From a comparative perspective, we are a relatively monomorphic mammal, with relatively monomorphic minds. - Steve Stewart-Williams

People who object to the by-product hypothesis [for female orgasm] are doing something strange: They're saying that it's hugely important to them that female orgasm turns out to be an adaptation, like vomiting, cobra venom, and the scorpion's stinger, rather than a "mere" cultural invention, like science, medicine, and the Universal Declaration of Human Rights.

The claim that women have a stronger average parental urge than men is sometimes viewed as a sexist generalization. But it’s only sexist if we take a dim view of the trait in question: the parental urge. One could turn the accusation on its head: Those who view the evolutionist’s claim (that women are more parental than men) as sexist are actually being sexist themselves, because they’re taking a negative view of a trait that’s usually found more strongly in females than males. They are therefore prizing prototypically masculine traits more highly than prototypically feminine ones.

Certainly, the human-animal distinction is still workable; after all, we rarely make errors in assigning entities to one category or the other. But after Darwin, the distinction suddenly seems arbitrary – as arbitrary as the equally workable distinction between, say, turtles and non-turtles.