the only factor of importance when evaluating mental capabilities, and further equating intelligence with IQ. IQ-test don't purport to measure how good people are at thinking abstractly, for example, or what their emotional intelligence is.

This post ended up somewhat longer than I had anticipated, so I will have to explore Stephen Ceci and Wendy M. Williams' opposing answer to the question about whether we should study intelligence differences in a later post.


  1. Interesting stuff. I think that there are real social problems with studying IQ - it's one of those subjects that is easily misunderstood, and which feed into a lot of very powerful psychological preconceptions about in-group:out-group thinking. You don't want to reinforce that by accident!

    Here's an interesting link, talking about cognitive biases that are uncorrelated with IQ. Just to reinforce the fact that, even if general intelligence exists, there is a lot more to be clever than just IQ!

  2. Some criticisms of Rose here on Gene Expression.

    Also, Steve Hsu links to the discussion where James Flynn shows a major flaw in Rose's argument:

    "Flynn: ...In Rose’s original paper [commentary], he asserts that the trait in question (intelligence) leaves aside other desirable traits and argues that the groups in question can be divided into subgroups that are more biologically coherent. He concludes that the hypothesis is not subject to scientific treatment; and therefore, no useful social policy will emerge. In his response to Ceci and Williams, he says something very different, namely, that by about 1975, it had been definitively shown that genes had no place in explaining group differences. So from that date, Jensen and everybody else had no excuse to persist.

    To assert both that a hypothesis is not scientifically testable and that it has been conclusively falsified is incoherent. The only way to reconcile them is to assume that Rose does not really mean Jensen had been refuted by 1975, but is saying that by that date, it should have been clear to everyone that the question was indeed unanswerable."

  3. "And, is it even possible to measure g?"

    Apparently so. Here is a paper by UCLA neuroscientist Paul Thompson & Yale Psychologist Jeremy Gray, explaining the neurobiology of intelligence.

    These characteristics, such as myelination appear to be significantly heritable.

    "The UCLA researchers took the study a step further by comparing the white matter architecture of identical twins, who share almost all their DNA, and fraternal twins, who share only half. Results showed that the quality of the white matter is highly genetically determined, although the influence of genetics varies by brain area. According to the findings, about 85 percent of the variation in white matter in the parietal lobe, which is involved in mathematics, logic, and visual-spatial skills, can be attributed to genetics. But only about 45 percent of the variation in the temporal lobe, which plays a central role in learning and memory, appears to be inherited.

    Thompson and his collaborators also analyzed the twins' DNA, and they are now looking for specific genetic variations that are linked to the quality of the brain's white matter. The researchers have already found a candidate--the gene for a protein called BDNF, which promotes cell growth. "People with one variation have more intact fibers," says Thompson."


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