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Brooks J, van Heijst K, Epping A, Lee SH, Niksarli A, Pope A, Clay Z, Kret ME, Taglialatela J, Yamamoto S. Increased alertness and moderate ingroup cohesion in bonobos' response to outgroup cues. PLoS One 2024; 19:e0307975. [PMID: 39167568 PMCID: PMC11338468 DOI: 10.1371/journal.pone.0307975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 07/15/2024] [Indexed: 08/23/2024] Open
Abstract
In a number of species, including humans, perceived outgroup threat can promote ingroup cohesion. However, the distribution and selection history of this association across species with varied intergroup relations remains unclear. Using a sample of 8 captive groups (N = 43 individuals), we here tested whether bonobos, like chimpanzees, show more affiliative ingroup behaviour following perception of outgroup cues (unfamiliar male long-distance vocalisations). We used comparable methods to our previous study of captive chimpanzees, and found that, although weaker, there was an association for more frequent social grooming in response to the outgroup condition than the control condition, alongside more alert posture and increased self-directed behaviour. This provides preliminary evidence for an ancestral origin to the proximate association between outgroup cues and ingroup cohesion, at least prior to the Pan-Homo split, and suggests the presence of intergroup competition in our last common ancestor.
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Affiliation(s)
- James Brooks
- Institute for Advanced Study, Kyoto University, Kyoto, Japan
- Wildlife Research Center, Kyoto University, Kyoto, Japan
- Kumamoto Sanctuary, Kyoto University, Kyoto, Japan
| | | | - Amanda Epping
- Ape Cognition and Conservation Initiative, Des Moines, Iowa, United States of America
| | - Seok Hwan Lee
- Wildlife Research Center, Kyoto University, Kyoto, Japan
| | - Aslihan Niksarli
- Department of Anthropology, Yeditepe University, İstanbul, Türkiye
| | - Amy Pope
- Department of Psychology, University of Warwick, Coventry, United Kingdom
| | - Zanna Clay
- Department of Psychology, Durham University, Durham, United Kingdom
| | - Mariska E. Kret
- Department of Cognitive Psychology, Institute of Psychology, Leiden University, Leiden, Netherlands
- Leiden Institute for Brain and Cognition (LIBC), Leiden University, Leiden, Netherlands
| | - Jared Taglialatela
- Ape Cognition and Conservation Initiative, Des Moines, Iowa, United States of America
- Department of Ecology, Evolution, and Organismal Biology, Kennesaw State University, Kennesaw, Georgia, United States of America
| | - Shinya Yamamoto
- Institute for Advanced Study, Kyoto University, Kyoto, Japan
- Wildlife Research Center, Kyoto University, Kyoto, Japan
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2
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Shibata S, Furuichi T. Comparative analysis of intragroup intermale relationships: a study of wild bonobos (Pan paniscus) in Wamba, Democratic Republic of Congo and chimpanzees (Pan troglodytes) in Kalinzu Forest Reserve, Uganda. Primates 2024; 65:243-255. [PMID: 38816634 DOI: 10.1007/s10329-024-01134-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 04/24/2024] [Indexed: 06/01/2024]
Abstract
Although chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) share a multi-male/multi-female societal organization and form male-philopatric groups, disparities in terms of male aggression and stability of temporary parties are thought to exist among them. However, existing research in bonobos has mainly focused on the high social status, prolonged receptivity, and characteristic sexual behaviors of females, leaving the behaviors of males understudied. Moreover, prior comparative studies on Pan suffer from methodological inconsistencies. This study addresses these gaps by employing a uniform observation method to explore party attendance and aggressive interactions among male bonobos in Wamba and male chimpanzees in Kalinzu. Unlike male chimpanzees, which exhibit dispersion in the absence of receptive females in the group, male bonobos showed a lesser degree of such dispersion. Although the overall frequency of aggressive interactions per observation unit did not significantly differ between the two species, the nature of these interactions varied. Notably, severe aggressive behaviors such as physical confrontations among adult males were absent in bonobos, with most aggression occurring between the sons of the two highest-ranking females. Additionally, in bonobos, females actively engaged in polyadic aggressive behavior as aggressors, while all instances of coalitionary aggression in chimpanzees originated from male aggressors. These findings underscore the substantial impact of female behaviors on the observed distinctions in male aggressive interactions between the two species.
