The IQ Genes That Weren't

Long-time readers of this blog may well remember the excitement generated in "race realist" [sic] circles by Bruce Lahn's research some 15 months ago, and the lengthy response I wrote at the time giving sound reasons for scepticism. At the time I was attacked for my emphasis on caution and rigorous thinking by certain arts school types fond of passing themselves off as knowledgeable about genetics, and informed in no uncertain terms that at last the hour of "proof" had come for the claim that blacks are by their very natures of lesser intelligence than the rest of humanity. We supposedly timid and hopelessly "politically correct" types were soon to be brushed aside by the unstoppable march of scientific knowledge, or so certain individuals had it at the time. How, then, have matters subsequently turned out?

Time has a funny way of working, and as the months have gone by, my words of caution have subsequently been completely borne out by the research, which has thus far failed to uncover any association whatsoever between variation in the ASPM and MCPH1 genes and standardized measures of intelligence. What is even more interesting is that now, in a profile of Bruce Lahn by Michael Balter in Science (also see this accompanying article), Lahn's follow-up research is given coverage, and the results disclosed are hardly what those who celebrated his "proof" were expecting, especially in light of the identity of at least one investigator seeking to build on Lahn's research:

Soon after the Science papers were published, Lahn set out to see whether the variants give a cognitive advantage. In one study, Lahn helped controversial psychologist Philippe Rushton of the University of Western Ontario in London, Canada, test whether people who carry the favored variants have higher IQs. Rushton is well known for his claims that African Americans have lower intelligence than whites, and Lahn had found that some genetic variants are common in Europeans and Asians but less frequent among sub-Saharan Africans. But Rushton reported last week at the annual meeting of the International Society for Intelligence Research in San Francisco, California, that he had struck out: The variants conferred no advantage on IQ tests. "[We] had no luck," Rushton told Science, "no matter which way we analyzed the data." Lahn was not a co-author, but his group genotyped the 644 adults of differing ethnicity in the study.

Now, given Rushton's less than disinterested research history with this topic, it really says something that the man was unable to torture the numbers into confessing that blacks are congenitally stupid: surely if anyone were capable of doing such a thing, it would be the Pioneer Fund boss and American Renaissance speaker himself. At any rate, a similar, even larger study by Lahn himself also failed to turned up anything meaningful.

Lahn is a leading author, however, of a similar international study of about 2500 subjects. Most of the results are unpublished, but findings from Australia were presented at a meeting in Brisbane last August. Nicholas Martin's team at the Queensland Institute of Medical Research in Brisbane found no statistically significant correlations between the supposedly favored variants and IQ.

Indeed, despite the knowledge that defects in the microcephalin gene have been firmly linked to microcephaly, it has not even been possible to establish an association between brain-size and normal variation in said gene. I quote:

Some mutations in microcephalin and ASPM lead to microcephaly, or very small brains, so Lahn had hypothesized that the variants might influence brain growth in normal people. But that idea was challenged last May by neuroscientist Roger Woods of the University of California, Los Angeles. Woods's team found no correlation between brain volume and the variants in 120 normal subjects, as reported in Human Molecular Genetics.

As I noted to litte effect way back in September 2005,

Underlying all the ignorant chatter about how the ASPM and microcephalin variants written about by Dr. Lahn must be genes "for" cognition is the assumption that because faults in both genes have been implicated in brain disorders, and because differences exist between humans and chimps in both genes, then "the" purpose of the existence of these new variants has to be to code for "IQ" or some such thing: but the reality is that with an organ as complex as the human brain, there are very many ways for a gene malfunction to lead to devastating consequences, often through causal chains nobody would have guessed beforehand.

I even gave a concrete example of how a defect in a gene said nothing as such about what normal variation in said gene implied, also to no avail:

To illustrate how things aren't always what they seem, and why it is important to understand the underlying biochemistry before jumping to conclusions, let us consider phenylketonuria: this is a genetic disorder which is characterised by mental retardation, and an uninformed observer might easily jump to the conclusion that this means defects in the gene implicated in it must result in some crucial feature of the brain being wired wrongly, leading to lower IQ scores. And yet, as we now know, the depressed IQ which accompanies phenylketonuria has nothing to do with brain wiring, but is the result of an inability of the sufferers' metabolic systems to produce sufficient levels of phenylalanine hydroxylase: in the presence of a diet which makes up for this deficiency, the IQ scores of the genes carriers turn out to be normal, and what might have been ascribed to an "IQ gene" is in fact just one particularly visible manifestation of an enzyme deficiency which has several other side-effects.

