Ecological variation influences the appearance and maintenance of tool use in animals, either due to necessity or opportunity, but little is known about the relative importance of these two factors. Here, we combined long-term behavioural data on feeding and travelling with six years of field experiments in a wild chimpanzee community. In the experiments, subjects engaged with natural logs, which contained energetically valuable honey that was only accessible through tool use. Engagement with the experiment was highest after periods of low fruit availability involving more travel between food patches, while instances of actual tool-using were significantly influenced by prior travel effort only. Additionally, combining data from the main chimpanzee study communities across Africa supported this result, insofar as groups with larger travel efforts had larger tool repertoires. Travel thus appears to foster tool use in wild chimpanzees and may also have been a driving force in early hominin technological evolution.
- Thibaud Gruber
- Klaus Zuberbühler
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Permission to conduct the chimpanzee research was given by Uganda Wildlife Authority (UWA, permit FOD/33/02 to TG) and Uganda National Council for Science and Technology (UNCST, permit ns431 to TG). Research protocols were reviewed and approved by the veterinary staff at Budongo Conservation Field Station. Ethical approval was given by the Ethics Committees at the School of Psychology, University of St Andrews and the University of Neuchâtel.
- Russ Fernald, Stanford University, United States
© 2016, Gruber et al.
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