John Medina’s brain rule 11 says, “Mail and female brains are different.” He’s examining gender differences, which can be genetic, neuroanatomic, or behavioral.

Genetically, all men are momma’s boys. Women inherit two sets of X chromosomes (one from mom, one from dad), and apparently individual cells choose, randomly, which inheritance to activate. But men receive the X chromosome only from their mothers. And many genes on the X chromosome create proteins involved in the manufacturing of the brain.

So what are some of the neuroanatomical differences?

• Difference in the size and thickness of the cortex.
• Differences in the limbic system, which influences emotions.
• Differences in the amygdala, which controls and remembers emotions.
• Differences in regulating serotonin, which regulates emotion and mood. (Men synthesize serotonin 50% faster than women.)

Do these differences mean anything? Medina says we don’t know. But we’re trying to find out.

You have probably heard the term left brain vs. right brain. You may have heard that this underscores creative vs. analytical people. That’s a folk tale, the equivalent of saying the left side of a luxury liner is responsible for keeping the ship afloat, and the right side is responsible for making it over through the water.

Both sides are involved in both processes. That doesn’t mean the hemispheres are equal, however. The right side of the brain tends to remember the gist of an experience, and the left brain tends to remember the details.

Behavioral differences

Males suffer more from mental retardation, and the X chromosome is often involved. (Remember, women have a backup set of X chromosomes; men don’t.)

Men are more severely afflicted by schizophrenia; women, by depression.

Most alcoholics and drug addicts are male; most anorexics are female.

Medina discusses the work Deborah Tannen has done in studying verbal behavior. His summary: “Women are better at it.”

How much is genetic and how much is socially influenced may be impossible to tell — but the differences are clear early in life in such areas as building relationships and negotiating status. Those patterns are reinforced and greatly influence our interpersonal verbal behavior as adults.

Some final thoughts from Medina on using this data in the real world:

Get the facts straight on emotions.

Emotions matter because they make the brain pay attention. Men and women process certain emotions differently. That means they pat attention in different ways.

Medina recounts an experiment dealing with how men and women reaction to emotional stress. The tendency is for men to activate the right side of the brain (the gist), and for women to activate the left (details).

Question gender arrangements.

Are single-sex classrooms better? We haven’t experimented enough to know. They may depend on age, on subject, and certainly on the techniques for fostering learning.

Notice gender in the workplace.

Here’s Medina, recounting a presentation at the Boeing Leadership Center:

I said, “Sometimes women are accused of being more emotional than men, from the home to the workplace. I think that women might not be any more emotional than anyone else.”

I explained that because women perceive their emotional landscape with more data points (that’s the detail) and see it in greater resolution, women may simply have more information to which they are capable of reacting. If men perceived the same number of data points, they might have the same number of reaction.

Take management training, Medina says. Often it involves various complex simulations. Have unisex teams and mixed-gender teams. Then give one team of each type some training related to these real gender differences and their implications.

So you’ve got uni-untrained, mixed-untrained, uni-trained, mixed-trained. Real-world outcomes (and maybe a master’s thesis).

Which side of your brain is firing right now?

Photo of the General Post Office in Dublin by informatique / William Murphy.
Detail of the GPO’s name in Irish by jaqian.