The definitive edition of Darwin's classic a brilliantly entertaining and accessible exploration of human and animal behaviour, reissued to mark the 200th anniversary of Darwin's birth. Why do we bite people we feel affection towards? Why do dogs wag their tails? Or cats purr? Why do we get embarrassed, and why does embarrassment make us blush? These and many other questions about the emotional life of man and animals are answered in this remarkable book. Expression is the only book in which Darwin sketches out his revolutionary ideas about human behaviour in detail: he discusses childhood learning, insanity, painting and sculpture, animal behaviour and the differences in facial expression of the world's peoples.