Cultural evolution, social ratcheting and the evolution of human division of labour.

While ecological specialization, social differentiation and division of labour are found in many species, extensive and irreversible interdependence among culturally specialized producers is a characteristic feature of humans. By extending the concept of cultural ratcheting (or the evolution of cultural products of such complexity that they become very unlikely to be recreated from scratch by naive individuals), we present simulation models showing how cumulative cultural evolution may have engendered a parallel process of 'social ratcheting' or the origin of culturally differentiated and irreversible interdependent individuals and groups. We provide evidence that the evolution of cultural division of labour in humans may have been associated with social network structures splitting the cognitive costs of cultural production across differentiated specialists, significantly reducing the burden of cultural learning on individual cognition and memory. While previous models often assumed agents with unlimited memories, we show that limiting individual memories to a fraction of available cultural repertoires has a noticeable accelerating effect on both cultural evolution and social differentiation among producers. We conclude that cultural and social ratcheting may have been two linked outcomes of cultural evolution in the hominin lineage.This article is part of the theme issue 'Division of labour as key driver of social evolution'.