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Malherbe M, Samuni L, Ebel SJ, Kopp KS, Crockford C, Wittig RM. Protracted development of stick tool use skills extends into adulthood in wild western chimpanzees. PLoS Biol 2024; 22:e3002609. [PMID: 38713644 DOI: 10.1371/journal.pbio.3002609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 03/28/2024] [Indexed: 05/09/2024] Open
Abstract
Tool use is considered a driving force behind the evolution of brain expansion and prolonged juvenile dependency in the hominin lineage. However, it remains rare across animals, possibly due to inherent constraints related to manual dexterity and cognitive abilities. In our study, we investigated the ontogeny of tool use in chimpanzees (Pan troglodytes), a species known for its extensive and flexible tool use behavior. We observed 70 wild chimpanzees across all ages and analyzed 1,460 stick use events filmed in the Taï National Park, Côte d'Ivoire during the chimpanzee attempts to retrieve high-nutrient, but difficult-to-access, foods. We found that chimpanzees increasingly utilized hand grips employing more than 1 independent digit as they matured. Such hand grips emerged at the age of 2, became predominant and fully functional at the age of 6, and ubiquitous at the age of 15, enhancing task accuracy. Adults adjusted their hand grip based on the specific task at hand, favoring power grips for pounding actions and intermediate grips that combine power and precision, for others. Highly protracted development of suitable actions to acquire hidden (i.e., larvae) compared to non-hidden (i.e., nut kernel) food was evident, with adult skill levels achieved only after 15 years, suggesting a pronounced cognitive learning component to task success. The prolonged time required for cognitive assimilation compared to neuromotor control points to selection pressure favoring the retention of learning capacities into adulthood.
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Affiliation(s)
- Mathieu Malherbe
- Ape Social Mind Lab, Institut des Sciences Cognitives Marc Jeannerod, UMR5229 CNRS, Lyon, France
- Department of Human Behavior, Ecology and Culture, MPI for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, CSRS, Abidjan, Côte d'Ivoire
| | - Liran Samuni
- Taï Chimpanzee Project, CSRS, Abidjan, Côte d'Ivoire
- Cooperative Evolution Lab, German Primate Center, Göttingen, Germany
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Sonja J Ebel
- Comparative Cultural Psychology, MPI for Evolutionary Anthropology, Leipzig, Germany
- Human Biology & Primate Cognition, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Kathrin S Kopp
- Comparative Cultural Psychology, MPI for Evolutionary Anthropology, Leipzig, Germany
- Human Biology & Primate Cognition, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Catherine Crockford
- Ape Social Mind Lab, Institut des Sciences Cognitives Marc Jeannerod, UMR5229 CNRS, Lyon, France
- Taï Chimpanzee Project, CSRS, Abidjan, Côte d'Ivoire
| | - Roman M Wittig
- Ape Social Mind Lab, Institut des Sciences Cognitives Marc Jeannerod, UMR5229 CNRS, Lyon, France
- Department of Human Behavior, Ecology and Culture, MPI for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, CSRS, Abidjan, Côte d'Ivoire
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2
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Pascual-Garrido A, Carvalho S, Almeida-Warren K. Primate archaeology 3.0. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24835. [PMID: 37671610 DOI: 10.1002/ajpa.24835] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 07/25/2023] [Accepted: 08/03/2023] [Indexed: 09/07/2023]
Abstract
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.
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Affiliation(s)
- Alejandra Pascual-Garrido
- Primate Models for Behavioural Evolution Lab, Institute of Human Sciences, University of Oxford, Oxford, UK
| | - Susana Carvalho
- Primate Models for Behavioural Evolution Lab, Institute of Human Sciences, University of Oxford, Oxford, UK
- Interdisciplinary Centre for Archaeology and the Evolution of Human Behaviour, University of Algarve, Faro, Portugal
- Gorongosa National Park, Sofala, Mozambique
| | - Katarina Almeida-Warren
- Primate Models for Behavioural Evolution Lab, Institute of Human Sciences, University of Oxford, Oxford, UK
- Interdisciplinary Centre for Archaeology and the Evolution of Human Behaviour, University of Algarve, Faro, Portugal
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3
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Friederici AD, Wittig RM, Anwander A, Eichner C, Gräßle T, Jäger C, Kirilina E, Lipp I, Düx A, Edwards LJ, Girard-Buttoz C, Jauch A, Kopp KS, Paquette M, Pine KJ, Unwin S, Haun DBM, Leendertz FH, McElreath R, Morawski M, Gunz P, Weiskopf N, Crockford C. Brain structure and function: a multidisciplinary pipeline to study hominoid brain evolution. Front Integr Neurosci 2024; 17:1299087. [PMID: 38260006 PMCID: PMC10800984 DOI: 10.3389/fnint.2023.1299087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 12/07/2023] [Indexed: 01/24/2024] Open
Abstract
To decipher the evolution of the hominoid brain and its functions, it is essential to conduct comparative studies in primates, including our closest living relatives. However, strong ethical concerns preclude in vivo neuroimaging of great apes. We propose a responsible and multidisciplinary alternative approach that links behavior to brain anatomy in non-human primates from diverse ecological backgrounds. The brains of primates observed in the wild or in captivity are extracted and fixed shortly after natural death, and then studied using advanced MRI neuroimaging and histology to reveal macro- and microstructures. By linking detailed neuroanatomy with observed behavior within and across primate species, our approach provides new perspectives on brain evolution. Combined with endocranial brain imprints extracted from computed tomographic scans of the skulls these data provide a framework for decoding evolutionary changes in hominin fossils. This approach is poised to become a key resource for investigating the evolution and functional differentiation of hominoid brains.
