PhilosophyMemes

So the fundamental definition is that sex is defined as the type of gametes that one's body is organized around producing. Everything flows from there.

If someone is born without the ability to produce gametes they still fall into the binary, because their body is still organized around the production of one of exactly two options, sperm or ova. Their body still has structures for producing those gametes, and if not for a developmental issue, would produce those gametes. There is nobody whose body just doesn't have the concept of gamete production. Nobody is healthy and mature and simply lacks any structures related to gamete production.

Going backwards from there, chromosomes are merely how sex is determined in humans. It has a strong correlation with sex, which is why people often use it as a shorthand, but it's technically incorrect to define sex that way. The reason it's how sex is determined is because humans are very different than other animals such as chickens, with ZW chromosomes, or alligators that have sex determined by the temperature as they incubate. The animal kingdom varies drastically in how sex is determined, and it would be impossible to find any universal way of talking about sex if you tried to define it through that lens, to speak nothing of plants.

So how do we know which animals and plants are male or female? Through the type of gametes they produce! That definition is universal across all anisogamous species, and provides an explanatory framework for higher level abstractions like behavior. We can talk about how female hyenas have a pseudopenis. How do we know they're female? Because they produce the larger of two gamete types. Male seahorses can get pregnant. How do we know they're male then? Because they produce the smaller of two gamete types. Sex has also evolved several times independently in very different ways, and was clearly highly selected for. We can't talk about why that is by obscuring sex and talking about anything other than gametes.

Going back to the OP, ovaries can be used as shorthand for gametes, because it's correct 99.999+% of the time in humans. It's not moving the goalposts to talk about sex through gonads, it's just a slightly-technically-incorrect way. It's really the case of ovotestes that needs particular consideration, and when gamete production matters more than gonads. Ovotestes doesn't disprove the sex binary either, because it's not "perfectly healthy mature ovaries and testes" as you might think, it's "maybe a somewhat function gonad, with bits of non-functional streak tissue of the other gonad". Much like above, nobody's body is organized around the production of both gametes. It's not impossible that it could happen someday, through science or evolution. Other species are hermaphroditic and produce both gametes, but not humans. Even if you found somebody technically capable of producing both gametes due to some rare ovotestes situation, they're still missing the rest of the body organization for the second gamete (and probably the first), unlike those hermaphroditic species that are organized around the production of both gametes. In other words, if you graft an ovary into a man, that doesn't make him a hermaphrodite, it just makes him a man with an ovary grafted onto him.

Now as far as the binary goes, the simplest way I can explain it is that the type is binary, even though each type has variation in it. If you have a vending machine that dispenses either juice or crackers, there's a binary option of juice or crackers, even though the juice and crackers aren't each perfectly the same as each other in their category. There's exactly 0 overlap, just like there's exactly 0 overlap in sperm and ova. This is backed up by the links you posted as well (in order of which you linked them):

• The bottom line is that while animal gametes can be described as binary (of two distinct kinds) [..]

• In your piece 'Sex Redefined' are you making the claim there are more than 2 sexes?

  No, not at all. Two sexes, with a continuum of variation in anatomy/physiology.

  • https://xcancel.com/ClaireAinsworth/status/888365994577735680

• Both arguments demonstrate that from the fact of two types of gametes [..]

• Some people who advance a binary view of sex have embraced a concept called anisogamy, which defines sex according to gametes—reproductive cells such as sperm and eggs. Anisogamy says that an organism is male if it produces small, mobile gametes and female if it has large, immobile gametes.

• In the Wikipedia articles for Anisogamy and others, you'll see text like "Anisogamy is a form of sexual reproduction that involves the union or fusion of two gametes that differ in size and/or form". This is a binary, because there are two options.

Nobody is disputing the binary nature of gametes in anisogamous species, not even people wanting to redefine sex. They're just pushing for a definition of sex that isn't gamete-based. The reason you see biology as a field pushing back is because then you lose a useful description of reality. Biologists would quickly invent a new term that described what sex does now.