The ultimatum game as monkey business

Well, chimp business, more specifically. There’s some hootenanny afoot now that German researchers found that chimps play the “ultimatum game” more rationally than people. That is, when one chimps is given a reward which it can share with another chimp. Chimps tend to offer small rewards to the other chimp, which then readily accepted. People playing this game tend to offer closer-to-even rewards to the second player who tends to reject the entire offer when it is deemed unfair.

Now, this is economically “irrational” because even an unfair reward is a positive gain compared to nothing at all. This is true in a one-off situation. Without making any assumptions about whether the chimps’ game was iterated, it seems that the human strategy is more rational when the game is repeated. So it makes sense that human and “irrational” fairness is just a rational response to iteration.