Social females rarely live in groups with their adult sons, presumably, according to evolutionary theory, to avoid inbreeding. If a son does stay with his natal group when he reaches maturity, he might mate with his mother, as has been seen rarely for chimpanzees (Goodall, 1986). For example, in a small family of gibbons in Thailand (Hylobates lar), the adult male disappeared leaving his presumed son, almost an adult at eight years of age, with his mother and an empty territory (Brockelman et al., 1998). The son duetted with his mother and could have set up a new life with her, but instead chose to leave both her and their domain.

When mothers and adult sons do live in the same group, however, and if she is high-ranking in a species with a dominance hierarchy, she can be of great help to her son. It is to her advantage to help increase the chances that he will become a breeding male who can pass along their DNA to the next generation. Here we will consider the behaviors of bonobos, chimpanzees, woolly spider monkeys, coyotes, leopards, and lastly, the pros and cons of researchers providing food such as bananas and sugar cane to “their” animals. This activity has both positive (it speeds up individual identification and habituation of the animals) and negative (it interferes with the natural lives of the animals and fosters unnatural behavior to an unknown extent) results.