Anyone wishing to spot changes from our pre-print:
1. We included a section on pre-pubertal differences (that is, even young boys outperform young girls, thus the performance gap is not solely down to pubertal T).
2. We extended our analysis of CV capacity changes and potential impact on endurance performance (although we had acknowledged a likely effect, we have drilled deeper into mechanism).
3. We have *significantly* extended our discussion of impact on athlete transwomen and the mitigating effects of exercise (that is, moderate training can mitigate or even reverse muscle/strength loss during T suppression).
The remaining differences are minor, and represent no significant change from the pre-print.
Let’s have a think what hormone categories looks like. And let’s assume that @neiltyson is considering a high/low T category. This has also been proposed by @AliceDreger
The proposal only works if you don’t deny evolution and sexual selection. Remarkably, there are academics who argue there is no biological basis for why males run faster than females. While it is plausible ongoing underinvestment in female sport means female athletes have not yet reached their full potential, it is frankly ridiculous to think this can explain the entirety of the performance gap.
See Sheree Bekker et al for more details on why, because one time, this one female figure skater won a medal, Usain Bolt should be allowed to race against females.
The proposal only makes sense if we recognise that the action of T on a body gives advantage in sport. This is by no means universally-accepted. Many humanities types argue T is not a key part of sports performance, citing males with low T and people registered as female with high T. Even though both phenomena are explicable by factors like illness, doping and male DSDs, still this argument persists.
See Veronica Ivy, Katrina Karkazis et al for why we should pretend that the stupidly high prevalence of weightlifting males with low T is not because they have just finished an off-period jacking up.
Why male advantage in sport is not a social construct: height.
Height is a key difference between males and females. What is nature v nurture? What does that mean for sport?
Bigger skeletons are most obviously driven by longer bone growth. Key bones like those in your thigh (“long bones”) grow from their end to get longer, making you taller.
The site of bone lengthening is called the “epiphyseal plate” or “growth plate”. Here, cells divide/enlarge, making new tissue that pushes the bone ends apart. This tissue calcifies and is replaced by bone, leading to lengthwise growth.
Let’s set a concrete example: the 10 second barrier (100m sprint).
Wiki - allowing for small errors - tells me that around 200 male sprinters have broken it. We know, of course, that no female sprinter has been close (Flo Jo record 10.49s).
For the following, I’m going to ignore the premise that humans might be close to biomechanical limits over a 100m sprint. It’s just an illustration.
If we follow world record progressions, we see trends (not just in sprinting, the graph below is from a swimming event).
As the latest on Olympic boxer Imane Khelif is reported, a diagnosis of 5ARD is almost certain. I and others first raised the likelihood of this DSD a few months ago.
Understanding how the developmental biology of DSDs interacts with sports categorisation is crucial.
I spoke about this with Andrew Gold during the competition:
And I recently gave a talk at a meeting, on DSDs, male advantage and sports categorisation. I will add some slides below.