THE LEARNING AND USE OF GESTURAL SIGNALS BY YOUNG CHIMPANZEES - A TRANS-GENERATIONAL STUDY

Observations of chimpanzee gestural communication are reported. The ob servations represent the third longitudinal time point of an ongoing s tudy of the Yerkes Primate Center Field Station chimpanzee group. In c ontrast to observations at the first two time points, the current obse rvations are of a new generation of infants and juveniles. There were two questions. The first concerned how young chimpanzees used their ge stures, with special focus on the flexibility or intentionality displa yed. It was found that youngsters quite often used the same gesture in different contexts, and different gestures in the same context. In ad dition, they sometimes used gestures in combinations in a single socia l encounter, these combinations did not convey intentions that could n ot be conveyed by the component gestures however. It was also found th at individuals adjusted their choice of signals depending on the atten tional state of the recipient. The second question was how chimpanzees acquired their gestural signals. In general, it was found that there was little consistency in the use of gestures among individuals, espec ially for non-play gestures, with much individual variability both wit hin and across generations. There were also a number of idiosyncratic gestures used by single individuals at each time point. It was conclud ed from these results that youngsters were not imitatively learning th eir communicatory gestures from conspecifics, but rather that they wer e individually conventionalizing them with each other. Implications of these findings for the understanding of chimpanzee communication and social learning are discussed.