Unlike any other species, humans can learn and use language. This book explains how the brain evolved to make language possible, through what Michael Arbib calls the Mirror System Hypothesis. Because of mirror neurons, monkeys, chimps, and humans can learn by imitation, but only "complex imitation," which humans exhibit, is powerful enough to support the breakthrough to language. This theory provides a path from the openness of manual gesture, which we share with nonhuman primates, through the complex imitation of manual skills, pantomime, protosign (communication based on conventionalized manual gestures), and finally to protospeech. The theory explains why we humans are as capable of learning sign languages as we are of learning to speak. This fascinating book shows how cultural evolution took over from biological evolution for the transition from protolanguage to fully fledged languages. The author explains how the brain mechanisms that made the original emergence of languages possible, perhaps 100,000 years ago, are still operative today in the way children acquire language, in the way that new sign languages have emerged in recent decades, and in the historical processes of language change on a time scale from decades to centuries. Though the subject is complex, this book is highly readable, providing all the necessary background in primatology, neuroscience, and linguistics to make the book accessible to a general audience.

Michael Arbib was a pioneer in the interdisciplinary study of computers and brains, and has long studied brain mechanisms underlying the visual control of action. For more than a decade he has devoted much energy to understanding the relevance of this work, and especially of mirror neurons, to the evolution of the language-ready brain.

Part I. Setting the Stage 1. Underneath the Lampposts 2. Perspectives on Human Languages 3. Vocalization and Gesture in Monkey and Ape 4. Human Brain, Monkey Brain, and Praxis 5. Mirror Neurons and Mirror Systems Part II. Developing the Hypothesis 6. Signposts: The Argument of the Book Revealed 7. Simple and Complex Imitation 8. Via Pantomime to Protosign 9. Protosign and Protospeech: An Expanding Spiral 10. How Languages Got Started 11. How the Child Acquires Language 12. How Languages Emerge 13. How Languages Keep Changing