Abstract

Humans exhibit a uniquely broad array of complex tool-use, showing extraordinary talent in using objects to achieve their goals or change the environment. The use of tools makes difficult tasks easier. If this is the case in humans, why do we not find tool-use of similar sophistication in other animals? What are non-human animals' behavioural and cognitive responses to the similar challenges as those faced by humans living in close proximity to them for accessing some of the same food resources? These are the questions that we want start exploring with this project. To answer them, we need to look to the tool-use behaviour of other members of our own order, the Primates. Among non-human primates, chimpanzees show the most diverse, flexible and complex tool-using repertoires, that can include the combination of two or more tools for a single goal. The primary objective of the proposed research is to study tool-use behaviour of chimpanzees in Guinea-Bissau(GB), and to understand the cognitive responses applied to the solution of specific problems associated with obtaining inaccessible food items, not only in terms of complexity, but also in terms of cognitive flexibility. This objective will be reached by combining four different, but complementary approaches. Following Ingold's idea for studying human technology, to understand chimpanzee technical accomplishments we should not look only at the tools, but we have to understand users' knowledge associated with their use. This means putting the focus on the individuals' behaviour. As there is no published record of chimpanzee tool-use in GB, we will start by conducting a survey in three main areas of chimpanzee distribution range (Quinara, Tombali, Boé). Previous work in Cantanhez NP (Tombali) already confirmed the use of leaves for drinking water and also the use of tools for extracting honey from bee hives by chimpanzees. This initial phase will provide us with details on the diversity of the tool-kit, and will assist in planning future studies. In a second approach we will concentrate on central CNP, where we have been studying a chimpanzee community, to document resource availability (food items and raw material to use as tools). This information will allow us to test for a hypothesised correlation between scarcity of wild foods and increased frequency of tool-use behaviours to access for items otherwise inaccessible. It will also provide us with potential explanations for the absence of certain tool-use behaviours described for other wild chimpanzee populations. In a third approach we will study the behaviour of chimpanzees in extracting honey from beehives, using video trap-cameras and, whenever possible, direct observation and video-recording. This will allow us to subsequently code and analyse in detail the behaviour. The rationale for studying in detail chimpanzee honey extraction is three fold: (1) it is one of the only two tool-use behaviours confirmed for this community; (2) it is more complex than the use of leaves for drinking water, because it needs the use of more than one tool; (3) there is recent information (KH) that they not only extract honey from natural beehives, but that they have been increasing the frequency in accessing man-made beehives and extracting the honey, providing us with the opportunity to explore and compare different solutions given to the same cognitive problem, by the two species (chimpanzees and humans). A last approach will be to record and study human technique and use of tools to harvest honey from man-made beehives. Locals use tools made of materials available in the surrounding environment. This will allow us to compare the techniques and tools used by both species, in order to understand the solutions that different but closely related species devise for the same problem. The information gathered will also allow us to explore the possibility that proximity with humans might attract chimpanzees' attention to particular stimuli (food items) that they might not have explored otherwise. Important information about chimpanzee technology in nature continues to develop our understanding of their cognitive flexibility. The new information on chimpanzee tool-use from GB is valuable because it increases our understanding of their technological and behavioural variation. Our understanding of the degree of behavioural diversity and differences across populations is recent, and still in a state of continuous expansion. Knowledge about chimpanzee behaviour, cognitive capacities, and, in particular, technology is important to shed light on human behaviour, our evolutionary history, and on the evolutionary origins of the earliest human technology. As chimpanzees are in danger of extinction, from a conservation perspective it is urgent to document their local behavioural traditions. Priority populations to be conserved are selected considering not only their genetic, but also behavioural diversity.

Team