The importance of kinship for the evolution of altruism is very widely accepted today, on both theoretical and empirical grounds. However, kinship is really only a way of ensuring that altruists and recipients both carry copies of the altruistic gene, which is the fundamental requirement. If altruism is to evolve, it must be the case that the recipients of altruistic actions have a greater than average probability of being altruists themselves. Kin-directed altruism is the most obvious way of s