Technological response of wild macaques (Macaca fascicularis) to anthropogenic change

Anthropogenic disturbances have a detrimental impact on the natural world; the vast expansion of palm oil monocultures is one of the most significant agricultural influences. Primates worldwide consequently have been affected by the loss of their natural ecosystems. Long-tailed macaques (Macaca fascilularis) in Southern Thailand have, however, learned to exploit oil palm nuts using stone tools. Using camera traps, we captured the stone tool behavior of one macaque group in Ao Phang-Nga National Park. Line transects placed throughout an abandoned oil palm plantation confirmed a high abundance of nut cracking sites. Long-tailed macaques previously have been observed using stone tools to harvest shellfish along the coasts of Thailand and Myanmar. The novel nut processing behavior indicates the successful transfer of existing lithic technology to a new food source. Such behavioral plasticity has been suggested to underlie cultural behavior in animals, suggesting that long-tailed macaques have potential to exhibit cultural tendencies. The use of tools to process oil palm nuts across multiple primate species allows direct comparisons between stone tool using nonhuman primates living in anthropogenic environments

In search of animal normativity : a framework for studying social norms in non-human animals

Funding: K. A. and E. W. were supported by the Templeton World Charity Foundation through the Diverse Intelligence initiative. K. A. was supported by SSHRC 435-2022-0749. S. F. B. was supported by NSF 2127375, NSF SES 1919305, and TWCF0471. T. G. was supported by Swiss National Science Foundation PCEFP1_186832. C. H. was supported by European Union's 8th Framework Programme, Horizon 2020 802719. L. M. H. was supported by NIH U42 OD013117-15A. C. K. was supported by TWCF-20647 and the CIFAR Azrieli Global Scholars program. L. V. L. was supported by the Max Planck Society. J. T. was supported by NIH R21 MH129902 and NIH R01 AG071173.Social norms – rules governing which behaviours are deemed appropriate or inappropriate within a given community – are typically taken to be uniquely human. Recently, this position has been challenged by a number of philosophers, cognitive scientists, and ethologists, who have suggested that social norms may also be found in certain non-human animal communities. Such claims have elicited considerable scepticism from norm cognition researchers, who doubt that any non-human animals possess the psychological capacities necessary for normative cognition. However, there is little agreement among these researchers about what these psychological prerequisites are. This makes empirical study of animal social norms difficult, since it is not clear what we are looking for and thus what should count as behavioural evidence for the presence (or absence) of social norms in animals. To break this impasse, we offer an approach that moves beyond contested psychological criteria for social norms. This approach is inspired by the animal culture research program, which has made a similar shift away from heavily psychological definitions of ‘culture’ to become organised around a cluster of more empirically tractable concepts of culture. Here, we propose an analogous set of constructs built around the core notion of a normative regularity, which we define as a socially maintained pattern of behavioural conformity within a community. We suggest methods for studying potential normative regularities in wild and captive primates. We also discuss the broader scientific and philosophical implications of this research program with respect to questions of human uniqueness, animal welfare and conservation.Publisher PDFPeer reviewe

Group-specific archaeological signatures of stone tool use in wild macaques

Stone tools in the prehistoric record are the most abundant source of evidence for understanding early hominin technological and cultural variation. The field of primate archaeology is well placed to improve our scientific knowledge by using the tool behaviours of living primates as models to test hypotheses related to the adoption of tools by early stone-age hominins. Previously we have shown that diversity in stone tool behaviour between neighbouring groups of long-tailed macaques (Macaca-fascicularis) could be explained by ecological and environmental circumstances (Luncz et al., 2017b). Here however, we report archaeological evidence, which shows that the selection and reuse of tools cannot entirely be explained by ecological diversity. These results suggest that tool-use may develop differently within species of old-world monkeys, and that the evidence of material culture can differ within the same timeframe at local geographic scales and in spite of shared environmental and ecological settings

In search of animal normativity: a framework for studying social norms in non-human animals

Social norms – rules governing which behaviours are deemed appropriate or inappropriate within a given community – are typically taken to be uniquely human. Recently, this position has been challenged by a number of philosophers, cognitive scientists, and ethologists, who have suggested that social norms may also be found in certain non-human animal communities. Such claims have elicited considerable scepticism from norm cognition researchers, who doubt that any non-human animals possess the psychological capacities necessary for normative cognition. However, there is little agreement among these researchers about what these psychological prerequisites are. This makes empirical study of animal social norms difficult, since it is not clear what we are looking for and thus what should count as behavioural evidence for the presence (or absence) of social norms in animals. To break this impasse, we offer an approach that moves beyond contested psychological criteria for social norms. This approach is inspired by the animal culture research program, which has made a similar shift away from heavily psychological definitions of ‘culture’ and to become organized around a cluster of more empirically tractable concepts of culture. Here, we propose an analogous set of constructs built around the core notion of a normative regularity, which we define as a socially maintained pattern of behavioural conformity within a community. We suggest methods for studying potential normative regularities in wild and captive primates. We also discuss the broader scientific and philosophical implications of this research program with respect to questions of human uniqueness, animal welfare and conservation