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Affiliation(s)
- Shohei Shibata
- Wildlife Research Center, Kyoto University, 41-2, Kanrin, Inuyama, Aichi, 484-8506, Japan.
| | - Takeshi Furuichi
- Wildlife Research Center, Kyoto University, 41-2, Kanrin, Inuyama, Aichi, 484-8506, Japan
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3
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Mouginot M, Wilson ML, Desai N, Surbeck M. Differences in expression of male aggression between wild bonobos and chimpanzees. Curr Biol 2024; 34:1780-1785.e4. [PMID: 38614078 PMCID: PMC11167569 DOI: 10.1016/j.cub.2024.02.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 01/22/2024] [Accepted: 02/28/2024] [Indexed: 04/15/2024]
Abstract
Researchers investigating the evolution of human aggression look to our closest living relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes), as valuable sources of comparative data.1,2 Males in the two species exhibit contrasting patterns: male chimpanzees sexually coerce females3,4,5,6,7,8 and sometimes kill conspecifics,9,10,11,12 whereas male bonobos exhibit less sexual coercion13,14 and no reported killing.13 Among the various attempts to explain these species differences, the self-domestication hypothesis proposes negative fitness consequences of male aggression in bonobos.2,15,16 Nonetheless, the extent to which these species differ in overall rates of aggression remains unclear due to insufficiently comparable observation methods.17,18,19,20,21,22,23 We used 14 community-years of focal follow data-the gold standard for observational studies24-to compare rates of male aggression in 3 bonobo communities at the Kokolopori Bonobo Reserve, Democratic Republic of Congo, and 2 chimpanzee communities at Gombe National Park, Tanzania. As expected, given that females commonly outrank males, we found that bonobos exhibited lower rates of male-female aggression and higher rates of female-male aggression than chimpanzees. Surprisingly, we found higher rates of male-male aggression among bonobos than chimpanzees even when limiting analyses to contact aggression. In both species, more aggressive males obtained higher mating success. Although our findings indicate that the frequency of male-male aggression does not parallel species difference in its intensity, they support the view that contrary to male chimpanzees, whose reproductive success depends on strong coalitions, male bonobos have more individualistic reproductive strategies.25.
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Affiliation(s)
- Maud Mouginot
- Institute for Advanced Study in Toulouse (IAST), Toulouse School of Economics, Université Toulouse Capitole, 31000 Toulouse, France; Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Michael L Wilson
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA; Institute on the Environment, University of Minnesota, Saint Paul, MN 55108, USA
| | - Nisarg Desai
- Emory National Primate Research Center, Emory University, Atlanta, GA 30329, USA
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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4
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Potel H, Niatou Singa FS, Cipolletta C, Neba Fuh T, Bardino G, Konyal E, Strampelli P, Henschel P, Masi S. Lethal combats in the forest among wild western gorillas. iScience 2024; 27:109437. [PMID: 38523787 PMCID: PMC10960106 DOI: 10.1016/j.isci.2024.109437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/13/2024] [Accepted: 03/04/2024] [Indexed: 03/26/2024] Open
Abstract
Lethal intergroup encounters occur in many species because of sexual selection. While documented in mountain gorillas, they are absent in western gorillas as, instead, it is predicted by their higher feeding (frugivory) and mate competition (single-vs. multi-male groups). We investigate whether the injuries on three dead silverbacks and one adult female from four groups of western gorillas in the Central African Republic, resulted from interactions with gorillas or leopards. We identified two distinct injury patterns caused by gorillas (isolated lacerations, round wounds) and leopards (punctures clustered on head/neck) by analyzing injuries caused by mountain gorillas and leopards to gorillas and non-gorilla species, respectively. The western gorilla injury pattern is similar to that of mountain gorillas suggesting that lethal encounters occur, albeit infrequently, as predicted by sexual selection in a one-male society. While sexual dimorphism and polygynous sociality favored the evolution of violent encounters, multiple males in groups may influence their frequency.
