So would every male, regardless of ability, be handicapped for having higher-than-female testosterone? As you suggest, each sport would require its own metrics, but I also can't help thinking of Vonnegut and Harrison Bergeron
Again, this is an interesting thought experiment and I'm enjoying discussing it
I'm surprised, birdman, that you're thinking this way with your training re: sexual dimorphism and biological diversity. As a humanist, I try to acknowledge and even accentuate difference as much as possible because I feel like that's important in identifying things like structural discrimination and cultural richness.
I haven't worked out all the kinks of this "solution" so maybe a handicapping system doesn't work. But I do think, just like in wrestling, you could build more than just boy/girl classification systems that don't pit very tall heavily testosteroned females against short low testosteroned females. If we are so concerned about the fairness of transwomen competing against other women, where does the concern stop? Is it "fair" for tall women to race against short women? Super buff dudes, to compete against small dudes in weight lifting? If the true issue for conservatives is fairness in competition, then it should go further than just trans athletes, or what is to stop it from going further?
From my biologically informed perspective there is individual variation among competitors. Splitting competition up into genders is an attempt to control for some of that variation among men and women and make things "fair" for women. But, gender fluidity undermines that singular classification system so some kind of a classification system that accounts for more than just male vs female variability seems warranted.
Plus, sex determination is not as hard wired in animals as people want to believe. Plenty of species regularly switch sexes. Some as a matter of life history progression (i.e., they are males when they are small because sperm are easy and cheap to produce, and females when they are large because eggs require energy and size to make and store), some as a matter of environmental conditions (e.g., if sex female to male ratio declines, larger males will start switching to female). It happens in fish, amphibians, reptiles and even birds. It is actually really common in tropical reef fish and salt water fish as a whole. It is pretty rare in mammals to fully switch sexes because our organ structures are so specialized they are difficult to modify once built. But sex determination, especially sexual behavior, is governed by hormones. However, if a genetic male experience reduced testosterone levels during development, they may actually develop as female. Further, adjustments in hormone production or reception can alter sexual function and behavior in mammals. Just for example, there are plenty of studies on how BPA, a chemical in plastics, functions as a hormone disruptor for testosterone and can reduce and even cease sperm production, reduces sex drive and in extreme cases can lead to developing secondary sex characteristics (e.g., moobs) in human males. (all of this ignores the fact that sex is biological and gender it's self is cultural.) So, I don't adhere to stick definitions of gender because my biological training tells me it's inaccurate.