Social Insects and the Individuality Thesis: Cohesion and the Colony as a Selectable Individual

Abstract

EVOLUTIONARY THEORY IS GENERAL in a way that is often not appreciated (Okasha 2006), partly because of the long-standing focus at the organism and gene levels. In the abstract, however, there is nothing special from an evolutionary perspective about any particular level of biological organization. One concrete problem for researchers is determining which levels are special because of the causal or historical circumstances of evolutionary change. John Maynard Smith captured the issue with characteristic pith in 1988: “Any population of entities with the properties of multiplication (one entity can give rise to many), variation (entities are not all alike, and some kinds are more likely to survive and multiply than others), and heredity (like begets like) will evolve: A major problem for current evolutionary theory is to identify the relevant entities.” Our task in this chapter is to point to a new way to frame this problem as it pertains to social insect colonies and to colony-level selection. We argue below that there are two general superorganism approaches: one focused on similarities between organisms and colonies that has its roots in the developmental and organicist traditions followed by William Morton Wheeler (Wheeler 1911, 1928; Seeley 1995; Moritz and Southwick 1992; Moritz and Fuchs 1998), and one that emphasizes the colony as a unit of selection and has its roots in kin and group selection theory (Wilson and Holldobler 2005; Reeve and Holldobler, 2007). The similarity approach is very widely used, but we think it obscures important issues about