Why do we shiver when we are scared? Why do we "bare our teeth" when we are angry? What do dogs and cats do when they feel pleasure, fear, or sadness? Do monkeys smile? And why, in any case, did Darwin decide to touch on a subject that seems at first glance so different from his other evolutionary works?

The Expression of Emotions in Man and Animals – Darwin's most accessible work for the non-specialist reader – does not just include a vast wealth of fascinating and insightful observations on how domestic and wild animals, humans, and their children express their joy, sadness, fear, and anger.

It aimed to deal a final blow to creationism by offering evidence for the common ancestry of all species, including humans, which would be not only strong but also easy for anyone to verify. It's no coincidence that The Expression is the first scientific work accompanied by photographs.

This volume is the most complete edition of The Expression: It includes not only all the notes and corrections that Darwin wished to add but also additional commentary by Paul Ekman on all the modern research developments, as well as a comprehensive account of the adventures that Darwin's theory of emotions has gone through in almost a century and a half since its publication.