When I was thirty-two, during a period of my life when my conscious GID was fairly remote (apart from the fact I was taking - er - something), I decided to go to the NHS to have my bowel dysfunction investigated, partly because I wanted to place myself in the position of a typical NHS patient as experience to help my own future patients. I found there was a tendency to be lulled into passivity, which interested me. I was booked in for a barium enema. I heard various horror stories about them, none of which were actually in any way an issue. My main concern was in fact that I was to be exposed to a humongous dose of X-rays, presumably because otherwise the pelvis would get in the way.
One of the interesting things which happened was the hyoscine injection, whose purpose was to allow the bowel to dilate to the point where it would be easily imaged. Hyoscine is anticholinergic and antimuscarinic, so in other words it acts on the autonomic nervous system.
This was fifteen years ago. Thus far I seem to have experienced two long-term effects from this investigation. One was the appearance of a wart on my left wrist, shortly after the X-ray exposure. The other was the apparent intermittent appearance of Holmes-Adie pupils. I should explain. For some time after the injection, and I mean several years and still on occasion, my left pupil would not constrict much in response to light, leading to difficulties in reading and discomfort in bright light. Moreover, it emerged that during my training as a herbalist, a number of deep tendon reflexes were completely absent. To be honest, I didn't notice if my sweating was abnormal.
This so-called Adie Syndrome I think of as a mere feature of my body rather than a problem. It's not serious in any way although the absence of deep tendon reflexes occasionally meant my knees would tend to buckle, which again still happens on occasion. The Holmes-Adie pupil phenomenon is generally thought to be caused by a viral infection of the ciliary ganglion. When the nerves recover, some of them are said to supply the muscles which control the iris better than others and there is an imbalance leading to this effect. Presumably I had chicken pox or glandular fever or something which led to this at some point and the administration of hyoscine triggered it off. The deep tendon reflex thing is again due to infection, this time of the dorsal root ganglia in the spine.
So far so good. It's pretty clear that it's at least very similar to Holmes-Adie pupils even if it isn't actually that, and in fact I think it is.
What makes it interesting to me is the gender distribution of the phenomenon. The mean age of onset is thirty-two, which for me is right on the button (yay for being able to type that without freaking out! You have no idea!), and it's said to be mainly a problem for younger women with about 70% of the cases being female.
Imagine, then, that you know nothing about me other than the fact that I have two eyes, and you can shine a light in them, and do a neurological exam generally on my deep tendon reflexes. You are then asked to guess my sex. The safest guess would be that I'm female. In fact every person I've noticed with Adie pupils is female with the possible exception of myself.
Of course, men do get Adie pupils and the rest, and it isn't like 95% are female or something like that. However, to me this is a fairly strong indication that my central nervous system is typically female, not typically male. It's not a clincher, but it is a bit close, and the facts that I am also M2F gender dysphoric and that the claim is often made that M2F gender dysphoric people have typically female brains. Moreover, one's sense of gender identity is said to be based on whether certain parts of one's brain, notably for some strange reason the corpus striatum, which links the basal ganglia, are typically female or male in structure. It's not based on the current hormonal regime, socialisation or the perception of one's body. In other species, allegedly, brain "sex" (not necessarily chromosomally) determines the gender of the whole animal. I'm afraid I can't remember much about that apart from this.
This is interesting because Adie pupils and the absence of deep tendon reflexes are not psychological but neurological. They're not to do with emotional trauma during childhood, social construction or even free will. So this amounts to a very unreliable test of brain sex. It's far from perfect, but given the circumstances, it's, to use the cliche, a "smoking gun". It really does seem that I have a female brain. As I've said before, I'm not my brain, but maybe my gender is the same as the gender of my brain. Perhaps that is what gender identity is, at least for me. That means that in theory I could go around wearing a suit and tie, be into fast cars and loose women, be muscular and hairy and generally do nothing outward to indicate that my gender was female, but I would still be female. There is no need for me to conform to any gender stereotype to make myself female. I just am female, because my brain is female.
The question arises of why I haven't thought in that way much until recently. I would suggest that the answer lies in my practice of scepticism. I am very reluctant to attribute the word "knowledge" to anything. It's possible to doubt rationally the existence of the external world, of other minds, of the past, and so on. All of those things might not be real and as a philosopher I have in fact experimented with doubting them. However, whereas I might have sat in a seminar as an undergraduate and pontificated about the non-existence of consciousness in other "people", when I left that seminar I would still be confronted with the fact that one of the other people in that seminar had recently been freaked out and disgusted by my inappropriate gushing of undying love for her, and those things - being freaked out and disgusted - are real experiences in her mind which I have no doubt were actually there. That horribly embarrassing, cringeworthy elicitation of a negative response did include those experiences for her.
However, because I was so used to the idea that it's possible to doubt almost anything other than logically necessary propositions, bits of maths and qualia, it was equally possible to doubt that I was female. In fact, I think I may even be putting the cart before the horse here. I think the truth may be that it's the other way round. The reason I was so good at metaphysical doubt was that I was immediately, at a very early age, confronted with the fact that something I had such a strong feeling of certainty about, that I was female, was doubted, and in fact completely discounted, by absolutely everyone I came into contact with. This is the origin of my philosophising.
Therefore, suppose I do decide, as practically everybody does, to accept that life is not a dream, that we are not brains in vats, that other people are not zombies and that we didn't all spontaneously spring into existence five minutes ago with ready-formed false memories. A further incontrovertible fact for me would be that I am female.
Therefore in recent days I have been looking into my eyes, which occasionally respond oddly to changes in light, and knowing that when I do that, I am looking into a woman's eyes.