Sandra F. Witelson
Professor, Department of Psychiatry, McMaster University

Born in Montreal, Quebec, Canada.

Dr. Sandra Freedman Witelson is a professor in the Department of Psychiatry and Behavioural Neurosciences at McMaster University in Hamilton, Ontario, Canada. She is the inaugural recipient of the Albert Einstein/Irving Zucker Chair in Neuroscience at the university's Michael G. DeGroote School of Medicine.

Her current research is focused on the relationship between brain structure and function using postmortem neuroanatomical study of the brains banked in her brain collection at McMaster University—currently an international public resource for neuroscience, neuroimaging, and molecular biology.

She earned a bachelor's of science, a master's of science, and a PhD in psychology from McGill University in Montreal. She won a postdoctoral fellowship from the National Institute of Mental Health, working at the New York University Medical Center's departments of psychiatry and neurology.

At McMaster University, Dr. Witelson began research into the neural substrate of children with early learning difficulties, exploring functional lateralization of the brain, leading to publication in the journal Science in 1976 and 1977.¹ Early research in brain anatomy led to a joint publication with Dr. W. Pallie in the September 1973 issue of Oxford's Brain: A Journal of Neurology, followed by a major research grant from the National Institutes of Health to study the relationship between the structure and the language function in the human brain.

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For the next 25 years, Dr. Witelson concentrated on expanding the brain bank at McMaster University, as well as her research in cognitive neuroanatomy to understand the relationship between the structure of the brain and the behavior of human beings.

In 1995, Dr. Witelson's discovery of significant differences between men's and women's brains, specifically in the density of brain cells in the language region, was reported extensively in the media. She was then invited to study the brain of the late Dr. Albert Einstein, and with her associates, published the research findings in the June 1999 issue of Lancet, a prominent British medical journal.

Dr. Witelson has been honored with numerous awards, including the Morton Prince Award of the American Psychopathological Association (1976); the John Dewan Prize, awarded by the Ontario Mental Health Foundation (1978), recognizing an outstanding researcher for contribution to significant new knowledge or concepts bearing upon mental health; and the Clarke Institute of Psychiatry Research Fund Award (1978), awarded for outstanding research in the field of mental health conducted in Canada.

Dr. Witelson has been elected a fellow at several, highly regarded professional and scientific associations and societies, including the Canadian Psychological Association (1980), the American Psychological Association (1987), the American Association for the Advancement of Science (1987), and the Royal Society of Canada, Academy of Science (1996).

She was elected as one of the only 250 worldwide members of The Dana Alliance for Brain Initiatives (1998) and inducted into the City of Hamilton (Ontario) Gallery of Distinction (2007).

Since the 1970s, the media worldwide has considered Dr. Witelson as the “go-to authority” on topics of childhood brain development, sex differences in brain structure, biological basis of sexual orientation, Einstein's brain and genius, and a host of other neuroscience topics.

Elizabeth Ghaffari: I read that in high school, you were in French, music, and debating clubs, which are three linguistic foundations. Was your early primary interest in languages?

Dr. Sandra Witelson: My forte was never in writing skills. Oral language, yes, but not written language—as in creative, literary language. I was not very good in French. My interest was always in math and sciences. I don't remember that there was even any biology available when I went to high school, but I was always interested in math and the sciences.

I do remember that when I was in elementary school, six or seven years old, I liked to give speeches. When we all had to do a presentation, the other students recited poems or songs. I knew I couldn't carry a tune at all, so I gave a speech instead.

When I was in university, I chose to be in a debating club because that's what I liked to do—to debate and to speak. I still do. I enjoy giving lectures—the one-to-one or the one-to-a-group. I truly enjoy communicating information or ideas orally.

Ghaffari: Would you tell me a little about your family—your father, your mother, your siblings? Your father was an accountant, but he wanted to be a physicist. Where did that interest come from?

Witelson: My father was the youngest of five children. There was not that much money in the family, but he was the first in his family to go to university in Montreal. He was a scholar who wanted to be a physicist. He just loved reading and absorbing information. But, to become a physicist would have meant many more costly years in the university, so he ended up going into accounting. He never really enjoyed it, though—he was not passionate about his work.

My mother was a very bright, energetic woman who never worked outside of the home. She would have been a wonderful businesswoman, but my mother acquiesced to my father, who was quite conservative. He said that he didn't want my mother to work because it would reflect poorly on him—suggesting that he couldn't make a sufficient financial living.

