Wednesday, May 09, 2007
PZ Myers is against forcibly sterilizing low-IQ people (or sending them into space). This is a brave, progressive position, and I applaud him for standing up to those who would have the underclass living off nothing but moon dust. However, his righteous argument makes an absolute butchery of much of population/quantitative genetics. Let's take two examples:
1. One issue at hand here is whether, should low-IQ people reproduce at a rate higher than high-IQ people, lower IQ could then evolve in humans. This should be self-evident, but perhaps must be spelled out more clearly.
What is necessary for a phenotype to evolve by natrual selection? Richard Lewontin, in 1970, set out the three requirements (I limit myself to considering the evolution of phenotypes; Lewontin considers the evolution of any "unit"). They are:
1. There must be phenotypic variability in the population.
2. The phenotypic variation must have fitness consequences.
3. The phenotype (and thus fitness) must be heritable.
IQ is obviously variable, there is an inverse relationship between IQ and fertility (for example), and heritability estimates for g are in the range of 60%. Thus, intelligence satisfies all the requirements for phenotypic evolution. Note that there is no claim made about the precise molecular machinery or genes underlying intelligence; this knowledge is irrelevant to the arguement-- as long as there is variability, heritability and selection, the breeder's equation will do the rest.
2. Another issue here is whether there are populations with different distributions of genetic variants underlying intelligence. Dr. Myers writes, "You'd be hard-pressed to argue that the diverse groups marked by ethnic and class distinctions in the U.S. even count as distinct populations in any biological sense. There are social barriers to breeding, but they are sufficiently porous that over the course of time needed to set up genetic differences that matter, they're negligible." This is absurd. Ethnic groups can be distringished based on genetic data alone (at least in the US, where this has been explicitly tested, and see also my longer post on the topic of race). And unless he doesn't consider things like hair color and skin color to be genetic, some genetic differences, at least, should be readily visible.
Different population groups have different distributions of intelligence, and different distributions of genetic variation genome-wide. True, the explicit connection between the two has not yet been made, but the study of human genetic variation is in its infancy. The genetic change underlying much of the variation in skin color between European and African populations, for example, was discovered less than two years ago. There is much to be learned, and not all of it will be palatable.
Unless one believes that biologically identity is required for political equality, this should not have any major political consequences. But knowledge of the genetics underlying "desirable" traits does raise the spectre of eugenics. Is this necessarily a bad thing?
As Razib has pointed out before the "new eugenics" will not take the heavy-handed route of forced sterilization or government coersion; it will likely be an entirely individually-pushed enterprise-- many parents would choose to give their children a boost of a couple IQ points if doing so were simple and painless. Dr. Myers seems to be a fan of Richard Dawkins, so I'll quote a couple paragraphs from him:
IN THE 1920s and 1930s, scientists from both the political left and right would not have found the idea of designer babies particularly dangerous - though of course they would not have used that phrase. Today, I suspect that the idea is too dangerous for comfortable discussion, and my conjecture is that Adolf Hitler is responsible for the change.