Well, here are a few thoughts, for what it's worth...
I'm not at all convinced IQ actually measures anything that could be said to represent general intelligence. I find it doubtful that a single number can somehow represent and measure everything there is to know about intelligence. I suspect there is a definitional and/or category error going on. A gross over simplification.
Further, I'm not at all convinced performance on IQ tests isn't effected by special preparation. I received a masters in chemistry (computational/physical), and I spend one year in grad. school for mathematics, and I'm absolutely convinced this rigorous mathematical background specially prepared me to do well on the IQ test. At least the one I took. I used to spend hours sitting around thinking about problems of a similar nature. Or at least problems that are solved by similar mental processes. It's hard for me to be convinced me this didn't prepare me somewhat, and gave me an edge over say, a cellist in an orchestra.
Recent studies in brain plasticity seem to suggest that there is actually a great deal of latitude in ones realized intelligence. Sure, ones maximal hypothetical intelligence may be largely determined by genetics, but most of us never achieve this due to environmental and other factors. The average black child in America is supposedly exposed to a much smaller vocabulary while growing up, due largely to their parents having less education, and there is a lot of evidence to suggest this difference in exposure could partly result in a difference in brain organization and development.
In short, ones intelligence seems to be much more fluid than we ever imagined, and my guess is growing up in a poor, somewhat unpredictable and dangerous environment, where there isn't much emphasis placed on education, and there are possible nutritional deficits, could definitely have an impact on ones performance on an IQ test.
Consider social factors as well... it's quite possible white people and asians are simply taking the test more seriously, and hence putting more effort into it. In these social groups, performing well on tests is socially encouraged and ones self worth is tied up in it. Black people may simply be more likely to consider the test a nuisance and to not take it seriously or give a rats ass how they do on it. They may be coming from a position of suspicion and animosity even, which could certainly affect their performance. Much of black culture seems like a giant middle finger to white America after all, and this IQ test is just another piece of B.S. from the man, if you get my drift.
So, I think it's safe to say there are plenty of other possible explanations, and I'm not convinced at all the research has conclusively ruled them all out.
And, of course, could be there is a real measurable difference that represents something significant and meaningful, but the difference is due to developmental and environmental issues and not heritable traits.
Merged post follows:
Consecutive posts mergedTo flesh out one of the ideas I mention above, I seem to remember a study that suggested much of the difference in mathematical competency between Asian children and European children could be accounted for by the fact that the Asian children were more inclined to stick with a difficult problem, whereas the white children were more likely to simply give up. The difference was partly attributed to differences in confidence levels, as well as in a desire to please. In short, tell someone they are good at math and they are likely to do better at math. Tell them they are not good and math, and well, you get the idea.
So, it's possible socio-cultural differences in test taking strategy, as well as in attitude towards tests in general, could be manifesting themselves.
Anyway, the various races went through a period of divergence lasting 60,000 years or more, so it's surely possible that differences have started to emerge. I'm just not yet convinced.
