The evolution of human collective ritual as a platform for communicating cooperative intentions

Collective ritual is virtually omnipresent across past and present human cultures and is thought to play an essential role in facilitating cooperation. Yet, little is known about its evolution in the hominin lineage. In this talk, I will present a model developed in collaboration with my colleagues explaining why and how collective ritual could have evolved under socio-ecological pressures in the Pleistocene. In this model, we identified similarity, coalitional, and commitment signals as the building blocks of the contemporary collective rituals in hunter-gatherers and trace the presence of these signals in non-human primates and the hominin archaeological and paleoanthropological record. Next, we established the underlying cognitive mechanisms facilitating these signals and reviewed the evidence of the earliest presence of these mechanisms as well as evidence for selective pressures on the evolution of cooperative communication. The synthesis of these streams of evidence suggests that ritualized cooperative signals might have first evolved in the Early Pleistocene in the form of similarity signals, whereas coalitional and commitment signals would start appearing in the early and late Middle Pleistocene until, eventually, coalescing into a ritual signaling system. By the arrival of Homo sapiens, it is possible that collective ritual as a staged and repetitively performed signaling act constituted an important adaptation facilitating collective action.