Don’t mess with a monkey. Because if you do, they might take revenge on your family and friends. That’s according to a study on Japanese macaques, which shows that monkeys keep track of each other’s associates and make use of that intel when it comes time for payback. The findings are in the Royal Society journal Open Science.
Researchers were interested in the question of how primates suss out social relationships, knowledge that can come in handy for maneuvering within a complex society. To assess how the macaques obtain and make use of such social know how, the researchers decided to focus on episodes of aggression a common feature of simian interactions.
They went through more than 500 hours of video recordings showing the exchanges that took place in a group of 57 macaques living in the Rome Zoo monkeys whose genealogical relationships are well known. And they parsed some 15,000 episodes of aggression, noting the relationships among the individuals involved.
First, the researchers confirmed that monkeys who found themselves being attacked tended to take their anger out on third parties. Such retaliation is usually directed against the relatives of the original attacker.
But how do the monkeys determine who’s kin? Well, one way would be that they’ve been around long enough to have watched each other grow up. But that doesn’t seem to be the case. When researchers looked specifically at conflicts involving older monkeys, it didn’t seem that relatives were singled out for revenge.
What does seem to be true is that victims will target their attacker’s associates—the other monkeys he hangs around with. If they’re not his relatives, they’re probably his cronies. So, close enough.
Interestingly, there’s a benefit to hitting family members when you’re meting out justice. Macaques that sought out the kin of the monkeys they wanted to settle a score with were less likely to be picked on again in the future. Whereas wailing on the friends appeared to offer only present satisfaction, but no such future protection.
Which suggests if you’re gonna beat on someone for payback, it should at least be a monkey’s uncle.
