Sociological Conparison between Two Wild Groups of Anubis-Hamadryas Hybird Baboons

Abstract

In the Awash Valley, Ethiopia, observed were 2 groups of anubis-hamadryas hybrid baboons to make a comparative study of their social organizations. Morphologically and genetically, one group (the Gorge group) was closer to anubis, while the other (the Kerrayu group) was closer to hamadryas. The entire Kerrayu group was very cohesive, whereas the Gorge group often splitted into several parties without stable membership. In the Gorge group, 8 subgroups were distinguished: 3 multi-male groups and 5 one-male groups. The Kerrayu group had 2 large one-male units, several small one-male units, and 8-9 pair units. The infra-units within the Kerrayu group were spatially more cohesive than the Gorge subgroups. In both Kerrayu and Gorge groups, the distinctive affinitive bonds, which seemed to be based on kinship, existed among females. The males of the Kerrayu group had a stronger social disposition towards each other's proximity than those of the Gorge group. The linearity of dominance order among males in Gorge group was more distinctly established than in the Kerrayu group. In the Awash Valley anubis and hamadryas populations have had mutual gene flow. The inflow of anubis genes into the hamadryas band has strongly affected the possessive behavior of hamadryas males towards females, but has exerted little effect on the mutual bonds among the males. The inflow of hamadryas genes into the anubis troop has severely affected its integration. It was concluded that the band to be the basic social unit of hamadryas baboons, and it was speculated that some sociological and ecological factors promoted the formation of multi-level system of hamadryas baboons.