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Affiliation(s)
- Hugo Potel
- Ecoanthropologie, Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturelle, University Paris Diderot, Sorbonne Paris Cité, Musée de l’Homme, Paris, France
| | | | - Chloé Cipolletta
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Terence Neba Fuh
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Giulia Bardino
- Ecoanthropologie, Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturelle, University Paris Diderot, Sorbonne Paris Cité, Musée de l’Homme, Paris, France
- “La Sapienza” University, Department of Environmental and Evolutionary Biology, Rome, Italy
| | - Emmanuel Konyal
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | | | | | - Shelly Masi
- Ecoanthropologie, Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturelle, University Paris Diderot, Sorbonne Paris Cité, Musée de l’Homme, Paris, France
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5
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Milich KM. Male-philopatric nonhuman primates and their potential role in understanding the evolution of human sociality. Evol Anthropol 2024; 33:e22014. [PMID: 38109039 DOI: 10.1002/evan.22014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 12/19/2023]
Abstract
In most primate species, males transfer out of their natal groups, resulting in groups of unrelated males. However, in a few species, including humans, males remain in their groups and form life-long associations with each other. This pattern of male philopatry is linked with cooperative male behaviors, including border patrols and predator defense. Because females in male-philopatric species form weaker kin networks with each other than in female-philopatric species, they are expected to evolve counter-strategies to male sexual coercion that are relatively independent of support from other females. Studies of male-philopatric nonhuman primates can provide insight into the evolutionary basis of prosocial behaviors, cooperation, and group action in humans and offer comparative models for understanding the sociality of other hominin species. This review will discuss patterns of dispersal and philopatry across primates, explore the resulting male and female behaviors, and argue that male-philopatric nonhuman primate species offer insight into the social and sexual dynamics of hominins throughout evolution.
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Affiliation(s)
- Krista M Milich
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
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6
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Grueter CC. Social and economic interdependence as a basis for peaceful between-group relationships in nonhuman primates and humans. Behav Brain Sci 2024; 47:e9. [PMID: 38224071 DOI: 10.1017/s0140525x23002613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Glowacki asserts that interdependent relationships beyond group boundaries are exceptionally rare among nonhuman mammals. However, rudimentary forms of interdependence can be seen in primate species that form multilevel societies, that is, core social units embedded within higher-level grouping categories. Studies of primate multilevel societies can enrich discussions about the evolutionary origins of peaceful between-group interactions in humans.
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Affiliation(s)
- Cyril C Grueter
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia www.cyrilgrueter.net
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7
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Samuni L, Surbeck M. Cooperation across social borders in bonobos. Science 2023; 382:805-809. [PMID: 37972165 DOI: 10.1126/science.adg0844] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 09/29/2023] [Indexed: 11/19/2023]
Abstract
Cooperation beyond familial and group boundaries is core to the functioning of human societies, yet its evolution remains unclear. To address this, we examined grooming, coalition, and food-sharing patterns in bonobos (Pan paniscus), one of our closest living relatives whose rare out-group tolerance facilitates interaction opportunities between groups. We show that, as in humans, positive assortment supports bonobo cooperation across borders. Bonobo cooperative attitudes toward in-group members informed their cooperative relationships with out-groups, in particular, forming connections with out-group individuals who also exhibited high cooperation tendencies. Our findings show that cooperation between unrelated individuals across groups without immediate payoff is not exclusive to humans and suggest that such cooperation can emerge in the absence of social norms or strong cultural dispositions.
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Affiliation(s)
- Liran Samuni
- Cooperative Evolution Lab, German Primate Center, Göttingen, Germany
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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8
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Xie E, Li K, Gu R, Zhang D, Li X. Verbal information exchange enhances collective performance through increasing group identification. Neuroimage 2023; 279:120339. [PMID: 37611814 DOI: 10.1016/j.neuroimage.2023.120339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/05/2023] [Accepted: 08/21/2023] [Indexed: 08/25/2023] Open
Abstract
Information exchange is a key factor in the attainment of collective outcomes and the navigation of social life. In the current study, we investigated whether and how information exchange enhanced collective performance by combining behavioral and neuroimaging approaches from the perspective of multiparticipant neuroscience. To evaluate collective performance, we measured the collaborative problem-solving abilities of triads working on a murder mystery case. We first found that verbal information exchange significantly enhanced collective performance compared to nonverbal exchange. Moreover, both group sharing and group discussion positively contributed to this effect, with group discussion being more essential. Importantly, group identification mediated the positive effect of verbal information exchange on collective performance. This mediation was supported by higher interactive frequency and enhanced within-group neural synchronization (GNS) in the dorsolateral prefrontal cortex (DLPFC). Taken together, we provided a multiparticipant theoretical model to explain how verbal information exchange enhanced collective performance. Our findings deepen the insight into the workings of group decision-making.
