Chimpanzee intelligence and its vocal expressions. This book, "Chimpanzee intelligence and its vocal expressions. Volume 1", by Robert Mearns Yerkes, is a replication of a book originally published before 1925. It has been restored by human beings, page by page, so that you may enjoy it in a form as close to the original as possible. This book was created using print-on-demand technology. Thank you for supporting classic literature.