They know when it’s unfair and they won’t stand for it. In a groundbreaking new study, bonobos one of our closest primate relatives refused to participate in tasks when they were given worse rewards than their partners. Unlike chimpanzees, their reaction wasn’t just disappointment in the human handing out the treats. Even when a machine gave out the unequal rewards, they still protested.

Researchers from the Max Planck Institute for Evolutionary Anthropology and Utrecht University tested the bonobos in two experiments. In both cases, the bonobos clearly recognized inequality and often withheld cooperation when faced with unfairness. This behavior is known as inequity aversion a trait long debated in animals and seen as crucial to the development of cooperation and fairness in human societies.

But here’s where it gets even more interesting: when the bonobo getting the better deal was a close social partner someone they had groomed more often the reaction to unfairness was significantly reduced. Just like humans, strong social bonds softened their sense of injustice.

This study adds compelling evidence that the roots of our own sense of fairness may stretch deep into our evolutionary past.

Bonobos don’t just expect fairness. They demand it.

#fairness #evolution #sciencenews