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 live in a nested multi-level society, with ‘units’ composed of a ‘primary’ male, one to six associated females, and immatures at the core of the society. 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.