I knew that my mother wanted to work outside the home. There was a typical little cigar, newspaper, and candy shop at a major intersection in the Snowdon area of Montreal. She wanted to buy that and to run it. It was a brilliant business idea, and she would have been fantastic at it. She wanted to do that, but she listened to my father. Those were the times, but also that was her choice.

In reflecting on this as an adult, it had no effect on me, either positively or negatively. I think I did what I did because my temperament was different from hers in some ways.

I had a brother who was five years younger than I, and we were very close throughout our whole life. He ended up coming to live near us in Hamilton. Tragically, he just died this past January.

My father died when I was about thirty, so I didn't have a chance to really get to know him when I was an adult.

Ghaffari: Why did you attend McGill University in Montreal, Quebec—just because it was close to home?

Witelson: My mother started me in school a year early, because she convinced the school I was bright enough. In Montreal, at the time, there were only eleven years of elementary to high school, so I graduated high school when I was sixteen. In contrast to what I see my students doing nowadays, I went to McGill because it was there. I remember having absolutely no desire to go anywhere else. I wasn't interested in traveling to Europe or other distant places. My adventures were in my head. I had no desire to leave the city. I even lived at home during my university years until I was married because it was so easy.

Ghaffari: You went in quick succession from a bachelor's to a master's and to a doctorate at McGill. Were they all in psychology?

Witelson: In those days, some bachelor's degrees were “honors programs”—that just meant it was a focused specialization. I specialized in psychology.

When I started at McGill, I thought I was going to be a mathematician—an actuarian, only because it had something to do with numbers. I thought I'd be very good at that because I was good in math and liked numbers. It soon became clear to me that the few other students who were taking advanced math with me had a conception of, and passion for, math that I just didn't have.

So, I reconsidered and found psychology and never turned back. McGill University, in the sixties, had one of the best psychology departments in North America at the time. Psychology was in the science faculty, not in the arts faculty, as was the case at many other universities. They had prominent physiological psychologists like Professors Donald Hebb and Peter Milner. McGill definitely was on the forefront of biological psychology where anatomy, chemistry, and the workings of the brain were considered in the understanding of behavior and thinking.

When I was growing up, my father had shelves of hardcover books throughout the house—paperbacks were not yet available. I gravitated to the ones on biology, the structure of the body and how structure is important to the function. That's what intrigued me. Once, when I was about eight years old, I got into trouble with a friend's mother because I read to my friend, over the phone, the anatomy of male and female human genitalia. I'd found it in my father's books and thought nothing of it, but when my friend's mother heard my “lecture,” she forbade her daughter from speaking with me.

So, biology was something that intrigued me very much—one might say, like a chemical attraction. That's why I found psychology and behavior, as it's related to the brain, right up my alley. I never left. I ended up being in one of the best programs I could have selected.

Ghaffari: Was Donald Hebb your mentor?

Witelson: No, I wouldn't say he was my mentor. I had many teachers, but I really didn't have any mentors. Don Hebb was the role model that I tried to pattern myself after. He was my hero, although he probably never knew it. We all thought he was one of the most brilliant men. He was a theorist as well as an experimentalist. When he died, a CBC radio host requested that I comment on Dr. Hebb's contributions. I declined, feeling I was inadequate to the task and not senior enough to do this. In retrospect, I think this was a very “female” act. I do not think this way now.

One of the traits that I developed as a scientist is to be quite theoretical following the data. Some scientists stick very close to their data in developing theoretical considerations. I think I go a little further, which is what Hebb did.

Ghaffari: You went right on to get your doctorate in psychology at McGill?

Witelson: There were about fifteen of us who graduated at the same time from the same honors psychology program. We'd taken many psychology courses because it was such a specialized program. We all thought we really knew everything about psychology. I decided to go into a two-year master's program in clinical psychology so that I would learn something new before I went on to get my PhD in physiological psychology. I never intended to be a clinician or a clinical psychologist.

My doctorate also was in “physiological psychology,” what today would be called “cognitive neuroscience.” I was studying the effects on learning resulting from brain damage in children, sustained at different points in their development. In other words, if a child had brain damage at age two years as opposed to age twelve, were the consequences the same or not? The whole hypothesis that there would be differences, and that the differences would be in specific types of learning, came from a long, theoretical paper that Don Hebb had written and which I borrowed from his library numerous times. These were the days before photocopying.

