To read a response to Harvard President Larry Summers' assertion that "innate differences" underlie the under-representation of women in math, physics, and computer science, click here.

To review a summary of evidence that single-sex classrooms can inspire girls to pursue their interests in subjects such as math, physics, and computer science, click here.

Computers, Brains, and Gender Equity



            True story:

A distinguished Harvard professor suggests that women may be innately less capable of scholarship at the highest levels.  He asserts that the pursuit of an academic career will cause a woman’s body to shunt blood away from the uterus toward the brain, rendering that woman “irritable and infertile.”  A flurry of press coverage ensues.

The Harvard professor to whom I refer is Dr. Edward Clarke, who in 1873 published Sex in Education: or, a Fair Chance for the Girls.  The subtitle was misleading, because Dr. Clarke believed that all higher education for girls was unhealthy and “unnatural.”  But Dr. Clarke was not the last esteemed Harvard professor to suggest that when it comes to brains, the mere fact of being female may be an insurmountable obstacle. 

On January 14th, Dr. Lawrence H. Summers, who is (at least for the moment) still the president of Harvard University, attempted to explain why there are so very few women holding senior academic positions in math, physics, engineering, and technology.   Dr. Summers began by suggesting that women may be less willing to put in the long hours required to achieve top positions in those fields.  That remark might have been sufficient all by itself to start the ball rolling for Dr. Summers’ ouster.  But then he went on to suggest that maybe women just aren’t cut out for the hardest of hard sciences, that maybe there are “innate differences” between male and female brains which render most women incapable of doing really tough math.[i] 

Such remarks would not have been newsworthy had they been made by, say, Jerry Falwell.  But for the president of Harvard University to suggest that women are innately disadvantaged in math and science – well, stop the presses.  “Intellectual tsunami” is one description for what’s happened in the days since Dr. Summers’ remarks became public knowledge.[ii]  And the tsunami rolls in from all directions, left, right, and everywhere.  From the right has come a volley of articles in defense of Dr. Summers’ position, citing tidbits of research which supposedly demonstrate that Dr. Summers was in fact correct.  Conservative columnist Linda Chavez placed great weight on a Johns Hopkins study which showed that among pre-adolescent children gifted in math, boys outnumbered girls by 13-to-1.[iii]  From the left has come a flood of protest, most notably in the form of a letter signed by 50+ Harvard professors denouncing Dr. Summers’ remarks, stopping just short of a call for his resignation.

The biggest loser in this battle may not be Dr. Summers or women’s rights, but brain science itself.  Brain science has become the last refuge of dilettantes, invoked in support of everything from more funding for Head Start to an endless variety of educational reforms, and now as an explanation for the dearth of women in math and science.  Dr. Summer’s invocation of brain science is patently circular.  Summers observes, correctly enough, that despite all efforts to recruit women, there are still very few women professors in higher math, computer science, and physics.  He then cites this fact as evidence that men must have an innate, hardwired advantage in those subjects.  That innate advantage explains why there are so few women at the highest levels of proficiency in those subjects, or so Dr. Summers appears to believe.   The finding which is to be explained is itself cited as evidence to explain the finding.  Q.E.D.

In fact, the evidence does not support Dr. Summers’ belief.  I’ve spent the past four years reading every paper I can find – hundreds of them – about sex differences in the brain and in the ability to learn, in the course of writing a book on the subject.  I’ve also traveled to more than 60 schools around the United States and Canada, to sit in classrooms and watch how girls and boys are taught, and to speak with teachers.  Among adults, cognitive sex differences – sex differences in how adult women and men think – have turned out to be much smaller than previously believed, according to authoritative recent reviews.[iv]  There’s lots of variation within each sex and lots of overlap between the sexes. 

The most important breakthrough, in my judgment, has been the discovery that the various regions of the brain develop in a different sequence in girls compared with boys.  Researchers at Virginia Tech used sophisticated electrophysiologic imaging of the brain to examine brain development in 508 normal children -- 224 girls and 284 boys -- ranging in age from two months to 16 years.  These researchers found that while the areas of the brain involved in language and fine motor skills (such as handwriting) mature about six years earlier in girls than in boys, the areas of the brain involved in math and geometry mature about four years earlier in boys than in girls.  When it comes to learning math, the brain of a 12-year-old girl resembles the brain of an 8-year-old boy.  These researchers concluded that the various areas of the brain develop in “a different order, time, and rate” in girls compared with boys.[v] 

This finding puts much of the previous work on gender disparities in math and science in a different light.  I mentioned above how Linda Chavez cited a study showing that among young children, there are many more boys who are math geniuses than girls.  But if girls had the opportunity to learn math at their own pace, I think the odds are good, or better than good, that we would have many more teenage math geniuses who are girls.  Just as many boys are late bloomers with regard to literature and foreign languages, many girls are – or could be – late bloomers with regard to math and science.

