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
Body language develop a more personal rapport. Scholars have long debated on whether body language, particularly facial expressions, are universally understood. In Darwin’s (1872) evolutionary theory, he postulated that facial expressions of emotion are inherited. On the other hand, scholars have questioned if culture influences one’s bodily expression of emotions. Broadly, the theories can be categorized into two models: The cultural equivalence model predicts that "individuals should be equally accurate in understanding the emotions of ingroup and outgroup members" (Soto & Levenson, 2009). This model is rooted in Darwin’s (1872) evolutionary theory, where he noted that both humans and animals share similar