Learned about this interesting experiment that scoffs at the idea of rational beings. I especially enjoyed the part about results in particular tribes.
Imagine that someone offers you and some other anonymous person $100 to share. The rules are strict and known to both players. The two of you are in separate rooms and cannot exchange information. A coin toss decides which of you will propose how to share the money. If you are the proposer you can make a single offer of how to split the sum, and the other person—the responder—can say yes or no. If the responder’s answer is yes, the deal goes ahead. If the answer is no, neither of you gets anything. In both cases, the game is over and will not be repeated. What will you do?
Instinctively, many people feel they should offer 50 percent, because such a division is “fair” and therefore likely to be accepted. More daring people, however, think they might get away with offering somewhat less than half of the sum.
You may not be surprised to learn that two-thirds of the offers are between 40 and 50 percent. Only four in 100 people offer less than 20 percent. Proposing such a small amount is risky, because it might be rejected. More than half of all responders reject offers that are less than 20 percent. But why should anyone reject an offer as “too small”? The responder has just two choices: take what is offered or receive nothing. The only rational option for a selfish individual is to accept any offer. A selfish proposer who is sure that the responder is also selfish will therefore make the smallest possible offer and keep the rest. This game-theory analysis, which assumes that people are selfish and rational, tells you that the proposer should offer the smallest possible share and the responder should accept it. But this is not how most people play the game.