Monkey Cooperation and Fairness

What would happen when you pay too monkeys unequally?
Two Monkeys Were Paid Unequally: Excerpt from Frans de Waal’s TED Talk
Frans de Waal explored this in an experiment demonstrating that the concept of fairness exists within monkeys. The video below is a funny look at what can happen when you reward a couple of workers differently. Check out the video at the 1:50 mark for a good laugh and a great clip to share.
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?