Estudo de caso para alunos de microeconomia - jogo do ultimato (I): chipanzés são maximizadores racionais

Pesquisadores do Max Planck Institute for Evolutionary Anthropology, em Leipzig, desenharam uma versão do conhecido "jogo do ultimato" para ser jogada por chipanzés. Os resultados deste experimento foram reportados em The Economist - edição de 6 de outubro de 2007:
"The game started with a pair of trays far from the players' cages. Each tray had ten raisins divided in different ways between two pots— say eight and two, or five and five. One chimp was allotted the role of proposer. He could choose one of the trays, pulling it by way of a rope just halfway to the cage. The other, the responder, could then choose to pull on a rod, bringing the tray close enough for both to get the raisins, one pot for each. If the responder chose not to pull the tray closer within a minute, the offer was considered rejected, and the game concluded. The result is that chimps are simply rational maximisers. Though proposers consistently chose the highest possible number of raisins for themselves, responders rarely rejected even the stingiest offers. A number of researchers in the field of human evolution think that a sense of fairness— and a willingness to punish the unfair even at some cost to oneself— is humanity's 'killer app'. It is what allows large social groups to form. Previous experiments have shown that chimpanzees are willing to punish actual thieves. But this new experiment adds weight to the theory that the more sophisticated idea of fair shares, which underpins collaborative behaviour, appeared in the hominid line only after the ancestors of the two species split from one another".