Obsidian-bearing sites spanning the temporal framework of the Palaeolithic and located in Africa and Europe are analysed with the aim of elucidating the evolution of modern social behaviour. Obsidian is a rock that forms only under very special conditions; its geological sources are infrequent and distinguished from each other on the basis of unique chemical properties. As such it is possible to reconstruct the distances of its movement and use these data to infer the scale of social life during the Palaeolithic. A strong correlation between obsidian use and long distances is observed implying that the hominins involved in the circulation of the specific material were behaving in a socially modern way.