Structure and Function of Hindquarter Presentations in Yellow Baboons (Papio cynocephalus)

This paper summarizes analyses of the structure and function of 775 presentation sequences obtained during 603 h of observation on two groups of Amboseli baboons (Papio cynocephalus). Hindquarter presentations among Amboseli baboons could in most cases be unambiguously assigned to one of six categories Submissive, Sexual, Mixed Sexual-Submissive, Affiliative, Abbreviated and Grooming based on accompanying behavior elements, posture, context and response. Nearly half of all presentations were categorized as Submissive and in these sequences the presenter was generally subordinate to the recipient. Nearly one-third of all presentations were categorized as Sexual o r Mixed Sexual-Submissive and the presenter in these sequences was a sexually-cycling adult female proportionately more often than expected from the number of such females in the study groups. Additionally, pregnant females directed proportionately more Submissive presentations than expected both toward adult males and toward other adult females, and lactating females received proportionately more Affiliative presentations than expected from other adult females. The response of adult males to Sexual presentations by adult females was influenced most strongly by the reproductive history of those females (nulliparous vs. multiparous), but was also influenced by both male and female rank. These findings suggest that over the course of primate evolution the primary function of hindquarter presentation has been modified from that of copulation solicitation to that of preemption of aggression. Additionally, for individuals between whom rank relarjons are both highly discrepant and clear-cut (e.g., adult male/adult female; adult male/subadult male, etc.), hindquarter presentation appears to play an important role in the establishment and maintenance of social bonds.