Socially-guided vocal flexibility in nonhuman primates
Résumé
While most authors believe that it is legitimate to argue in favor of a coevolution between sociality and communicative complexity in vertebrates, the vocal repertoires of monkeys and apes, living in complex social systems, have traditionally been described as very rigid, compared to birds or cetaceans for instance. However, recent evidences of vocal flexibility under social influences have been provided in a growing number of nonhuman primate species. First, while the species call type repertoire is mainly genetically determined, juvenile and adult individual call structures are far more plastic than previously thought. Second, when investigating individual vocal repertoires using a multi-level approach (i.e. sound unit, call type, vocal sequence) a flexible organization which enables a complex acoustic encoding of information is revealed. Third, the analysis of the social context and organization of vocal interactions at a multi-individual level demonstrates another dimension of vocal flexibility in both juveniles and adults. All those recent findings converge towards the idea that vocal flexibility in nonhuman primates has been largely underestimated so far. More comparative studies are now needed to understand the evolution of acoustic plasticity and communicative abilities in the primate lineage.