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Affiliation(s)
- Angela D. Friederici
- Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Roman M. Wittig
- Evolution of Brain Connectivity Project, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Institute for Cognitive Sciences Marc Jeannerod, UMR CNRS, University Claude Bernard Lyon, Bron, France
- Taï Chimpanzee Project, CSRS, Abidjan, Côte d'Ivoire
| | - Alfred Anwander
- Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Cornelius Eichner
- Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Tobias Gräßle
- Epidemiology of Highly Pathogenic Microorganisms, Robert Koch Institute, Berlin, Germany
| | - Carsten Jäger
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Medical Faculty, Center of Neuropathology and Brain Research, Paul Flechsig Institute, University of Leipzig, Leipzig, Germany
| | - Evgeniya Kirilina
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Ilona Lipp
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Ariane Düx
- Epidemiology of Highly Pathogenic Microorganisms, Robert Koch Institute, Berlin, Germany
- Helmholtz Institute for One Health, University of Greifswald, Greifswald, Germany
| | - Luke J. Edwards
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Cédric Girard-Buttoz
- Evolution of Brain Connectivity Project, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Institute for Cognitive Sciences Marc Jeannerod, UMR CNRS, University Claude Bernard Lyon, Bron, France
| | - Anna Jauch
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Kathrin S. Kopp
- Department of Comparative Cultural Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Michael Paquette
- Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Kerrin J. Pine
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Steve Unwin
- School of Bioscience, University of Birmingham, Birmingham, United Kingdom
| | - Daniel B. M. Haun
- Department of Comparative Cultural Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Fabian H. Leendertz
- Epidemiology of Highly Pathogenic Microorganisms, Robert Koch Institute, Berlin, Germany
- Helmholtz Institute for One Health, University of Greifswald, Greifswald, Germany
| | - Richard McElreath
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Markus Morawski
- Medical Faculty, Center of Neuropathology and Brain Research, Paul Flechsig Institute, University of Leipzig, Leipzig, Germany
| | - Philipp Gunz
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Nikolaus Weiskopf
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Faculty of Physics and Earth System Sciences, Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany
| | - Catherine Crockford
- Evolution of Brain Connectivity Project, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Institute for Cognitive Sciences Marc Jeannerod, UMR CNRS, University Claude Bernard Lyon, Bron, France
- Taï Chimpanzee Project, CSRS, Abidjan, Côte d'Ivoire
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Tkaczynski PJ, Mafessoni F, Girard-Buttoz C, Samuni L, Ackermann CY, Fedurek P, Gomes C, Hobaiter C, Löhrich T, Manin V, Preis A, Valé PD, Wessling EG, Wittiger L, Zommers Z, Zuberbuehler K, Vigilant L, Deschner T, Wittig RM, Crockford C. Shared community effects and the non-genetic maternal environment shape cortisol levels in wild chimpanzees. Commun Biol 2023; 6:565. [PMID: 37237178 DOI: 10.1038/s42003-023-04909-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 05/03/2023] [Indexed: 05/28/2023] Open
Abstract
Mechanisms of inheritance remain poorly defined for many fitness-mediating traits, especially in long-lived animals with protracted development. Using 6,123 urinary samples from 170 wild chimpanzees, we examined the contributions of genetics, non-genetic maternal effects, and shared community effects on variation in cortisol levels, an established predictor of survival in long-lived primates. Despite evidence for consistent individual variation in cortisol levels across years, between-group effects were more influential and made an overwhelming contribution to variation in this trait. Focusing on within-group variation, non-genetic maternal effects accounted for 8% of the individual differences in average cortisol levels, significantly more than that attributable to genetic factors, which was indistinguishable from zero. These maternal effects are consistent with a primary role of a shared environment in shaping physiology. For chimpanzees, and perhaps other species with long life histories, community and maternal effects appear more relevant than genetic inheritance in shaping key physiological traits.
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Affiliation(s)
- Patrick J Tkaczynski
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire.
