Abstract # 5956 Event # 13:

Scheduled for Saturday, September 13, 2014 01:45 PM-02:00 PM: Session 4 (Decatur A) Oral Presentation


COMMUNICATIVE DIFFERENCES BETWEEN CHIMPANZEES AND BONOBOS AND THEIR IMPLICATIONS FOR THE ORIGINS OF HUMAN SPEECH

J. P. Taglialatela1,2, B. A. Moore1 and W. D. Hopkins2,3
1Kennesaw State University, Department of Biology and Physics, Kennesaw, GA 30144, USA, 2Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, 3Neuroscience Institute and The Language Research Center, Georgia State University
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     Despite being closely related – diverging from a common ancestor only approximately 1 million years ago - bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) exhibit some notable behavioral differences. One of the most striking, but least studied, differences between these species are their vocal repertoires. Whereas chimpanzees produce low frequency, noisy barks and grunts, bonobos produce relatively high-frequency, tonal peeps and yelps. We hypothesized that differences between the Pan species’ feeding ecology may have favored bonobos to become increasingly reliant on vocalizations to coordinate social behaviors and therefore subsequent selection for increased vocal control and flexibility occurred – a situation that may have been similar to the selection pressures faced by early hominins. To evaluate this hypothesis, 1571 chimpanzee vocal events and 612 bonobo vocal events were analyzed from digital audio/video recordings of communicative interactions among captive apes. The data indicate that chimpanzees were more likely than bonobos to pair their vocalizations with signals from other communicative modalities, and to direct vocalizations to specific individuals. In contrast, bonobos were more likely than chimpanzees to produce vocalizations that were not bound to a specific social context. These results support the hypothesis that observed differences in the communicative strategies of the two Pan species were driven by differences in foraging strategies since they diverged from a common ancestor approximately one million years ago.