Maestripieri argues that bullying helps dominant animals to intimidate their subordinates, and that this has clear evolutionary benefits. It ensures that the dominant individuals have better access to food and to the opposite sex.
“The more a female is bullied by a particular male, the more that male gets to mate her. Sad but true,” says Wrangham. “And we know it leads to him having more babies with her.”
In line with this, a 2014 genetic study looked at the parents of all chimps born between 1995 and 2003, and revealed a direct link. Dominant and aggressive chimps fathered more offspring than their milder counterparts. It seems it makes sense for dominant members to spend so much time maintaining their status.
Even in captivity, where food is plentiful, bullying is still frequent in both rhesus macaques and chimps. “That means they [monkeys and apes] can invest more time and energy into maintaining their status,” says Maestripieri. He says that is simply how they are wired.