 There has been some semantic confusion about the phrase “group selection,” for which I may be partly responsible. For me, the debate about levels of selection was initiated by Wynne-Edwards’ book. He argued that there are group-level adaptations…which inform individuals of the size of the population so that they can adjust their breeding for the good of the population. He was clear that such adaptations could evolve only if populations were units of selection…. Perhaps unfortunately, he referred to the process as “group selection.” As a consequence, for me and for many others who engaged in this debate, the phrase cane to imply that groups were sufficiently isolated from one another reproductively to act as units of evolution, and not merely that selection acted on groups.