Wednesday, January 30, 2013

Brain Rule #11: Gender


My summaries of the book Brain Rules continue...
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Chapter 11: Gender
Rule #11: Male and female brains are different.

Stephen Jay Gould said the following about the nature-nature controversy, the question of whether our inherited genetics or the environment we grow up in affects who we are more: "It is logically, mathematically, and scientifically impossible to pull them apart" (252). Society has expectations of men and women that affect our perceptions and expectations.  Our "sex" may be biological, but "gender" is mostly a matter of social expectations.

In one experiment, a corporate executive was said to be a male to one group, a female to another.  With no other difference in the description, the group described the male as likable and competent, the female as likable and not very competent.  Two other groups were given the same descriptions with the added information that the executive was a superstar on the rise.  They again described the male as likable and very competent, the female as very competent but unlikable, perhaps even hostile.

The genetic differences between male and female come from our different chromosome make-up.  Women have two X chromosomes. Men have an X and a Y chromosome. We know now, of course, that the man determines the sex of a child.  The woman contributes an X chromosome to the child. Then the man either contributes another X chromosome to make a girl or a Y chromosome that makes a boy.

The X chromosome is much longer (some 1500 genes) than a Y one (less than 100)--and the far more significant of the two. The default setting of a mammalian embryo is to make a female. A small gene in the middle of a Y chromosome called SRY will make the embryo become male.

Because a female has two Xs from which to chose, she genetically shuts off half the genetic material somewhat randomly, some from the father and some from the mother. But the male has to use all the X material from his mother.  This implies that a male is more genetically biased toward his mother. It also implies that a male has more at stake if a gene on the X chromosome is damaged.

There are also some regular differences in the brains of men and women.  Men tend to have a much larger amygdala than women, the part of the brain that creates and remembers emotions. The amygdala of a woman also tends to interact more with the left side of the brain, male amygdalas with the right. This is not the right brain-left brain folk tale (both sides of the brain are used in both creativity and analysis). But the right side of the brain tends more to get the gist of things, the left side more the details. It thus does seem to be true that women tend to remember more the details of an emotional event while men more remember the gist.

Male brains generate serotonin about 52% faster than women do. Serotonin is sometimes connected to the regulation of mood and maintenance of a sense of well being, but brain scientists strongly disagree over such things.  The precise significance of brain differences relating to the size of the amygdala and the rate of serotonin production are not agreed.

Studies of differences between male and female brains have to do with populations rather than individuals. That is to say, these analyses have to do with large groups of men and women rather than any individual male or female in particular.  Just because most male or female brains would seem to function in a particular way does not mean that all do.

There are, however, some observable trends. Men are more likely to have mental retardation than women. Men tend to have more severe cases of schizophrenia than women. But women are twice as likely to experience chronic depression than men.  Men are more likely to be anti-social or be addicted to alcohol or drugs. Women are more likely to have anxiety.

Women tend to be better at verbal communication than men, and they use both sides of their brains when speaking and processing verbal information. Men primarily use one of the hemispheres. Women tend to cement relationships through conversation, while boys seem to do it by "commotion," by physical interaction and competition.

When boys jockey for status, the dominant one tends to give orders, the less dominant tend to withdraw.  In some studies, women tend not to give top down orders.  If the male leader says, "Do this," the female more likely to say, "Let's do this." Intimacy among females often involves sharing secrets.

Medina's ideas have to do with paying attention to gender differences.  He suggests in the workplace that  an employers might experiment a little with teams of varied gender arrangements to see how it affects projects. He suggests that women are not more emotional than men but that they have more details of emotional experiences to deal with than men do. In the classroom, he suggests that boys or girls may need some separate attention to keep social dynamics from preventing them from reaching their potential.

1 comment:

Angie Van De Merwe said...

Are there REALLY Gender differences? Temperament/Personality differences seem to be the categories that make for most of our differences. How can psychologists study with control groups when there are so many variations to a person to test whether these are true gender differences, or whether they are differences related to personality or experiences? I understand the genetic distinctions, but how are our brains (personalities involved with our genes in a distinctly gender defined way?

I listened to a talk on how the brain responded to different stimuli based on personality (myer-briggs) which was interesting.

Just wondering.

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