On the plane recently I read Consanguinity, Inbreeding, and Genetic Drift in Italy. Excellent book-I recommed it to the usual suspects. But, ironically I find that for a book relating to consanguinity, it displayed a symptom of intellectual incest, the ability of a lay non-specialist to pick out an error in a field tangential, but relevant, to the subject matter at hand.

On page 3, the authors note, "uncle-niece marriages comprise up to 20% of all marriages in several north Indian tribes...." Yet, on page 285, they display a map which shows clearly that the higher incidence of consanguinity in southern India. In fact, north Indian Hindus (though not Muslims) are very exogamous, and uncle-niece marriage is known to be widely practiced by south Indians. I know this is nit-picking, but, if I can pick out simple errors like this, that indicates to me there are other small detriments of detail. None of the authors of the monograph, Luigi Luca Cavalli-Sforza, Antonio Moroni or Gianni Zei, are cultural anthropologists, to my knowledge, but surely they know someone who could have picked out these minor errors. I see this tendency in many papers that geneticists submit that make inferences about human population movements. As Andrew Reeves has noted, those outside specialties are often decades behind the consensus within a given field outside their conventional stomping grounds.

If you go back to the thread on Crooked Timber that I referred to earlier, I think you'll see evidence of intellectual incest. Those who make what I feel is an overly-enthusiastic denunciation of Darwinism in the context of sociology cite Richard Lewontin & Steven Rose. No matter the validity of Lewontin & Rose' critiques, I do think it is safe to say that they are "dissidents." Stating baldly that "...the mind is not a Swiss Army knife and the division of psychological entities into modules is something without anatomical basis...." might have some support from the likes of Rose, but it is a display of intellectual incest (or ignorance) to behave as if this is the scholarly consensus. To take the point reductio ad absurdum, many conservative Christians of an intellectual bent who have qualms about evolution might cite Hugh Ross, Michael Behe and William Dembski as scientific authorities on the topic at hand. Of course, their position is a vanishingly small fraction of scientists, while Lewontin & Rose hold to a view that is espoused by a non-trivial minority of scholars, nonetheless, the general tendency remains (by analogy, I am always been a bit perturbed when libertarians make arguments grounded in the Austrian School of economics, seeing as how it is marginal in contemporary economic scholarship at best-and so are simply re-affirming how kooky they are to the general public).