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Affiliation(s)
- Enhui Xie
- Shanghai Key Laboratory of Mental Health and Psychological Crisis Intervention, Affiliated Mental Health Center (ECNU), School of Psychology and Cognitive Science, East China Normal University, Shanghai 200062, China
| | - Keshuang Li
- Shanghai Key Laboratory of Mental Health and Psychological Crisis Intervention, Affiliated Mental Health Center (ECNU), School of Psychology and Cognitive Science, East China Normal University, Shanghai 200062, China
| | - Ruolei Gu
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Beijing 100101, China
| | - Dandan Zhang
- Institute of Brain and Psychological Sciences, Sichuan Normal University, Chengdu, China
| | - Xianchun Li
- Shanghai Key Laboratory of Mental Health and Psychological Crisis Intervention, Affiliated Mental Health Center (ECNU), School of Psychology and Cognitive Science, East China Normal University, Shanghai 200062, China; Shanghai Changning Mental Health Center, Shanghai 200335, China; Institute of Wisdom in China, East China Normal University, Shanghai 200062, China.
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9
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Friedman WR, Krützen M, King SL, Allen SJ, Gerber L, Wittwer S, Connor RC. Inter-group alliance dynamics in Indo-Pacific bottlenose dolphins (Tursiops aduncus). Anim Cogn 2023; 26:1601-1612. [PMID: 37391478 PMCID: PMC10442264 DOI: 10.1007/s10071-023-01804-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 06/16/2023] [Accepted: 06/18/2023] [Indexed: 07/02/2023]
Abstract
The social intelligence hypothesis holds that complex social relationships are the major selective force underlying the evolution of large brain size and intelligence. Complex social relationships are exemplified by coalitions and alliances that are mediated by affiliative behavior, resulting in differentiated but shifting relationships. Male Indo-Pacific bottlenose dolphins in Shark Bay, Australia, form three alliance levels or 'orders', primarily among non-relatives. Strategic alliance formation has been documented within both first- and second-order alliances and between second-order alliances ('third-order alliances'), revealing that the formation of strategic inter-group alliances is not limited to humans. Here we conducted a fine-scale study on 22 adult males over a 6-year period to determine if third-order alliance relationships are differentiated, and mediated by affiliative interactions. We found third-order alliance relationships were strongly differentiated, with key individuals playing a disproportionate role in maintaining alliances. Nonetheless, affiliative interactions occurred broadly between third-order allies, indicating males maintain bonds with third-order allies of varying strength. We also documented a shift in relationships and formation of a new third-order alliance. These findings further our understanding of dolphin alliance dynamics and provide evidence that strategic alliance formation is found in all three alliance levels, a phenomenon with no peer among non-human animals.
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Affiliation(s)
- Whitney R Friedman
- Department of Environmental Studies, University of California Santa Cruz, Santa Cruz, 95064, USA.
- Department of Cognitive Science, University of California San Diego, San Diego, 92093, USA.
| | - Michael Krützen
- Evolutionary Genetics Group, Department of Evolutionary Anthropology, University of Zurich, Zurich, Switzerland
| | - Stephanie L King
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
- School of Biological Sciences, University of Western Australia, Crawley, WA, 6009, Australia
| | - Simon J Allen
- Evolutionary Genetics Group, Department of Evolutionary Anthropology, University of Zurich, Zurich, Switzerland
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
- School of Biological Sciences, University of Western Australia, Crawley, WA, 6009, Australia
| | - Livia Gerber
- Evolutionary Genetics Group, Department of Evolutionary Anthropology, University of Zurich, Zurich, Switzerland
- Australian National Wildlife Collection, National Research Collections Australia, CSIRO, Canberra, ACT, 2601, Australia
| | - Samuel Wittwer
- Evolutionary Genetics Group, Department of Evolutionary Anthropology, University of Zurich, Zurich, Switzerland
| | - Richard C Connor
- Biology Department, University of Massachusetts Dartmouth, North Dartmouth, MA, 02747, USA.
- Institute of Environment and Department of Biological Sciences, Florida International University, North Miami, FL, 33181, USA.
