This book investigates the nature of human language and its importance for the study of the mind. It asks what language is from a biological point of view and what the relative contribution of nature and nurture is when a child learns his or her language. Finally it asks how human language evolved and considers the similarities and differences between human language and animal communication systems. Uniquely, it argues that genetic or biological endowment plays a more central role in the aquisition of language than instruction, learning, or cultural determinants.