When I finished my doctorate, I learned that McGill didn't like to take their undergraduates into graduate school because they believed that students should have experience with different departments and different approaches. I didn't know this. I had gone ahead and did what I wanted to do. I applied to the master's program, and then I applied to the PhD program. Somehow, along the way, the administrators allowed me to get into the doctoral program, not realizing that I already had two McGill degrees.

Ghaffari: Did you encounter any negative feedback as a woman in science?

Witelson: I was married right after completing my bachelor's degree. My husband was a medical student at the time. Our daughter was born a year and a half later. I was already in the master's program when I applied for my doctorate. At the interview, the chairman of the department asked me, “What would happen if you get pregnant and have another child?” I suspect that many women today would consider that an inappropriate question. I did not. I remember very clearly that I thought it was most appropriate because I would be receiving a graduate stipend, and the department would be putting a lot of resources into giving me a slot in the doctoral program. He was trying to assure himself that I would complete my studies. I told him, “I don't intend to have another child while in graduate school as it would interfere with my studies.” And that was the end of that discussion.

Ghaffari: Was your family supportive of your academic and professional work?

Witelson: I was in the middle of my PhD when my husband graduated from medical school. He chose ophthalmology and was accepted into a residency program in New York City, where there were some of the best ophthalmology programs in the United States. I had about a year and a half left to finish my PhD program and was working at the Montreal Neurological Institute, which is one of the best places for brain research as well as clinical work.

So, he went to New York, and I stayed behind to finish my PhD. It just never dawned on me that anybody would think this was unusual. It never occurred to me, or even to him, as far as I know, that I should leave my PhD studies to join him right away in New York, even though we were already parents. Subsequently, I learned that his family thought that we might be separating but didn't want to tell anybody. Anyway, I didn't have another child when I was in graduate school. We weren't separated or getting a divorce. And I graduated and received my PhD.

Ghaffari: How did you manage child care while you were working and studying?

Witelson: My daughter, Tamar, stayed with me in Montreal. She was in a wonderful pre-nursery program. I had a wonderful Hungarian babysitter, Zezi, who became a very close friend—she would come every day to look after Tamar and take her to ballet classes, art classes, and pre-nursery classes. Eventually, after two years, Tamar and I moved to join my husband in New York City.

Ghaffari: What was your first “real job” in New York?

Witelson: By this time, I knew that I was going to have a career. I wanted to do something with all the psychology that I enjoyed so much. I applied for, and won, a National Institute of Mental Health postdoctoral fellowship working at New York University Medical Center, located on First Avenue near Thirtieth Street, right in Bellevue Hospital, which is part of the center.

In fact, in the movie Midnight Cowboy, Dustin Hoffman goes into the door of Bellevue, which was the exact same door I used to go in and out of several times a day.

The work was very exciting, and there were some very extraordinary scientists who were working in the department of psychiatry and neurology, which is where my postdoc position was. One of them subsequently won a Nobel Prize in Medicine and Physiology for his work in neuroscience.

Ghaffari: Were there any people that you'd consider mentors from that era?

Witelson: Just faculty, fellow students, and people from whom I learned a great deal. Certainly, there would be useful discussions, but I never had a mentor of any kind on a continuing basis—someone who might have guided me in any way.

I was already a married woman and a mother who would go home right at the end of the day. My life in those days was not all wrapped up with my colleagues, fellow students, or the faculty. Also, I always seemed to be generating ideas and hypotheses that I thought were worth doing, and then I would just go do them within the context of where I was in the program. I never seemed to be part of a little group where everyone was doing something together.

Ghaffari: How did you come to write your first seminal work on the study of the anatomical asymmetry in newborns, published in 1973?

Witelson: That was a key paper, both in terms of neuroscience but also for me professionally. After I finished my postdoc, my husband and I decided to go back to Canada and chose Hamilton, Ontario, where I joined McMaster University. I was hired to work on brain function in children with learning disabilities following my master's and PhD work on that topic.

At McMaster, I focused on brain lateralization—why the two hemispheres of the human brain are involved with different aspects of cognition—the left side is more important for language functions, while the right side for visual perception. In my research on children, I was finding that lateralization seemed to be present early on, before the development of speech might have caused the different localization of functions to emerge. Functional lateralization was present before behavior developed.

