Reminder also that the supposed universality of biological s x across the animal kingdom is kind of an artifact of science education tries to describe things in "relatable" language https://twitter.com/holymoley/status/1308415811950870530

When we talk of snails having "both male and female parts", we're projecting our (human-derived) labels onto them in an effort to make them more comprehensible to non-biologists

If humans reproduced like pulmonate snails, would we use "male parts" and "female parts" to describe their genitals? Almost certainly not. We'd probably describe them with much the same sort of terminology we use for other body parts like ears, lungs, and intestines.

As a child I used to think that biological sex boiled down to XX and XY: one sex has two big chromosomes, the other has one big and one small. Then I learned that in birds it's the opposite: males have the equivalent of an XX karyotype, and females have the equivalent of XY[1].

[1] It's not the exact same as the mammalian system of chromosomes, which is why we call the chromosomes Z and W instead of X and Y. The effects that they have on sexual differentiation in birds are also slightly different.

That, and learning about honeybees' absolutely buckwild system of sex chromosomes, confused me for a while, until I found a biologist[2] and asked them "wait so we're just calling animals 'female' if they produce the bigger gametes, right?"

[2] Relatively easy to do when you're growing up in a college town

The biologist conformed that yeah, that's really all there is to it, we just decided that was how we were gonna define "female" across the animal kingdom.

The "female" is whoever makes the egg, whether that's a hard egg like a chicken, a soft egg like a frog, or an internal egg like a human.

What's interesting is at that age, I could have just as easily imagined it going the other way, where the birds with two big chromosomes would be called "female" and the ones with one big and one small would be called "male"

And then it would simply be the case that in birds, the males lay the eggs, while the females grow bright feathers, build dance for the males, and climb on top of them during mating

Now as long as we're just thinking about birds and mammals, there's nothing particularly factually inaccurate about this system. It's merely applying different labels to the same underlying phenomena.

Kind of like how when Ben Franklin was experimenting with electricity, he chose to call a glass rod rubbed with silk "positively" charged, and a piece of amber rubbed with fur "negatively charged". He could have totally chosen to name them the other way around.

But he did what he did and that's why we have the totally arbitrary convention that electrons are negative and protons are positive, which makes introductory physics kind of a pain because you need to use a lot of minus signs to simulate an electric current passing through a wire

Which in turn is why the convention is to kind of cheat a little and pretend that you have positive particles going backwards through the circuit, instead of negative particles going forward - for a lot of basic stuff the results are the same!

This is also why in chemistry you say that a chemical "gets reduced" when you ADD electrons to it. The CHARGE gets reduced because you're adding negatively charged particles to it.

All this is part of a larger point that the scientific names we use for things were often often dreamed up by people who at the time barely understood the things they were naming ~because that's how science works~

You gotta name the things that nobody understands yet, so you can start writing observations of them or doing experiments

Like nowadays we take for granted that "genes", "chromosomes", and "DNA" refer to roughly the same things but if you dig into the history of their names you find very different discovery stories, and as a matter of fact it was a BIG DEAL in biology when people connected the three

And then there's the story of how we ended up naming human genes things like "sonic hedgehog" which is one of the funnier examples of science terminology stories I can think of

I think this is the kind of stuff that I was trying to get at when I said I wanted to connect it back to biology in this thread? I don't know. https://twitter.com/DiscoDeerDiary/status/1306684704352088066?s=19

I'm not getting paid enough (in clout) to bother tying my threads up into neat essays