Baboons are one of the most important models for understanding the evolution of primate social systems. From their presumed origin in southern Africa, baboons advanced to the north during the pleistocene. Guinea baboons (Papio papio) constitute the western extreme of the baboon dispersal. They live in savannahs and gallery forests of West-Africa. Group sizes vary from about 10 to 300 individuals. They presumably live in multi-male multi-female groups which are composed of several smaller units that split and meet again several times during the day (fission-fusion). In comparison to other Papio-taxa relationships among males seem to be exceptionally relaxed. In contrast to other baboon species whose social and vocal behaviour has been extensively studied, however, the social system and vocal communication of Guinea baboons is only poorly understood.