, Volume 36, Issue 4, pp 489–500

Pestle-pounding behavior of wild chimpanzees at Bossou, Guinea: A newly observed tool-using behavior

  • Gen Yamakoshi
  • Yukimaru Sugiyama

DOI: 10.1007/BF02382871

Cite this article as:
Yamakoshi, G. & Sugiyama, Y. Primates (1995) 36: 489. doi:10.1007/BF02382871


A new type of tool-using behavior was observed in a group of wild chimpanzees (Pan troglodytes verus) at Bossou, Guinea. The chimpanzees used the leaf-petiole of oil-palm trees (Elaeis guineensis) as a pounding tool to deepen a hole in the oil-palm crown which appeared after the chimpanzees had pulled out the central young shoots. Finally, the chimpanzees extracted and ate the apical meristem or apical bud of the oil-palm tree which is edible but inaccessible without such tool use. The motor pattern which the chimpanzees employed is similar to that used for termite-nest digging but it is more exaggerated and requires great force. The behavior is reminiscent of pestlepounding. The chimpanzees exploit substantial amounts of food with this tool-using skill, compensating for insufficient fruit foods in the primary forest. This tool-using behavior was first observed in 1990 and, to date, almost half of the group members have been confirmed to use the pestle tool. It appears that this tool-using behavior was invented recently and has since spread widely throughout the group as a habitual one.

Key Words

Chimpanzees Pestle-pounding Oil-palm Tool use Nutritional compensation 

Copyright information

© Japan Monkey Centre 1995

Authors and Affiliations

  • Gen Yamakoshi
    • 1
  • Yukimaru Sugiyama
    • 1
  1. 1.Primate Research InstituteKyoto UniversityAichiJapan

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