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10
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Mouginot M, Cheng L, Wilson ML, Feldblum JT, Städele V, Wroblewski EE, Vigilant L, Hahn BH, Li Y, Gilby IC, Pusey AE, Surbeck M. Reproductive inequality among males in the genus Pan. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220301. [PMID: 37381849 PMCID: PMC10291431 DOI: 10.1098/rstb.2022.0301] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 03/21/2023] [Indexed: 06/30/2023] Open
Abstract
Reproductive inequality, or reproductive skew, drives natural selection, but has been difficult to assess, particularly for males in species with promiscuous mating and slow life histories, such as bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). Although bonobos are often portrayed as more egalitarian than chimpanzees, genetic studies have found high male reproductive skew in bonobos. Here, we discuss mechanisms likely to affect male reproductive skew in Pan, then re-examine skew patterns using paternity data from published work and new data from the Kokolopori Bonobo Reserve, Democratic Republic of Congo and Gombe National Park, Tanzania. Using the multinomial index (M), we found considerable overlap in skew between the species, but the highest skew occurred among bonobos. Additionally, for two of three bonobo communities, but no chimpanzee communities, the highest ranking male had greater siring success than predicted by priority-of-access. Thus, an expanded dataset covering a broader demographic range confirms that bonobos have high male reproductive skew. Detailed comparison of data from Pan highlights that reproductive skew models should consider male-male dynamics including the effect of between-group competition on incentives for reproductive concessions, but also female grouping patterns and factors related to male-female dynamics including the expression of female choice. This article is part of the theme issue 'Evolutionary ecology of inequality'.
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Affiliation(s)
- Maud Mouginot
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Leveda Cheng
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany
| | - Michael L. Wilson
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA
- Institute on the Environment, University of Minnesota, Saint Paul, MN 55108, USA
| | - Joseph T. Feldblum
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA
| | - Veronika Städele
- School of Human Evolution and Social Change, and Institute of Human Origins, Arizona State University, Tempe, AZ 85287, USA
- Cognitive Ethology Laboratory, German Primate Center, Göttingen 37077, Germany
| | - Emily E. Wroblewski
- Department of Anthropology, Washington University in St Louis, St Louis, MO 63130, USA
| | - Linda Vigilant
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany
| | - Beatrice H. Hahn
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yingying Li
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ian C. Gilby
- School of Human Evolution and Social Change, and Institute of Human Origins, Arizona State University, Tempe, AZ 85287, USA
| | - Anne E. Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany
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11
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Townsend C, Ferraro JV, Habecker H, Flinn MV. Human cooperation and evolutionary transitions in individuality. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210414. [PMID: 36688393 PMCID: PMC9869453 DOI: 10.1098/rstb.2021.0414] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 10/31/2022] [Indexed: 01/24/2023] Open
Abstract
A major evolutionary transition in individuality involves the formation of a cooperative group and the transformation of that group into an evolutionary entity. Human cooperation shares principles with those of multicellular organisms that have undergone transitions in individuality: division of labour, communication, and fitness interdependence. After the split from the last common ancestor of hominoids, early hominins adapted to an increasingly terrestrial niche for several million years. We posit that new challenges in this niche set in motion a positive feedback loop in selection pressure for cooperation that ratcheted coevolutionary changes in sociality, communication, brains, cognition, kin relations and technology, eventually resulting in egalitarian societies with suppressed competition and rapid cumulative culture. The increasing pace of information innovation and transmission became a key aspect of the evolutionary niche that enabled humans to become formidable cooperators with explosive population growth, the ability to cooperate and compete in groups of millions, and emergent social norms, e.g. private property. Despite considerable fitness interdependence, the rise of private property, in concert with population explosion and socioeconomic inequality, subverts potential transition of human groups into evolutionary entities due to resurgence of latent competition and conflict. This article is part of the theme issue 'Human socio-cultural evolution in light of evolutionary transitions'.
