I really appreciate Cristina Rad recording and posting some of the panels from SkepchickCon/CONvergence this year. In addition to providing one more place where new people can see for themselves the Rebecca Watson Evil Cootie (Ugh!) Effect, this exposes us to audiences we don’t get at the convention itself. That, in turn, brings up questions and criticisms we don’t get at the panels themselves.
A prime example of this has been the reaction to two statements on the “Vive le Difference” panel, which covered gender and sex differences. (You can view the session itself here. If you like it, consider giving it some YouTube love. That RWECU Effect I mentioned above means that this hour-long video already had several downvotes less than an hour before it went up.)
The first statement, called sexist by many viewers, was Heina Dadabhoy’s comment that the Y chromosome is a broken X chromosome. The other, called outrageously sexist, was Greg Laden’s statement that the male brain is a female brain that has been damaged at various times throughout development by testosterone. The question is, however, are these statements true?
Heina’s statement is the easier to address. A number of people did so in the YouTube comments, but I’ll do it here as well. Yes, the Y chromosome is definitely a broken X chromosome. A good write-up of the evolution of the Y chromosome makes that clear.
Part 3. Comparison of sex-chromosome recombination in males and females
After our lineage diverged from the ancestors of the monotremes, such as the duck-billed platypus, another inversion further scrambled the genes on the proto Y. In males, only the tips of the Y chromosome were left able to recombine with homologous genes on the X chromosome. In contrast, in females, recombination continued to occur across the full length of the two identical X chromosomes.
Part 4. Autosomal expansion of X and Y chromosomes
About 130 million years ago (Ma), an autosome donated a block of genes that extended the length of both the X and the Y chromosome. The X and Y were able to recombine in these expanded regions of the chromosomes. Subsequently, inversions rearranged the order of genes on the Y chromosome. Additional rearrangements occured almost exclusively on the Y. Without recombination to preserve its integrity, the Y continued to lose genes and, over time, shrank.
This has undesirable consequences for male humans as well, at every stage of development. A short sex chromosome means that males have only one copy of some genes. Sex-linked hemophilia is one of the specific vulnerabilities of males caused by this arrangement. There are plenty of others, and there are a number of vulnerabilities that we’re still not sure to what degree are sex-linked and to what degree our screening processes and social expectations make it more likely that males will be diagnosed. Some of those may also turn out to be attributable to having a Y chromosome.
So, yes, the X chromosome is the original in this situation, and the development of the Y chromosome both depleted the X chromosome and did so in ways that are not helpful to those who carry it. It is a broken X chromosome. If it weren’t for the fact that the Y chromosome also causes masculinization, and our society highly values masculinization, we would talk broadly about how unfair that is. But it creates our semi-science-literate society holds the Y chromosome responsible for creating boys and men, so it’s all good, and the commenters say that calling it broken is very sexist of Heina.
Now for Greg’s statement. Does testosterone damage a female brain on the way to making it a male brain? This is harder to answer only because it is very difficult for us to tease out what causes the differences observed between male and female brains. There does seem to be a role for testosterone (used generically for androgenizing hormones) during gestation in the establishment of gender identity.
After birth, however, things get much more complicated. Perceived gender leads to different treatment. Stereotypes are enforced with social sanctions. Gender identity may interact with societal gender roles as early as two or three years of age. A mother with high testosterone levels may interact differently with her children. Acceptable behavior differs by gender and can lead to different educational and developmental opportunities (see this pdf of the study Greg mentioned about gender, spatial processing, and video games for one example). Testosterone levels fluctuate in response to some of the very behaviors we are interested in studying.
As I said, complicated.
The best information we have suggests that any differences between the function of male and female brains tends to be quite small and unimportant relative to the vast similarities in the capabilities that we find when we compare the two. It is decidedly not enough to account for the large differences we still see in opportunities and performance between men and women.
Now, all this doesn’t mean that there is no tiny grain of truth to the words of those who insist there are some innate differences between the genders. There may, in fact, be some skills that men are better at than women by virtue of masculinization of a female brain due to the presence of higher levels of testosterone in males.
However–and this is a very important however–Greg’s statement about testosterone damaging female brains to make them male is true to exactly that same degree.
I’ll give you a moment to let that sink in, but do not start a comment until you’ve composed yourself and read the rest of this post.
All set? Okay, on we go.
If you have a complex system that is capable in a general sense, and you retool it to specialize, you lose some of that general capability. In other words, you have damaged the ability of that system to generalize.
To make this more specific to hypothesized sex-related differences, if you take a cooperative system and retool it to be more competitive, you have damaged its ability to cooperate. If you take a highly verbal system and retool it to a more spatial system, you have damaged its verbal abilities. If you take a “female brain” (whatever precisely that is) and, through the application of testosterone, retool it to act like a “male brain” (whatever precisely that is), you have damaged its abilities as a “female brain”. How can you have done anything else?
That the people who present these differences as innate present their evidence to demonstrate some superiority of the male brain doesn’t change the fact that construction requires destruction. It just means that when they start calling statements like Greg’s “sexist”, the irony is delicious, much like the…er, arguments put forward in this comment thread. “Oh, no. It’s not innate/valid/well-measured if it makes us look bad.”
Could Greg’s statement have been a little more complete? Sure, but the format of the panel is limiting. Take a race and gender course from him sometime if you want the full story. But as with Heina’s statement, the outrage over Greg’s is directly attributable to challenging our societal notion that “male” equals “good”. Without that, we’d all already be able to see that if masculinization gains you something, it loses you something as well.