This is key: “on any test designed to measure IQ or academic achievement”
IQ stands for Intelligene Quotient, and was designed to measure how much you have learnt compared to your age.
Try to find a proper definition of intelligence. It’s hard! There are thousands.
I take intelligence to be the capacity to learn to be smart.
But IQ tests don’t say a lot about your capacity for learning to be smart. Even when they are used in their proper context, i.e. to measure development of children, you will measure they’re capacity to learn in their environment, in the specific school they go to, the parents and family they have around them to learn from, the kids they play with.
Give someone an IQ test in adulthood, as happens a lot now, and then make him do that test again a day later - he or she will score higher. Now let me have someone for a day to prepare him for IQ tests in general. I will simply teach for the kinds of patterns they look for on average. He or she will generally score lots higher.
I thought one particular bit of research in the UK was interesting, where they measured performance of children in school. White boys did worst. Asian kids did best. On average, girls do better and more of them get into university in many Western countries.
Sure, more of them still choose the Arts rather than the Sciences, but it’s easy enough to see how that is culturally determined too when comparing data from Eastern Europe to Western Europe for instance: in Eastern Europe more women choose Exact sciences because their foremost concern is money, not personal development.
Also, girls just get different toys from guys, have different stuff marketed to them, and the people they look up are role-models who grew up a generation before them. However much the opportunities change over the decades, cultural role models always take much longer to catch up.
And that holds for skin-color as much as anything else.
Equally important to remember is that individual variation has always been much, much larger than statistical differences between sexes, races and what not. For instance, there was research that suggested that men scored 0.50% better than women on certain spatial tasks, or certain mathematical tasks. Wow. In a group of a 100, that means half a person (if such a thing existed outside of statistics). In the meantime, the brightest girl is typically going to be smarter than 98 of the other kids, including 49 of the boys, and she will be a lot smarter than the dumbest boy.
There is only one area that interests me in terms of possible genetic factors, and that is that ADHD-like afflictions detected in youth seem to stand out among Afro-Americans compared to any other race, and seemingly irrespective of culture. Again, this is not a difference that affects the general population of Afro-Americans as a whole, remember the part about individual differences - just that it seems to occur more often.
Anyway, I made my point. The Bell Curve is a stupid book. 