Some of Wade's stories, moreover, employ questionable logic. Is it really obvious, for instance, that it takes more intellectual firepower to know when to make a loan (and at what rate of interest) than to know when to take out a loan (and at what rate of interest)? [Darth Quixote: Yes.] Moreover, Wade's focus on recent human history saddles him with a systematic problem: adaptation by natural selection takes time and many of his stories provide precious little of it, at least by
evolutionary standards. The Church's proscription against usury, for example, was in effect for centuries, not millennia. This might be long enough to yield a perceptible response to natural selection on intelligence but the case is far from obvious.

Wade's account is based on recent work by G. Cochran, J. Hardy, and H. Harpending, all of the University of Utah, who claim that the moderately high frequencies of several disease mutations, including that causing Tay-Sachs, among Ashkenazi Jews might be explained by natural selection. Because the genes involved also play some role in the brain, Cochran and colleagues speculate that the relevant mutations might increase intelligence, perhaps reflecting a history of selection among medieval European Jews, who often worked in finance or related professions. Such a hypothesis is certainly possible; the critical issue is the strength of the empirical evidence.

Population genetics now provides a set of reasonably powerful statistical tools that allow us to determine whether a gene evolved under Darwinian natural selection. In principle, then, one might ask questions like: Do genes that play a role in the brain evolve much faster in certain human races than in others? If so, were the DNA changes involved driven by natural selection? The answers to such questions could clearly be awkward, if not incendiary. Wade's only comment on this issue is to insist that by turning our backs on free inquiry into the human genome, we would "retreat into darkness." While I tend to agree, the issue is not merely whether refusal of such studies would mean a retreat into scientific darkness, but whether performing them would also mean a march into moral darkness. After all, we rightly forbid scientists from performing all manner of repugnant or disturbing experiments (think of those committed under the Nazis).

The interesting point--and it's not widely appreciated--is that this question is rapidly becoming moot. Vast quantities of information about the human genome now pour into publicly available databases on a daily basis. These data are collected with the noblest of intentions (often medical) and are also made public for perfectly good reasons: citizens should have ready access to the fruits of publicly funded science. Indeed it's almost impossible to imagine how one could stop the sorts of studies I described above. In previous times, granting agencies, such as the NIH or NSF, could block funding for undesirable experiments or scientific journals could refuse to publish them. But with genomic data, minimal money is required (an Internet connection is enough) and any bright graduate student working in his parents' garage could ask and answer any awkward question he likes. And the Internet thoroughly dashes any chance of preventing the publication of unpleasant results.

The reality, then, is that the pace of technological change is rendering irrelevant what is essentially a question of policy. On the other hand, I suspect we have little to fear. Over the next decade or so, discomfiting analyses will surely be performed and bold claims will certainly be made but, in the end, biologists will likely conclude that we are all much more alike than we are different. It's hard to believe, after all, that in genetics, millions of years of shared evolution don't count for far more than a few tens of thousands of years of separate history.