Gift Giving and the Evolution of Cooperation
用演化模型分析礼物赠送如何促进信任与合作，预测适合作为礼物的商品特征（如低使用价值），并指出虽然礼物本身无用，但这一制度并非如此。
Gift giving is a practice common to many societies. In an evolutionary model the social custom of giving gifts at the beginning of a relationship can lead to trust and cooperation. The evolutionary approach makes predictions about the character of the goods that can be used as gifts. For example, gift goods may have little use value even at low levels of consumption. Although the gifts themselves are useless, the institution is not.