A radical reconsideration of how we develop the qualities that make us human, based on decades of cutting-edge experimental work by the former director of the Max Planck Institute for Evolutionary Anthropology. Virtually all theories of how humans have become such a distinctive species focus on evolution. Here, Michael Tomasello proposes a complementary theory of human uniqueness, focused on development. Building on the seminal ideas of Vygotsky, his data-driven model explains how those things that make us most human are constructed during the first years of a child’s life.