Years ago, while doing research on education and IQ, I happened to be in the principal's office at a black school in Cincinnati, as he was preparing to open a large brown envelope containing the results of IQ tests that his students had taken. Before he opened the envelope, I offered to bet him that a large majority of the students with IQs over 110 would be girls.
He was too smart to take the bet. Studies had shown that females predominated among high-IQ blacks. One study of blacks whose IQs were 140 and up found that there were more than five times as many females as males at these levels.
This is hard to explain by either heredity or environment, as those terms are usually defined, since black males and black females have the same ancestors and grow up in the same homes. Meanwhile, white males and white females have the same average IQs, with slightly more males at both the highest and lowest IQs.
This is just one of many unsolved mysteries that is likely to remain unsolved, because doing research on race and IQ has become taboo in many places. My own research was financed in part by a grant from a foundation that told me to remove any mention of IQ research from the activities listed in my project's application.
They didn't care if I used their money for that purpose but they did not want it on the record that they had financed research into race and intelligence. Many schools and boards of education also did not want it on the record that they had cooperated by supplying data for any such research. Only when assured of complete anonymity would they let me into their records.
A well-known black "social scientist" urged me not to do any such research. His stated reason was that it would "dignify" Professor Arthur Jensen's thesis of a genetic basis for black-white differences in IQ scores. But my own suspicion was that he was afraid that the research would prove Jensen right.
As it turned out, the research showed that the average IQ difference between black and white Americans -- 15 points -- was nothing unusual. Similar IQ differences could be found between various culturally isolated white communities and the general society, both in the United States and in Britain. Among various groups in India, mental test differences were slightly greater than those between blacks and whites in the United States.