In fact, although IQ explains more academic achievement and income than any other measurable psychometric factor, it still doesn’t explain very much of them. It explains only about 15-25% of variation in individual income and only about 25% of variation in individual academic achievement. Most of the rest is due to factors that are not measured.
By contrast, per capita income explains 46% of variation in average IQ among countries, and even more of the variation in academic performance. (Average academic performance explains over 50% of the variation in average IQ among countries.)
So, does high average income cause people to have high IQs and good academic performance, or the other way around? http://sitemaker.umich.edu/salas.356/more_money__better_grad... documents a study that found children’s academic performance improves when their parents’ income increases.
The TIMSS data you’re citing show the opposite of what you claim them to. The variations in academic achievement between countries are much larger than variations in IQ between ethnicities.
TIMSS doesn’t include a lot of African countries, but of those it does include, 8th-grade achievement in Ghana is 309, in Botswana is 364, in Egypt is 391, and in Tunisia is 420, compared to 508 in the US. The TIMSS scale is normalized so that one standard deviation is 100 points. If we estimated that the 508 score were a weighted average of 85% “white people” and 15% “black people” one standard deviation lower, then the “white people” would be at 523 and the “black people” would be at 423 --- closer to the “white US people” only one s.d. higher than to the Ghanaians 1.14 s.d.s lower. Even Botswana (perhaps the “upmarket” African country you’re thinking of?) would be 0.59 s.d.s below the “black US people”.
(The above breakdown is roughly correct. In the NAEP, the grade 8 mathematics average score for white students in 2009 was 293, the s.d. was 33, and the average for black students was 261, almost exactly one s.d. lower. http://nces.ed.gov/nationsreportcard/naepdata/ doesn’t let me link the results, though.)
In general, the TIMSS rankings are much better explained by median income than by average intelligence. The Taiwan average is almost two s.d.s above the international average, which would be like an average IQ of 130, while the Qatar average is almost two s.d.s below, which would be like an average IQ of just over 70, “borderline mentally retarded”. If you’ve ever traveled, it’s obvious that Qatar isn’t actually half populated with mentally retarded people and Taiwan isn’t actually half populated with geniuses.
According to the book you linked, the measured average IQs are 105 for Taiwan and 78 for Qatar.
If you look at this map, you can see how little relationship there is between ethnic composition and national IQ:
http://en.wikipedia.org/wiki/File:National_IQ_Lynn_Vanhanen_...
There are enormous differences between Brazil and Congo, between Vietnam and China, between Singapore (which you can’t even see) and Indonesia.
The Bell Curve has been amply debunked already, and in any case is decades out of date.