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK.
| | - Fabrizio Mafessoni
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
- Weizmann Institute of Science, Department of Plant and Environmental Sciences, Rehovot, Israel.
| | - Cédric Girard-Buttoz
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- The Ape Social Mind Lab, Institut des Sciences Cognitives, CNRS UMR 5229, Lyon, France
| | - Liran Samuni
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Centre for Social Learning & Cognitive Evolution, School of Psychology & Neuroscience, University of St Andrews, St Andrews, UK
| | - Corinne Y Ackermann
- Universite de Neuchatel, Institut de Biologie, Cognition Compare, Neuchatel, Switzerland
| | - Pawel Fedurek
- Division of Psychology, University of Stirling, Stirling, UK
| | - Cristina Gomes
- Tropical Conservation Institute, Institute of Environment, College of Arts, Science and Education, Florida International University, Miami, FL, USA
| | - Catherine Hobaiter
- Centre for Social Learning & Cognitive Evolution, School of Psychology & Neuroscience, University of St Andrews, St Andrews, UK
| | - Therese Löhrich
- World Wide Fund for Nature, Dzanga Sangha Protected Areas, BP 1053, Bangui, Central African Republic
- Robert Koch Institute, Epidemiology of Highly Pathogenic Microorganisms, Berlin, Germany
| | - Virgile Manin
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | - Anna Preis
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | - Prince D Valé
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- Unité de Formation et de Recherche Agroferesterie, Université Jean Lorougnon Guédé, Daloa, Côte d'Ivoire
| | - Erin G Wessling
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | | | - Zinta Zommers
- Perry World House, University of Pennsylvania, Philadelphia, USA
| | - Klaus Zuberbuehler
- Universite de Neuchatel, Institut de Biologie, Cognition Compare, Neuchatel, Switzerland
| | - Linda Vigilant
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Tobias Deschner
- Institute of Cognitive Science, Comparative BioCognition, University of Osnabrück, Osnabrück, Germany
| | - Roman M Wittig
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- The Ape Social Mind Lab, Institut des Sciences Cognitives, CNRS UMR 5229, Lyon, France
| | - Catherine Crockford
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- The Ape Social Mind Lab, Institut des Sciences Cognitives, CNRS UMR 5229, Lyon, France
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Lonsdorf EV, Sanz CM. Behavioral and cognitive perspectives on the evolution of tool use from wild chimpanzees. Curr Opin Behav Sci 2022. [DOI: 10.1016/j.cobeha.2022.101144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Carvajal L, Schuppli C. Learning and skill development in wild primates: toward a better understanding of cognitive evolution. Curr Opin Behav Sci 2022. [DOI: 10.1016/j.cobeha.2022.101155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Mikeliban M, Kunz B, Rahmaeti T, Uomini N, Schuppli C. Orangutan mothers adjust their behaviour during food solicitations in a way that likely facilitates feeding skill acquisition in their offspring. Sci Rep 2021; 11:23679. [PMID: 34880303 PMCID: PMC8655057 DOI: 10.1038/s41598-021-02901-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/10/2021] [Indexed: 11/20/2022] Open
Abstract
Immature orangutans acquire their feeding skills over several years, via social and independent learning. So far, it has remained uninvestigated to what extent orangutan mothers are actively involved in this learning process. From a fitness point of view, it may be adaptive for mothers to facilitate their offspring’s skill acquisition to make them reach nutritional independence faster. Food solicitations are potential means to social learning which, because of their interactive nature, allow to investigate the degree of active involvement of the mother. To investigate the role of food solicitation and the role of the mother in immatures’ foraging skill acquisition, we analysed 1390 food solicitation events between 21 immature Sumatran orangutans (Pongo abelii) and their mothers, collected over 13 years at the Suaq Balimbing orangutan population. We found that solicitation rates decreased with increasing age of the immatures and increased with increasing processing complexity of the food item. Mothers were more likely to share complex items and showed the highest likelihoods of sharing around the age at which immatures are learning most of their feeding skills. Our results indicate that immature Sumatran orangutans use food solicitation to acquire feeding skills. Furthermore, mothers flexibly adjust their behaviour in a way that likely facilitates their offspring’s skill acquisition. We conclude that orangutan mothers have a more active role in the skill acquisition of their offspring than previously thought.
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Affiliation(s)
- Mulati Mikeliban
- Development and Evolution of Cognition Research Group, Max Planck Institute of Animal Behavior, 78467, Konstanz, Germany
| | - Belinda Kunz
- Department of Anthropology, University of Zurich, CH-8006, Zurich, Switzerland
| | - Tri Rahmaeti
- Department of Biology, Graduate School, Universitas Nasional, Jakarta, 12520, Indonesia
| | - Natalie Uomini
- Department of Linguistic and Cultural Evolution, Max Planck Institute for Evolutionary Anthropology, 04103, Leipzig, Germany
| | - Caroline Schuppli
- Development and Evolution of Cognition Research Group, Max Planck Institute of Animal Behavior, 78467, Konstanz, Germany. .,Department of Anthropology, University of Zurich, CH-8006, Zurich, Switzerland.
