Abstract

Group-living animals, from insects to mammals, often form dominance hierarchy, which is a directed network. The direction of the link represents aggression by one individual on the other subordinate individual. In small groups of animals, it has been long known that the hierarchy is often perfectly linear, allowing unique ranking of the individuals. However, perfect linearity is often violated in large groups. I present analysis of aggressive dominance hierarchy formed by worker ants as large directed networks and then discuss evolutionary implications of the results. I also present some results on generative models to account for the observed connectivity patterns, built on the assumption of heterogeneously distributed intrinsic strengths of individual nodes.