Recognition of other individuals' social relationships by female baboons

We describe a series of playback experiments designed to test whether free- ranging baboons, Papio cynocephalus ursinus, recognize the calls of other g roup members and also associate signallers with their close genetic relativ es. Pairs of unrelated females were played sequences of calls that mimicked a fight between their relatives. As controls, the same females heard seque nces that involved either (1) only the more dominant female's relative or ( 2) neither of the females' relatives. When call sequences involved their re latives, subjects looked towards the speaker for a longer duration than whe n the sequences involved nonkin. When the sequences involved the other fema le's relative, they also looked towards that female. Subjects did not look towards one another when call sequences involved nonkin. Dominant subjects were more likely to supplant their subordinate partners following playbacks of sequences that mimicked a dispute between their relatives than followin g the two control trials. In contrast, both subjects were more likely to ap proach one another and to interact in a friendly manner following the two c ontrol trials than following the test trial. Results indicate that female b aboons recognize the screams and threat grunts not only of their own close relatives but also of unrelated individuals. They also replicate previous s tudies in suggesting that female monkeys recognize the close associates of other individuals and adjust their interactions with others according to re cent events involving individuals other than themselves. (C) 1999 The Assoc iation for the Study of Animal Behaviour.