For the lurkers, here is some sense from Dawkins.
https://richarddawkins.substack.com/p/is-the-male-female-divide-a-social
"I shall advocate instead what I shall call the Universal Biological Definition (UBD), based on gamete size. Biologists use the UBD as the only definition that applies all the way across the animal and plant kingdoms, and all the way through evolutionary history.
Gametes come in two radically different sizes: the phenomenon of anisogamy. Female gametes are very much larger than male gametes, with no intermediates whatsoever, and that is how biologists define female and male. A human egg contains at least 10,000 times as much matter as a human sperm. The UBD is universal in the sense that it applies to all animals, vertebrate and invertebrate. All plants, too, unless you count algae as plants. Admittedly, not all individuals produce gametes at all, or throughout their life. Worker bees are sterile females. We call them female because they have the potential to produce macrogametes. Every worker would have turned out as a queen if she had been fed differently as a larva. That’s “potential”. A human male baby or foetus has the potential to produce microgametes, for all that he doesn’t produce any yet. An old woman remains female, though she has ceased to produce ova.
The UBD has the virtue that, in addition to being universally applicable, it explains a diverse load of facts. And it’s grounded in a body of powerful and widely illuminating theory. It’s an argument that should appeal to economists. When two gametes unite to make a zygote they must, between them, provide the expensive nourishment it needs. In a fair and equitable world, you might expect the two parents to contribute equally, each bearing half the necessary costs. Such a system is known as isogamy. It doesn’t exist in animals and plants, but can be found in some microorganisms and algae. Clever mathematical modelling, by various scientists including Geoffrey Parker7 of the University of Liverpool, indicates that, under plausible conditions, isogamy is unstable. It tends to be replaced, in evolutionary time, by its opposite, anisogamy: two different kinds of gamete, one bearing all the economic costs, the other nothing more than DNA."