Watch What Happens When Two Monkeys Were Paid Unequally

In an experiment focused on measuring moral behavior in animals, two monkeys were each taught to place a rock into a scientist’s hand.

After each monkey completed this, they would then be rewarded with a snack: a cucumber and a grape.

When the monkey who received the cucumber realized the fellow on the other side of the fence was receiving more grapes than he was for doing the same task, he began exhibiting pure frustration.