From grasping to grooming to gossip: innovative use of chimpanzee signals in novel environments supports both vocal and gestural theories of language origins

Leavens, David A, Taglialatela, Jared P and Hopkins, William D (2014) From grasping to grooming to gossip: innovative use of chimpanzee signals in novel environments supports both vocal and gestural theories of language origins. In: Pina, Marco and Gontier, Nathalie (eds.) The evolution of social communication in primates: a multidisciplinary approach. Interdisciplinary evolution research, 1 . Springer, New York, pp. 179-194. ISBN 9783319026688

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Abstract

The unique challenges posed by ecologically novel situations can illuminate the limits of flexibility in animal signaling systems. Here we describe the innovative application of species-typical calls by chimpanzees exposed to the novel circumstances in which the animals are dependent upon others to act on the world for them, what we have previously termed The Referential Problem Space. When chimpanzees are put into the Referential Problem Space, they frequently display attention-getting calls and other auditory signals, and they do this significantly more often when a human interlocuter is facing away from them than facing towards them. Here we report that the kinds of calls that chimpanzees use in these evolutionarily novel circumstances are, for the most part, amplified versions of the same calls that they display in grooming contexts. Thus, this class of auditory signals, used in affiliative, grooming contexts, is chosen overwhelmingly by chimpanzees for application towards novel ends. This is consistent with Dunbar's (1996) hypothesis that early humans substituted auditory contact for manual grooming as group sizes exceeded ca. 150 people. Moreover, these calls are primarily produced by supra-laryngeal modulation of the airstream. This is consistent with Corballis's (2002) hypothesis that intentional communication in humans moved from the hands to the mouth and then into the larynx. In contemporary chimpanzees, we find intentional modulation of calls focused at the fronts of their oral cavities, for most grooming calls. These patterns suggest that the last common ancestor of humans and the other great apes already had substantial voluntary control over non-voiced sounds. If this is correct, then the magnitude of neuroanatomical adaptations necessary for elaborated sound production in our hominin ancestors, after our split from the other great apes, is substantially reduced: humans were pre-adapted for speech.

Item Type: Book Section
Schools and Departments: School of Psychology > Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology > BF0180 Experimental psychology
B Philosophy. Psychology. Religion > BF Psychology > BF0309 Consciousness. Cognition Including learning, attention, comprehension, memory, imagination, genius, intelligence, thought and thinking, psycholinguistics, mental fatigue
B Philosophy. Psychology. Religion > BF Psychology > BF0608 Will. Volition. Choice. Control
B Philosophy. Psychology. Religion > BF Psychology > BF0660 Comparative psychology. Animal and human psychology
G Geography. Anthropology. Recreation > GN Anthropology > GN049 Physical anthropology. Somatology > GN280.7 Man as an animal. Simian traits versus human traits
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Depositing User: David Leavens
Date Deposited: 17 Mar 2014 09:37
Last Modified: 02 Sep 2015 15:01
URI: http://sro.sussex.ac.uk/id/eprint/46252

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