Marlene Zuk’s elegant book addresses the sort of American man who believes that everything was simpler and better in the Palaeolithic, and that the real mistake humanity made was to emerge from its caves and start farming. The wilder reaches of the internet have provided her with an inexhaustible supply of people who have taken the central message of evolutionary psychology to be that civilisation is an alien imposition on our properly evolved nature. Put like that, this is simply the latest way of telling the story of the noble savage, which has already passed through the treatments of Rousseau and of Freud. In contemporary America, however, people no longer worry about freedom or sex, believing that their culture has solved all the problems associated with either. Instead, they find existential significance in their diets.