I read a paper written in 1968 by the prominent neurologist, Norman Geschwind, who observed an anatomical difference between the left and the right hemisphere in the normal adult brain. He read German fluently and had found reports of this in the German literature. He was able to get one hundred brains to study from various sources. He looked at the brains in a very systematic way and found that the left side—the region that we know is related to language skills—is visibly larger, by about 30 percent, compared to the right side in about seventy to 80 percent of people. He interpreted this as possibly a biological substrate to explain why language is usually represented in the left hemisphere.

Up to that point, I had never held a human brain in my hand. I had never worked on brain tissue, but it seemed to me that this was the missing link that we needed in order to understand how the brain was lateralized.

Anyway, in an academic setting, one always is giving seminars and lectures to various groups, and I enjoyed doing that very much. So, I gave an in-house lecture on brain development, mentioning Geschwind's article. The chairman of anatomy at McMaster, Wazir Pallie, was not able to attend, but heard about it. Because he had become interested in how the brain functioned, not just its anatomy, he called and asked if we could have lunch so that I could tell him about my findings. I said I'd be happy to give him a private version. That conversation led to our collaboration.

Ghaffari: Did you and Dr. Pallie share the same views?

Witelson: In some ways, no. The collaboration was good because I was biased in one direction, while he was biased in the opposite.

Dr. Pallie was very senior in his career and had worked in Malaysia doing thousands of autopsies. He told me he'd never seen any systematic difference between the left and the right hemispheres. I told him that that could be because he never did a study—he only looked at these brains case by case. I was so sure that the two hemispheres had to be different that I suggested we skip right to chimpanzees and show that we evolved that way.

It's actually difficult to obtain chimpanzee brains, so we compromised and studied human infant brains to examine whether lateralization was present from birth. As an anatomist, he had access to a nearby hospital for children and was able to obtain the brains of children who had died very soon after birth from non-neurological causes. We also obtained some adult brains to see if we could replicate the findings of Geschwind's paper, which we did very closely.

Ghaffari: Why did he miss finding lateralization in his autopsies?

Witelson: Every brain is as different from another brain as every face is different from another face. There are major variations in the actual brain topography, but unless you're specifically looking for something and documenting what you see, you're not going to notice any general principles. A clinician is dealing with an individual case, and a scientist is trying to get the general principles about an issue. If you are not asking the right question, you'll never find the answer to that question.

When we did this research study, we began with just a small sample of sixteen adult cases and saw that the left side was greater than the right area, replicating the Geschwind results. After we did just thirteen neonates [infants' brains], it was absolutely clear that the asymmetry existed right from the beginning. So we submitted the paper, by mail, to a very excellent journal, and they accepted it, immediately, by return mail.

Ghaffari: Did publication change anything about the way you were seen or treated by your colleagues?

Witelson: Publication of our findings was a very major event for me professionally. It enabled me to win a large, American contract to start the work that I ended up focusing on for the next twenty-five years—namely direct study of the relationship between structure and function in the human brain. I left the field of pure neuropsychological research and moved over into the cognitive neuroanatomical area.

In thinking back, when my brother and I were growing up, I don't remember that my parents treated us differently in any way. The environment seemed sex-irrelevant. I think that's how I have always treated everything, except of course things specifically related to being a woman—romantic and motherhood issues.

One thing that was crucial for me, as I progressed in my career, was the way I responded to people's treatment of me. When I wanted to do this study on neonatal brains, in those days there was an unwritten system that you were supposed to tell the head of the unit where you worked about the study you planned to do.

I went to talk to the head of the unit and, of course, brought Wazir with me as my collaborator. We were not asking for grant money. I explained the proposed study to the head of the unit, who was a psychiatrist. When I finished, he looked at Wazir and asked him, “Does this make sense? Do you think you can do it?” I remember thinking, “This guy's so inappropriate! I'm the one who's explaining it. The project is all about language lateralization.”

It didn't matter, though. All we needed was the go-ahead, which we got, and we did the project. I realized that maybe he was turning to Wazir because he was an established scientist already. Or maybe because he was a man. Who knows? The point is that I really didn't care—it didn't disturb me at all. All I wanted to do was ensure that we could go ahead—that he wouldn't stand in our way.

