eric,
i am not one of the pc crowd, yet i find your unqualified dog-native comparison deeply offensive. yes, i do know you did not want to say that papua-neuguineans have the same iq as dogs. if you don't understand where my problem is, imagine how a similar comparison would sound to you if you found it on a arabic muslim website directed at white americans. eg "infidels are chaste like a dog is chaste". remember also that verbally dehumanizing people has a rather long tradition in the context of kinds of behaviour, like mass murder, that presumably you do not want to be associated with. i am ill in bed at the moment and have been surfing around a bit, and let me tell you that on some german nazi blogs, discourse about race is less aggressive in tone and less full of contempt for races and cultures not one's own than i have recently found on a number of presumably non-nazi english-language websites.
i thought cowen wanted to say that mexican villagers seem and probably are intelligent, yet would fail on a standard written iq test because of lack of familiarity with written material and written tests in general, that is, for cultural reasons. if that was not his point, then indeed his comment was not particularly pertinent. (nor by the way was your dog comment, because dogs are instinctive hunters physically well equipped for hunting and humans aren't. humans use the their intelligence and general learning and problem solving abilities "to live off the land", so diamond's obeservation was quite legitimate and relevant.)
having read up the subject race/iq quite extensively in the scholarly journals a few years ago, my conclusion was that genetic iq differences between races are not as well attested as people like Lynn (who is extremely unknowleadgabe about a number of subjects he would have needed to research for his argument, like, for example, cultural, economic and demographic history) claim.
Reseach so far has, for obvious reasons, been largely epidemiological,
and epidemiological studies (eg showing population-level associations between nutrition and diabetes, between american nationality and aggression, african race and iq) are not particularly good at sorting out cause-effect relationships. in medicine, you use them for hypthesis-building rather than for hypothesis-testing. what you need is controlled experiments (especially with a trait like iq that is clearly influenced by more than one variable). twin/adoption studies come close to doing that for iq, but these studies are small and at least the ones i have read are contradictory.
also, there are those epidemiological data that don't quite fit the trend.
why, for example, do pakistani immigrant children have dismal educational achievement in britain, while children from an indian background excel, far surpassing the white british group? that doesn't fit the thesis that race is the main factor in population-level differences, or even that it is a significant factor, the difference in educational achievement between indians and pakistais in britain being rather more noticable than the black-white divide in the states. (Perhaps you will tell me there are large genetics difference between Pakistanis/Bangladeshis and Indians. Are there? Intuitively, it's abit unlikely. Also, lynn lumps them with the middle easterners as having low iq, so obviously, they have low average iq in india. or they have in the studies lynn cites, his selection is not always impeccably impartial.)
just as people on the contra side of the debate on racial differences in iq should drop their attitide that something they do not want to be true cannot be true, so people on the other side of the divide should be a bit more cautious and less gleeful.