There sure would be a lot less genders if good old natural selection was still in play.

:D

Oh, it still exists? Ever heard of one of them getting laid?

So many people this could apply to ! Love it.

Natural selection is sort of like a force of nature, and can't be stopped.
What is cutting down genders is cultural evolution.
During the darker ages, sexual mutations were considered demonical, and most offspring were killed. Later it became a christian thing to decide a sex for the mutant and then medically remove the rest, which is pretty much how Things are now. Since natural selection let's cultural selection override it most countries remain physically two-sexed, but natural evolution IS working around that on the inside.