Geographic variation in the calls of wild chimpanzees: A reassessment

Abstract

Male chimpanzees produce a species‐typical call, the pant hoot, to communicate to conspecifics over long‐distances. Calls given by males from the well‐known Gombe and Mahale populations typically consist of four different phases: an introduction, build‐up, climax, and let‐down. Recent observations suggest that chimpanzees living in the Kibale National Park, Uganda, consistently give calls that lack a build‐up and are thus qualitatively distinguishable acoustically from those made by other East African conspecifics. We analyzed additional recordings from Mahale and Kibale to re‐examine geographic variation in chimpanzee calls. Results indicate that males from both sites produce pant hoots containing all four parts of the call. Calls made by chimpanzees from the two populations, however, differ in quantitative acoustic measures. Specifically, males at Kibale initiate their calls with significantly longer elements and build‐up over briefer periods at slower rates than individuals from Mahale. Kibale males also deliver acoustically less variable calls than chimpanzees at Mahale. Although climax elements do not differ between populations in any single acoustic feature, discriminant function analysis reveals that acoustic variables can be used in combination to assign calls to the correct population at rates higher than that expected by chance. Ecological factors related to differences in habitat acoustics, the sound environment of the local biota, and body size are likely to account for these observed macrogeographic variations in chimpanzee calls. Am. J. Primatol. 47:133–151, 1999. © 1999 Wiley‐Liss, Inc.

Convergence of calls as animals form social bonds, active compensation for noisy communication channels, and the evolution of vocal learning in mammals.

“…For example, early papers on geographical variation in pant hoots of chimpanzees (Pan troglodytes) suggested that this variation was evidence for production learning in this species (Mitani et al 1992;Mitani and Brandt 1994;Clark Arcadi 1996). Mitani et al (1999) reassessed the interpretation of geographical variation in chimpanzee calls. They concluded "The preceding observations suggest that genetically based rather than cultural [sensu McGrew, 1992] differences are likely to underlie any vocal variations that exist between Mahale and Kibale chimpanzees."…”

Auditory capacities in Middle Pleistocene humans from the Sierra de Atapuerca in Spain

“…Of course, this relative loss does not mean that chimpanzees cannot hear in the midrange frequencies, but rather that they are adapted to hear best at Ϸ1 kHz and 8 kHz. It is interesting to note that the species-specific pant-hoots regularly emitted by wild chimpanzees to communicate with conspecifics over long distances concentrate the acoustic information at Ϸ1 kHz (10).…”

Usage and comprehension of manual gestures in wild chimpanzees

“…van Hooff, 1971, van Hooff, 1967, Parr et al, 2007, Parr et al, 2002, Marler and Tenaza, 1977, Marler and Hobbett, 1975, Marler, 1969, Mitani et al, 1999. Repertoire of manual gestural communication in chimpanzees to date received limited research attention and has been studied within broader framework of the whole gesture repertoire focusing on all communicative bodily movements.…”

“…In addition, the gestural repertoire size identified here is similar to the repertoire size van Hooff, 1971, van Hooff, 1967, Parr et al, 2007, Marler and Tenaza, 1977, Marler and Hobbett, 1975, Marler, 1969, Mitani et al, 1999. with both the complexity of the social system and the complexity of cognitive skills in primates (see also Aiello and Dunbar, 1993, Dunbar, 1998, Dunbar, 1993, Dunbar, 1996.…”