How can the intelligence of monkeys and apes, and the huge brain expansion which marked human evolution be explained? In 1988, Machiavellian Intelligence was the first book to assemble the early evidence suggesting a new answer: that the evolution of intellect was primarily driven by selection for manipulative, social expertise within groups where the most challenging problem faced by individuals was dealing with their companions. Since then a wealth of new information and ideas has accumulated. This new book will bring readers up to date with the most important developments, extending the scope of the original ideas and evaluating them empirically from different perspectives. It is essential reading for reseachers and students in many different branches of evolution and behavioural sciences, primatology, and philosophy.