The first major and most comprehensive synthesis of results from ecological, naturalistic behavioral, comparative psychological, and humanoid language research on apes since the classic work, The Great Apes, by Robert M. and Ada Yerkes in 1929. Based on more than 1,360 references from scientific journals, monographs, symposium volumes, and other public sources, the book contains a wealth of current information on the taxonomy, ecology, postural and locomotive behavior, natural communications, and social behavior of the apes. Topical discussions in the book are organized to show the extent of progress, including the development of new research questions, and the way our views of apes have changed as new information has become available since 1929.