Big brains, small worlds: material culture and the evolution of the mind.

New developments in neuroimaging have demonstrated that the basic capacities underpinning human social skills are shared by our closest extant primate relatives. The challenge for archaeologists is to explain how complex human societies evolved from this shared pattern of face-to-face social interaction. We argue that a key process was the gradual incorporation of material culture into social networks over the course of hominin evolution. Here we use three long-term processes in hominin evolution-encephalization, the global human diaspora and sedentism/agriculture-to illustrate how the cultural transmission of material culture allowed the 'scaling up' of face-to-face social interactions to the global societies known today. We conclude that future research by neuroimagers and archaeologists will need to investigate the cognitive mechanisms behind human engagement with material culture as well as other persons.