Gender Differences, The Brain, and Testosterone

In a new book by Cordelia Fine she claims that there is no innate genetic difference between men and women’s brains.  I haven’t read the book so I’m going to make only a quick statement based upon the reviews I just read:  here, here, and here.

Here are some basical claims, as far as I can tell:

  1. The gender differences sometimes seen in behavioral and neuroscience studies are not innate.
  2. Much of the related science is flawed anyway, so even if it does seem to show innateness we shouldn’t take it seriously.

I worry about the first claim.  The reason comes down to our definitions of “innate”.  If we mean “at birth” when we say “innate”, then I agree with her.  But, if we mean that there is some genetic code that at some point will cause men and women to have (at least slight) differences in behavior, then I disagree with her.

The reason is puberty.  Far too many of the studies that “debunk” innateness of gender differences are done on babies and young children.  I find these to be stupid.  Boys and Girls are far more similar (in a whole lot of ways) than Men and Women. 

Before puberty, a boy has about as much testosterone as his little sister does.  But, during puberty he has more testosterone running through his system than Mark Mcgwire!

Why does this matter?  Because testosterone affects the brain – a lot.  Testosterone has been implicated in a whole host of different behavior and cognitive differences including memory, attention, spatial perception, mood.  Men with abnormally low testosterone are more prone to depression, aggression, and anxiety and may even be at a higher risk of cognitive decline and Alzheimer’s.

The “trigger” that gets pulled in boys as they go through puberty that releases all of that Man-making testosterone IS genetic.  How much of it that gets released is partly related to environment (of course), but that is missing the point.

Men, on average, have something like 10 times the levels of circulating testosterone than women do.  We can’t pretend like this isn’t going to be expressed in some way as behavioral differences.


Anecdotally, I’ve worked as a strength coach for a long time, and I’ve known a lot of women on steroids.  Trust me, they are more like men than most men.  Hormones change behavior.

“Normal” men have bodies that produce a substantially greater amount of this hormone than women’s bodies do.  So, as a group, men will likely exhibit more of the characteristics associated with high levels of testosterone than women will.  The brain can’t be taken as something separate from the hormones that affect it. That’s like talking about how a car works but pretending that it won’t matter if we try to run it without any gas or oil in it. 

This is an under-researched area, no doubt.  But, until I see some studies showing that these hormone levels don’t change behavior, I’m sticking to the view that there are “genetic” behavioral differences between the sexes in the broad and general sense.


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