1. Autoeroticism in female mammals, as well as heterosexual and homosexual intercourse (especially in primates), often involves direct or indirect stimulation of the clitoris [...].

2. We know that autoeroticism is widespread among mammals and that it turns up in birds and reptiles, too.

3. Sexual pleasure, including autoeroticism, is a source of physical, psychological, intellectual and spiritual well being.

4. Despite this bestiary of autoeroticism, scientists have spent relatively little time on the question of why animals might have evolved to masturbate.

5. Although it's sometimes said that only mammals masturbate, we have clear examples of autoeroticism among birds, which rub their cloacae on whatever's handy.