Batshit biologists

[DdraigGoch]

Apparently researchers should not use the terms "male" and "female" in case it leads people to believe that sex is binary. Instead "sperm-producing" and "egg-producing" should be used, or "XY/XX individual".

I've rolled my eyes so far that they're stuck looking at the back of my head.

www.telegraph.co.uk/news/2023/02/14/words-male-female-should-banned-science-enforce-idea-sex-binary/

Almost everyone who has XX chromosomes is female and almost everyone who has XY chromosomes is male, but 'male' and 'female' are not defined by the sex chromosomes XX and XY. Some people have rare chromosomal development disorders and can end up with X, XXY, XYY or other complexities. These people are not new sexes, they are all either male or female.

Male bodies are those that are structured towards the production of sperms. Female bodies are those structured towards the production of ova. I say 'structured towards' because such a body might not actually manage to create the relevant gamete, but infertile people are not considered sexless.

The Galapagos giant turtle was once endangered and scientists took some eggs and hatched them under tightly controlled conditions with a view to releasing them into the wild. All of the baby turtles turned out to be female. It turns out the turtles' sex is not determined by chromosomes, but by the temperature at which the eggs hatch. The concept of sex is distinct from chromosomes.

Chromosomal anomalies in humans do not imply extra sexes. There are just two types of gamete: sperms and ova (eggs) so there just two sexes. No human has ever had structures for production of both sperms and ova.

The X chromosome contains all the information needed to construct a human being, either male or female. The genes for constructing a male are switched off by default. The Y chromosome is a tiny runt of a thing that contains very few genes, but the most important one is the SRY master gene. If the chromosomes are XX the process normally proceeds to the production of a female body. This is called the Mullerian process. If the chromosome are XY the SRY gene switches off the genes responsible for the production of specifically female body parts and switches on the production of specifically male body parts. This new pathway is called the Wolfian pathway.

What can go wrong? If the SRY gene on the Y chromosome is defective the switch to the Wolfian pathway does not take place and some ends up female but with XY chromosomes. If the chromosomes are X only (Turner syndrome) obviously there is no switch and the body is female. If the chromosomes are XXY (Klinefelter syndrome) the SRY is still present and the presence of an extra X doesn't prevent the switch to Wolfian, so the body ends up male. Similarly XYY. Very rarely the SRY gene can end up on an X chromosome instead of a Y chromosome and the Wolfian process is followed to a male body in an XX person.

Sometimes the Wolfian process is followed and the relevant male-producing hormones are produced but the androgen receptors are not working so the conversion to male never happens. That's another case of a female body with XY chromosome.

Lots of possibilities, but only ever two sexes and everyone is one or the other.

Yep. You deserve a mic 🎤 drop for that.

What are all those other chrosomes for if all the information required to make a human is on the X chromosome?

My guess is so that you don't make exactly the same human each time, but I may be wrong.

Isn't that the current mystery of genetics ? Plus number of chromosomes has no relation to the resultant complexity.

There was a fascinating Monkey Cage a while back about "unknown unknowns" and the panel geneticist submitted the real mystery is how chromosomes lead to organisms. With the suspicion that DNA is a sideshow. to the main event.

No, I think the poster worded it badly. We have 22 pair of autosomes which carry a huge amount of information and we would miss every one of these autosomes. We can't make a human just with an X chromosome.
The surprising finding of the human genome project was that we have fewer genes than predicted, but that can be explained.

No human has ever had structures for production of both sperms and ova

I am not sure that is completely correct. There have been reports of people with ovotesticular syndrome producing both gametes, (though, as it's such a phenomenally rare condition and can have more than one karotype, increasing the potential for confusion, I am not sure how accurate these are). I guess this is logically possible, especially for a 46,XX/46,XY chimera.

I totally agree with all your other points, and am not trying to contradict them - am just anticipating a gotcha from some TRA.

It isn't.

You can make a human with the full set of autosomes plus 1 X chromosome, so it's 'all the information to complete making a human once you've got all the non-sex ones sorted' (that is, you don't require anything from the Y; whereas you can't make a human with a full set of autosomes and just 1 Y without an X).

I misspoke. There's enough there to trigger everything needed for creation of a male or female body.