It is often the case in interdisciplinary accounts of human evolution that archaeological data are either ignored or treated superficially. This article sets out to redress this position by using archaeological evidence from the last 2.5 million years to test the social brain hypothesis (SBH) - that our social lives drove encephalization. To do this we construct a map of our evolving social complexity that concentrates on two resources - materials and emotions - that lie at the basis of all s...