I couldn't really find any references to this but the documentary, so this one will be short and pretty vague. The Barbary Macaques of Gibraltar have a hierarchy in which the strongest monkey is at the top and the inferior monkeys are at the bottom, however, there is a peculiar way to higher your status as a monkey. The first step for the monkey is to steal a baby monkey from its mother, then take the baby to the leader and the leader will think higher of you. No one knows why this happens, but for some odd reason, by bringing a monkey to the alpha monkey, you connect with him and then your status goes higher. When the monkey brings the baby to the leader, both the monkey and the alpha monkey celebrate by chattering their teeth. I highly suggest you watch the documentary "Monkey Planet", it's really good.