There exists an undeniable chasm between the capacities of humans and those of animals. Our minds have spawned civilizations and technologies that have changed the face of the Earth, whereas even our closest animal relatives sit unobtrusively in their dwindling habitats. Yet despite longstanding debates, the nature of this apparent gap has remained unclear. What exactly is the difference between our minds and theirs?

In The Gap, psychologist Thomas Suddendorf provides a definitive account of the mental qualities that separate humans from other animals, as well as how these...