'Stop Using Phony Science to Justify Transphobia' is another Scientific American article using the complexities of sex determination and the diversity of sex differences to argue that sex is not binary.

Let's talk about it!

THREAD (citations numbered) https://blogs.scientificamerican.com/voices/stop-using-phony-science-to-justify-transphobia/

The author writes that three subjects help explain the transgender experience: "(1) genetics, (2) neurobiology and (3) endocrinology."

True so far. Compared to the population, certain trans individuals may have unique differences in these three systems, and some might not.

The biological experience of trans individuals, like everyone else, can be affected by:

(1) genetics
(2) neurobiology (the structure and connections of the brain)
(3) endocrinology (the influence of hormones on the body)

Here, the author begins with genetics.

PART ONE--Genetics

"Nearly everyone in middle school biology learned that if you’ve got XX chromosomes, you’re a female; if you’ve got XY, you’re a male."

The author claims this is a tired simplification. But even with the existence of X or XXY, is this a simplification?

First, using atypical karyotypes (like X or XXY) in arguments to support trans identities is disingenuous.

Why? Because trans individuals almost always have typical XX or XY karyotypes.

How do we know? Because we've done the karyotype tests.

In one study, conducted with over 300 trans individuals, 97.55% had typical karyotypes of XX or XY, matching their birth sex. Only 3 out of 368 had Klinefelter syndrome.[1]

Such studies show us that using chromosomal anomalies to explain trans experience is ignorant or dishonest

Second, 99.98% of births are unambiguously male or female.[2]

Even in cases of chromosomal anomalies like X or XXY, the fetus still develops a reproductive system organized to support ova (in X cases) or a system organized to support sperm (in XXY cases).

The reason why chromosomal anomalies still produce a female or male is thanks to the activation of the SRY gene (usually found on the short arm of the Y chromosome).

If the SRY gene is present and active, it initiates a complex set of gene cascades causing male development.[3]

Fetuses with only one X do not have the SRY gene, and thus develop as females. Fetuses with XXY DO have the SRY gene, and thus develop as males.

This genetic system is so consistent that even in cases of XXX or XXXY, the fetus still develops as a female or male, respectively.[4]

The author then brings up additional congenital medical conditions to argue against the sex binary: "XX individuals could present with male gonads. XY individuals can have ovaries," he writes.

Those unfamiliar with sex development might be confused. How does this happen?

Simple: the activation or inactivation SRY gene.

For XX individuals with testes, this occurs when the SRY gene moves onto an X chromosome, causing male development.

And for XY individuals with ovaries, this occurs when the SRY gene is not activated, causing female development.

Thus, despite the author's claims that sex does not arise from chromosomal makeup alone, sex is indeed largely determined by the activation or inactivation of the SRY gene.[5]

Variation of body types occurs downstream of SRY activation or inactivation.

Next, the author discusses how SRY activation initiates additional genes such as DMRT1 and FOXL2, which help and maintain testicular tissue.

This is true. If these genes are not present during fetal development, the testes may not develop, and you will develop as a female.

But again, you might ask, what do congenital conditions of the reproductive tract (DSDs) have to do with trans individuals, who almost always develop with typical chromosomes and typical reproductive systems?

Perhaps these DSDs are being used for ideological means?

PART TWO--Neurobiology.

Here, the author uses neuroscience in brain differences to argue that male and female cannot be clearly defined: "A half century of empirical research has repeatedly challenged the idea that brain biology is simply XY = male brain or XX = female brain."

It is true that there are indeed no black and white "male" and "female" brains.

But this variation in brain differences does not mean there is no clearly defined 'male' or 'female,' because we define sex through one of two evolved reproductive anatomies.[7]

However, there are average differences in the brain within and between males and females that when aggregated together allow us to predict someone's sex with up to 97% accuracy.[8]

This is specifically done through analyzing the overall morphology of the cerebral cortex.

It is true that trans individuals may have specific structures in the brain that are similar to that typically seen in the opposite sex. As the author mentions, some specific regions in gay men are similar to straight women.

But these similarities do not change one's sex.

The existence of subtle brain similarities to the opposite sex does not mean that such individuals ARE the opposite sex. It just means that one might have specific structures that are atypical.

This does not change your sex anymore than other atypical physical differences.

Using brain similarities and differences to argue that someone IS the opposite sex is akin to using sex differences in height to argue that a short male who falls in the typical female range IS a female.

