Winner of the William James Book Award
Winner of the Eleanor Maccoby Book Award

“A landmark in our understanding of human development.”
—Paul Harris, author of Trusting What You’re Told

“Magisterial…Makes an impressive argument that most distinctly human traits are established early in childhood and that the general chronology in which these traits appear can…be identified.”
—Wall Street Journal

Virtually all theories of how humans have become such a distinctive species focus on evolution. Becoming Human looks instead to development and reveals how those things that make us unique are constructed during the first seven years of a child’s life.

In this groundbreaking work, Michael Tomasello draws from three decades of experimental research with chimpanzees, bonobos, and children to propose a new framework for psychological growth between birth and seven years of age. He identifies eight pathways that differentiate humans from their primate relatives: social cognition, communication, cultural learning, cooperative thinking, collaboration, prosociality, social norms, and moral identity. In each of these, great apes possess rudimentary abilities, but the maturation of humans’ evolved capacities for shared intentionality transform these abilities into uniquely human cognition and sociality.

“How does human psychological growth run in the first seven years, in particular how does it instill ‘culture’ in us? …Most of all, how does the capacity for shared intentionality and self-regulation evolve in people? This is a very thoughtful and also important book.”
—Tyler Cowen, Marginal Revolution

“Theoretically daring and experimentally ingenious, Becoming Human squarely tackles the abiding question of what makes us human.”
—Susan Gelman

“Destined to become a classic. Anyone who is interested in cognitive science, child development, human evolution, or comparative psychology should read this book.”
—Andrew Meltzoff

“Ontogeny recapitulates phylogeny” was Haeckel’s answer—the wrong one—to the most vexing question of nineteenth-century biology: what is the relationship between individual development (ontogeny) and the evolution of species and lineages (phylogeny)? In this, the first major book on the subject in fifty years, Stephen Jay Gould documents the history of the idea of recapitulation from its first appearance among the pre-Socratics to its fall in the early twentieth century.

Mr. Gould explores recapitulation as an idea that intrigued politicians and theologians as well as scientists. He shows that Haeckel’s hypothesis—that human fetuses with gill slits are, literally, tiny fish, exact replicas of their water-breathing ancestors—had an influence that extended beyond biology into education, criminology, psychoanalysis (Freud and Jung were devout recapitulationists), and racism. The theory of recapitulation, Gould argues, finally collapsed not from the weight of contrary data, but because the rise of Mendelian genetics rendered it untenable.

Turning to modern concepts, Gould demonstrates that, even though the whole subject of parallels between ontogeny and phylogeny fell into disrepute, it is still one of the great themes of evolutionary biology. Heterochrony—changes in developmental timing, producing parallels between ontogeny and phylogeny—is shown to be crucial to an understanding of gene regulation, the key to any rapprochement between molecular and evolutionary biology. Gould argues that the primary evolutionary value of heterochrony may lie in immediate ecological advantages for slow or rapid maturation, rather than in long-term changes of form, as all previous theories proclaimed.

Neoteny—the opposite of recapitulation—is shown to be the most important determinant of human evolution. We have evolved by retaining the juvenile characters of our ancestors and have achieved both behavioral flexibility and our characteristic morphology thereby (large brains by prolonged retention of rapid fetal growth rates, for example).

Gould concludes that “there may be nothing new under the sun, but permutation of the old within complex systems can do wonders. As biologists, we deal directly with the kind of material complexity that confers an unbounded potential upon simple, continuous changes in underlying processes. This is the chief joy of our science.”