brains of humans

Differences Between the Brains of Men and Women

brains of humans

Human Brain


Although it seems self-evident that men and women would have different brains — what could be more fundamental about us than whether we’re male or female?

By: Marianne J. Legato, FACP and Laura Tucker

While there do seem to be gender-specific ways of thinking, remembering, and experiencing emotion, those differences do not necessarily connote superiority. Dr. Kandel’s groundbreaking research assures us that our brains aren’t set in stone, even if our sex is. If we learn from each other, then these differences become opportunities, not divisions.

True or False: There are significant differences between the brains of men and women.

True. It seems self-evident that men and women would have different brains — after all, what could be more fundamental about us than whether we’re male or female? And yet, for most of medical history, doctors and scientists assumed that all the organs of men and women were the same, except for those directly involved in reproduction. Research suggesting otherwise is very new: Scientists first made the observation that there were differences in the physical structure of the brains of female and male rats a little more than three decades ago. It has now been confirmed that this is true not only in other species with two sexes, like songbirds and monkeys, but in our own as well: The anatomy of the brain and how it works are different in men and women.

True or False: The brain has a sex at birth.

True. Our sex is fixed and immutable — and not just at birth, but from the very moment of conception. That sex has implications for all the systems in our bodies, including our brains.

But in a sense, this is a trick question, because while we are undeniably and indelibly male or female from the very beginning, there are a variety of factors that contribute to the process by which we acquire our sex over the course of our lives. So, although you’re always male or female, other factors are working on you at specific stages throughout your life to make you more or less that way.

What are those factors? Our genes are the unique cellular blueprint that makes us who we are, including our sex: The sex chromosome we get from our fathers at conception determines which sex organs we’ll develop. An X chromosome from Dad means the baby will have two Xs and develop into a female. A Y chromosome means that there will be an XY complement, creating a boy. The sex organs we develop, in turn, release sex-specific hormones, which continue the process not only in the uterus but also during certain windows of time throughout life — puberty and menopause, for example — when hormone levels change precipitously. Those hormones also turn certain genes on or off, which further influences the sex-specific functions of our tissues, which is why more than one teenage girl has cursed her mother for the size (large or small) of her new breasts.

These genes are also why hormone levels vary from person to person. Those hormone levels affect our behavior. Individuals with high testosterone levels, for instance, are bolder, more aggressive, and more focused on a single goal. They smile less, have a higher libido, and are more likely to engage in extramarital sex.

There’s one more factor influencing our sex — our experiences. A striking example of this is the conduct of some of the female soldiers at Abu Ghraib, the American-run prison in Iraq. Many of us were shocked — not just by the brutalities these women meted out, but at the discovery that women were just as capable of acts of humiliation and savagery as men. Clearly, experience is an important factor in modifying behavior.

About the Authors:
Marianne J. Legato, FACP, is an internationally known academic physician, author, and lecturer. She is a professor of clinical medicine at Columbia University, where she founded and heads the Partnership for Gender-Specific Medicine. One of the world’s foremost experts on gender medicine and winner of many awards for her work, she is the author of The Female Heart, What Women Need to Know, andEve’s Rib. She recently edited the widely acclaimed academic textbook, Principles of Gender-Specific Medicine.

Laura Tucker is the coauthor of several health and medical books. She lives in Brooklyn, New York, with her husband and daughter.

Copyright © 2005 Marianne J. Legato, MD, FACP and Laura Tucker

Reprinted from: Why Men Never Remember and Women Never Forget by Marianne J. Legato, MD, FACP and Laura Tucker © 2005 Rodale Inc. Permission granted by Rodale, Inc., Emmaus, PA 18098. Available wherever books are sold or directly from the publisher by calling (800) 848-4735 or visit their website at

Photo: D_J_