This text explores the evidence on animal mental capacities. The authors use examples to show how, in some cases, seemingly ingenious and complex behaviours turn out to be more or less pre-programmed, while others reveal evidence of quite developed mental life. For instance, whilst no raven has ever voiced Edgar Allan Poe's nevermore, these birds do, for example, cast stones in an apparently novel way. The authors suggest that the mental capacities of many animals are greater than we might have supposed - and the complexity of our own not unique, as we would like to belive. This volume provides a wide-ranging exploration of the behaviour of different species and the experiments that tease innate reflex actions apart from strategic action.