Filling in the gaps: Acoustic gradation increases in the vocal ontogeny of chimpanzees ( Pan troglodytes )

Autor: Guillaume Dezecache, Marina Davila-Ross, Derry James Taylor
Přispěvatelé: University of Portsmouth, Laboratoire de Psychologie Sociale et Cognitive (LAPSCO), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: American Journal of Primatology
American Journal of Primatology, 2021, 83 (5), ⟨10.1002/ajp.23249⟩
American Journal of Primatology, Wiley, 2021, 83 (5), ⟨10.1002/ajp.23249⟩
Taylor, D, Dezecache, G & Davila-Ross, M 2021, ' Filling in the gaps: Acoustic gradation increases in the vocal ontogeny of chimpanzees ( Pan troglodytes ) ', American Journal of Primatology . https://doi.org/10.1002/ajp.23249
ISSN: 0275-2565
1098-2345
DOI: 10.1002/ajp.23249⟩
Popis: International audience; Human vocal ontogeny is considered to be a process whereby a large repertoire of discrete sounds seemingly emerges from a smaller number of acoustically graded vocalizations. While adult chimpanzee vocal behavior is highly graded, its developmental trajectory is poorly understood. In the present study, we therefore examined the size and structure of the chimpanzee vocal repertoire at different stages of ontogeny. Audio recordings were collected on infant (N = 13) and juvenile (N = 13) semi-wild chimpanzees at Chimfunshi Wildlife Orphanage, Zambia, using focal and ad libitum sampling. All observed call types were acoustically measured. These were predominantly grunts, whimpers, laughs, screams, hoos, and barks and squeaks. A range of spectral and temporal acoustic parameters were extracted, and fuzzy c-means clustering was used to quantify the size and structure of the repertoire. The infant and juvenile vocal repertoires were both best described with the same number of clusters. However, compared to infants, juvenile call clusters were less distinct from one another and could be extracted only when a low level of overlap between call clusters was permitted. Moreover, the acoustic overlap between call clusters was significantly higher for juveniles. Overall, this pattern shows greater acoustic overlap in juvenile vocalizations compared to infants, suggesting a trend toward increased acoustic gradation in chimpanzee vocal ontogeny. This may imply in contrast to humans, chimpanzees become increasingly proficient in using graded signals effectively rather than developing a larger repertoire of more discrete sounds in ontogeny.
Databáze: OpenAIRE
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