Variation does not make someone 'less male' or 'less female'

PART THREE--Endocrinology

The author uses hormone levels to 'disprove' the sex binary: "But like all things biology, hormones cannot be limited to the pubescent idea of “estrogen = female and testosterone = male."

This is true, as males and females are both exposed to T and E.

These hormone levels, like differences in the brain, exist as bimodal distributions, an average for males and an average for females.[9]

But variance in hormones, even extreme variance, does not disprove the sex binary.

For example, a male who has less T than the average male does not become 'less male' or 'more female.' He is still a male, as his body is organized around small gametes.

Other variations in physiology and anatomy do not disprove the binary, but rather show the variation within.

Thus, you may notice a pattern in all three aspects: (1) genetics, (2) neurobiology, and (3) endocrinology.

In all three categories, variation does not mean sex itself is a spectrum, but rather, that sex-related traits are bimodal--an avg for males and an avg for females.

Sex differences within and between males and females exist as bimodal distributions. There is variation of hormone production, brain structure, and external appearance, but this does not make a 'sex spectrum.'

Rather, it makes a spectrum of anatomy and physiology.[10]

The reason why we can place traits such as hormone levels on bimodal distributions is BECAUSE of the sex binary.

Because there are two gametes of differing size, there are two sexes, with variation within males and variation within females.[11]

The author does not go wrong in presenting basic scientific facts about the variation of sex-related traits.

Where they go wrong is arguing that because variation of genes, brain structure, and hormones, that male and female cannot be reliably defined.

"The science is clear and conclusive: sex is not binary, transgender people are real," they write.

The problem is that sex on the reproductive level IS binary. There are only two reproductive functions, and thus, two sexes.

The existence of trans people does not disprove this model, and it does not invalidate them. Rather, trans individuals represent the variation in biology, identity, and expression found within the sex binary.

We don't have to deny the fundamental reality of sex to accept them.

The author tells us to stop using phony science to justify transphobia.

But I have a different request: when will activists and authors of major publications stop using complex medical conditions such as DSDs in arguments about unrelated identities?

And finally, when will activists stop using the beautiful complexity and diversity of biology to justify the dismantling of male and female under the guise of 'science'?

Sources:
[1] Inoubli, A., et al. (2011). Karyotyping: Is It Worthwhile in Transsexualism? The Journal of Sexual Medicine, 8(2).

[2] Sax, L. (2002). How common is lntersex? A response to Anne Fausto‐Sterling. Journal of Sex Research.

[3] Gilbert, SF. (2000). Chromosomal sex determination in mammals. Developmental Biology, 6th edition. Sunderland (MA), Sinauer Associates.

[4] Kimball, J. (2020). Sex chromosomes. http://LibreText.org .

[5] Kashimada, K., Koopman, P. (2010). Sry, the master switch in mammalian sex determination. Development, 137.

[6] Matson, C., et al. (2011). DMRT1 prevents female reprogramming in the postnatal mammalian testis. Nature.

[7] Lehtonen, J., Parker, G. (2014). Gamete competition, gamete limitation, and the evolution of two sexes. Molecular Human Reproduction, 20(12).

[8] Luo, Z., et al. (2019). Gender identification of human corticol 3-D morphology using hierarchical sparsity. Frontiers in Neuro.

[9] Ellis, L. (2011). Identifying and explaining apparent universal sex differences in cognition and behavior. Personality and Individual Differences, 51.

[10] Schmitt, D. (2016). Sex and gender are dials, not switches. Psychology Today.

[11] Lehtonen, J., Parker, G. (2014).

[12] Hayward, A., Gillooly, J. (2011). The cost of sex, Quantifying energetic investment in gamete production by males and females. PLoS ONE, 6(1).

[13] Marinov, GK. (2020). In humans, sex is binary and immutable. Academic Quest.

[14] Epelman, M., et al. (2005). Anisogamy, expenditure of reproductive effort, and the optimality of having two sexes. Operations Research, 53(3).

[15] D Sun, S. (2019). Stop using phony science to justify transphobia. Scientific American.

Thanks for reading! Constructive feedback is welcome, and if you have other research you'd like me to know about, let me know

'Why Sex Is Binary'

And if you're interested in learning more about why bimodal sex differences are the result of the sex binary, check out this thread: https://twitter.com/zaelefty/status/1279802563517276166?s=20

And finally, here's my response to the other Scientific American article, 'The New Science of Sex and Gender.' https://twitter.com/zaelefty/status/1280324312914894848?s=20

Haha thank you