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Health

Race & IQ: information will be free

Gene ExpressionBy Razib KhanFebruary 18, 2009 9:58 AM

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Dan the man's post on Race & IQ generated a lot of feedback. A lot. Those of you who are familiar with my weblog oeuvre know I used to be more interested in psychometrics. No more. Rather, if you don't want to believe in IQ or general intelligence, fine. My own experience is that very intelligent people (e.g, Mark, PhD physiology, now getting his MD, undergraduate background in physics) often are the most robust and cogent objectors to IQ or psychometric testing as a relatively useful reflection of intelligence. Dumb people know very well they're dumb, and they're not too coherent or interested in such abstract topics as whether the Raven's Matrices have instrumental value in predicting someone's ability to crunch through tasks requiring rational-abstraction heft. Let's think like an economist; assume that intelligence tests are useful in measuring intelligence, that intelligence is around 50% heritable, so it has an underlying genetic component. With these assumptions it is theoretically possible that scientists might be able to map from genotype-to-phenotype with some level of plausibility. That an allele, X, might have an effect on the trait value of Y, within a population. As it happens IQ genes haven't really been found. The behavior genetic data imply that loci which effect population level variation are going to be small, perhaps far less than 1% of the variation in IQ being due to any given polymorphic locus. That means there are perhaps thousands of extremely small effect alleles scattered through the genome which effect IQ. There might be levels of nuance within the genetic architecture, perhaps there are larger effect alleles which are found only among the extremely intelligent, 2 or more standard deviations above the norm (top 2-3% in IQ). So far the standard genetic methodologies haven't yielded anything promising, linkage studies which are better are looking for larger effect if rare variants didn't find anything, and newer association studies which are better at picking out smaller effect but more common variants within populations haven't picked up anything of a high likelihood (yes, IQ genes pop up every year, but do enough studies and you'll start digging up spurious associations here and there). Obviously catching IQ genes is not a trivial task. They might be scattered and relatively numerous, but if their effect size is vanishingly small how will you distinguish the faint signal from the noise? In other words, those who tremble at the thought of differences in intelligence being adduced to genotypic variation probably shouldn't stay up at night with worry. But times change. Here are some issues: 1) Genome sequencing is getting hella cheap, and way more thorough. What might it be like in 10 years? We're talking exponential increases in bang for the buck. 2) The computational power to munge its way through the data sets is getting more robust year after year. Again, exponential increase in bang for the buck. 3) It seems likely that widespread sequencing will be a habitual feature of the landscape in around 10 years due to considerations of preventive health. Personal genomics for this reason might be overhyped, but if the costs come down low enough people will likely do it even for marginal benefit. But even then you might need really large sample sizes to get enough statistical power to pick up the IQ QTLs. This is why I think #3 will be important, if most people have a thumb drive (or whatever cool thing we have by then) with their whole genome the key issue becomes.... 4) Getting people to do the tests. This is where the concerns of the likes of Mr. Rose become important. There happens to be several large scale institutions which do a great deal of psychometric testing: the armed forces of various nations. Nations which have conscription have been some of the best sources for detailed longitudinal data because of this. If in 10-20 years most of these soldiers-to-be already have a personal genome hanging around, perhaps one of the Nordic countries who have socialized medicine where the government might keep a central database, it might be easy to cross-reference with the psychometric data. As it is I suspect there will be a lot of resistance to this through lobbying. But I don't think it will matter in the long run, someone will figure out a way to get a large enough sample size, or synthesize the two disparate data sets. It's a big world, and I don't think this will be Big Science of the type which will require enormous outlays of funds. Perhaps for various reasons Western nations will manage to tamp down on exploration of IQ related loci. Well, we always have the Chinese, with a 10 million or more man army to order around. Perhaps the technical hurdles will be too high, perhaps the QTLs are infinitesimal in a manner that Charles Darwin or R. A. Fisher would appreciate. But let's say that the Chinese state find many candidate loci which sum up to a substantial fraction of the presumed heritable variation. Can they keep this a state secret? In the age of the telegraph they could, but I doubt they could in 2020. There will naturally be objections. Epistasis? Or, perhaps people will discover the importance of "genetic background" (this is code for another word!) and claim that effects of allele A in the Chinese background don't apply to other populations. Perhaps there'll be no difference, and everyone can breath easy. Thinking like an economist, presuming that the QTLs for IQ are discovered, neoeugenics, gene therapy or perhaps some sort of magical drugs (I have no idea how this would work, so "magical") which modulate the regulation of the QTLs in question will emerge. A race for intelligence might ensue, up to the physiological limit. People in the 2-4 standard deviation range are sometimes weird, but trust me, not that weird. At that point questions about differences within the population will be rendered moot as the ethical implications of differences between generations, and the extent to which parents will go to give their kids "an edge," will come to the fore. The whole point there is that I don't think we're talking Large Hadron Collider or Human Genome Project scale big science. There won't be any issue of a huge debate about the ethical implication of the NIH throwing money in this direction: it simply won't happen, no way that any politically associated agency would fund such a project. Rather, it will happen when the technology makes it cheap enough that people can synthesize data sets from projects that are going on for other reasons (obviously lots of genomes + powerful computers are going to be an area where medical genetics is going to slouch), or, a rich individual funds it. If anything is discovered, it will spread at the speed of light. Of course, if many of the QTLs are discovered, and they differ between populations in a manner which suggest that allele differences map onto phenotype, preimplantation screenings could perhaps mitigate the difference within a generation. Well, unless all the white liberals turn Nazi because they snap after finding out that their socially constructed population has a somewhat different mix of alleles resulting in higher IQ, and all us colored folk get sent to the gas chambers because now they know we're stupid because of our genes (or in the case of East Asians, smarter because of their genes, rather than the evilness of white people). Note More comfort, economists are idiots, so thinking like them might mean the whole project fails even in thought!

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