The Expression of the Emotions in Man and Animals

"The Expression of the Emotions in Man and Animals" is Charles Darwin's third major work of evolutionary theory, following "On the Origin of Species" and "The Descent of Man." In this book, Darwin concerns the biological aspects of emotional life. For example, he explores the animal origins of such characteristics as the lifting of the eyebrows in moments of surprise and the raising of the upper lip in an aggressive sneer.