If men in our evolutionary past did not invest in offspring, they would not have evolved strict mate preferences and thus women would be as drab as p… - 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.

Seen through a Darwinian lens, men’s stronger interest in a partner’s looks is initially quite mysterious. In most species, it’s the females that care more about looks. Among peacocks, for instance, peahens will only mate with the males with the sexiest tails; males, in contrast, are less shallow and will mate with any female who’ll have them. If peacocks had pornography, it would be the females, not the males, that would spend their time staring at images of the other sex, and the males that would complain about being treated as sex objects. And what’s true of peacocks is true as well of most animals. In our species, however, it’s the other way around. Why?

If we decide – and this is our decision; it’s not imposed on us from above – if we decide that reducing the amount of suffering in the world is a good ethical principle to live by, then it becomes entirely unjustified and arbitrary to extend this principle to human beings but not also to extend it to other animals capable of suffering. Why should the suffering of nonhumans be less important than that of humans? Surely a universe with less suffering is better than one with more, regardless of whether the locus of suffering is a human being or not, a rational being or not, a member of the moral community or not. Suffering is suffering, and these other variables are morally irrelevant.