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Ehmann B, van Schaik CP, Ashbury AM, Mörchen J, Musdarlia H, Utami Atmoko S, van Noordwijk MA, Schuppli C. Immature wild orangutans acquire relevant ecological knowledge through sex-specific attentional biases during social learning. PLoS Biol 2021; 19:e3001173. [PMID: 34010339 PMCID: PMC8133475 DOI: 10.1371/journal.pbio.3001173] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 03/05/2021] [Indexed: 11/22/2022] Open
Abstract
As a part of growing up, immature orangutans must acquire vast repertoires of skills and knowledge, a process that takes several years of observational social learning and subsequent practice. Adult female and male orangutans show behavioral differences including sex-specific foraging patterns and male-biased dispersal. We investigated how these differing life trajectories affect social interest and emerging ecological knowledge in immatures. We analyzed 15 years of detailed observational data on social learning, associations, and diet repertoires of 50 immatures (16 females and 34 males), from 2 orangutan populations. Specific to the feeding context, we found sex differences in the development of social interest: Throughout the dependency period, immature females direct most of their social attention at their mothers, whereas immature males show an increasing attentional preference for individuals other than their mothers. When attending to non-mother individuals, males show a significant bias toward immigrant individuals and a trend for a bias toward adult males. In contrast, females preferentially attend to neighboring residents. Accordingly, by the end of the dependency period, immature females show a larger dietary overlap with their mothers than do immature males. These results suggest that immature orangutans show attentional biases through which they learn from individuals with the most relevant ecological knowledge. Diversifying their skills and knowledge likely helps males when they move to a new area. In sum, our findings underline the importance of fine-grained social inputs for the acquisition of ecological knowledge and skills in orangutans and likely in other apes as well.
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Affiliation(s)
- Beatrice Ehmann
- Department of Anthropology, University of Zürich, Zürich, Switzerland
| | | | - Alison M. Ashbury
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Julia Mörchen
- Behavioral Ecology Research Group, Institute of Biology, Faculty of Life Science, Leipzig University, Leipzig, Germany
- Research Group Primate Behavioural Ecology, Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Helvi Musdarlia
- Department of Biology, Graduate School, Universitas Nasional, Jakarta, Indonesia
| | - Suci Utami Atmoko
- Faculty of Biology and Primate Research Center, Universitas Nasional, Jakarta, Indonesia
| | | | - Caroline Schuppli
- Department of Anthropology, University of Zürich, Zürich, Switzerland
- Leipzig Research Center for Early Child Development, Leipzig University, Leipzig, Germany
- Development and Evolution of Cognition Research Group, Max Planck Institute of Animal Behavior, Konstanz, Germany
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Schuppli C, Atmoko SSU, Vogel ER, van Schaik CP, van Noordwijk MA. The development and maintenance of sex differences in dietary breadth and complexity in Bornean orangutans. Behav Ecol Sociobiol 2021; 75:81. [PMID: 34776592 PMCID: PMC8550522 DOI: 10.1007/s00265-021-03014-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/23/2021] [Accepted: 03/29/2021] [Indexed: 11/03/2022]
Abstract
ABSTRACT Orangutans show a pronounced sexual dimorphism, with flanged males (i.e., males with fully grown secondary sexual characteristics) reaching twice the size of adult females. Furthermore, adult orangutans show sex-specific dispersal and activity patterns. This study investigates sex differences in adult foraging behavior and sheds light on how these differences develop in immatures. We analyzed 11 years of feeding data on ten adult female, seven flanged male, and 14 immature Bornean orangutans (Pongo pygmaeus wurmbii) at Tuanan in Central Kalimantan, Indonesia. We found that the diets of the adult females were significantly broader and required more processing steps before ingestion than the diets of flanged males. We also found evidence for a similar difference in overall diet repertoire sizes. For the immatures, we found that whereas females reached 100% of their mothers' diet spectrum size by the age of weaning, males reached only around 80%. From the age of 4 years on (i.e., years before being weaned) females had significantly broader daily diets than males. We found no difference in daily or overall diet processing intensity of immature males and females but found preliminary evidence that immature males included fewer items of their mother's diet in their own diets that were processing-intensive. Overall, our results suggest that by eating a broader variety and more complex to process food items, female orangutans go to greater lengths to achieve a balanced diet than males do. These behavioral differences are not just apparent in adult foraging behavior but also reflected in immature development from an early age on. SIGNIFICANCE STATEMENT In many species, males and females have different nutritional needs and are thus expected to show sex-specific foraging behavior. Sex differences in several aspects of foraging behavior have been found in various species, but it remains largely unclear when and how those develop during ontogeny, which is especially relevant for long-lived altricial species that learn foraging skills over many years. In our study, we analyzed a cross-sectional and longitudinal data set containing more than 750,000 feeding events of adult and immature Bornean orangutans (Pongo pygmaeus wurmbii). We found that adult females had significantly broader and more complex diets than males. We also found that these differences started to develop during infancy, suggesting that immature orangutans prepare for their sex-specific foraging niches long before those become physiologically relevant while they are still in constant association with their mothers and before being frequently exposed to other role models. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00265-021-03014-3.
