A defense of sociobiology.

To counter recent claims that sociobiology is in disarray or requires reformulation, I discuss the semantics, theory, and data that underlie the field. A historical perspective is used to identify the cause of current debates. I argue that semantic precision is required in discussing terms such as kin selection, group selection, and altruism, but once care is taken, the objections to the unity of theoretical sociobiology largely evaporate. More work is required, however, to understand group adaptation, which might be taken to be the process of optimizing phenotypes that is driven by group, rather than individual, context. From the empirical perspective, the eusocial insects with their fixed division between work and reproduction are often a sounding board in discussions. Here, one finds clear evidence for the role of kin selection and relatedness in both the origin of eusociality and its maintenance. Data from other systems including the social vertebrates, microorganisms, and even plants also support the role of relatedness and particularly family life in the evolution of cooperation and altruism. These data, however, in no way invalidate the claim that group selection is also a central process in social evolution and I discuss the empirical evidence for group selection. The foundations of sociobiology are solid and the future should build on these foundations. Exciting new areas include the importance of community and species-level selection in evolution and elucidating the molecular mechanisms that underlie social traits.