Why only humans and social insects have a division of labour

Abstract

AbstractHumans and social insects are located at extreme points of the set of possible evolutionary paths. However, they share a complex division of labour and comprise a large proportion of the earth’s biomass. These observations prompt two questions: If there are evident evolutionary advantages of cooperation and specialisation, why have only few species been able to increase their fitness in this way? Why have these characteristics emerged as such extremely different forms of life? In order to answer these two questions, we will focus on possible ‘transition societies’ in the evolutionary paths towards social species. We will argue that, in both the human and social insect cases, sexual selection had a crucial role in the development of the division of labour and entailed that the division of labour required either minimum or maximum unitary investments in the offspring. The species located in between these two extremes could not exploit the advantages of specialisation.