Bro, we all have biological urges, but we can learn to deal with these too. Men and women alike. I think this is less about sexual liberalization, but more about general degeneration of group morals (of which monogamy doesn't necessarily have to be one)they do not have opinions on this, they have biological urges. Which is exactly why we should be considering their status in a society. That basically seems to be the point of the book as well