This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science.
Two years ago, Sarah Brosnan and Frans de Waal at the Yerkes National Primate Research Center found that brown capuchin monkeys also react badly to receiving raw deals. Forget bananas - capuchins love the taste of grapes and far prefer them over cucumber. If monkeys were rewarded for completing a task with cucumber while their peers were given succulent grapes, they were more likely to shun both task and reward.
That suggested that the human ability to compare own efforts and rewards with those of our peers evolved much earlier in our history than we previously thought. Of course, animal behaviour researchers always need to be careful that they're not reading too much into the actions of the animals they study.
It's easy to suggest that the monkeys were motivated by envy, fuelled by directly weighing ...
