A few Responses to: Biological truth? WTF? (Part 1)
Original exchange was on Bluesky
I posted a link to “Biological truth” WTF? (Part 1) on Bluesky. Cathy Devine @womensportfeminism.bsky.social responded with several questions. I am reproducting our exchange here because she raises issues that may be troubling others as well. Please forgive the staccato prose, but Bluesky limits the number of characters in each post. As it was, I had to do a several part thread, which I find hard to follow.
In her first post she wrote “Oh dear. Is the paper cited for the graph above, about humans? Here's a clue” (The clue was an image from the paper illustrating multiple sex systems in several different animals). Despite the mildly mocking tone I chose to directly address her concern, which seems to be: can we apply data from animals to humans?”
My answer was simple: “Not about humans. But the models abstracted are clearly applicable to humans, and my discussion of the models focuses on humans.”
Her next post contained several questions, offered in a more conversational tone.
These were: 1. Are women with smaller breasts more male than women with bigger breasts? 2. What is the orange line? 1 3. Is she suggesting there is an overlap in plasma T between males & females?
I responded: the question is, what traits can reliably distinguish between males and females? This differs in different parts of the life cycle.; also: is it a have/don't have situation or a continuous variation. So: re: breasts. Of course this applies to adults, not children. And some men have larger breast sizes than some women.
The orange line (I called it yellow, sorry): could be any hormone related to reproductive physiology--estrogen, testosterone, luteinizing hormone which affects ovarian development AND under the name ICSH (Interstitial cell stimulating hormone) affects testis development, follicle stimulating hormone, etc. Each of these differs in plasma levels at different times in the life cycle, differ with nutrition, under stress and even time of day. Hence the variability in trait value.
With regard to plasma levels of testosterone. Generally, adult men and women under the age of 50 do not overlap. BUT there is individual variation with genetics and also time of day, general health, stress levels etc. And plasma T levels in infants and children do not differ at all. Here is a graph that shows variation in the general population and in people with certain medical conditions. I can't vouch for the quality of this review or how comparable the methods are in the different pubs cited. One other point about this graph: Look at the T levels for CAIS and PAIS WOMEN! They are XY and despite high T levels, their cells cannot bind the T (defective androgen receptor), so they often have vaginal labia and large breasts. Breast and genital morphology diverge from T levels.
Devine included this graph from my original post:
also worth mentioning the reason anyone during natal development low in or insensitive to testosterone develop labia and other normatively female-typed morphology (beginning as Muellerian ducts) is because the only thing that stops such development is Anti-Muellerian Hormone, which can be inhibited or fail to be produced by several different conditions simply by interference in the activation of the AMH gene or reception of AMH. also that higher androgens in people assigned female nonetheless induces greater phallic development, and the only concrete difference between male-assigned and female-assigned phalli (penis vs clitoris) is the location of the urethra, which also fails to be binary. i rly wish more people cared about intersex health and autonomy and that the language about all this stuff would historically contextualize the gendered terminology used to type it, sex, by instead referring to the normative assumptions embedded in sex assigned at birth