The nature and function of social interactions between infant and adult male yellow baboons (papio cynocephalus)

Abstract

Interactions between infants and adult males were observed for one year in a group of yellow baboons in Amboseli National Park. Adult males spent a larger proportion of their time in proximity, in contact, and connected <i.e., carrying, embracing, holding, etc.) with infants if the male was involved in an agonistic interaction w i th another adult male than if not. This was due to the higher frequency with which both infants and males approached, contacted, and connected with one another during inter-male conflicts, and to the fact that for both infants and adult males the proportion of their spatial transitions that increased spatial intimacy was higher during male-male contests. When males were connected with an infant, they initiated agonistic interactions at a higher frequency and initiated a larger proportion of their agonistic interactions than when they were not. This was overwhelmingly due to the activity of the subordinate males. In spite of infants being used in fights disproportionately often when the expected level of aggression was particularly high, and agonistic interactions in which infants were used being two to three times as long as others, the proportion of encounters in which a male received aggression was not

any higher when he was connected with an infant than when he was not. In fact, when the subordinate male was connected with an infant during a male-male conflict, the dominant male was much more likely to be the first to retreat than otherwise. This effect was nearly identical to the effect of the subordinate male displaying signs of submission. There was additionally some indication that infant involvement decreases the incidence of wounding. There were no clear gender differences in infant participation in male-male agonistic interactions, but younger infants were used more often than expected on the basis of their availability. Infants were carried by their potential fathers 34% of the time and by males absent at the time the infant was conceived 15%. Infants were carried against their potential fathers 35% of the time and against a male absent at the time of conception 31%. While a male was fighting, about half of his interactions with infants were initiated by the infant. Infants and their mothers rarely showed distress during such interactions, and males did not carry resisting infants. A specialized communication system seemed to develop between infants and adult males in which the male grunted to the infant during male-male tension and the infant ran to the male emitting stereotyped, stylized geckering vocalizations. Infants apparently benefit from their participation as agonistic buffers through long-term, reciprocal