Periodic changes in the bare skin areas of Theropithecus gelada

Abstract

Daily examination of five adult female gelada baboons (Theropithecus gelada) exhibiting menstruation discharges showed noncyclic changes in the coloration of the bare areas of skin in throat, chest, and pubic areas. The intensity of red color in these areas were, on the other hand, markedly affected by the social context (bouts of threats or fights generally heighten the intensity of red) and by sickness or injury (generally lessening color intensity). The features showing most marked cyclic variations were color and degree of swellings of the cutaneous vesicles present around the chest and ventral patches, the intensity of both increasing in the middle of the menstrual cycle and descending as menstruation approaches, to gain intensity again a few days after cessation of the discharges. Of these two features vesicle color appears to be more sensitive to the hormonal changes underlying the variations. © 1973 Japan Monkey Centre.