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Affiliation(s)
- Cathryn Townsend
- Department of Anthropology, Baylor University, Waco, TX 76798-7334, USA
| | - Joseph V. Ferraro
- Department of Anthropology, Baylor University, Waco, TX 76798-7334, USA
| | - Heather Habecker
- Department of Psychology and Neuroscience, Baylor University, Waco, TX 76798-7334, USA
| | - Mark V. Flinn
- Department of Anthropology, Baylor University, Waco, TX 76798-7334, USA
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12
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Fox SA, Muller MN, González NT, Enigk DK, Machanda ZP, Otali E, Wrangham R, Thompson ME. Weak, but not strong, ties support coalition formation among wild female chimpanzees. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210427. [PMID: 36440557 PMCID: PMC9703227 DOI: 10.1098/rstb.2021.0427] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/23/2022] [Indexed: 11/29/2022] Open
Abstract
In social species, individuals may be able to overcome competitive constraints on cooperation by leveraging relationships with familiar, tolerant partners. While strong social ties have been linked to cooperation in several social mammals, it is unclear the extent to which weak social ties can support cooperation, particularly among non-kin. We tested the hypothesis that weakly affiliative social relationships support cooperative coalition formation using 10 years of behavioural data on wild female chimpanzees. Female chimpanzees typically disperse and reside with non-kin as adults. Their social relationships are differentiated but often relatively weak, with few dyads sharing strong bonds. Females occasionally form aggressive coalitions together. Three measures of relationship quality-party association, five-metre proximity and whether a dyad groomed-positively predicted coalitions, indicating that relationship quality influenced coalition partnerships. However, dyads that groomed frequently did not form more coalitions than dyads that groomed occasionally, and kin did not cooperate more than expected given their relationship quality. Thus, strong bonds and kinship did not bolster cooperation. We conclude that cooperative coalitions among female chimpanzees depend on social tolerance but do not require strong bonds. Our findings highlight social tolerance as a distinct pathway through which females can cultivate cooperative relationships. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.
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Affiliation(s)
- Stephanie A. Fox
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Martin N. Muller
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Nicole Thompson González
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106-3210, USA
| | - Drew K. Enigk
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Zarin P. Machanda
- Department of Anthropology, Tufts University, Medford, MA 02155, USA
| | - Emily Otali
- Kibale Chimpanzee Project, Fort Portal, Uganda
| | - Richard Wrangham
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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13
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Nolte S, Sterck EHM, van Leeuwen EJC. Does tolerance allow bonobos to outperform chimpanzees on a cooperative task? A conceptual replication of Hare et al., 2007. ROYAL SOCIETY OPEN SCIENCE 2023; 10:220194. [PMID: 36686553 PMCID: PMC9810421 DOI: 10.1098/rsos.220194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Across various taxa, social tolerance is thought to facilitate cooperation, and many species are treated as having species-specific patterns of social tolerance. Yet studies that assess wild and captive bonobos and chimpanzees result in contrasting findings. By replicating a cornerstone experimental study on tolerance and cooperation in bonobos and chimpanzees (Hare et al. 2007 Cur. Biol. 17, 619-623 (doi:10.1016/j.cub.2007.02.040)), we aim to further our understanding of current discrepant findings. We tested bonobos and chimpanzees housed at the same facility in a co-feeding and cooperation task. Food was placed on dishes located on both ends or in the middle of a platform. In the co-feeding task, the tray was simply made available to the ape duos, whereas in the cooperation task the apes had to simultaneously pull at both ends of a rope attached to the platform to retrieve the food. By contrast to the published findings, bonobos and chimpanzees co-fed to a similar degree, indicating a similar level of tolerance. However, bonobos cooperated more than chimpanzees when the food was monopolizable, which replicates the original study. Our findings call into question the interpretation that at the species level bonobos cooperate to a higher degree because they are inherently more tolerant.
