I keep seeing this article held up as "proof" that biological sex is a spectrum. I'm not here to cast aspersions on Scientific American, which is an excellent pop science magazine & has been around since the 1840s. However, this article needs an answer: https://blogs.scientificamerican.com/voices/stop-using-phony-science-to-justify-transphobia/

First of all, we should look at the source. Even in peer reviewed, scientific journals, there is often an editorial or opinion column.

"Voices" in SA is a guest blog page. That doesn't mean it's crap. It just means that it's not based on anything reviewed by others.

Here's the opening paragraph:

The Intellectual dark web (if you click on the link) is actually a series of intellectuals that have broken with traditional viewpoints (either conservative or liberal) and debate about messy topics publicly. Usually on the internet.

This used to be called academia.

Another thing that bothers me is that the author, who I gather knows better, mixes "sex" and "gender" in the first paragraph.

Understanding that sex is biological and gender is psychological is KEY to having this discussion. I believe that misuse of the terms is deliberate.

So, moving on....

The next section "Biological Sex and how You Get It" is misleading IMO. First of all, IN ITALICS, it tells you that your biological sex isn't written in stone. I'm sorry to disappoint the author, but sex is, even if reproductive function can be lost.

The article claims that sex is more complicated than XX and XY. In the sense that genetics IS elegantly complicated, we can definitely make it SOUND more confusing than it is....

...However, essentially, human (and placental mammals) have one gene that determines if a person is male. One. It's either on or off. Hence the binary.

SRY is the gene in question. The author states that it isn't an off/on switch but a precisely timed start button.

That's just simply not true. Delayed activation of this gene results in underdeveloped testes. Not some third form of sexual anatomy.

The author also mentions two other genes with links: DMRT1 and FOXL2.

DMRT1 insufficiency creates something called "sex reversal" which sounds very trans, but it isn't. It's a developmental disorder A person is XY, the testes start developing, can't finish, so revert to female structure IN THE WOMB.

Formed testes are NOT turning into ovaries.

The same is true for FOXL2. These are genes that function in the womb. We can't create the protein products of these genes, give them to males, and watch their testes turn into ovaries because it doesn't happen.

Just as an aside, consider Mendelian genetics for a moment. Mendel was the one came up with the idea that not everything was a spectrum. People believed at that time that all traits were blended.

However, during his crosses, he never saw a yellow-green seed.

That's because those traits DON'T form a spectrum in this instance. A single gene accounted for the trait (like sex) and it was either one expression of that trait or the other (like sex).

Then the author states that nowhere is a sexual binary harder to support than in brain structure. To which I would reply... no, duh. The brain is not a sex organ, contrary to Vogue.

It's like saying there's no such thing as sexual binary when we talk about ear structure.

I do love this sentence: "As if the brain and body weren’t complicated enough, another biological factor influences the expression of biological sex in an individual: hormones."

Because hormones aren't part of the body. Nor is the brain. But that's just a writing issue, I think.

The author goes on to talk about the range of sex hormones in males & females. Here's an image for you:

Men always have more T than women, no matter how complicated we make it sound. There is a range: a range for men and one for women.

Science is clear and conclusive, as the author states. Sex is a binary. Add extra X's with a Y, you still get a male. Put 4 X's together, you still get a female. move the SRY gene to the X and you get a male.

Phenotype is what we base sex on, after all.