Uncanny how what I wrote forshadowed subsequent developments, isn't it? But all I did was apply a little of that old-fashioned sceptical reasoning which certain individuals were so keen on telling me no longer had a place in science.

Now, it would be one thing if it could be said that Bruce Lahn's papers, however lacking in validity the speculations raised in them might turn out to be, were in of themselves unimpeachable in terms of the conclusions they drew, but as the Science profile informs us, even this is not necessarily the case:

In a Technical Comment published 14 July online in Science, Sarah Otto of the University of British Columbia in Vancouver, Canada, and colleagues argued that Lahn's findings reflected not a signature of selection but rather the genetic traces of population movements as modern humans migrated out of Africa. And in October, a team led by geneticist David Reich of the Broad Institute in Cambridge, Massachusetts, reported at the meeting of the American Society of Human Genetics that it found no evidence for recent selection on ASPM when it used a method of analysis it considered superior to Lahn's.

Of course, Lahn continues to stand by his work, and for all one knows he might even win this particular debate, but at this point his research hardly looks like the firm foundation upon which self-described bold new thinkers can build a politically-incorrect, "race realist" theory of innate differences in intelligence. Thus has it always been with such types: a decade ago it was Murray and Herrnstein's "Bell Curve" book, with its curious statistical manipulations and reliance on dubious data; four years ago they were hyping the imminent completion of the HapMap project as the moment when the innate shortcomings of blacks would be indubitably established, but nothing came of that; then they moved on to Lahn's work, and now nothing's come of it as well; no doubt they shall soon latch unto some other development, perhaps even another collection of wild speculations by some ambitious young researcher looking to generate a buzz for his work, in order to lend their quackery an air of scientific respectability. What saddens me is that I'm certain that this next time too the press will seize upon their claims and give them an entirely undeserved currency in the mainstream, even as it once again fails to provide anything like a similar level of coverage to the latter research which shows up the new claims as meaningless: "blacks are innately stupid!" sells papers and journals in a way "no evidence for innate racial differences in intelligence" does not, and it doesn't take a sky-high IQ to understand why that is the case.

PS: You might also want to take a look at my first response to hearing of Lahn's research. It's amusing to see how thoroughly on the mark Andrew's and my warnings were: not only have all sorts of nuts repeatedly harped on the "politically incorrect" implications of this one study in the interim - a Google search turns up quite a few kooks* using the standard right-wing rhetoric - "pc liberals" supposedly "stifling" brave researchers committed only to the hard truth, etc. - but even my admonition as to the unestablished link between the microcephalin gene and normal brain size variation was right on the money. We "pc" types do have our strengths, it would seem.

*How is it possible for a supposedly rational person like Alex Tabarrok to patronize cranks like Randall Parker and Steve Sailer without sharing their ill-founded obsessions? Frankly, I don't believe it is, which is why I gave up reading Marginal Revolution a long time ago.

Comments

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But all I did was apply a little of that old-fashioned sceptical reasoning which certain individuals were so keen on telling me no longer had a place in science.

Oc{c,k}am got an eclectic razor, see, and the shortest distance between two paths became hyperbolic. Or, perhaps hyperbolic, one can't really know until we get there, right? cf. Strauss, Leo.

no doubt they shall soon latch unto some other development

I think they're getting off on Muslims at the moment, or alternately, in the US, Mexicans.

How is it possible for a supposedly rational person like Alex Tabarrok to patronize cranks like Randall Parker and Steve Sailer without sharing their ill-founded obsessions?

I think that goes a little too far. Tabarrok suffers from a classic disease - Economica Academia, which, by way of making one seek out and consume counterintuitive propositions that happen to have to do with real people, seems to cause credulousness to any dumb theory that (a) looks like it there's research behind it and (b) is contrarian enough to catch the eye. I think he's sharp, but is a little caught up in a "ohh, sparkley" approach to econ. But he isn't dumb. And Cowen isn't, either, even if he is a little myopic at times.

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Gah, my HTML was stripped. Sorry that that reads poorly - I'll remember that.