We are an intensely social species — it has been argued that our social nature defines what makes us human, what makes us conscious or what gave us our large brains. As a new field, the social brain sciences are probing the neural underpinnings of social behaviour and have produced a banquet of data that are both tantalizing and deeply puzzling. We are finding new links between emotion and reason, between action and perception, and between representations of other people and ourselves. No less important are the links that are also being established across disciplines to understand social behaviour as neuroscientists, social psychologists, anthropologists, ethologists and philosophers forge new collaborations.