Analysis of wild macaque stone tools used to crack oil palm nuts

The discovery of oil palm (Elaeis guineensis) nut-cracking by wild long-tailed macaques (Macaca fascicularis) is significant for the study of non-human primate and hominin percussive behaviour. Up until now, only West African chimpanzees (Pan troglodytes verus) and modern human populations were known to use stone hammers to crack open this particular hard-shelled palm nut. The addition of non-habituated, wild macaques increases our comparative dataset of primate lithic percussive behaviour focused on this one plant species. Here, we present an initial description of hammerstones used by macaques to crack oil palm nuts, recovered from active nut-cracking locations on Yao Noi Island, Ao Phang Nga National Park, Thailand. We combine a techno-typological approach with microscopic and macroscopic use-wear analysis of percussive damage to characterize the percussive signature of macaque palm oil nut-cracking tools. These artefacts are characterized by a high degree of battering and crushing on most surfaces, which is visible at both macro and microscopic levels. The degree and extent of this damage is a consequence of a dynamic interplay between a number of factors, including anvil morphology and macaque percussive techniques. Beyond the behavioural importance of these artefacts, macaque nut-cracking represents a new target for primate archaeological investigations, and opens new opportunities for comparisons between tool using primate species and with early hominin percussive behaviour, for which nutcracking has been frequently inferred

Social network analysis shows direct evidence for social transmission of tool use in wild chimpanzees

The authors are grateful to the Royal Zoological Society of Scotland for providing core funding for the Budongo Conservation Field Station. The fieldwork of CH was funded by the Leverhulme Trust, the Lucie Burgers Stichting, and the British Academy. TP was funded by the Canadian Research Chair in Continental Ecosystem Ecology, and received computational support from the Theoretical Ecosystem Ecology group at UQAR. The research leading to these results has received funding from the People Programme (Marie Curie Actions) and from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007–2013) REA grant agreement n°329197 awarded to TG, ERC grant agreement n° 283871 awarded to KZ. WH was funded by a BBSRC grant (BB/I007997/1).Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition-that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, "moss-sponging'' and "leaf-sponge re-use,'' in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most "cultural'' of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans.Publisher PDFPeer reviewe

Food cleaning in gorillas: Social learning is a possibility but not a necessity

Food cleaning is widespread in the animal kingdom, and a recent report confirmed that (amongst other behaviours) wild western lowland gorillas also show food cleaning. The authors of this report conclude that this behaviour, based on its distribution patterns, constitutes a potential candidate for culture. While different conceptualisations of culture exist, some more and some less reliant on behavioural form copying, all of them assign a special role to social learning processes in explaining potentially cultural behaviours. Here we report the results of an experiment that tested to what extent food cleaning behaviour in a group of captive Western lowland gorillas (Gorilla gorilla gorilla) relies on social learning processes. Subjects were provided with clean and dirty apples. When they were provided with dirty apples, all subjects showed evidence of food cleaning in at least 75% of trials. Preferred cleaning techniques differed between individuals, four out of five of subjects expressed a behaviour analogous to that reported in wild conspecifics. Given this occurrence of food cleaning in a culturally unconnected population of gorillas, we conclude that social learning is unlikely to play a central role in the emergence of the food cleaning behavioural form in Western lowland gorillas; instead, placing a greater emphasis on individual learning of food cleaning’s behavioural form

Object manipulation and tool use in Nicobar long-tailed macaques (Macaca fascicularis umbrosus)

This is an accepted manuscript of an article published by Springer in International Journal of Primatology on 08/09/2020, available online: https://link.springer.com/article/10.1007%2Fs10764-020-00141-y The accepted version of the publication may differ from the final published version.Object manipulation and tool use by non-human primates have received considerable attention from primatologists and anthropologists, because of their broad implications for understanding the evolution of tool use in humans. To date, however, most of the studies on this topic have focused on apes, given their close evolutionary relationship with humans. In contrast, fewer studies on tool use and object manipulation have been conducted on monkeys. Documenting and studying object manipulation and tool use in species that are more distantly related to humans can provide a broader perspective on the evolutionary origins of this behaviour. We present a detailed description of toolaided behaviours and object manipulation by Nicobar long-tailed macaques ( Macaca fascicularis umbrosus ) living along the coastlines of Great Nicobar Island. We made observations from December 2018 to March 2019, using ad libitum and focal sampling methods. We observed behaviours related to object manipulation and tool use in six different behavioural contexts (foraging, hygiene, communication, play, selfdirected and self-hygiene behaviour) involving eight different types of objects, namely resonance rod, play object, rolling platform, scraping tool, dental groom, pounding substrate, leaves as grip pads and wipers, and stimulation tool. We observed that males were involved in tool use and object manipulation more frequently than females. Our results add to existing records of object manipulation, tool-use behaviour and tool variants displayed by non-human primates, showing that Nicobar macaques perform multiple and diverse tool-aided behaviours

Supplementary Material 2 from Analysis of wild macaque stone tools used to crack oil palm nuts

Dimensional and UAI data for all hammerstones studie

Supplementary Material 1 from Analysis of wild macaque stone tools used to crack oil palm nuts

Video of macaque oil palm nut cracking on Yao Noi Island, Thailan

Tool transfers are a form of teaching among chimpanzees

Teaching is a form of high-fidelity social learning that promotes human cumulative culture. Although recently documented in several nonhuman animals, teaching is rare among primates. In this study, we show that wild chimpanzees (Pan troglodytes troglodytes) in the Goualougo Triangle teach tool skills by providing learners with termite fishing probes. Tool donors experienced significant reductions in tool use and feeding, while tool recipients significantly increased their tool use and feeding after tool transfers. These transfers meet functional criteria for teaching: they occur in a learner’s presence, are costly to the teacher, and improve the learner’s performance. Donors also showed sophisticated cognitive strategies that effectively buffered them against potential costs. Teaching is predicted when less costly learning mechanisms are insufficient. Given that these chimpanzees manufacture sophisticated, brush-tipped fishing probes from specific raw materials, teaching in this population may relate to the complexity of these termite-gathering tasks

Complexity in animal behaviour: towards common ground

International audienceThe ambiguity of the term ‘complex’ in studies of animal behaviour and cognition can lead to theoretical and methodological disputes, as there seems to be little common ground regarding the features thought to introduce complex- ity. Based on examples not only in human and nonhuman primates but also in some species of birds, we explore three dimensions of complexity: motor precision, coordination, and anticipatory planning. We argue that it is necessary to identify which dimensions are present in each study to formulate and explore relevant questions in behavioural sciences, especially with an evolutionary perspective