Some months later, I had the chance to ask Margaret Mead if she knew of any societies in which human mothers do the same as do chimpanzee mothers in keeping their babies clean. Her answer was no. Among the people of Bali, in Indonesia, however, small dogs lick the babies clean. When a Balinese mother carries her baby on her thigh in a cloth hammock slung from her shoulders, she is accompanied by her pet dog. The dog's assigned duty is to provide diaper service by licking clean the baby, and the mother, whenever the baby soils. Subsequently I have learned that Eskimo mothers once had a custom of licking their babies clean.

Even though human primates have graduated from using the mother's snout end to keep the baby's tail end clean, it is safe to assume that, as a species, we still possess in the brain the same phyletic circuitry for infant hygiene as do the subhuman primates. Just as males and females have nipples, so also do both sexes have these brain pathways that relate to drinking urine and eating feces. These are the pathways that, when they become associated with neighboring erotic/sexual pathways, produce urophilia and coprophilia as paraphilias.