Facial expressions of papio ursinus and some other higher primates
South African Journal of Science 76(9): 413-418
The facial expressions of P. ursinus are described in terms of the classification of higher primate facial expressions proposed by Van Hooff, and illustrated by photographs. Certain facial expressions, which either do not occur in P. ursinus, or only in very incomplete form, are also dealt with as seen in the chimpanzee, Pan troglodytes or in the pig-tailed macaque, Macaca nemestrina. The facial expressions of P. ursinus are divisible into 2 groups. There are the agonistic faces, relatively primitive reactions of the whole facial masculature which accompany strong emotion, especially aggressiveness and fear. In the 2nd group, facial displays, are seen notably lipsmacking and eyebrow raising, which involve only 1 or two facial muscles, and which are important signals during periods of relatively peaceful social contact.