It was the same thing as when the department head asked me, “What if you were to have another child?” It just didn't register with me. I just wanted the end result —to be accepted into graduate school.

Ghaffari: When did you start actually building the brain bank at McMaster?

Witelson: In the late 1970s. Winning this contract from the National Institutes of Health was a big coup. It was a lot of money—something like a quarter of a million dollars for each of three years. Subsequently, I was promoted to the rank of full professor in 1977, which was only eight years after I was at the university—a very rapid promotion.

Ghaffari: How would you describe the study?

Witelson: The aim of the study was to see whether this anatomic asymmetry was, in fact, the basis of language lateralization. Our approach was to study people who had metastatic cancer, while they were alive, using neuropsychological tests to find out which hemisphere was the dominant one for language. Most of these research volunteers succumbed to their disease and left their brains to the brain bank. We then related their test results to their pattern of anatomical asymmetry. We studied the gross anatomical pattern and also the microscopic anatomy.

Ghaffari: Is that where you started finding sex differences in brain structure?

Witelson: That's right. By this time, my colleagues in this work were neuroanatomist Dr. Marc Colonnier and research associate Debra Kigar. It happened that, while we were counting the number of cells, we discovered a major difference between men's and women's brains in how the cells were packed together in the language region, the region where there is anatomical asymmetry. We found a sex difference in “cell packing density”—that is the number of cells packed per unit of volume.

That paper got a lot of attention from the media, partially because anything related to sex, whether it's the brain or anything else, gets a lot of attention. That paper was described in an article in the New York Times in February 1995.²

The New York Times piece caught the attention of Dr. Thomas Harvey, a retired pathologist from New Jersey, who had removed and retained Einstein's brain after a clinical autopsy and was looking for someone to study it. That NYT article led him to contact me at McMaster. Ultimately, that led me to the opportunity to study Einstein's brain.

In June 1999, we published “The Exceptional Brain of Albert Einstein” in The Lancet, the British medical journal. The article discussed what my colleagues and I found when we compared anatomical measurements of the late physicist's brain with those of normal intelligence people whose brains were in our brain bank.

You know, one thing leads to another in any aspect of life, right?

Ghaffari: You've received a number of awards. Are most of these related to your NIH project?

Witelson: The awards related to my work on the development of language lateralization in normal children and in children with dyslexia, neuroanatomical studies of cognition, and sex differences in the brain.

Ghaffari: It looks as if most of your collaborative writing started after this NIH work. Would you agree?

Witelson: Yes, by that time I was working with senior neuroanatomists, a staff of assistants, and a group of PhD graduate students, so it became a much more multidisciplinary research starting in about the 1980s.

Ghaffari: What are the awards or recognitions you value the most, personally?

Witelson: One of the most memorable awards was the one from the American Psychopathological Association in New York City. I remember that well.

I knew somebody from my days as a postdoc and met him at a conference. He told me about the Association, and I said, “Maybe you could invite me to give one of the lectures because then I could also visit New York.” So, he invited me to give a talk. I was one of just a few presenters who were not psychiatrists. I was certainly was not part of the group. I was a young neuropsychologist.

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I gave my talk—I thought it was a good one. The next thing I knew, I received a letter saying that I'd won the award for that year for the best talk and the work behind the presentation. The letter said, “Your award will be sent to you.” The next thing I knew, I had to pick this package up at the US-Canadian border. They sent me a beautiful, black-lacquered captain's chair with an inlaid medal with my name and the award inserted in the back of the chair. That was very exciting. Everyone likes to be patted on the back. I still have the chair in my living room.

Then again, to be named a fellow of the Royal Society is the highest honor that a Canadian scientist or scholar can have bestowed on them. So, obviously, that is very, very important to me.

Finally, the other recognition was being invited to be a member of the Dana Alliance for Brain Initiatives in New York because there are only around two hundred and fifty neuroscientists who are members from around the world. At the time I was asked to be a member, about 1997 or '98, there were only six Canadians, so that was exciting.

Ghaffari: What is the Dana Alliance? Do you work with them or is it more a recognition?

Witelson: The Dana Alliance is a nonprofit, volunteer organization committed to advancing public awareness of the progress and promise of brain research and to disseminate information on the brain in an understandable fashion. The Alliance was established by the Dana Foundation, a New York philanthropy dedicated to support activities and publication in science, health, and education, particularly the neurosciences.

