Both chimpanzees and six-year-old children want to see just punishment meted out, even at a cost to themselves, reports a paper published online this week in Nature Human Behaviour. These findings bring new insight into the evolution of peer-punishment as a way to enforce social norms and ensure cooperation.
Previous research has shown that both humans and some animal species experience empathetic distress and concern when seeing others harmed. However, human adults have also been shown to experience feelings of pleasure when the harm is perceived as a deserved punishment for antisocial actions.
Natacha Mendes, Nikolaus Steinbeis and colleagues devised a novel experiment to test when human children develop a motivation to see punishment happen, and also whether the same motivation exists in our closest living relatives, chimpanzees. The participants were introduced to a character who shared food or a toy with them (prosocial) and one who withheld these (antisocial). The characters then received physical punishment out of the view of the participants, who could choose to pay a cost (for children, valuable stickers; for chimps, physical effort) to witness the punishment. The authors found that chimpanzees and six-year-olds, but not four- or five-year-old children, were more motivated to see antisocial others punished than prosocial others.
The findings support evidence that the sixth year is an important time in human emotional and cognitive development, when children become willing to sacrifice resources in the interests of fairness. That this personal motivation to see fair punishment enacted is shared by chimpanzees may suggest deep evolutionary roots as a strategy to maintain fair cooperation.