"The study of language is pertinent to many fields of inquiry. It is relevant to psychology, anthropology, philosophy, and medicine. It encroaches upon the humanities, as well as upon the social and natural sciences. We may pursue investigations that concentrate on what man has done with or to specific languages; or we may regard language as a natural phenomenon- an aspect of his biological nature, to be studied in the same manner as, for instance, his anatomy. Which of these approaches is to be chosen is entirely a matter of personal curiosity. This book is concerned with the biological aspects of language." -- Preface