Sarah Brosnan, a researcher at the Yerkes National Primate Research Center of Emory University in Atlanta, recently discovered that capuchin monkeys have a strong sense of fairness. From Capuchins Don’t Settle for Any Monkey Business:
She and her colleague Frans de Waal uncovered the sense of fair play in a study of the small brown primates from central and South America while giving pairs of monkeys who knew each other well jobs to perform.They received food in exchange for doing a certain task. But each partner did not always get the same quantity or quality of food for equal amounts of effort.
‘We showed the subjects compared their rewards with those of their partners and refused to accept a lower-value reward if their partners received a high-value reward,’ said Brosnan.
If both members of the pair did not get the same reward, the monkey that was short-changed refused to accept it or threw it away, in a reaction similar to that of humans.
‘That active response toward reward is really unusual. They were clearly not pleased with the way things were going,’ Brosnan added.
Naturally, this points to our own sense of fairness having evolved:
She believes the findings, which are reported in the science journal Nature, settle the question of whether a sense of fairness is something that is taught or an evolved behavior.“Finding this in capuchin monkeys does indicate that a sense of fairness has evolved. Clearly it is an extremely beneficial behavior,” Brosnan added.