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Affiliation(s)
- Suska Nolte
- Animal Behaviour and Cognition, Department of Biology, University Utrecht, Utrecht, The Netherlands
- Department of Comparative Cultural Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Elisabeth H. M. Sterck
- Animal Behaviour and Cognition, Department of Biology, University Utrecht, Utrecht, The Netherlands
- Animal Science Department, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Edwin J. C. van Leeuwen
- Animal Behaviour and Cognition, Department of Biology, University Utrecht, Utrecht, The Netherlands
- Department of Comparative Cultural Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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14
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Why bonobos show a high reproductive skew towards high-ranking males: analyses for association and mating patterns concerning female sexual states. Primates 2022; 63:483-494. [PMID: 35931876 DOI: 10.1007/s10329-022-01004-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 07/13/2022] [Indexed: 10/16/2022]
Abstract
Among non-human primates, male dominance rank is not necessarily a good indicator of mating success, and relationships between male dominance rank and mating or reproductive success are affected by female behavior and sexual states implying their probability of conception. Although comparisons of the behavior of male chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) suggest that the effect of male dominance rank on mating success is expected to be less prominent in bonobos, recent genetic studies have shown that high-ranking male reproductive skew is higher in bonobos than in chimpanzees. One possible reason for the higher reproductive skew in bonobos could be that female behavior and their sexual states may have much more influence on male mating and reproductive success in bonobos than in chimpanzees. In the current study on bonobos, we conducted focal animal observation of females and analyzed the influence of female sexual swelling, the number of days after parturition, and dominance rank of males on female associations, and copulation with adult males. Our results showed that females with maximum swelling (MS) had more proximity with high-ranking males and copulated more frequently with higher-ranking males than with lower-ranking males. Females for whom longer time had elapsed since parturition, and therefore had higher probabilities of conception, had 5-m proximity with adult males more frequently than females whom shorter time had elapsed since parturition, but did not have more copulation with adult males. Females with MS had proximity and copulated with high-ranking males frequently, which partly explains why the reproductive skew is so high in bonobos. These results are discussed in relation to previous hypotheses on the influence of long-lasting mother-son relationships on mating success of males and on the contribution of female receptivity during non-conceptive nursing periods to moderate intermale aggression in bonobos.
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15
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Danaher-Garcia N, Connor R, Fay G, Melillo-Sweeting K, Dudzinski KM. The partial merger of two dolphin societies. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211963. [PMID: 35950199 PMCID: PMC9346368 DOI: 10.1098/rsos.211963] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 07/11/2022] [Indexed: 05/17/2023]
Abstract
Interactions between mammalian social groups are generally antagonistic as individuals in groups cooperate to defend resources from non-members. Members of the family Delphinidae inhabit a three-dimensional habitat where resource defence is usually impractical. Here, we describe a long-term partial fusion of two communities of Atlantic spotted dolphins (Stenella frontalis). The northern community, studied for 30 years, immigrated 160 km to the range of the southern community, observed for 20 years. Both communities featured fission-fusion grouping patterns, strongest associations between adult males, and frequent affiliative contact between individuals. For the 5-year period following the immigration, we found members of all age classes and both sexes in mixed groups, but there was a strong bias toward finding immigrant males in mixed groups. Some association levels between males, and males and females, from different communities were as high as the highest within-community associations. Affiliative contacts indicate that these individuals were forming social relationships. The mixing of two separate social groups with new bond formation is rare in terrestrial mammal groups. Such mixing between spotted dolphin groups suggests that adaptations to respond aggressively to 'outsiders' are diminished in this species and possibly other ecologically similar dolphins.
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Affiliation(s)
- Nicole Danaher-Garcia
- Department of Biological Sciences, Institute of the Environment, Florida International University, 3000 NE 151st Street, North Miami, FL 33181, USA
- Dolphin Communication Project, PO Box 7485, Port Saint Lucie, FL 34984, USA
- University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA, USA
| | - Richard Connor
- Dolphin Alliance Project, PO Box 6449, New Bedford, MA 02742, USA
| | - Gavin Fay
- School for Marine Science and Technology, University of Massachusetts Dartmouth, 836 S Rodney French Boulevard, New Bedford, MA 02744, USA
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16
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Vlaeyen JMR, Heesen R, Kret ME, Clay Z, Bionda T, Kim Y. Bared-teeth displays in bonobos (Pan paniscus): An assessment of the power asymmetry hypothesis. Am J Primatol 2022; 84:e23419. [PMID: 35848310 DOI: 10.1002/ajp.23419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 06/22/2022] [Accepted: 06/26/2022] [Indexed: 11/10/2022]
Abstract
Facial expressions are key to navigating social group life. The Power Asymmetry Hypothesis of Motivational Emancipation predicts that the type of social organization shapes the meaning of communicative displays in relation to an individual's dominance rank. The bared-teeth (BT) display represents one of the most widely observed communicative signals across primate species. Studies in macaques indicate that the BT display in despotic species is often performed unidirectionally, from low- to high-ranking individuals (signaling submission), whereas the BT display in egalitarian species is usually produced irrespective of dominance (mainly signaling affiliation and appeasement). Despite its widespread presence, research connecting BT displays to the power asymmetry hypothesis outside the Macaca genus remains scarce. To extend this knowledge, we investigated the production of BT in relation to social dominance in dyadic interactions (N = 11,377 events) of 11 captive bonobos (Pan paniscus). Although adult bonobos were more despotic than previously suggested in the literature, BT displays were produced irrespective of dominance rank. Moreover, while adults produced the BT exclusively during socio-sexual interactions, especially during periods of social tension, immature bonobos produced the BT in a wider number of contexts. As such, the results indicate that the communicative meaning of the BT display is consistent with signaling appeasement, especially in periods of social tension. Moreover, the BT display does not seem to signal social status, supporting the prediction for species with a high degree of social tolerance. These results advance our understanding of the origins of communicative signals and their relation to species' social systems.
