Infant carrying by adult male mangabeys (Cercocebus atys)

Sixty-five interactions where an adult male carried an infant in the proximity of a second male were observed during a 19-mo period in a captive sooty mangabey (Cercocebus atys) social group. The behavior was distributed nonrandomly in both the adult male and infant classes. In all but three of the interactions, the recently deposed alpha male carried an infant in the presence of the newly ascendant dominant male. In the first phase of the study, infants that were carried included the entire unweaned infant cohort (n = 5) born before the rank reversal. The rate of carrying in this class declined as a function of increasing infant age and time since the rank reversal. Infant carrying was not observed in the context of fighting, which was rare, and intermale aggression never preceded the behavior. However, in 40% of the cases, carrying occurred after an infant had been threatened by the dominant male. These results suggest that infant carrying served to protect the infant from aggression rather than to exploit the infant as an agonistic buffer. The data did not unequivocally support the postulate that carrying may be a form of paternal care since paternity could not be assessed. The similar structural and contextual patterns of infant carrying in this species suggest a common origin for triadic male-infant interactions in mangabeys and baboons.