The evolution of costly displays, cooperation and religion: credibility enhancing displays and their implications for cultural evolution

This paper lays out an evolutionary theory for the cognitive foundations and cultural emergence of the extravagant displays (e.g., ritual mutilation, animal sacrifice and martyrdom) that have so tantalized social scientists, as well as more mundane actions that influence cultural learning and historical processes. In Part I, I use the logic of natural selection to build a theory for how and why seemingly costly displays influence the cognitive processes associated with cultural learning — why do “actions speak louder than words?” The core idea is that cultural learners can both avoid being manipulated by their models (those they are inclined to learn from) and more accurately assess their belief commitment by attending to displays or actions by the model that would seem costly to the model if he held beliefs different from those he expresses verbally. Part II examines the implications for cultural evolution of this learning bias in a simple evolutionary model. The model reveals the conditions under which this evolved bias can create stable sets of interlocking beliefs and practices, including quite costly practices. Part III explores how cultural evolution, driven by competition among groups or institutions stabilized at alternative sets of these interlocking belief-practice combinations, has led to the association of costly acts, often in the form of rituals, with deeper commitments to group beneficial ideologies, higher levels of cooperation within groups, and greater success in competition with other groups or institutions. I close by discussing the broader implications of these ideas for understanding various aspects of religious phenomena.