The Expression of the Emotions in Man and Animals Robert Grant's Lamarckist philosophy) ridiculed Bell's theological explanations, pointing instead to the striking similarities of human and animal biology. The meeting then ended in uproar. Forty-five years later, Darwin revisits these arguments and recruits Duchenne's (1862) unmasking of the facial mechanisms, shifting the argument from philosophical speculation to scientific discourse. Darwin's response to Bell's natural theology is discussed by Lucy Hartley (2001). In the composition of the book, Darwin drew on worldwide responses to his questionnaire (circulated in the early months of 1867) concerning emotional expression in different ethnic groups; on anthropological memories from his time on ; on conversations
The Expression of the Emotions in Man and Animals with engravings of the Darwin family's domestic pets by the zoological illustrator T. W. Wood as well as work by the artists Briton Rivière, Joseph Wolf and A.D. May. It also included portraits by the Swedish photographer Oscar Rejlander (1813–1875), anatomical diagrams by Sir Charles Bell (1774–1842) and Friedrich Henle (1809–1885), as well as illustrational quotations from the "Mécanisme de la physionomie humaine" (1862) by the French neurologist Duchenne de Boulogne (1806–1875). As a result of his domestic psychology experiments, Darwin reduced the number of commonly observed emotions from Duchenne's calculation of more than sixty facial expressions, to just six