You know that story that as embryos we all start out as female, with just a couple of genes on the male Y chromosome responsible for modifications that make male embryos develop into actual men?
A classic example might be Androgen Insensitivity Syndrome, a genetic condition that prevents or inhibits the expression of male sex hormones in XY-chromosome cells. People with AIS often have externally-indistinguishable female genitals and develop breasts at puberty but have no uterus, fallopian tubes or cervix and may have no upper vagina.
This and other similar intersex syndromes are responsible for the conclusion that genetically and developmentally speaking men are just special-case women.
I’m not sure why that’s supposed to matter but it gets buzzed about a lot.
Turns out that while the basic outline of the story remains approximately correct it’s… more complicated than that.
Richard Alleyne, Science Correspondent at The Telegraph
Researchers have found that the body is in a constant fight to remain either female or male and the suppression of just one gene could cause it to “flip” from one to the other.
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In mammals, males have XY chromosomes and females XX. The new research shows that another gene is responsible for switching women into men.
If the FOXL2 is switched on then the body grows ovaries, switched off and they are replaced by testicles.
But what really surprised the researchers is that the process continues after birth and the body remains in a constant tussle to either switch on or off the gene – even in adulthood.
Hard core gender essentialists might find this frustrating. Men aren’t just women with an X-degenerate Y chromosome. Women aren’t “pure” humans. On the other hand male embryos don’t actively make ourselves men, nor do female embryos passively default into women. Instead, at the genetic level anyway, we all take active steps to differentiate, switching on some genes and switching off others, in order to become who we are.
(Via Joanna Cake, Violet Blue, and others.)
