Suddendorf provides a definitive account of the mental qualities that separate humans from other animals, as well as how these differences arose. He surveys the abilities most often cited as uniquely human-- language, intelligence, morality, culture, theory of mind, and mental time travel-- and finds that two traits account for most of the ways in which our minds appear so distinct: our open-ended ability to imagine and reflect on scenarios, and our insatiable drive to link our minds together.