Like children who complain "no fair," capuchin monkeys throw fits when their companions get better treats.
In a new study, envy reared its ugly head if capuchins, primates like us, landed slices of cucumber while their cage mates received tasty grapes—considered more desirable.
The recognition of an unfair situation could be critical for maintaining relationships in cooperative societies such as those of capuchins, as well as among humans, the researchers said. The study also suggests the roots of human fairness stretch well back in evolutionary time.
"In a cooperative species, being able to distinguish when one is being treated inequitably is very useful for determining whether or not to continue cooperating with a partner," said psychologist Sarah Brosnan at Georgia State University.
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