A model is presented to account for the natural selection of what is termed reciprocally altruistic behavior. The model shows how selection can operate -against the cheater (non-reciprocator) in the system. Three instances of altruistic behavior are discussed, the evolution of which the model can explain: (1) behavior involved in cleaning symbioses; (2) warning cries in birds: and (3) human reciprocal altruism. Regarding human reciprocal altruism, it is shown that the details of the psychological system that regulates this altruism can (...) be explained by the model. Specifically, friendship,d islike, moralistic aggression, gratitude, sympathy, trust, suspicion, trustworthiness, aspects of guilt, and some forms of dishonesty and hypocrisy can be explained as important adaptations to regulate the altruistic system. Each individual human is seen as possessing altruistic and cheating tendencies, the expression of which is sensitive to developmental variables that were selected to set the tendencies at a balance appropriate to the local social and ecological environment. (shrink)

From Charles Darwin to Edward Wilson, evolutionary biologists have attempted to construct systems of evolutionary ethics. These attempts have been roundly criticized, most often for having committed the naturalistic fallacy. In this essay, I review the history of previous efforts at formulating an evolutionary ethics, focusing on the proposals of Darwin and Wilson. I then advance and defend a proposal of my own. In the last part of the essay, I try to demonstrate that my revised version of evolutionary ethics: (...) (1) does not commit the naturalistic fallacy as it is usually understood; (2) does, admittedly, derive values from facts; but (3) does not commit any fallacy in doing so. (shrink)