Earlier this year the president of Harvard University got into a great deal of trouble when he suggested--at a conference on women and minorities in the science and engineering workforce--that intrinsic aptitude differences might be one reason fewer women than men advance to the highest levels in science- and math-related careers. While he also alluded to some more politically correct but no less valid possible causes--discrimination in the workplace and mommy-tracking, for example--it was Laurence Summers's suggestion that there might be innate differences hardwired into male and female brains that drew all the fire.

Although I am neither a scientist nor a mathematician, I am a working woman in charge of raising three young men. I wonder why there aren't more female winners of Nobel science prizes--or more female members of corporate boards or writers of op-ed pieces. I think a lot about how I and society in general may be forming my children's ideas about what they can do with their lives. And while I would bristle at the suggestion that women are in any way inferior to men, my own experiences in the workplace and life at home with my sons have made it difficult for me to maintain a belief that a woman's brain must be exactly the same as a man's.

The nature/nurture question

I cut my feminist teeth on the belief that any gender differences beyond the obvious anatomical ones could be attributed entirely to socialization. Little girls were given dolls and toy vacuum cleaners and rewarded for being nurturing and domestic. Little boys were given model race cars and toy guns and rewarded for being daring and assertive. They grew up to fulfill societal expectations by becoming mommies and mechanics, housewives and soldiers, administrative assistants and vice presidents.

This was the accepted wisdom of my generation of incipient have-it-all career women. Burned into my memory is a September day in 1973 when the bells at my all-female college rang out to celebrate Bobby Riggs's nationally televised thrashing by Billie Jean King--a woman who, as a little girl, had been given a tennis racquet.

But when I was finally in a position to put the power-of-nurture theory into practice--my first son was born in 1987--latent seeds of doubt began to germinate. I found that, while I could dress my little blank slate in pink T-shirts, I couldn't make him cuddle Harvey, his Cabbage Patch Doll. The final blow to my long-cherished conviction that socialization was all came on the day I watched four-year-old Dylan, raised solely on PBS and pacifistic, gender-neutral playthings, take strategic bites from his peanut butter sandwich to fashion a sticky revolver with which to shoot his baby brother.

As Stephen Pinker, Harvard Psychology professor and author of How the Mind Works, puts it, "there is a technical term for people who believe that little boys and little girls are born indistinguishable and are molded into their natures by parental socialization. The term is "childless."

Matters of fact
No one in today's scientific community seriously questions the existence of physical differences in the way male and female brains are built. It has been scientifically established that men's brains have more neuron-filled gray matter, while women's have more of the white matter that makes connections among different areas of the brain. Parts of the frontal cortex--an area of the brain that, among other functions, controls language use--are larger in women. Parts of the parietal cortex, involved in space perception, are larger in men.

With the aid of recently developed technology that allows them to observe a brain in action, neuroscientists have documented differences in the way men and women use their brains, too. For example, when male and female subjects listened to a novel being read aloud, male brains showed activity in only one hemisphere; scans of female brains revealed activity in both hemispheres.

These structural and functional differences--reinforced by recent experiments which have found, for example, that baby vervet monkeys have the same gender-based toy preferences as human children, or that day-old baby girls prefer to gaze at a human face while their male counterparts exhibit a greater interest in a mechanical mobile--seem to suggest that biology is indeed destiny.

In his book, The Essential Difference: The Truth About the Male and Female Brain, Cambridge professor Simon Baron-Cohen makes the case quite succinctly:

"The female brain is predominantly hard-wired for empathy. The male brain is predominantly hard-wired for understanding and building systems."

Baron-Cohen suggests that survival of the species required and rewarded a male/female division of labor and that human brains evolved accordingly. It just worked best back on the savannah if our prehistoric foremothers stayed in the cave and tended the babies while their mates went out to hunt food. Consequently, female brains developed specialized areas in the brain for negotiating peaceful solutions among warring siblings and cognitive processes that favored the ability to multi-task. Males developed more of the type of circuitry that would help them navigate in the forest while tracking dinner or envision how a spear will move through space--and less of the type that would prompt them to feel badly about killing Bambi's mom.

Of two minds

So how does this all play out in the modern workplace? In Baron-Cohen's view, male and female brains still complement each other nicely.

"People with the female brain make the most wonderful counselors, primary-school teachers, nurses, carers, therapists, social workers, mediators, group facilitators, or personnel staff. Each of these professions requires excellent empathizing skills. People with the male brain make the most wonderful scientists, engineers, mechanics, technicians, musicians, architects, electricians, plumbers, taxonomists, catalogists, bankers, toolmakers, programmers, or even lawyers. Each of these professions requires excellent systemizing skills."

Comparing these lists, the first thing I note is that most of the empathizer occupations tend to pay significantly less than most of the systemizer ones. But that, I suppose, is a topic for another essay. One could argue, I think, that there is a useful place for both brain types within any profession. Surely healthcare-providing teams need people adept at developing error-proof systems for distributing medications. Recent incidents of corporate corruption suggest that boards of directors could use some members who are able to think about the human implications of business decisions.

And, as Baron-Cohen and other proponents of the nature theory (including a certain Ivy League college president) are quick to point out, gender-based skills overlap as well as complement. Some women have better spatial skills than some men, and some men are more empathetic than some women.

Neither does anyone in the scientific world argue that nurture doesn't play a significant role alongside nature in forming gender roles. Even from a biological standpoint, first causes seem hopelessly tangled. Our brains may be hardwired for some things, but they are also highly programable, continually making new connections in response to environmental stimuli. What if Mozart had never seen a piano or Billie Jean had been prohibited from using public tennis courts?

What if Dylan had never been given a doll? Today I asked my tall and sinewy basketball-playing son (who has done volunteer work in daycare and at the local Humane Society) why he never loved Harvey. His eyes widened reproachfully. "I did love Harvey," he said.

Debra Wierenga is a frequent contributor to jugglezine.