The Expression of the Emotions in Man and Animals major revision which made Darwin "sick of the subject and myself, and the world". It quickly sold around 7,000 copies and was widely praised as a charming and accessible introduction to Darwin's evolutionary theories. A second edition was published by Darwin's son in 1890, without several revisions suggested by Darwin; these were not published until the third edition of 1999 (edited by Paul Ekman). Published as a sequel to "The Descent of Man", "The Expression" was assured of a wide readership in mid-Victorian England. However, the early death of George Romanes (1848 - 1894) robbed Darwin of a powerful advocate
Emotion in animals could be used to include all the animal kingdom as well as some plants. The second approach, mechanistic, requires an examination of the mechanisms that drive emotions and search for similarities in animals. The mechanistic approach is utilized extensively by Paul, Harding and Mendl. Recognizing the difficulty in studying emotion in non-verbal animals, Paul et al. demonstrate possible ways to better examine this. Observing the mechanisms that function in human emotion expression, Paul et al. suggest that concentration on similar mechanisms in animals can provide clear insights into the animal experience. They noted that in humans, cognitive biases vary according