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Affiliation(s)
- Caroline Schuppli
- Max Planck Institute of Animal Behavior, Konstanz, Germany
- Leipzig Research Center for Early Child Development, University of Leipzig, Leipzig, Germany
- Department of Anthropology, University of Zürich, Zürich, Switzerland
| | | | - Erin R. Vogel
- Department of Anthropology, Rutgers University, New Brunswick, NJ USA
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Motes-Rodrigo A, Tennie C. The Method of Local Restriction: in search of potential great ape culture-dependent forms. Biol Rev Camb Philos Soc 2021; 96:1441-1461. [PMID: 33779036 DOI: 10.1111/brv.12710] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 12/18/2022]
Abstract
Humans possess a perhaps unique type of culture among primates called cumulative culture. In this type of culture, behavioural forms cumulate changes over time, which increases their complexity and/or efficiency, eventually making these forms culture-dependent. As changes cumulate, culture-dependent forms become causally opaque, preventing the overall behavioural form from being acquired by individuals on their own; in other words, culture-dependent forms must be copied between individuals and across generations. Despite the importance of cumulative culture for understanding the evolutionary history of our species, how and when cumulative culture evolved is still debated. One of the challenges faced when addressing these questions is how to identify culture-dependent forms that result from cumulative cultural evolution. Here we propose a novel method to identify the most likely cases of culture-dependent forms. The 'Method of Local Restriction' is based on the premise that as culture-dependent forms are repeatedly transmitted via copying, these forms will unavoidably cumulate population-specific changes (due to copying error) and therefore must be expected to become locally restricted over time. When we applied this method to our closest living relatives, the great apes, we found that most known ape behavioural forms are not locally restricted (across domains and species) and thus are unlikely to be acquired via copying. Nevertheless, we found 25 locally restricted forms across species and domains, three of which appear to be locally unique (having been observed in a single population of a single species). Locally unique forms represent the best current candidates for culture-dependent forms in non-human great apes. Besides these rare exceptions, our results show that overall, ape cultures do not rely heavily on copying, as most ape behaviours appear across sites and/or species, rendering them unlikely to be culture-dependent forms resulting from cumulative cultural evolution. Yet, the locally restricted forms (and especially the three locally unique forms) identified by our method should be tested further for their potential reliance on copying social learning mechanisms (and in turn, for their potential culture-dependence). Future studies could use the Method of Local Restriction to investigate the existence of culture-dependent forms in other animal species and in the hominin archaeological record to estimate how widespread copying is in the animal kingdom and to postulate a timeline for the emergence of copying in our lineage.
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Affiliation(s)
- Alba Motes-Rodrigo
- Department of Early Prehistory and Quaternary Ecology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Claudio Tennie
- Department of Early Prehistory and Quaternary Ecology, Eberhard Karls University of Tübingen, Tübingen, Germany
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Morrison RE, Eckardt W, Colchero F, Vecellio V, Stoinski TS. Social groups buffer maternal loss in mountain gorillas. eLife 2021; 10:62939. [PMID: 33752800 PMCID: PMC7987338 DOI: 10.7554/elife.62939] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
Mothers are crucial for mammals’ survival before nutritional independence, but many social mammals reside with their mothers long after. In these species the social adversity caused by maternal loss later in life can dramatically reduce fitness. However, in some human populations these negative consequences can be overcome by care from other group members. We investigated the consequences of maternal loss in mountain gorillas and found no discernible fitness costs to maternal loss through survival, age at first birth, or survival of first offspring through infancy. Social network analysis revealed that relationships with other group members, particularly dominant males and those close in age, strengthened following maternal loss. In contrast to most social mammals, where maternal loss causes considerable social adversity, in mountain gorillas, as in certain human populations, this may be buffered by relationships within cohesive social groups, breaking the link between maternal loss, increased social adversity, and decreased fitness. Most mammals depend entirely upon their mothers when they are born. In these species, losing a mother at a young age has dramatic consequences for survival. In cases where orphaned individuals do reach adulthood, they often suffer negative effects, like reduced reproductive success or lower social status. But this is not the case for humans. If a child loses their mother, relatives, friends and the wider community can take over. This does not tend to happen in nature. Even our closest relatives, chimpanzees, are much less likely to survive if their mothers die before they reach adolescence. Although orphan survival is not the norm for mammals, humans may not be entirely unique. Mountain gorillas also live in stable family groups, usually with a dominant male and one or more females who care for their offspring for between 8 and 15 years. It is possible that gorillas may also be able to provide community support to orphans, which could buffer the costs of losing a mother, just as it does in humans. To answer this question, Morrison et al. examined 53 years of data collected by the Dian Fossey Gorilla Fund to assess the effects of maternal loss in mountain gorillas. The analysis examined survival, reproduction and changes in social relationships. This revealed that, like humans, young gorillas that lose their mothers are not at a greater risk of dying. There is also no clear long-term effect on their ability to reproduce. In fact, gorillas who lost their mothers ended up with stronger social relationships, especially with the dominant male of the group and young gorillas around the same age. It seems that gorilla social groups, like human families, provide support to young group members that lose their mothers. These findings suggest that the human ability to care for others in times of need may not be unique. It is possible that the tendency to care for orphaned young has its origins in our evolutionary past. Understanding this in more depth could provide clues into the social mechanisms that help to overcome early life adversity, and have a positive impact on future health and survival.
