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 that seven emotions are universally recognized, regardless of cultural background: happiness, surprise, fear, anger, contempt, disgust, and sadness. Recently, scholars have shown that the expressions of pride and shame are universal. Tracy and Robins (2008) concluded that the expression of pride includes an expanded posture of the body with the head tilted back, with a low-intensity face and a non-Duchenne smile (raising the corner of the mouth). The expression of shame includes the hiding of the face, either by turning it down or covering it with the hands. Fundamentally, body language is seemed as an involuntary and unconscious phenomena that