内集団ひいき行動の適応的基盤 : 進化シミュレーションを用いた検討

概要

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When people behave more cooperatively toward in-group members than to out-group members, we call it "in-group favoring behavior." However, previous studies have not yet provided a satisfactory explanation for why in-group favoritism can be adaptive. In the current study, we conducted a series of simulations to explain such behaviors from an evolutionary perspective. We used the giving game and constructed a society composed of two groups, A and B. In the game, every player was given a fixed amount of resources and decided how much and to whom he gave. The results showed that the in-group favoring strategy is adaptive only when it has a strict criterion for recipients (not giving any resources to players who had helped other players who did not adopt the in-group favoring strategy). Furthermore, they showed that there were other strategies which have a strict criterion for recipients that could be adaptive as well. These findings suggest that strategies which form a circle of exchange only among themselves by excluding other strategies can be adaptive.
2013-11-30