Most girls attend coed schools, in which girls and boys are taught the same subjects in the same sequence.  The result of that kind of gender-blind education is too often that by age 12, the girls think they’re no good at math and that they’ll never be any good at math.  The irony is that many of those girls might be math geniuses, if only they were taught in schools in which the curriculum was tailored to the individual, schools in which they might have the freedom to explore their own potential at their own pace. 

All-girls schools hold great promise for eliminating the gender imbalance in math and science.  A study of graduates of girls’ high schools in the United States found that 13% of those girls went on to major in college in the “hard sciences” and math, compared with only 2% of girls who attended coed schools.[vi]  In other words, girls who attend all-girls schools are more than six times as likely subsequently to earn degrees in the very subjects about which Dr. Summers professes such concern (13% compared with 2%).  By comparison, only about 10% of boys who attend coed schools go on to major in those subjects.  A 2002 study of 370,000 students in the United Kingdom came to a similar conclusion: namely, that girls who attend all-girls schools are far more likely to study advanced math, computer science, and physics, compared to girls of comparable ability attending coed schools.[vii]  Both these studies echo a classic 1986 study by Professor Elizabeth Tidball, in which she found that women who graduated from all-women’s colleges were more than five times as likely to earn doctorates in math, physics, and chemistry, compared with women who graduated from coed colleges.[viii]

Dr. Summers would like to believe that “brain science” accounts for the continuing gender disparity in the hard sciences, because if girls are hardwired to be dumb in math, then the gender disparity isn’t anybody’s fault and there’s nothing anybody can do about it.  That argument is a cop-out.  Girls aren’t hardwired to be dumb in math any more than boys are hardwired to be dumb in art – a subject in which women now monopolize all the highest academic positions.  If you look at the history of Western civilization, you’ll find more than a few men who excelled in art – Leonardo da Vinci, Michelangelo, Vermeer, Monet, Renoir, and Picasso, to name just a few – but every one of those men attended all-boys schools.  If they had been born and raised in this time and place, attending coed schools, the odds are good that they never would have picked up a brush.  At coed schools, the boys will tell you that drawing is for girls.

Brain science can and indeed should inform the debate about gender equity and education policy.  But the first requirement is that the “brain science” should be science rather than stereotype.



Leonard Sax, M.D., Ph.D., is the founder and director of the National Association for Single Sex Public Education, and the author of “Why Gender Matters:  what parents and teachers need to know about the emerging science of sex differences,” which will be released February 15th by Doubleday.  See for more information about the book.

Copyright 2005, Leonard Sax, MD, PhD

A shortened version of this article was published by the Los Angeles Times on January 23, 2005. You can read the shortened version as it appeared in the LA Times here.



[i]  See for example: 

·        Marcella Bombardieri, “Harvard women's group rips Summers,” Boston Globe, January 19, 2005;

·        Sam Dillon and Sara Rimer, “No Break in the Storm Over Harvard President's Words,” New York Times, January 19, 2005;

·        Sam Dillon, “Harvard Chief Defends His Talk on Women,” New York Times, January 18, 2005.

[ii]  The article by Dillon & Rimer (see previous note) quoted an unnamed Harvard dean describing the outpouring of protest occasioned by Summers’ remarks as an “intellectual tsunami.”

[iii]  Linda Chavez, “The shibboleths of academe,” January 19, 2005, available online at:

[iv]  See for example Diane Halpern, Sex Differences in Cognitive Abilities, 3rd edition, 2000.

[v]  Harriet Hanlon, Robert Thatcher, and Marvin Cline, “Gender differences in the development of EEG coherence in normal children,” Developmental Neuropsychology, 16(3):479-506, 1999.   The quotation comes from page 502.  Similar results were reported in a smaller study by A. P. Anokhin and associates, “Complexity of electrocortical dynamics in children: developmental aspects.”  Developmental Psychobiology, 36:9-22, 2000.

[vi]  A summary of this study is available online at .

[vii] A summary of the British study is available at   See pages 40 – 43 for the results showing that girls at girls’ schools are far more likely to study advanced math, computer science, and physics, compared with girls of comparable ability attending coed schools.