I once had the opportunity to speak, along with other scientists, on Capitol Hill, about the importance of research funds for neuroscience. It is hoped that input such as this helps government officials allocate resources.

Ghaffari: You compared Einstein's brain to those in the brain bank and wrote about it in 1999. To how many brains did you compare Einstein's brain?

Witelson: We had about 110 brains in the bank at that time, which we used as a comparison group.

Ghaffari: In the January 2005 presentation that Lawrence Summers gave before the National Bureau of Economic Research,³ in which he discussed the issue of women's underrepresentation in tenured positions in science and engineering at top universities and research institutions, was he suggesting that the mental divide between the sexes is more complex and more rooted in the fundamental biology of the brain than many scientists once suspected?

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Witelson: Yes, he said that, but no—many scientists have been aware of the sex differences for some time. However, his audience at the NBER was not cognizant of the literature nor were they familiar with the hypotheses he put forward.

Not only are there structural differences between the sexes, but there are also neurochemical and neurophysiological differences between male and female brains. So, it's not just at the structural level, but it's also in the functioning of the brain.

In experimental work with other mammals, it's possible to manipulate things and see the resulting modified behavior—that is, alter the structure of the brain, either by a hormone or some other method, which results in a change of behavior.

For example, the ability to run mazes is better among male rats compared to females. If a hormone, say testosterone, is introduced into the immature brain of a newborn female rat, the result is an improved ability to negotiate mazes (an example of spatial learning) relative to normal rats.

In humans, there are certain tasks that involve spatial learning where men consistently outperform women. Of course, you can't introduce hormones to experiment with humans. But, there are clinical conditions in which the hormonal environment, either in utero or early in development, is not typical. Neuropsychological studies of such groups of patients reveal that their ability on some spatial tasks is closer to an average male than to an average female.

In other words, depending on the hormonal changes, there are some conditions where little girls have had more exposure to testosterone, and they show more rough-and-tumble play, better ability with certain kinds of puzzles, which are things more often seen in boys more than in girls.

Ghaffari: Did the press come to you for elaboration on the discussion that followed the Lawrence Summers' comment about “different availability of aptitude at the high end” between the genders?

Witelson: There were several newspaper articles that included me and my research along with other scientists. I was very pleased to be involved in the interview with Gwenn Ifill for the PBS show, NewsHour with Jim Lehrer. I was one of three women. The other two disagreed with Dr. Summers' comments. My opinion was and is that he was correct—dead on. I had read the actual transcript of his talk. I thought he was very cautious and deliberate. I re-read part of that transcript to the participants of the recent Wall Street Journal “Conference on Women in the Economy.” Many were in agreement compared to what they had gleaned from media reports.

The question posed to him was, “Why are there fewer women full-professors with tenure in fields such as math and natural sciences in the top universities in the States?”

Dr. Summers cited three reasons he thought might explain the fact that there are fewer women. Firstly, women, for various reasons, are less likely to want or be able to spend eighty hours a week in their careers. He was criticized by some people who argued that that should not be required to get tenure, but that was not the issue he was addressing. Academia is a competitive arena.

Secondly, he said that in math test scores—measuring quantitative skills—the mean scores for men are slightly higher, but the biggest sex difference is that the distribution is much wider for men. There easily are four or five men who are approximately three or four standard deviations beyond the mean compared to one woman. It would follow that there are more competitive men than women for jobs requiring quantitative skills.

Thirdly, he said there could be effects of different socialization and patterns of discrimination. He was describing, not condoning. Other scientists before and since Dr. Summer's talk have made very similar statements.

Ghaffari: Aren't there also some studies about the different responses of men and women to stressful situations?

Witelson: That's right. There are studies which show that when animals are stressed, the neurons in the hippocampus—the center for learning and memory—undergo structural changes that differ between the sexes. In the male, there is more of an increase in the outgrowth of the neuropil—the little sprouting structures surrounding the cell—which is advantageous for learning. The reverse happens in a female. Therefore, stress has different consequences for behavior in the male and female brain, which may be a fact of biology.

There is inferential evidence that this is true in humans, too. If this is the case, then it would be advantageous for men and women to know this biological reality, rather than to pretend the difference does not exist. A plan of action to deal with this reality would appear warranted.