A primate model for the origin of flake technology

When and how human ancestors first used tools remains unknown, despite intense research into the origins of technology. It has been hypothesized that the evolutionary roots of stone flake technology has its origin in percussive behavior. Before intentional stone flaking, hominins potentially engaged in various percussive behaviors resulting in accidental flake detachments. We refer to this scenario as the 'by-product hypothesis.' In this scenario, repeated detachments of sharp stone fragments eventually resulted in intentional flake production. Here, we tested the circumstances of accidental flake production as a by-product of percussive foraging in wild capuchin monkeys (Sapajus libidinosus) from Brazil, the only nonhuman primate known to habitually produce sharp-edged flakes through a percussive behavior. We conducted field experiments where we tested the potential for accidental flake production during nut cracking. We provided three different types of stone with varied material properties as anvils to assess the circumstances in which accidental production of sharp-edged flakes occurs during nut cracking. A further freehand knapping experiment, with the raw material that exhibited accidental flake detachments, allows a direct comparison of flakes that have been intentionally produced by an experienced knapper and flakes produced during nut cracking by capuchin monkeys. Our results show that raw material quality and morphology significantly affect the rate of sharp-edged flake production as well as the resulting lithic signature of this behavior. In addition, accidental flakes produced during capuchin nut cracking on highly isotropic raw material are similar in many respects to intentionally produced flakes by a human knapper. Our field experiments highlight the fact that nut-cracking behavior can lead to the unintentional production of substantial quantities of sharp-edged flakes and therefore supports the 'by-product hypothesis' as a potential mechanism for the emergence of hominin flake technology

Simulation and social network analysis provide insight into the acquisition of tool behaviour in hybrid macaques

The pathways through which primates acquire skills are a central focus of cultural evolution studies. The roles of social and genetic inheritance processes in skill acquisition are often confounded by environmental factors. Hybrid macaques from Koram Island (Thailand) provide an opportunity to examine the roles of inheritance and social learning to skill acquisition within a single ecological setting. These hybrids are a cross between tool-using Burmese long-tailed (Macaca fascicularis aurea) and non-tool-using common long-tailed macaques (Macaca fascicularis fascicularis). This population provides an opportunity to explore the roles of social learning and inheritance processes while being able to exclude underlying ecological factors. Here, we investigate the roles of social learning and inheritance in tool use prevalence within this population using social network analysis and simulation. Agent-based modelling (ABM) is used to generate expectations for how social/asocial learning and inheritance structure the patterning in a social network. The results of the simulation show that various transmission mechanisms can be differentiated based on associations between individuals in a social network. The results provide an investigative framework for discussing tool use transmission pathways in the Koram social network. By combining ABM, network analysis, and behavioural data from the field we can investigate the roles social learning and inheritance play in tool acquisition of wild primates

Modeling Oldowan tool transport from a primate perspective

Living nonhuman primates have long served as a referential framework for understanding various aspects of hominin biological and cultural evolution. Comparing the cognitive, social, and ecological contexts of nonhuman primate and hominin tool use has allowed researchers to identify key adaptations relevant to the evolution of hominin behavior. Although the Oldowan is often considered to be a major evolutionary milestone, it has been argued that the Oldowan is rather an extension of behaviors already present in the ape lineage. This is based on the fact that while apes move tools through repeated, unplanned, short-distance transport bouts, they produce material patterning often associated with longdistance transport, planning, and foresight in the Oldowan. Nevertheless, remain fundamental differences in how Oldowan core and flake technology and nonhuman primate tools are used. The goal of the Oldowan hominins is to produce sharp-edged flakes, whereas nonhuman primates use stone tools primarily as percussors. Here, we present an agent-based model that investigates the explanatory power of the ape tool transport model in light of these differences. The model simulates the formation of the Oldowan record under the conditions of an accumulated short-distance transport pattern, as seen in extant chimpanzees. Our results show that while ape tool transport can account for some of the variation observed in the archaeological record, factors related to use-life duration severely limit how far an Oldowan core can be moved through repeated short-distance transport bouts. Thus, the ape tool transport has limitations in its ability to explain patterns in the Oldowan. These results provide a basis for discussing adaptive processes that would have facilitated the development of the Oldowan. (c) 2023 Elsevier Ltd. All rights reserved.info:eu-repo/semantics/publishedVersio