Chimpanzee alarm call production meets key criteria for intentionality.

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Schel, Anne Marijke; Townsend, Simon W; Machanda, Zarin; Zuberbühler, Klaus; Slocombe, Katie E
Year of Publication: 2013
Journal: PLoS One
Volume: 8
Issue: 10
Pagination: e76674
Date Published: 2013
Publication Language: eng
ISSN: 1932-6203
Keywords: Animals, Fixation, Ocular, Gestures, Humans, Intention, Pan troglodytes, Snakes, Sound Spectrography, Vocalization, Animal

Determining the intentionality of primate communication is critical to understanding the evolution of human language. Although intentional signalling has been claimed for some great ape gestural signals, comparable evidence is currently lacking for their vocal signals. We presented wild chimpanzees with a python model and found that two of three alarm call types exhibited characteristics previously used to argue for intentionality in gestural communication. These alarm calls were: (i) socially directed and given to the arrival of friends, (ii) associated with visual monitoring of the audience and gaze alternations, and (iii) goal directed, as calling only stopped when recipients were safe from the predator. Our results demonstrate that certain vocalisations of our closest living relatives qualify as intentional signals, in a directly comparable way to many great ape gestures. We conclude that our results undermine a central argument of gestural theories of language evolution and instead support a multimodal origin of human language.

DOI: 10.1371/journal.pone.0076674
Alternate Journal: PLoS ONE