Abstract # 217:

Scheduled for Friday, June 21, 2013 12:45 PM-01:00 PM: Session 26 (San Geronimo Ballroom B) Oral Presentation


VOCAL SIGNALING IN CAPTIVE CHIMPANZEES (PAN TROGLODYTES) AND BONOBOS (PAN PANISCUS): IMPLICATIONS FOR THE ORIGIN OF AUTONOMOUS 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, 2Yerkes National Primate Research Center, 3Georgia State University
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     Despite being closely related, bonobos and chimpanzees exhibit notable behavioral differences. One of the most striking, but least studied, differences is in their vocal repertoires. In contrast to the low-frequency and noisy grunts and barks of chimpanzees, bonobos produce high-frequency tonal peeps and yelps. Although, it is unknown what accounts for these differences, one possibility is that differences in feeding ecology may have driven bonobos to become increasingly reliant on vocalizations to coordinate social behaviors and therefore subsequent selection for increased vocal control and flexibility occurred. We predicted that bonobos would pair their vocalizations with signals from other modalities less frequently than chimpanzees as their vocalizations contain sufficient information, without the need for greater specificity. We further predicted that interactions among bonobos would frequently occur when they are not in direct proximity of one another, whereas chimpanzees would be more likely to communicate face to face as they would require additional information than what is contained in the vocalization. Data were collected from 12 chimpanzees and 8 bonobos interacting with conspecifics. For each vocalization, whether or not there was a concomitant communicative signal (CCS), and whether or not the vocalization was directed towards another conspecific was recorded. Data (N=326) indicate that chimpanzees were more likely than bonobos to produce vocalizations with a CCS (chi-square, p<.001), and direct those vocalizations to a specific individual (chi-square, p<.001).