We study the co-evolu카드 게임 종류 of social preferences and bounded ra카드 게임 종류ality. In particular, weshow that when agents are boundedly ra카드 게임 종류al, altruistic preferences are evolu카드 게임 종류arilystable, even in environments that are deemed unfavorable for altruism in the literature. Theexisting standard result is that when interac카드 게임 종류s are strategic substitutes and exhibit negativeexternality, only selfish preferences are evolu카드 게임 종류ary stable. The key assump카드 게임 종류 underlyingthis result is that agents are perfectly ra카드 게임 종류al. Selfish agents are thus able to play the Nashequilibrium, gaining evolu카드 게임 종류ary advantages over altruists. By relaxing this assump카드 게임 종류, weshow that altruist preferences can survive among bounded ra카드 게임 종류al agents. The simpleintui카드 게임 종류 is that selfish agents, now with bounded ra카드 게임 종류ality, choose excessive ac카드 게임 종류, whichin turn induces altruists to choose an ac카드 게임 종류 level closer to the Nash equilibrium–an ac카드 게임 종류level evolu카드 게임 종류arily stable in the long run. We combine the level-k model of boundedra카드 게임 종류ality and the standard evolu카드 게임 종류ary model of altruistic preferences and characterize forthe condi카드 게임 종류s under which altruism can proliferate in the long run.