Face touching in monkeys, apes and man evolutionary origins and cerebral asymmetry.
The evolution of face touching, i.e. the use of the hand to touch the individual's own face, was studied in monkeys, apes and man with the object of examining which hand is used and which part of the face is touched. Monkeys show little if any face touching. Gorillas, orang- utans and chimpanzees show face-touching comparable to man. Left-hand face touching was superior to right-hand touching for both apes and humans. One feature which distinguished humans from other apes was the frequency of chin touching, which is generally high for man. It has been suggested that emotions are expressed more intensely on the left side of the face and it was thought that the left hand is used by the right hemisphere as a special pointer to heighten the effect of this.