Korb, Judith. “Social insects, major evolutionary transitions and multilevel selection.” In Animal Behaviour: Evolution and Mechanisms , pp. 179-211. Springer, Berlin, Heidelberg, 2010.
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The history of life is characterised by an increase in biological complexity from simple replicators to multicellular organisms. These major evolutionary transitions have in common that independent entities came together and cooperated and that finally a new entity was formed with a new fitness and a single evolutionary fate. Yet, the stable evolution of cooperation poses a classical Darwinian puzzle: Organisms compete over reproduction and selfish individuals that reap the benefits of the cooperation without paying the costs (cheaters) can invade a population of cooperators and drive the disappearance of cooperation. Social insects have become model organisms to study stable cooperation and how conflict between individuals is resolved. Here, I will first summarise what we have learned from social insect research about the evolution of stable cooperation. Besides little-studied ecological factors that determine the benefits and costs of cooperation, two common mechanisms to prevent the spread of cheaters have been identified: (i) common ancestry and aligned evolutionary interests mainly achieved through relatedness and (ii) enforcement mechanisms that make cheating costly. Then, I will show that similar mechanisms have evolved at other levels of the biological hierarchy that favour cooperation. Thirdly, I will present the multilevel selection approach, which promises to be a useful tool to study evolution at multiple selection levels. I will end by showing how a multilevel selection approach in future research might help to quantify benefits and costs of cooperation, so that insect societies and all major evolutionary transitions alike are being recognised as more than the sum of their components.