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
Gender and emotional expression involves both detection and expression of emotions or moods. The ability to detect non-verbal cues leads to successful communication of emotions. In computer-mediated communication (CMC), the absence of body language and visibility restricts one's ability to correctly recognize other's emotions. For this reason, emoticons are widely used in online communication to replace non-verbal behaviors that emphasize or clarify one's feelings. Surprisingly, there is no static gender difference in the use of emoticons. In some studies, both men and women display an increase in emoticon use in the context of a mixed-gender group chat. Others show that men use more emoticons