Human uses of mammals that "one is well advised to study the behaviour rather than attempting to get at any underlying emotion". Charles Darwin however had accepted the idea of emotion in animals, writing his 1872 book "The Expression of the Emotions in Man and Animals" on the subject. Darwin believed that mammals had social, mental and moral lives. In "The Descent of Man" (1871), he wrote: "There is no fundamental difference between man and the higher mammals in their mental faculties." Biologists remained wary of the idea, even for the great apes, but this led to serious difficulties, as Donald O. Hebb explained
The Expression of the Emotions in Man and Animals West Yorkshire. Darwin corresponded intensively with James Crichton-Browne, the son of the phrenologist William A. F. Browne and now the medical director of the Wakefield asylum. At the time, Crichton-Browne was preparing his extremely influential "West Riding Lunatic Asylum Medical Reports", and Darwin remarked to him that "The Expression" "should be called by Darwin "and" Browne". Darwin also drew on his personal experience of the symptoms of bereavement and studied the text of Henry Maudsley's 1870 Gulstonian lectures on "Body and Mind". He considered other approaches to the study of emotions, including their depiction in the arts – discussed by