Kin Selection and Social Insects

Social insects so dominate many terrestrial habitats (Wilson 1990) that they can hardly escape the attention of biologists, but even if they were rare, they would still attract special interest because of the intricate cooperation within their societies. William Morton Wheeler (1911) described the social insect colony as an organism (or as a higher-level organism or superorganism) because of the degree to which individuals appear to operate as a unit that is dedicated to the perpetuation and reproduction of the colony as a whole. The reinvention of the organism at a higher level has occurred at a number of crucial junctures in the history of life (Maynard Smith and Szathmary 1995). For example, the eukaryotic cell arose from several prokaryotic ancestors (Margulis 1970), and multicellular plants, animals, and fungi arose from single-celled ancestors (Buss 1987). Because insect societies are macroscopic, and because they span the entire range from solitary individuals to essentially superorganismal colonies, they offer an accessible model for how such transitions can happen.