title: Body language: The interplay between positional behavior and gestural signaling in the genus Pan and its implications for language evolution.
abstract: OBJECTIVE
  The gestural repertoires of bonobos and chimpanzees are well documented, but the relationship between gestural signaling and positional behavior (i.e., body postures and locomotion) has yet to be explored. Given that one theory for language evolution attributes the emergence of increased gestural communication to habitual bipedality, this relationship is important to investigate.
  
  
  METHODS
  In this study, we examined the interplay between gestures, body postures, and locomotion in four captive groups of bonobos and chimpanzees using ad libitum and focal video data.
  
  
  RESULTS
  We recorded 43 distinct manual (involving upper limbs and/or hands) and bodily (involving postures, locomotion, head, lower limbs, or feet) gestures. In both species, actors used manual and bodily gestures significantly more when recipients were attentive to them, suggesting these movements are intentionally communicative. Adults of both species spent less than 1.0% of their observation time in bipedal postures or locomotion, yet 14.0% of all bonobo gestures and 14.7% of all chimpanzee gestures were produced when subjects were engaged in bipedal postures or locomotion. Among both bonobo groups and one chimpanzee group, these were mainly manual gestures produced by infants and juvenile females. Among the other chimpanzee group, however, these were mainly bodily gestures produced by adult males in which bipedal posture and locomotion were incorporated into communicative displays.
  
  
  CONCLUSIONS
  Overall, our findings reveal that bipedality did not prompt an increase in manual gesturing in these study groups. Rather, body postures and locomotion are intimately tied to many gestures and certain modes of locomotion can be used as gestures themselves.
authors: Thompson Writing Program, Duke University, NC.|New York Consortium in Evolutionary Primatology, NY.
authors: Lindsey W
authors: LW
authors: Smith
authors: New York Consortium in Evolutionary Primatology, NY.|Department of Biological Sciences, Human & Evolutionary Biology, University of Southern California, CA.|AAAS Science & Technology Policy Fellow, Assigned to the National Science Foundation, VA.
authors: Roberto A
authors: RA
authors: Delgado
mesh_terms: D000819:Animal Communication; D000818:Animals; D000885:Anthropology, Physical; D005075:Biological Evolution; D005260:Female; D005868:Gestures; D008297:Male; D019974:Pan paniscus / Q000502:physiology*; D002679:Pan troglodytes / Q000502:physiology*; D011187:Posture / Q000502:physiology*
keywords: bonobos; chimpanzees; gestures; locomotion; postures