The paper identifies three reasons why social scientists have not readily accepted a Darwinian perspective: first, in the relative importance they attribute to variability in social and cultural systems; second, in their conception of social evolution; third, in their emphasis on the emergent properties of social interaction. I locate the social sciences’ position in the late nineteenth century debate between Durkheim and Tarde, but point out that Durkheim is wrongly accused of presenting the human mind as a ‘blank slate’. Durkheim and Tarde took different lessons from Darwin's Origin of Species. The concept of co-evolution, as applied in behavioural ecology and complex systems theory, promises to bring the social and evolutionary sciences closer together. Our species has evolved a complex capacity for sustaining social relations, and outbreaks of violence must be explained not only in terms of evolved psychological dispositions, but also put in their social context. The diffusion of innovations in a farming economy must likewise be explained as a response to changes in the economic environment for which the farmers themselves are partly responsible through their engagement with the market economy. Cross-cultural applications of game theory indicate a fruitful way forward.