Evolutionary paths towards the division of labor

As the famous evolutionary biologist O. E. Wilson has pointed out in his book "The Social Conquest of the Earth" (Norton 2012, New York), social species include around two thirds of the earth's biomass. These social species - humans and social insects - are located at extreme forms of life. The queens of small social insects produce thousand of larvae, whereas the much larger human females invest heavily in their children who are directly born with an even relatively larger brain. In spite of these and many other obvious differences, social insects and humans have conquered the earth because of common characteristics: a very developed system of social cooperation and an articulated division of labor. These observations suggest several puzzles. In this paper we will focus on two questions: 1) If there are evident evolutionary advantages of cooperation and specialization why only few species were able to increase their fitness in this way? 2) Why did these characteristics emerged at such extremely different forms of life? In order to answer these two questions, we will focus on possible "transition societies" 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 labor and it provides a possible explanation for the emergence of sophisticated cooperation at such extreme forms of life.