The aquatic ape?

Frans de Waal answers the questions of Freakonomics readers:

[T]ogether with Sarah Brosnan, we did a study in which capuchin monkeys received either a grape or a piece of cucumber for a simple task.

If both monkeys got the same reward, there never was a problem. Grapes are by far preferred (as real primates, like us, they go for sugar content), but even if both received cucumber, they’d perform the task many times in a row.

However, if they received different rewards, the one who got the short end of the stick would begin to waver in its responses, and very soon start a rebellion by either refusing to perform the task or refusing to eat the cucumber.

This is an “irrational” response in the sense that if profit-maximizing is what life (and economics) is about, one should always take what one can get. Monkeys will always accept and eat a piece of cucumber whenever we give it to them, but apparently not when their partner is getting a better deal. In humans, this reaction is known as “inequity aversion.”

I actually don’t think the response is irrational at all, but related to the fact that in a cooperative system, one needs to watch what kind of investment one makes and what one gets in return. If your partners always ends up getting a greater share, this means that you’re being taken advantage of. So, the rational thing to do is withhold cooperation until the reward division improves.

(Hmmm, I cannot resist observing that it would be quite interesting to see what would happen in my department if I started withholding cooperation until the reward division improves?!? It seems woefully impractical as well as temperamentally implausible, but it is a fine notion!)