With the continuing flap over Caster Semenya, it may be interesting to get some background on the biology involved. A recent article I saw mentions testosterone levels, and that made me think that perhaps (yet another) post on the biology might be useful. So this isn’t about social gender, athletics, Caster Semenya herself, or anything but biology. Modal concepts of gender see it as a binary, either-or matter, but in reality it’s way fuzzier than that.

The good old X and Y chromosomes themselves don’t always come in pairs, to start with. You can have XXX, XXY, XXXXY, XYY, and the like. This is possible for two reasons. One is that even in a typical XX situation, one of the X chromosomes is silenced early in development. With more than one X, the extras are also silenced, so it doesn’t wreak the havoc of having, say, an extra chromosome 13 or 21. The second X is needed early on to develop functional ovaries, which is why XO (Turner’s Syndrome) people are infertile. The Y chromosome has very little information on it, and an extra copy or so therefore doesn’t do much damage.

So the X has its “ovary determining factor,” and there’s a sex-determining region on the Y (SRY). This is where things get even more interesting. All our chromosomes come in pairs, and despite their vast difference in size, the X and the Y are a pair. That means they can exchange bits of material in crossovers. It’s a bit like an elephant dancing with a hamster, but they manage. So you have a couple of unexpected possibilities, both of which would look quite ordinary on a regular count, i.e. 46 chromosomes, of which two are sex chromosomes.

1) XY, but the Y is missing the SRY. In this case, the person is anatomically female, but sterile. Since there’s a lack of testis determining factor (TDF), there’s also female levels of testosterone. That has particular relevance in the case of an athlete.

2) XX, but the SRY has translocated onto one of the Xs. In this case the person is anatomically male, and probably infertile unless the Y regions that code for sperm production also translocated. Testosterone is produced at male levels.

3) There are also genetic factors that alter the sensitivity of cells to circulating testosterone. Ordinary amounts of the hormone might be produced, but the rest of the body’s cells can over- or under-react (e.g. androgen-insensitivity syndrome, AIS).

The real point here is that the only valid concern is testosterone. That will give you an advantage in sports like sprinting, and that’s why doping yourself up with it is considered cheating. (When they talk about “steroids” in sports, they don’t mean any old steroids. Corticosteroids, for instance, wouldn’t do any good.) That’s also why there’s a concern about the femaleness of athletes, but not the maleness, in those sports where testosterone helps. (Just for the record, it’s not a huge advantage in all sports. Look at the early history of English Channel swimmers, for instance. Even against a tide of social disbelief, a number of early record holders were female.)

What the committee is really worrying about is that Semenya might have a testosterone advantage and be unfairly matched against other women who produce less and/or react less to it. They don’t need to know whether she’s a “girl.” They need to be measuring long term circulating testosterone and androgen sensitivity. To do it right, that could take years.

But there are implications far beyond that. The point that an athlete like Semenya brings home is that there are variations in testosterone among people. This has always been true. So, if the Committee really wants to be fair, they should be doing long term testosterone tests for everyone, male and female. Then, to continue being fair, they have to accommodate our non-binary reality properly and have different testosterone-based classes, like boxers do for weight. We could have quintiles 1 through 5, for instance, from the barely-measurable class up to the watch-for-eventual-heart-problems class.

That would involve acknowledging differences. Real differences as opposed to “vive la difference” differences. What do you think? Conceptually feasible? I mean, I realize I’m suggesting that a committee consider more than two categories at the same time.

athletics, gender verification, Semenya