Agonistic Interactions of Juvenile Savanna Baboons

Abstract

Abstract19 juvenile members of known genealogies in two wild baboon groups were studied over a 16‐month period to compare the ontogeny of agonistic experience and dominance relations for males and females. Juveniles of all age‐sex classes were disproportionately likely to receive aggression from and submit to adult males per unit of time spent in proximity. This pattern intensified with increasing juvenile age. With age, juvenile females more often submitted to unrelated adult females from higher‐ranking families, whereas this was not true for juvenile males. All juveniles received aggression from older group members more often during feeding than was expected by chance. High rates of agonistic interaction with unrelated adult females accounted for old juvenile females (3–5.5 years‐old) interacting agonistically more frequently than male age peers and young juveniles of either sex (1–2.5 years‐old). Adult females were also more aggressive toward females among young juveniles, suggesting that adult females target females among juveniles for aggression and resistance to rank reversal. Within juvenile age groups, males dominated all females and all younger males, irrespective of maternal dominance status. Dominance relations among female age‐peers were generally isomorphic with relations among their mothers. No juvenile targeted any older male for rank reversal. Males targeted all older females, whereas females typically targeted only older females from families lower‐ranking than their own. The strong sexual dimorphism in adult body size in baboons may explain why juvenile males' dominance relations with peers and adult females are not structured along lines of family membership as is true for the less dimorphic macaques. Acquisition of higher agonistic status probably allows juveniles of both sexes to increase their success in within‐group feeding competition during late stages of juvenility, which, in turn, could affect important life‐history traits such as age at menarche and adult body size.