Jan J Kreider, Ido Pen

The evolution of eusociality has long been recognized as an evolutionary paradox. We identify three different but complementary approaches to the study of the evolution of eusociality. Kin selection models explain why individuals can evolve to have distinct reproductive or non-reproductive roles. Division of labour models elucidate how specialisation can emerge and evolve. Conceptual models from evolutionary developmental biology propose hypotheses for the origin and evolutionary fixation of a helper-phenotype. However, we argue that none of these three approaches is a sufficient explanation for the evolution of eusociality on its own. Consequently, we plead for novel unifying explanations and formal models to better understand the interrelation of reproductive altruism, task specialisation and phenotypic plasticity.