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Affiliation(s)
- Robin E Morrison
- Dian Fossey Gorilla Fund, Musanze, Rwanda.,Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom
| | | | - Fernando Colchero
- Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark.,Interdisciplinary Center on Population Dynamics, University of Southern Denmark, Odense, Denmark
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12
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Lonsdorf EV, Stanton MA, Wellens KR, Murray CM. Wild chimpanzee offspring exhibit adult-like foraging patterns around the age of weaning. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 175:268-281. [PMID: 33713419 DOI: 10.1002/ajpa.24267] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/28/2021] [Accepted: 02/24/2021] [Indexed: 01/27/2023]
Abstract
OBJECTIVES The prolonged juvenile period exhibited by primates is an evolutionary conundrum. Here we examine wild chimpanzee feeding development in the context of two hypotheses regarding prolonged development in primates: the needing-to-learn hypothesis and the expensive brain hypothesis. MATERIAL AND METHODS We studied wild chimpanzee (Pan troglodytes schweinfurthii) offspring at Gombe National Park, Tanzania. We analyzed 41 years of observational behavioral data collected between 1975 and 2016 from 81 offspring. We characterized feeding development in the first 10 years of life via four different measures: (1) proportion of observation time spent feeding; (2) diet composition; (3) diet breadth; and (4) diet maturity as measured by similarity to maternal diet. We used mixed effects models to examine changes with age and by sex, while controlling for season. RESULTS Feeding time, diet breadth, and diet maturity exhibited the most substantial increases with age in the first 6 years, with no significant change thereafter. Males and females showed different patterns of change in diet breadth by age, but did not differ by age 10. Diet composition did not change significantly with age and did not differ by sex. DISCUSSION We found that chimpanzee offspring attained adult-like feeding behaviors between 4 and 6 years of age, concomitant with the completion of weaning. Thus, our data do not support the needing-to-learn feeding skills hypothesis of a prolonged juvenile period, but additional data are needed to evaluate how and when adolescent chimpanzees are able to make foraging decisions independent of their mothers. Existing data on growth provides support for the expensive brain hypothesis, however, these hypotheses are not necessarily mutually exclusive. As more studies across taxa accumulate sufficient datasets on a range of developmental metrics, we will be able to achieve a more robust understanding of prolonged development in primates.
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Affiliation(s)
- Elizabeth V Lonsdorf
- Department of Psychology, Franklin and Marshall College, Lancaster, Pennsylvania, USA.,Biological Foundations of Behavior Program, Franklin and Marshall College, Lancaster, Pennsylvania, USA
| | - Margaret A Stanton
- Department of Psychology, Franklin and Marshall College, Lancaster, Pennsylvania, USA.,Biological Foundations of Behavior Program, Franklin and Marshall College, Lancaster, Pennsylvania, USA.,School of Social and Behavioral Sciences, University of New England, Biddeford, Maine, USA
| | - Kaitlin R Wellens
- Department of Biology, Trinity Washington University, Washington, District of Columbia, USA
| | - Carson M Murray
- Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA
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13
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Resende B, Ballesteros-Ardilla A, Fragaszy D, Visalberghi E, Izar P. Revisiting the fourth dimension of tool use: how objects become tools for capuchin monkeys. EVOLUTIONARY HUMAN SCIENCES 2021; 3:e18. [PMID: 37588559 PMCID: PMC10427319 DOI: 10.1017/ehs.2021.16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Culture allows humans to adapt to a diversity of contexts. Participatory experience in technical activities and activity with artefacts provide the basis for learning traditional technical skills. Some populations of non-human animals use tools. The ways in which artefacts influence the development of a traditional skill in non-human species can provide insight into essential supports for technical traditions in humans and shared learning processes across species. In wild bearded capuchins, nut cracking leaves edible pieces of nuts, nut shells and stones used as hammers at anvil sites. We addressed how mastery of cracking nuts by young monkeys is associated with interactions with these objects. We studied monkeys' reuse of nuts, hammers and anvils and the outcome of attempts to crack nuts, and from these data derived their behavioural variability and proficiency in nut cracking. Behavioural variability was the most robust predictor of whether a monkey collects pieces of nuts cracked by others or reuses stones and nuts, and was a stronger predictor of proficiency than age. Young monkeys were increasingly likely to reuse the stone used by another after the other monkey had left the anvil as they increasingly focused their behaviour on actions relevant to cracking nuts.
