Steven Pinker, discussing the Gregory Cochran, Jason Hardy & Henry Harpending paper on Ashkenazim intelligence, gets it pretty much spot on, IMHO:
CH&H, then, have provided prima facie evidence for each of the hypotheses making up their theory. But all the hypotheses would have to be true for the theory as a whole to be true--and much of the evidence is circumstantial, and the pivotal hypothesis is the one for which they have the least evidence. Yet that hypothesis is also the most easily falsifiable. By that criterion, the CH&H story meets the standards of a good scientific theory, though it is tentative and could turn out to be mistaken.
But is it good for the Jews? More to the point, is it good for ideals of tolerance and ethnic amity? On one interpretation, perhaps it is. Jewish achievement is obvious; only the explanation is unclear. The idea of innate Jewish intelligence is certainly an improvement over the infamous alternative generalization, a worldwide Jewish conspiracy. And attention to the talents needed in the middleman niche (whether they are biological or cultural) could benefit other middleman minorities, such as Armenians, Lebanese, Ibos, and overseas Chinese and Indians, who have also been targets of vicious persecution because of their economic success.
And yet the dangers are real. Like intelligence, personality traits are measurable, heritable within a group, and slightly different, on average, between groups. Someday someone could test whether there was selection for personality traits that are conducive to success in money-lending and mercantilism, traits that I will leave to the reader's imagination. One can also imagine how a finding of this kind would be interpreted in, say, Cairo, Tehran, and Kuala Lumpur. And the CH&H study could lower people's resistance to more invidious comparisons, such as groups who historically score lower, rather than higher, on IQ tests.
What can be done? In recent decades, the standard response to claims of genetic differences has been to deny the existence of intelligence, to deny the existence of races and other genetic groupings, and to subject proponents to vilification, censorship, and at times physical intimidation. Aside from its effects on liberal discourse, the response is problematic. Reality is what refuses to go away when you do not believe in it, and progress in neuroscience and genomics has made these politically comforting shibboleths (such as the non-existence of intelligence and the non-existence of race) untenable.
Rather than legislating facts, could we adopt a policy of agnosticism, and recommend that we "don't go there"? Scientists routinely avoid research that may have harmful consequences, such as injuring human subjects or releasing dangerous microorganisms. The problem with this line of thought is that it would restrict research based on its intellectual content rather than on its physical conduct. Ideas are connected to other ideas, often in unanticipated ways, and restrictions on content could cripple freedom of inquiry and distort the intellectual landscape.
Also, there are positive reasons to study the genetics of groups. Until the day that every person is issued a CD containing his or her genome, medicine will need the statistical boost of data on group differences when targeting tests and treatments to those most likely to benefit from them. Remember that the CH&H study grew out of research aimed at reducing the enormous suffering caused by genetic diseases. Many have effects on the nervous and endocrine systems, and connections with the psychological traits of sufferers and carriers may be unavoidable. And of course the tests could refute claims of group differences as easily as they could confirm them.
The genetics of groups is also an exciting frontier in the study of history. Many Jews have been thrilled by the discoveries of a common Y-chromosome among many of today's kohanim (believed to be descendants of the priestly caste in ancient Judea, who were themselves the descendants of Aaron), of genetic commonalities between the Ashkenazic and Sephardic Jews traceable to a common ancestry in the Middle East, and of the presence of these genes in isolated communities in Africa and Asia that retain some Jewish rituals. Studies of the genes of African, American, and Australian populations could shed light on their prehistory, filling in pages that are sadly missing from the history of our species, as well as enlightening curious individuals about their genealogy.
In theory, we have the intellectual and moral tools to defuse the dangers. "Is" does not imply "ought." Group differences, when they exist, pertain to averages, not to individual men and women. There are geniuses and dullards, saints and sinners, in every race, ethnicity, and gender. Political equality is a commitment to universal human rights, and to policies that treat people as individuals rather than as representatives of groups; it is not an empirical claim that people are indistinguishable. Many commentators seem unwilling to grasp these points.
The revolution in human genomics has spawned profuse commentary about the perils of cloning and human genetic enhancement. But these fears may be misplaced. When people realize that cloning is just forgoing a genetically unique child for an identical twin of one of the parents, rather than resurrecting a soul or investing in an organ farm, I suspect no one will want to do it. And when they realize that most genes have costs as well as benefits (a gene might raise a child's IQ but also predispose him to a genetic disease), "designer babies" will lose whatever appeal they have. In contrast, the power to uncover genetic and evolutionary roots of group differences in psychological traits is both more likely to materialize and more incendiary in its consequences. And it is a prospect that we are, intellectually and emotionally, very poorly equipped to confront.
