In a stimulating synthesis of cognitive science, anthropology, and linguistics, Philip Lieberman tackles the fundamental questions of human nature: How and why are human beings so different from other species? Can the Darwinian theory of evolution explain human linguistic and cognitive ability? How do our processes of language and thought differ from those of Homo erectus 500,000 years ago, or of the Neanderthals 35,000 years ago? What accounts for human moral sense?

Lieberman believes that evolution for rapid, efficient vocal communication forged modern human beings by creating the modern human brain. Earlier hominids lacked fully human speech and syntax, which together allow us to convey complex thoughts rapidly. The author discusses how natural selection acted on older brain mechanisms to produce a structure that can regulate the motor activity necessary for speech and command the complex syntax that enhances the creativity of human language. The unique brain mechanisms underlying human language also enhance human cognitive ability, allowing us to derive abstract concepts and to plan complex activities. These factors are necessary for the development of true altruism and moral behavior.

Lieberman supports his argument about the evolution of speech and the human brain by combining the comparative method of Charles Darwin, insights from archaeology and child development, and the results of high-tech research with computerized brain scanning and computer models that can recreate speech sounds made by our ancestors over 100,000 years ago. Uniquely Human will stimulate fresh thought and controversy on the basic question of how we came to be.