http://seshatdatabank.info/ One of the chief reasons I became an advocate of the Cultural Multilevel Selection (CMLS) theory is that it wonderfully clarifies the relationship between competition and cooperation. Competition between groups (up to whole societies) fosters within-group cooperation. Competition within groups (between their members) destroys cooperation. If you wanted a two-sentence summary of Ultrasociety this would be it. I’ve been applying these principles in my research on the evolution of complex societies (and a lot more is to come, now that the Seshat Databank have come of age and is generating a tremendous volume of empirical results—which you will see in a year or two, as academic publication mill-stones grind sooo slowly).