Why Is Sex Fun?: The Evolution of Human Sexuality (Science Masters)

Why are humans one of the few species to have sex in private? Why do humans have sex any day of the day of the year -- including when the female is pregnant, beyond her reproductive years or between her fertility cycles? Why are human females the only mammals to go through menopause? Why is the human penis so unnecessarily large? Why do we differ so radically in these and other important aspects of our sexuality from our closest animals and ancestors?