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Affiliation(s)
| | | | | | - Elisabetta Visalberghi
- Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
| | - Patrícia Izar
- Instituto de Psicologia, Universidade de São Paulo, SP, Brasil
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Crockford C, Samuni L, Vigilant L, Wittig RM. Postweaning maternal care increases male chimpanzee reproductive success. SCIENCE ADVANCES 2020; 6:6/38/eaaz5746. [PMID: 32948598 PMCID: PMC7500924 DOI: 10.1126/sciadv.aaz5746] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 07/28/2020] [Indexed: 06/01/2023]
Abstract
Humans are unusual among animals for continuing to provision and care for their offspring until adulthood. This "prolonged dependency" is considered key for the evolution of other notable human traits, such as large brains, complex societies, and extended postreproductive lifespans. Prolonged dependency must therefore have evolved under conditions in which reproductive success is gained with parental investment and diminished with early parental loss. We tested this idea using data from wild chimpanzees, which have similarly extended immature years as humans and prolonged mother-offspring associations. Males who lost their mothers after weaning but before maturity began reproducing later and had lower average reproductive success. Thus, persistent mother-immature son associations seem vital for enhancing male reproductive success, although mothers barely provision sons after weaning. We posit that these associations lead to social gains, crucial for successful reproduction in complex social societies, and offer insights into the evolution of prolonged dependency.
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Affiliation(s)
- Catherine Crockford
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
- Taï Chimpanzee Project, CSRS, Abidjan, Ivory Coast
- Human Behaviour, Ecology & Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Liran Samuni
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, CSRS, Abidjan, Ivory Coast
- Department of Human Evolutionary Biology, Harvard University, Cambridge, USA
| | - Linda Vigilant
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Roman M Wittig
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, CSRS, Abidjan, Ivory Coast
- Human Behaviour, Ecology & Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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15
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Musgrave S, Lonsdorf E, Morgan D, Sanz C. The ontogeny of termite gathering among chimpanzees in the Goualougo Triangle, Republic of Congo. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 174:187-200. [PMID: 33247844 PMCID: PMC7818130 DOI: 10.1002/ajpa.24125] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/15/2020] [Accepted: 06/30/2020] [Indexed: 11/10/2022]
Abstract
Objectives Acquiring tool‐assisted foraging skills can potentially improve dietary quality and increase fitness for wild chimpanzees (Pan troglodytes). In contrast to chimpanzees in East and West Africa, chimpanzees in the Congo Basin use tool sets and brush‐tipped fishing probes to gather termites. We investigated the ontogeny of these tool skills in chimpanzees of the Goualougo Triangle, Republic of Congo, and compared it to that for chimpanzees at Gombe, Tanzania. We assessed whether chimpanzees acquired simple tool behaviors and single tool use before more complex actions and sequential use of multiple tool types. Materials and Methods Using a longitudinal approach, we scored remote video footage to document the acquisition of termite‐gathering critical elements for 25 immature chimpanzees at Goualougo. Results All chimpanzees termite fished by 2.9 years but did not manufacture brush‐tipped probes until an average of 4.3 years. Acquisition of sequential tool use extended into juvenility and adolescence. While we did not detect significant sex differences, most critical elements except tool manufacture were acquired slightly earlier by females. Discussion These findings contrast with Gombe, where chimpanzees learn to both use and make fishing probes between ages 1.5–3.5 and acquire the complete task by age 5.5. Differences between sites could reflect tool material selectivity and design complexity, the challenge of sequential tool behaviors, and strength requirements of puncturing subterranean termite nests at Goualougo. These results illustrate how task complexity may influence the timing and sequence of skill acquisition, improving models of the ontogeny of tool behavior among early hominins who likely used complex, perishable technologies.
