摘要：美国研究人员指出，慷慨可能不只是社会压力的结果，还有可能是人类的天性。
加利福尼亚大学圣巴巴拉进化心理学研究中心马克斯·克拉斯诺博士表示，生物学家认为慷慨之举（在未来可能没有回报的情况下，花费财力物力让他人受益）不利于适者生存的环境，而经济学家认为这样的举动不理性。
克拉斯诺指出，如果传统理论没错的话，不管是进化还是利己主义早就该让这样的行为从世界上消失。他说：“在过去的研究中，研究人员仔细衡量人们的选择，他们发现不管在全球哪个地方，人们的表现都比经济学理论和生物学理论预期的要慷慨得多。即使他们认为和对方的互动可能是一次性的，他们也往往表现得十分慷慨。”
这项研究刊登在美国《国家科学院院刊》（PNAS）上。研究表明，慷慨是从合作进化中自然滋生的。
生物探索推荐英文论文摘要：
Evolution of direct reciprocity under uncertainty can explain human generosity in one-shot encounters
Abstract
Are humans too generous? The discovery that subjects choose to incur costs to allocate benefits to others in anonymous, one-shot economic games has posed an unsolved challenge to models of economic and evolutionary rationality. Using agent-based simulations, we show that such generosity is the necessary byproduct of selection on decision systems for regulating dyadic reciprocity under conditions of uncertainty. In deciding whether to engage in dyadic reciprocity, these systems must balance the costs of mistaking a one-shot interaction for a repeated interaction (hence, risking a single chance of being exploited) with the far greater costs of mistaking a repeated interaction for a one-shot interaction (thereby precluding benefits from multiple future cooperative interactions). This asymmetry builds organisms naturally selected to cooperate even when exposed to cues that they are in one-shot interactions.