[viii] M. Elizabeth Tidball, “Baccalaureate origins of recent natural science doctorates,” Journal of Higher Education, 57:606-620, 1986.

Science, computers, and gender equity

Single-sex classes increase girls’ participation in physics, computer science, etc.

Many studies provide support for this assertion.  The largest such study was published in July 2002 by the National Foundation for Educational Research.  This study examined the course choices of 369,341 pupils from 2,954 schools in the United Kingdom, whereas single-sex high schools are widely available in the public sector.  These researchers found that girls in girls-only schools were about 40% more likely to take advanced science courses than were girls of comparable ability at coed schools.  In this respect, "being in a girls school counteracted the effect of being a girl, since girls in mixed schools [i.e. coeducational schools] were less likely to take [advanced] sciences than boys" (p. 42).  More generally, they found that girls' schools break down the distinctions between traditional "girls subjects" such as English and foreign languages and "boys subjects" such as physics and computer science (p. 43).  You can read more about this study online, and link to the NFER Web site, at

 Jamaica is another country where single-sex public schools are widely available.  In a large study of Jamaican schools, girls at single-sex high schools did significantly better in math and science than girls at coed high schools. In fact, the girls at single-sex high schools often outperformed the boys in math and science.  The study concluded that "the effects of sex stereotyping are more sharply apparent in the coeducational setting, for here there appears to be a stronger need to differentiate between the sexes. Thus, even if subjects such as mathematics and the sciences are technically available to girls in this type of school, they are more likely than their single-sex institutional counterparts to get the message that such subjects are unfeminine, and beyond their grasp intellectually."

Other relevant studies:

  • Lawrie and Brown surveyed 284 students ages 14 and 15.  They found that girls at all-girls schools reported enjoying math more, and found math less difficult, than girls who attended coed schools.  Girls at the all-girls schools were more than twice as likely to say that they planned to take advanced math, compared with girls at coed schools.
  • Carolyn Jackson and Ian David Smith evaluated girls’ experience in single-sex math classes for five consecutive semesters, from 5th grade through 7th grade.  Eighty percent of girls said they were more confident in the single-sex class.  Only 15% of girls said they preferred the coed format.
  • Harvey and Stables surveyed 2,300 students regarding their attitudes toward science.  They found that girls at single-sex schools had significantly more positive attitudes toward science in general, and physics and chemistry in particular, compared with girls at coed schools.
  • Ann Colley, Matthew Gale, and Teri Harris asked 11- and 12-year-olds about their preferences for different subjects.  Girls attending all-girls schools were more likely to prefer math and science than were girls at coed schools.
  • Jones and Clark asked teenage girls how they felt about computers and computer science.  Girls at all-girls schools were far more positive in their feelings toward computers than were girls at coed schools – despite the fact that girls at both schools had the same amount of access to computers.


Ann Colley, Matthew Gale, and Teri Harris.  “Effects of gender role identity and experience on computer attitude components.”  Journal of Educational Computing Research, 10:129-137, 1994.


L. Culley. “Gender equity and computing in secondary schools: issues and strategies for teachers”. In J. Beynon & H. Mackay, Computers into classrooms: more questions than answers, London: Falmer Press, 2000, pp. 147-159.


Harriet Hamilton, "Performance levels in science and other subjects for Jamaican adolescents attending single-sex and coeducational high schools," International Journal of  Science Education, 69(4):535-547, 1985.


T. J. Harvey and A. Stables.  “Gender differences in attitudes to science for third-year pupils:  an argument for single-sex teaching groups in mixed schools.”  Research in Science and Technological Education, 4:163-170, 1986.


C. Jackson and I. D. Smith.  “Poles apart?  An exploration of single-sex and mixed-sex educational environments in Australia and England.”  Educational Studies, 26:409-422, 2000. 


T. Jones and V. Clarke.  “Diversity as a determinant of attitudes:  a possible explanation of the apparent advantage of single-sex settings.”  Journal of Educational Computing Research, 12:51-64, 1995.


L. Lawrie and R. Brown.  “Sex stereotypes, school subject preferences and career aspirations as a function of single/mixed-sex schooling and presence/absence of an opposite sex sibling.”  British Journal of Educational Psychology, 62:132-138, 1992.


P. Newton and E. Beck. Computing: an ideal occupation for women? In J. Beynon & H. Mackay, Computers into classrooms: more questions than answers, London: Falmer Press, 1993, pp. 130-146.