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.

In recent years, research by Professor James R. Flynn, an American expatriate living in New Zealand, has shaken up the whole IQ controversy by discovering what has been called "the Flynn effect." In various countries around the world, people have been answering significantly more IQ test questions correctly than in the past.

This important fact has been inadvertently concealed by the practice of changing the norms on IQ tests, so that the average number of correctly answered questions remains by definition an IQ of 100. Only by painstakingly going back and recalculating IQs, based on the initial norms, was Professor Flynn able to discover that whole nations had, in effect, had their IQs rising over the decades by about 20 points.

Since the black-white difference in IQ is 15 points, this means that an even larger IQ difference has existed between different generations of the same race, making it no longer necessary to attribute IQ differences of this magnitude to genetics. In the half century between 1945 and 1995, black Americans' raw test scores rose by the equivalent of 16 IQ points.

In other words, black Americans' test score results in 1995 would have given them an average IQ just over 100 in 1945. Only the repeated renorming of IQ tests upward created the illusion that blacks had made no progress, but were stuck at an IQ of 85. But we would never have known this if some researchers had not defied the taboo on studying race and IQ imposed by black "leaders" and white "friends."

Incidentally, Professor Jensen pointed out back in 1969 that black children's IQ scores rose by 8 to 10 points after he met with them informally in a play room and then tested them again after they were more relaxed around him. He did this because "I felt these children were really brighter than their IQ would indicate." What a shame that others seem to have less confidence in black children than Professor Jensen has had.