One of the most debated issues in evolutionary biology concerns the level at which natural selection operates. It is usually accepted that Darwin maintained that natural selection operates at the individual level. However, another line of interpretation suggests that Darwin conceived that natural selection could operate at the group level as well, specifically, that he was forced to accept this in order to explain the altruistic behavior. This paper aims to show that Darwin did not provide a clear model of group selection, and that he had recourse to explanations of selection at the individual level in order to explain altruistic behavior. I will defend this interpretation through passages in his texts that introduce the influence of parenthood and individual selection as forces that explain altruistic behavior and that appeal to the same points exploited by the contemporary models of inclusive fitness and reciprocal altruism.
Theory of evolution; Natural selection; Adaptation; Levels of selection; Group selection; Altruism