Re: Oh no, more sexual dimorphism of the brain!

Ralph L Holloway (rlh2@COLUMBIA.EDU)
Wed, 22 Feb 1995 10:27:06 -0500

Lynn Nordquist raises some important points regarding these purported sex
differences in the brain. Of course experience is important, but I know
of no studies which shows that the differences in socialization between
male and female kids really organizes neural nuclei and fiber tracts
differently. When deLaCoste and myself were studying the corpus callosum,
we found relative size differences in the fetal brains, well before one
could argue about cultural environmental influences. The sample sizes
were simply too small to be definitive. More on all this in a later post.
As to why study this in the first place and what to do with the results?
If ever I do have a stroke, or brain damage (beyond that already
experienced from this thread) please let the neurologist take my gender
into consideration with any sort of rehabilitation program that might
help me. Anyway, knowledge is precious, why throw it away?
R. Holloway.
On Tue, 21 Feb
1995, Lynn Nordquist wrote:

> I have been following with interest the debate over the study of the
> sexual dimorphism of the human brain. When I first read the article
> in the NYT I saw what appeared to me to be an obvious flaw in the
> conclusions drawn from the research. Perhaps the conclusions were
> more those of the journalist than of the researchers, or perhaps the
> flaw is in my own reasoning. Let me put forth my question and wait
> for the response of my peers.
> Given that the human brain develops neurological pathways as a
> result of experience, isn't it possible that the differences found in the
> cognitive patterns between men and women in the study is an artifact
> of their life experiences? If females and males are trained from birth
> to attend to certain stimuli in their environment, are encouraged in
> some ways of processing information and discouraged from others,
> etc., mightn't the female and male brains develop differently? I don't
> believe that the observed differences in brain functioning patterns
> proves that the patterns are genetic, which is what the article, if not
> the authors, implied, only that the brains of males and females, by
> the time that we are adults typically function differently in dealing with
> some ways of processing information.
> I have no objection to the idea that men's and women's brains might
> function differently in managing some tasks, in fact, I personally
> suspect that this is indeed the case. Still, I don't see how this study
> proves or disproves a genetic difference between female and male
> brains.
> Mr. Holloway, who first wrote about this article, noted that it would be
> interesting to see a study like this done cross-culturally. I suggest
> that the *only* way to study this question is to study it
> cross-culturally (or possibly to study infants), at least if one wants to
> conclude that there is some evolutionary process that has resulted in
> males and females necessarily processing information differently.
> Just one additional tidbit and that is that I wonder what the use of
> such research information might be. Why, exactly, does it make a
> difference if a statistical majority of males use a different part of their
> brains to process information than do a statistical majority of
> females? Also, is it necessary to think of males and females as
> existing in two discrete categories? I'm well aware of the genetics of
> sexual differentiation, but I'm also aware that we are discovering
> more and more about the "other" factors that go into determining
> sexual difference. For example, the recent study indicating that the
> brain of male homosexuals is structurally different from the brain of
> heterosexual males demonstrates that what might initially appear to
> be a case of binary oppositions (male or female) might very well be a
> more complex, more continuous sort of difference.
> O.k. that's more than enough. Thanks for sticking with me. If anyone
> wishes to comment on any of the above, I would be interested to get
> feedback.
> Lynn Nordquist
> University of Minnesota