Is being a trans woman (or just low-T) +20 IQ?

All the smart trans girls I know were also smart prior to HRT.

I always assumed that, since high IQ is correlated with high openness, the higher openness would be the cause of higher likelihood of becoming trans. 

(or, some more general situation where IQ is causing transness more than the other way around., e.g. high scores on IQ tests might be caused to some extent by earnestness/intensity etc., which could also cause more likelihood of becoming trans)

I think its more likely its the transgender - autism correlation....

• some forms of autism come with higher iq (and other forms, really really  dont)
• and there's the transgender autism correlation

which together would seem to predict transgender high iq people

(and also transgender low iq that you arent seeing due to ascertainment bias)

I buy that trans women are smart but I doubt "testosterone makes you dumber" is the explanation, more likely some 3rd factor raises IQ and lowers testosterone.

The trans IQ connection is entirely explained by woman’s clothing being less itchy.

Why aren't males way smarter than females on average? Males have ~13% higher cortical neuron density and 11% heavier brains...

Men are smarter than women, by about 2-4 points on average. Men are also larger, and so need bigger brains to compensate for their size (though this does not explain the entire difference you cite).

The part on trans males doesn't make that much sense. They may have male brain chemistry but I'm recalling research on finger digit ratios in transsexuals that seemed to point to transsexualism being caused by low prenatal testosterone levels across the board (2D/4D ratios were higher in transgender participants regardless of birth sex). Other studies suggest little correlation, so in the end, it's still quite hard to say.

Aside from that, I think it's a bit misguided to come to such conclusions based on anecdotal evidence, which is probably even less reliable owing to the general tendency where outliers of all sorts will be shared more as evidence. You don't tend to notice the average people in your life. Outliers form a group that is neither representative of the median person, nor is it usually large enough to be statistically significant.

I am transmale, if I were to have written this post, I might have come to a completely different conclusion. I know many highly intelligent female and trans male/trans masculine, enough to form jsut as many examples provided here, my own IQ is 150 so I could also speak from my own experience. Before hormones, I was a few inches above average height and already had test levels on the high end of normal (for females in both cases), but I'm more reserved and not very driven, though that could be explained more by my upbringing than anything else.

For science, the volume of my butt is so-so, do with that what you will. In any case I actually quite like it when folks share their thoughts on the internet. Always curious to know what other people's viewpoints are especially WRT stuff I've got some personal experience with.

Why is nobody in San Francisco pretty? Hormones make you pretty but dumb (pretty faces don't usually pay rent in SF). Why is nobody in Los Angeles smart? Hormones make you pretty but dumb. (Sincere apologies to all residents of SF & LA.)

Some other possibilities:

• Pretty people self-select towards interests and occupations that reward beauty. If you're pretty, you're more likely to be popular in high school, which interferes with the dedication necessary to become a great programmer.

• A big reason people are prettier in LA is they put significant effort into their appearance -- hair, makeup, orthodontics, weight loss, etc.

Then why didn't evolution give women big muscles? I think because if you are in the same strength range as men then you are much more plausibly murderable. It is hard for a male to say that he killed a female in self-defense in unarmed combat. No reason historically to conscript women into battle. Their weakness protects them. (Maybe someone else has a better explanation.)

Perhaps hunter/gatherer tribes had gender-based specialization of labor. If men are handling the hunting and tribe defense which requires the big muscles, there's less need for women to pay the big-muscle metabolic cost.

The U-Shaped Curve study you linked does not seem to support really any solid conclusion about a T-vs-IQ relationship (in this quote, S men = "successful educational level", NS men = "unsuccessful educational level"):

• In the total sample (S + NS men), the correlation between T to IQ was best described by a polynomial regression (3rd order), exhibiting an inverse U-shaped regression. 
• In S-men, the relationship between T and IQ was best described by a polynomial regression equation of the 3rd order; however, the relationship was not U-shaped, but rather a positive correlation (low T: low IQ and high T high IQ). 
• In NS-men, there was an inverse U-shaped correlation between T and IQ (low and very high T: low IQ and moderate T: high IQ)

So there are three totally different best regressions depending on which population you choose? Sounds fishy / likely to be noise to me.

And in the population that most represents readers of this blog (S men), the correlation was that more T = more IQ. 

I'm only reading the abstract here and can't see the actual plots or how many people were in each group. But idk, this doesn't seem very strong.

The other study you linked does say:

Interestingly, intellectual ability measured as IQ was negatively associated with salivary testosterone in both sexes. Similar results were found in our follow-up study showing significantly lower testosterone in gifted boys than controls (Ostatnikova et al. 2007).

which seems to support the idea. But it still doesn't really prove the causality - lots of things presumably influence intelligence, and I wouldn't be surprised if some of them influence T as well.

Alternative theory (which, to be clear, I dont actually believe, but offer for consideration)

• Many of the high iq people are too autistic to be successful
• but female hormones protects against the autism somehow, without impacting iq too much
• so the successful high iq people tend to be trans more often on average 

I would have guessed high T is associated with lower neuroticism, but studies found weak or no effects afaict.