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Affiliation(s)
- Stephanie Musgrave
- Department of Anthropology, University of Miami, Coral Gables, Florida, USA
| | - Elizabeth Lonsdorf
- Department of Psychology, Franklin and Marshall College, Lancaster, Pennsylvania, USA
| | - David Morgan
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois, USA
| | - Crickette Sanz
- Congo Program, Wildlife Conservation Society, Brazzaville, Republic of Congo.,Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA.,Kyoto University Institute for Advanced Study, Kyoto University, Kyoto, Japan
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16
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Bründl AC, Tkaczynski PJ, Nohon Kohou G, Boesch C, Wittig RM, Crockford C. Systematic mapping of developmental milestones in wild chimpanzees. Dev Sci 2020; 24:e12988. [DOI: 10.1111/desc.12988] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 04/17/2020] [Accepted: 05/05/2020] [Indexed: 01/29/2023]
Affiliation(s)
- Aisha C. Bründl
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
| | - Patrick J. Tkaczynski
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
| | - Grégoire Nohon Kohou
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
| | - Christophe Boesch
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
- Department of Primatology Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Roman M. Wittig
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
- Department of Primatology Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Catherine Crockford
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
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Neadle D, Bandini E, Tennie C. Testing the individual and social learning abilities of task-naïve captive chimpanzees ( Pan troglodytes sp.) in a nut-cracking task. PeerJ 2020; 8:e8734. [PMID: 32195057 PMCID: PMC7069405 DOI: 10.7717/peerj.8734] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 02/11/2020] [Indexed: 11/20/2022] Open
Abstract
Nut-cracking is often cited as one of the most complex behaviours observed in wild chimpanzees. However, the cognitive mechanisms behind its acquisition are still debated. The current null hypothesis is that the form of nut-cracking behaviour relies on variants of social learning, with some researchers arguing, more precisely, that copying variants of social learning mechanisms are necessary. However, to date, very few experiments have directly investigated the potentially sufficient role of individual learning in explaining the behavioural form of nut-cracking. Despite this, the available data provides some evidence for the spontaneous acquisition of nut-cracking by chimpanzees; later group acquisition was then found to be at least facilitated by (unspecified) variants of social learning. The latter findings are in line with both suggested hypotheses, i.e., that copying social learning is required and that other (non-copying) social learning mechanisms are at play. Here we present the first study which focused (initially) on the role of individual learning for the acquisition of the nut-cracking behavioural form in chimpanzees. We tested task-naïve chimpanzees (N = 13) with an extended baseline condition to examine whether the behaviour would emerge spontaneously. After the baseline condition (which was unsuccessful), we tested for the role of social learning by providing social information in a step-wise fashion, culminating in a full action demonstration of nut-cracking by a human demonstrator (this last condition made it possible for the observers to copy all actions underlying the behaviour). Despite the opportunities to individually and/or socially learn nut-cracking, none of the chimpanzees tested here cracked nuts using tools in any of the conditions in our study; thus, providing no conclusive evidence for either competing hypothesis. We conclude that this failure was the product of an interplay of factors, including behavioural conservatism and the existence of a potential sensitive learning period for nut-cracking in chimpanzees. The possibility remains that nut-cracking is a behaviour that chimpanzees can individually learn. However, this behaviour might only be acquired when chimpanzees are still inside their sensitive learning period, and when ecological and developmental conditions allow for it. The possibility remains that nut-cracking is an example of a culture dependent trait in non-human great apes. Recommendations for future research projects to address this question are considered.
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Affiliation(s)
- Damien Neadle
- School of Psychology, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom.,Department of Psychology, School of Social Sciences, Faculty of Business, Law and Social Sciences, Birmingham City University, Birmingham, United Kingdom
| | - Elisa Bandini
- Department of Early Prehistory and Quaternary Ecology, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
| | - Claudio Tennie
- Department of Early Prehistory and Quaternary Ecology, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
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Mazumder J, Kaburu SSK. Object Manipulation and Tool Use in Nicobar Long-Tailed Macaques
(Macaca fascicularis umbrosus). INT J PRIMATOL 2020. [DOI: 10.1007/s10764-020-00141-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Abstract
Understanding social influences on how apes acquire tool behaviors can help us model the evolution of culture and technology in humans. Humans scaffold novice tool skills with diverse strategies, including the transfer of tools between individuals. Chimpanzees transfer tools, and this behavior meets criteria for teaching. However, it is unclear how task complexity relates to this form of helping. Here, we find differences between 2 wild chimpanzee populations in rate, probability, and types of tool transfer during termite gathering. Chimpanzees showed greater helping in the population where termite gathering is a more complex tool task. In wild chimpanzees, as in humans, regular and active provisioning of learning opportunities may be essential to the cultural transmission of complex skills. Cumulative culture is a transformative force in human evolution, but the social underpinnings of this capacity are debated. Identifying social influences on how chimpanzees acquire tool tasks of differing complexity may help illuminate the evolutionary origins of technology in our own lineage. Humans routinely transfer tools to novices to scaffold their skill development. While tool transfers occur in wild chimpanzees and fulfill criteria for teaching, it is unknown whether this form of helping varies between populations and across tasks. Applying standardized methods, we compared tool transfers during termite gathering by chimpanzees in the Goualougo Triangle, Republic of Congo, and in Gombe, Tanzania. At Goualougo, chimpanzees use multiple, different tool types sequentially, choose specific raw materials, and perform modifications that improve tool efficiency, which could make it challenging for novices to manufacture suitable tools. Termite gathering at Gombe involves a single tool type, fishing probes, which can be manufactured from various materials. Multiple measures indicated population differences in tool-transfer behavior. The rate of transfers and probability of transfer upon request were significantly higher at Goualougo, while resistance to transfers was significantly higher at Gombe. Active transfers of tools in which possessors moved to facilitate possession change upon request occurred only at Goualougo, where they were the most common transfer type. At Gombe, tool requests were typically refused. We suggest that these population differences in tool-transfer behavior may relate to task complexity and that active helping plays an enhanced role in the cultural transmission of complex technology in wild apes.
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