The ontogeny of pant hoot vocalisations and social awareness in wild chimpanzees
Author(s)
Publisher
Neuchâtel : Université de Neuchâtel
Date issued
2023
Number of pages
194
Subjects
vocal development chimpanzees primates audience effect communication call combinations vocal behaviour social learning
Abstract
While some scholars have regarded primate vocal communication as innate, inflexible, and insensitive to the context, recent advances suggest instead that vocal behaviours can be flexible, insofar as they are affected by individual and situational factors, notably the social context. However, whether the same is true for the acquisition of communicative capacities remains largely unknown, particularly in great apes.
In my thesis, I address this by examining the ontogeny of vocal behaviours in the pant hoots of immature chimpanzees (Pan troglodytes schweinfurthii) of the Budongo Forest, Uganda. Furthermore, I investigate audience effects on pant hoot sequences used during displays to determine the extent to which these vocal structures are flexibly modulated depending on the social environment. Pant hoots are a multi-phase vocal sequence typically used to maintain contact and coordinate movements between individuals and groups over long distances. The question of how this complex and flexible vocal signal develops is key for a better understanding of how chimpanzees navigate dynamic social interactions in fission-fusion societies from both an ontogenetic and a comparative perspective.
Results from my thesis show that chimpanzees produced rudimentary pant hoot sequences since birth, suggesting that vocal repertoires are largely innate. However, these sequences presented some structural and acoustic differences when compared to those of older individuals, suggesting they also undergo ontogenetic changes. In addition, the vocal usage and responses to pant hoots in immature chimpanzees was enhanced by greater vocal and social exposure to key group members, such as the mother and adult males, when compared to the development of less gregarious immature individuals. Finally, social context modulated the use of pant hoot phases during vocal displays, likely enhancing the communicative capacities of a species with limited vocal production learning and relatively small vocal repertoire.
Taken together, findings from my thesis suggest that the ontogeny of complex chimpanzee vocalisations is socially mediated and that chimpanzee vocal communication is flexibly adjusted depending on the social environment.
In my thesis, I address this by examining the ontogeny of vocal behaviours in the pant hoots of immature chimpanzees (Pan troglodytes schweinfurthii) of the Budongo Forest, Uganda. Furthermore, I investigate audience effects on pant hoot sequences used during displays to determine the extent to which these vocal structures are flexibly modulated depending on the social environment. Pant hoots are a multi-phase vocal sequence typically used to maintain contact and coordinate movements between individuals and groups over long distances. The question of how this complex and flexible vocal signal develops is key for a better understanding of how chimpanzees navigate dynamic social interactions in fission-fusion societies from both an ontogenetic and a comparative perspective.
Results from my thesis show that chimpanzees produced rudimentary pant hoot sequences since birth, suggesting that vocal repertoires are largely innate. However, these sequences presented some structural and acoustic differences when compared to those of older individuals, suggesting they also undergo ontogenetic changes. In addition, the vocal usage and responses to pant hoots in immature chimpanzees was enhanced by greater vocal and social exposure to key group members, such as the mother and adult males, when compared to the development of less gregarious immature individuals. Finally, social context modulated the use of pant hoot phases during vocal displays, likely enhancing the communicative capacities of a species with limited vocal production learning and relatively small vocal repertoire.
Taken together, findings from my thesis suggest that the ontogeny of complex chimpanzee vocalisations is socially mediated and that chimpanzee vocal communication is flexibly adjusted depending on the social environment.
Notes
Thèse de doctorat présentée à la Faculté des sciences de l’Université de Neuchâtel (Suisse) ; approuvé par la Faculté des sciences sur le rapport des membres du jury composé comme suit :
Prof. Klaus Zuberbühler (co-directeur de thèse)
Prof. Josep Call (co-directeur de thèse)
Dr Juan-Carlos Gomez
Prof. Robert Seyfarth
Prof. Klaus Zuberbühler (co-directeur de thèse)
Prof. Josep Call (co-directeur de thèse)
Dr Juan-Carlos Gomez
Prof. Robert Seyfarth
Publication type
doctoral thesis
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