Biologically, the default body-plan, including humans, is “female,” without which there could be neither males nor females (I consider “selfers,” aka xerox-ers, as inherently female). And yet, sex obtains, a lot, to the point of hermaphroditism. Why even have males? Why halve reproductive success with a male partner? Halve-sies? You better have a good mother flipping reason to go “halve-sies,” because “half” is a large cut in pay. Selfers take the entire reproductive pot. “Why is there sex?” is a difficult question almost like “why is there air?” To pump up volley balls! Except “to pump up volley balls” is an evasive, smart-ass response. The problem of sex is deadly serious, perhaps not unrelated to our problems of empire.
Some say that sex evolved in order to stay one step ahead of the parasites; change the locks on the immune system every generation, and therein lays the value of going halve-sies. That sounds “just so,” but whatever the explanation, the sexes began specializing. We are all steeped and infused in piping hot myth.