The Relationship Between Tool Use and Prey Availability in Chimpanzees (Pan troglodytes schweinfurthii) of Northern Democratic Republic of Congo

Primate archaeology 3.0

The new field of primate archaeology investigates the technological behavior and material record of nonhuman primates, providing valuable comparative data on our understanding of human technological evolution. Yet, paralleling hominin archaeology, the field is largely biased toward the analysis of lithic artifacts. While valuable comparative data have been gained through an examination of extant nonhuman primate tool use and its archaeological record, focusing on this one single aspect provides limited insights. It is therefore necessary to explore to what extent other non-technological activities, such as non-tool aided feeding, traveling, social behaviors or ritual displays, leave traces that could be detected in the archaeological record. Here we propose four new areas of investigation which we believe have been largely overlooked by primate archaeology and that are crucial to uncovering the full archaeological potential of the primate behavioral repertoire, including that of our own: (1) Plant technology; (2) Archaeology beyond technology; (3) Landscape archaeology; and (4) Primate cultural heritage. We discuss each theme in the context of the latest developments and challenges, as well as propose future directions. Developing a more "inclusive" primate archaeology will not only benefit the study of primate evolution in its own right but will aid conservation efforts by increasing our understanding of changes in primate-environment interactions over time.

Tool use by Nigeria-Cameroon chimpanzees for driver ant predation in Kom-Wum Forest Reserve, North-West Region Cameroon

Chimpanzees feed on driver ants (Dorylus sp.) using different tools and predation techniques that vary among populations and can be affected by availability of ant species as well as ecological and social-learning factors. At the Kom-Wum Forest Reserve (KWFR) in Cameroon, we investigated tool use behavior in Nigerian-Cameroon chimpanzees (Pan troglodytes ellioti), examining the characteristics of tools used in driver ant predation, looking for possible seasonal patterns and comparing our results to those from other study sites. We recovered 83 tools along line transects and recces (reconnaissance) during two seasons. We found that chimpanzees used tools with blunting and dirty ends (possible digging and probing tools) and tools without (dipping tools), in driver ant predation. Tools with dirty ends tended to be thicker (N = 52), and thinner tools were less likely to have dirt (N = 31). Tools recovered in the wet season (N = 62), were significantly shorter and thicker than those recovered in the dry season (N = 21). Furthermore, driver ant tools recovered at KWFR are on average the longest yet recorded insect dipping tools for chimpanzees comparable to those used in North Uele. We found no evidence of nut-cracking, tool use for honey bee nor termite consumption and did not observe the potential prey remains in chimpanzee faeces despite their presence in the reserve. Our results suggest that seasonality significantly contributes to a divergence in the form of tools selected for driver ant predation.