Professor Murphy. You wrote: “If you can point me to the aspect of human biological sex that is not undergoing constant, dynamic change (if only at the molecular or physiological level) or which exists outside a social/cultural/environmental context, then I am prepared to entertain the possibility that “sex” is not socially constructed”.
As already stated: XX vs XY chromosomes. Once you are conceived, this won’t change. It is one scientific determinant for the sex of a human. Even if there are internal molecular changes, these don’t change it from XX to XY. Dark blue may change to light blue, but it is still blue. So, the fact that something changes does not mean it changes categories.
Biologists use several characteristics to determine what sex category a person is in. We can argue about the science of the determinants, but the vast majority of people naturally fall into one of the sex categories across all the determiners. If you don’t know the determiners scientist use, look it up. I won’t fill the space here. There is an established scientific definition of sex. There is a small percentage of people who have characteristics of both categories and science recognizes rare exceptions to the taxonomy. Most of these characteristics are fixed for life, others can change, perhaps by surgery. The discussion is about natural sex. So, no, natural sex is not constantly changing and dynamic as you claim. Give me one example of a human who has completely changed birth sex, even given all the wonders of hormone treatments and surgery. I’ve read the work you cite, and it makes some good points about other things, but this dynamic sex claim is just as absurd as your claim that our sex is changing because we breath. It’s disconcerting to see that you are a professor and subjecting young, impressional students to this nonsense. Please stick to gender issues, which I assume you know something about.