I don't understand why you need to invoke testosterone. Transgender brain is special, for example, transgender women have immunity to visual illusions. Anecdotally, I have friends with gender identity problems who do not make gender transition because it's costly and they don't have it this hard, they are STEM-level smart and they are not susceptible to visual illusions. So, assuming that this phenomenon exists (I don't quite believe your twitter statistics), it's likely explainable by transwomen innate brain structure.

The other weirdness in your hypothesis is that puberty blockers is a quite recent therapy and it's not ubiquous - most intellectually accomplished transwomen are likely to have standard male puberty. Even low-T male have mindboggingly large amount of testosterone compared to female, which implies really weird dose-dependency between testosterone and IQ in puberty.

There are plenty of stupid and/or distracting behaviors testosterone can push you for without any kind of "chemical brain damage", not only sex. Testosterone is likely to make you seek social status and status-seeking is notoriously incompatible with intellectual pursuits. I don't know my testosterone levels, but I have plenty of concussions due to my tastes for physical activity and I consider myself pretty average, stereotypical male. I suspect that concussions is the first direct source of male brain deterioration and testosterone is related here because it induces risk-seeking. The second and third, I think, smoking and drinking, and non-surpisingly, it's another sort of typical risky teenage male activity.

Copied from a reply on lukehmiles' short form:

The hypothesis I would immediately come up with is that less traditionally masculine AMAB people are inclined towards less physical pursuits.

If it is related to IQ, however, this is less plausible, although perhaps some sort of selection effect is happening here.

Here's some related points, which might seem a little far out:

1: Weak people are more intelligent, as they have a higher need for intelligence. Edit: What you lack in power you must make up for with strategy. Anxiety leads to overthinking and confidence leads to direct approaches. 

2: "Chad" types of people are simple, honest, straightforward, shallow. They have little need for being indirect, little need to overthink, little need to strategize.

By the way, I expect there to be differences in spatial and verbal IQ here. While autism seems to correlate the most with spatial intelligence, I find that social behaviour (and skillful manipulation of it) correlate with verbal intelligence. Also that pattern recognition correlates with anxiety, and that working memory and processing speed seems important in social situations (witty people are fast, and people who are socially skillful seem to have great working memory).

Strong upvote, because even if you didn't get the exact factors something wrong here, coming up with counter-examples is difficult. I do think the trade-off principle is being understated here though:

If a set of genes make you less beautiful, how are these genes not elimited from the gene pool yet? If a condition like autism makes life so much harder for you, why do genes which result in that still exist? Whenever I find people who seems to have aspects of life against them, I also see factors which help make up for this deficit. As intelligent and looks aren't aspects which you can influence consciously, I don't think this mechanism is driven by conscious necessity. I think they're actually genetic tradeoffs.

Your hypothesis is ignoring environmental factors. I'd recommend reading over the following paper: https://journals.sagepub.com/doi/10.1177/2332858416673617

A few highlights:

Evidence from the nationally representative Early Childhood Longitudinal Study–Kindergarten Class of 1998-1999 (hereafter, ECLS-K:1999) indicated that U.S. boys and girls began kindergarten with similar math proficiency, but disparities in achievement and confidence developed by Grade 3 (Fryer & Levitt, 2010; Ganley & Lubienski, 2016; Husain & Millimet, 2009; Penner & Paret, 2008; Robinson & Lubienski, 2011). [...]

A recent analysis of ECLS-K:1999 data revealed that, in addition to being the largest predictor of later math achievement, early math achievement predicts changes in mathematics confidence and interest during elementary and middle grades (Ganley & Lubienski, 2016). Hence, math achievement in elementary school appears to influence girls’ emerging views of mathematics and their mathematical abilities. This is important because, as Eccles and Wang (2016) found, mathematics ability self-concept helps explain the gender gap in STEM career choices. Examining early gendered patterns in math can shed new light on differences in young girls’ and boys’ school experiences that may shape their later choices and outcomes. [...]

An ECLS-K:1999 study found that teachers rated the math skills of girls lower than those of similarly behaving and performing boys (Robinson-Cimpian et al., 2014b). These results indicated that teachers rated girls on par with similarly achieving boys only if they perceived those girls as working harder and behaving better than those boys. This pattern of differential teacher ratings did not occur in reading or with other underserved groups (e.g., Black and Hispanic students) in math. Therefore, this phenomenon appears to be unique to girls and math. In a follow-up instrumental-variable analysis, teachers’ differential ratings of boys and girls appeared to account for a substantial portion of the growth in gender gaps in math achievement during elementary school (Robinson-Cimpian et al., 2014b).

In a lot of ways the way you are looking at the topic perpetuates a rather unhealthy assumption of underlying biological differences in competency that avoids consideration of contributing environmental privileges and harms.

You can't just hand wave aside the inherent privilege of presenting male during early childhood education in evaluating later STEM performance. Rather than seeing the performance gap of trans women over women presenting that way from birth as a result of a hormonal advantage, it may be that what you are actually ending up measuring is the performance gap resulting from the disadvantage placed upon women due to early education experiences being treated differently from the many trans women who had been presenting as boys during those grades. i.e. Perhaps all women could have been doing quite a lot better in STEM fields if the world treated them the way it treated boys during Kindergarten through early grades and what we need socially isn't hormone prescriptions but serious adjustments to presumptions around gender and biologically driven competencies.