What were our ancestors like before the domestication of plants and animals, before sedentary village life, before the earliest towns and states? That is the question Diamond sets himself to answer. In doing so, he faces nearly insurmountable obstacles. Until quite recently, archaeology recorded our history as a species in relation to the concentration of debris (middens, building rubble, traces of irrigation canals, walls, fossilised faeces etc) we left behind. Hunter-gatherers were typically mobile and spread their largely biodegradable debris widely; we don’t often find their temporary habitats, which were often in caves or beside rivers or the sea, and the vast majority of such sites have been lost to history. When we do find them, they can tell us something about their inhabitants’ diet, cooking methods, bodily adornment, trade goods, weapons, diseases, local climate and occasionally even causes of death, but not much else. How to infer from this scant evidence our ancestors’ family structure and social organisation, their patterns of co-operation and conflict, let alone their ethics and cosmology.