Monkey Cooperation and Fairness

A pair of capuchin monkeys (Cebus apella) show very compelling signs of cooperation and a sense of fairness, by working together to solve a problem using tools, and then sharing the reward.

They also show signs of understanding fairness: when unequal rewards are given to one monkey and not another, the monkey receiving the lesser treat would rather go hungry than accept anything less than an equal reward. How do the monkeys show equity and equality? How do the monkeys show that they feel they are underbenefited?