It's a well-known fact that the monkeys have been plotting against us since the days of yore. But their terrible plans will get sped up quite horribly once they've mastered the skill of banking. That's right. Someone's been teaching the little hellions how to use money! "[O]ne can get some clues as to how evolution prepared us for money from the burgeoning research that seeks to present animals with economic choices. To gain perspective on human financial decisions, one may ask, what would monkeys do?Keith Chen and Marc Hauser at Yale University taught monkeys about resources that bear a strong resemblance to money. Monkeys don't care about money, per se, but they do care about marshmallows."
"A resource (marshmallows) exchange task was introduced whereby pressing a lever would give another monkey a marshmallow; hence this was a task that involved a bit of altruism. Not only were monkeys taught about the game. Two specific monkeys were conditioned (entrained), such that one always pulled the lever for his monkey partner (thus being a very generous partner) and the other never pulled the lever for his partner (stingy). Then they let these conditioned monkeys play the game with other monkeys. Monkeys that played with the highly generous monkey figured it out and quickly took advantage of him. Monkeys that played with the stingy monkey also figured it out quickly and subsequently shunned or were aggressive toward him [...]
"Other work suggests that monkeys do not have a fully developed sense of fairness. There are signs that they are acutely sensitive to getting less than their fair share, such as if they see another monkey getting more than they get. If you have two dogs and give one a biscuit treat, the other will look at you with a mixture of expectancy and indignation. Getting less than your fair share is called being underbenefited, and many animals seem to have that.
"But a fully developed sense of fairness means that you are uncomfortable with being overbenefited as well. That is, it bothers you to get more than your fair share. Here is where humans seem to part company with other creatures.
"What happens when monkeys overbenefit from an exchange - do they experience guilt, embarrassment, shame, or try to rectify the situation? Apparently not." [Psychology Today]
Greedy, hungry, and with no sense of fairness. Oh, they're cute all right.