It can only help men and women in all phases of development to be aware and accept some of the biologically based differences in cognition, behavior, propensities, and to note the female skills for collegiality and their relative discomfort with high-risk competitive situations.

For example, the new International Monetary Fund chief, Christine Lagarde, stated that she's going to deal with her job as a woman. She said, “…the majority of women in [leadership] positions approach power … in a slightly different manner. Women inject less libido and less testosterone into the equation.” It sure sounds to me like Lagarde also thinks men and women deal with things differently, with hormones as part of the causes of the difference.

Ghaffari: Do you think that the opportunity for more girls to participate in sports at a young age on an equal basis, as a result of Title IX, might induce behavioral changes of the type that you're describing?

Witelson: The known differences of which I was speaking earlier are not the ones known to correlate with whether a woman was participating in sports or not. Those are different questions.

For women who are very involved in sports—does this have some effect on their body, on their brain, on their personality, on how they approach life? It may very well be the case because, even though the anatomy and the chemistry of the brain are partially genetically determined, that doesn't mean that environment doesn't have an effect. So, one always has to think of the interplay between nature and nurture.

Ghaffari: Do you think we should be developing different teaching tools to convey science and math information to help women absorb this information and retain such knowledge more effectively?

Witelson: There are some data that show that different approaches might make it easier for women to learn these subjects—especially in quantitative subjects such as physics, chemistry, and math. I don't know enough about the follow-up studies of differential educational programs. But, I don't think that one has to have different programs for the sexes in every aspect.

We have separate gymnastic classes because boys are able to do some physical things based on differences in muscle structure and bone strength. Remember, the brain is an organ sexually differentiated just like muscles and the genitalia, so it makes perfect sense that there might be certain tasks or subjects where it may be beneficial to have different types of teaching.

However, the different educational programs and learning of the material are not going to change the basic biological differences. Behavioral consequences that are the result of sexual differentiation of male and female brains are not going to change. The important thing is to be cognizant or aware of what those differences are because knowledge is power. It's important for a woman to understand not just her intellectual and cognitive strengths, but also to be cognizant of what her temperament is. How comfortable is she with competition? How driven is she to try to reach the top of whatever it is that she wants to do? How important is it for her to have a balanced family life? By dealing with those issues, an individual gets to know who she is and what satisfies her as she is making career choices.

Intelligence and education represent only one facet of an individual's life. We know there are leaking pipelines, with women leaving the professions earlier and in greater number than men, in science, medicine, law, and business. There are similar figures from different surveys. So, what is it that is making many women drop out? This is the issue we must face and be ready to accept nature and nurture factors.

Ghaffari: Aren't there women like you who are defining their economic and scientific world according to the parameters that they find comfortable and acceptable?

Witelson: Yes, but there also are women who work in the world as it exists today. I have a certain amount of competitiveness. I'm comfortable with a certain amount of risk. I'm passionate about the research and don't aim for any preplanned balance.

Ghaffari: Are women “leaking” into the isolation of the home rather than creating satisfactory alternative options that could provide them different environments in terms of stress and competitiveness? Are women constructing, by and for themselves, this alternative universe that is appropriate for them?

Witelson: What I learned at recent conferences is that there are many boutique businesses and law firms that women have developed when they “leaked out” of the mainstream or main institutions. The businesses are very successful, and the women are very happy and productive. That does seem to be happening. While that is one approach, not every woman may choose to do that. My hope would be that more women stay within the current reality because they have a lot to offer and to add to that experience. Maybe they might even modify the current reality a little bit and improve it.

There are studies that show that women are more risk-averse than men. Some of the biggest fortunes have been made by individuals who took big risks, predominantly men. Studies show that women invest more conservatively. Women are less competitive. Studies have followed very talented young math students into maturity. On follow-up, men had higher priorities for discovering a new product or idea, for being at the top. Women aimed for having balance in their lives and good relationships.

I would suggest, as many others have, that on average women are more driven to do things that they consider useful to society or helpful to people. Men, at least relative to women, may be more interested in personal accomplishments and success as measured by financial or power indicators. Very often, in the surveys, becoming wealthy is less of an important priority among women than among men.

So when you put these things together, it seems to me that we're dealing with two different strains within the same species, and the combination makes for a strong species. It's a reality that we have to recognize and understand.