The average man and the average woman share about the same level of intelligence, but men account for a higher proportion of both geniuses and the mental deficient, according to a new study of IQ test results.
Seven of every eight people in the top 1 percent on IQ tests are men, accounting for their overrepresentation in the elite ranks of the sciences and mathematics where such genius is crucial, University of Chicago researchers reported Friday in the journal, Science.
But men represent an almost equally large proportion of the mentally disadvantaged, especially in terms of reading and writing skills.
The test scores imply "that men are, on average, at a rather profound disadvantage in the performance of certain basic intelligence skills,'' said Chicago education Professor Larry Hedges.
"The U.S. has a larger number of men who can barely read, write or do arithmetic than is currently assumed,'' Hedges said. Increased attention from schools may be necessary to bring these men into the work force, he concluded.
Differences between the brains of men and women have been the subject of increasingly intense study in recent years, and it has become clear that there are structural distinctions between the two. Women's brains are, on average, smaller than men's -- a fact that has long been recognized.
Nonetheless, recent studies by neuroscientist Sandra Witelson of MacMaster University in Hamilton, Ontario, show that women's brains contain an average of about 11 percent more brain cells, suggesting that they work more efficiently.
Other studies have also shown that the corpus callosum, the tissue that connects the two sides of the brain, is larger in women, perhaps allowing the two halves to work together more effectively.
Recent studies using sophisticated techniques to observe brain cell activity have shown that male and female brains function differently when performing the same tasks. It has become increasingly clear that men and women do not think alike, and the new study by Hedges and graduate student Amy Nowell illuminate one facet of that difference.
Most previous studies of IQ differences, Hedges said, have used relatively small groups of individuals, most of them recruited from college communities. It is easy to argue that societal biases in favor of men could easily have influenced the outcomes of these studies, he said, and the total number of individuals involved did not allow close examination of the small numbers of individuals at the IQ extremes. In the new study, Hedges and Nowell combined data from six large population-based studies -- the smallest of which contained 10,000 people -- that represented a true cross-section of American society. For the first time, Hedges said, the sample populations were large enough to disclose discrepancies between the numbers of men and women at the extremes.
Among the conclusions:
?In math and science skills, boys outnumbered girls 3-to-1 in the top 10 percent of test scores and 7-to-1 in the top 1 percent. In some science and vocational aptitude tests, no girls scored in the top 1 percent to 3 percent.
?In reading comprehension and writing skills, however, boys outnumbered girls 2-to-1 at the bottom of the scale, and there were fewer boys than girls in the top 5 percent.
The reasons for the differences are not clear. Neuroscientist Roger Gorski of UCLA noted that brains, like sex organs, are basically feminine at conception and that male organs have to be molded from female "clay.'' "That molding could explain the variability,'' he said.
Neuroscientist Richard Haier of the University of California, Irvine noted that the efficiency of the brain, the fundamental basis of IQ, is regulated by "neural pruning,'' the elimination of redundant brain cells and pathways between the ages of 5 and 20, and that this pruning could be affected by hormone levels.
Hedges, however, argues the differences lie in the opportunities boys are exposed to, the encouragement they receive in technical areas, and the socialization involved in their upbringing.
Seven of every eight people in the top 1 percent on IQ tests are men, accounting for their overrepresentation in the elite ranks of the sciences and mathematics where such genius is crucial, University of Chicago researchers reported Friday in the journal, Science.
But men represent an almost equally large proportion of the mentally disadvantaged, especially in terms of reading and writing skills.
The test scores imply "that men are, on average, at a rather profound disadvantage in the performance of certain basic intelligence skills,'' said Chicago education Professor Larry Hedges.
"The U.S. has a larger number of men who can barely read, write or do arithmetic than is currently assumed,'' Hedges said. Increased attention from schools may be necessary to bring these men into the work force, he concluded.
Differences between the brains of men and women have been the subject of increasingly intense study in recent years, and it has become clear that there are structural distinctions between the two. Women's brains are, on average, smaller than men's -- a fact that has long been recognized.
Nonetheless, recent studies by neuroscientist Sandra Witelson of MacMaster University in Hamilton, Ontario, show that women's brains contain an average of about 11 percent more brain cells, suggesting that they work more efficiently.
Other studies have also shown that the corpus callosum, the tissue that connects the two sides of the brain, is larger in women, perhaps allowing the two halves to work together more effectively.
Recent studies using sophisticated techniques to observe brain cell activity have shown that male and female brains function differently when performing the same tasks. It has become increasingly clear that men and women do not think alike, and the new study by Hedges and graduate student Amy Nowell illuminate one facet of that difference.
Most previous studies of IQ differences, Hedges said, have used relatively small groups of individuals, most of them recruited from college communities. It is easy to argue that societal biases in favor of men could easily have influenced the outcomes of these studies, he said, and the total number of individuals involved did not allow close examination of the small numbers of individuals at the IQ extremes. In the new study, Hedges and Nowell combined data from six large population-based studies -- the smallest of which contained 10,000 people -- that represented a true cross-section of American society. For the first time, Hedges said, the sample populations were large enough to disclose discrepancies between the numbers of men and women at the extremes.
Among the conclusions:
?In math and science skills, boys outnumbered girls 3-to-1 in the top 10 percent of test scores and 7-to-1 in the top 1 percent. In some science and vocational aptitude tests, no girls scored in the top 1 percent to 3 percent.
?In reading comprehension and writing skills, however, boys outnumbered girls 2-to-1 at the bottom of the scale, and there were fewer boys than girls in the top 5 percent.
The reasons for the differences are not clear. Neuroscientist Roger Gorski of UCLA noted that brains, like sex organs, are basically feminine at conception and that male organs have to be molded from female "clay.'' "That molding could explain the variability,'' he said.
Neuroscientist Richard Haier of the University of California, Irvine noted that the efficiency of the brain, the fundamental basis of IQ, is regulated by "neural pruning,'' the elimination of redundant brain cells and pathways between the ages of 5 and 20, and that this pruning could be affected by hormone levels.
Hedges, however, argues the differences lie in the opportunities boys are exposed to, the encouragement they receive in technical areas, and the socialization involved in their upbringing.
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