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Affiliation(s)
- Jolinde M R Vlaeyen
- Animal Behaviour and Cognition, Utrecht University, Utrecht, the Netherlands.,Institute of Cognitive Science Comparative BioCognition, University of Osnabrück, Osnabruck, Germany
| | | | - Mariska E Kret
- Cognitive Psychology Unit, Institute of Psychology, Leiden University, Leiden, the Netherlands
| | - Zanna Clay
- Department of Psychology, Durham University, Durham, UK
| | | | - Yena Kim
- Cognitive Psychology Unit, Institute of Psychology, Leiden University, Leiden, the Netherlands
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17
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Brooks J, Kano F, Kawaguchi Y, Yamamoto S. Oxytocin promotes species-relevant outgroup attention in bonobos and chimpanzees. Horm Behav 2022; 143:105182. [PMID: 35537292 DOI: 10.1016/j.yhbeh.2022.105182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 11/30/2022]
Abstract
Previous research has found that oxytocin (OT) is associated with intergroup behaviour in humans as well as wild chimpanzees, and that exogenous OT affects Pan social attention. The two Pan species, bonobos and chimpanzees, differ drastically from one another in their intensity of intergroup competition, with lethal intergroup aggression often led by males in chimpanzees and more tolerant associations often centered around females in bonobos. However, it remains unclear how exogenous OT changes the two species' responses to ingroup and outgroup individuals. In this study, after intranasal administration of nebulized OT or placebo control, chimpanzees and bonobos viewed image pairs of ingroup and outgroup conspecifics while their eye movements were tracked with an eye-tracker. Although the overall effect of OT was small, we found that OT shifted bonobos' and chimpanzees' attention to outgroup images of the sex primarily involved in intergroup encounters in each species. Specifically, OT selectively shifted attention towards outgroup photos of female conspecifics in bonobos, and those of outgroup male conspecifics in chimpanzees. This suggests that OT generally promotes outgroup attention in both bonobos and chimpanzees but this effect is restricted to the sex most relevant in intergroup relations. These results suggest that, although OT may have a generally conserved role in hominid intergroup behaviour, it may act in species-relevant ways under the influence of their socio-ecological backgrounds.
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Affiliation(s)
- James Brooks
- Wildlife Research Center, Kyoto University, 6068203 Kyoto, Japan; Kumamoto Sanctuary, Kyoto University, 8693201 Kumamoto, Japan.
| | - Fumihiro Kano
- Kumamoto Sanctuary, Kyoto University, 8693201 Kumamoto, Japan; Center for the Advanced Study of Collective Behaviour, University of Konstanz, 78464 Konstanz, Germany; Max-Planck Institute of Animal Behavior, 78315 Radolfzell, Germany.
| | - Yuri Kawaguchi
- Messerli Research Institute, University of Veterinary Medicine Vienna, A-1210 Vienna, Austria; Japan Society for the Promotion of Science (JSPS), 1020083 Tokyo, Japan; Primate Research Institute, Kyoto University, 4848506 Inuyama, Japan
| | - Shinya Yamamoto
- Wildlife Research Center, Kyoto University, 6068203 Kyoto, Japan; Insitute for Advanced Study, Kyoto University, 6068501 Kyoto, Japan
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18
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Characterization of Pan social systems reveals in-group/out-group distinction and out-group tolerance in bonobos. Proc Natl Acad Sci U S A 2022; 119:e2201122119. [PMID: 35727986 DOI: 10.1073/pnas.2201122119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human between-group interactions are highly variable, ranging from violent to tolerant and affiliative. Tolerance between groups is linked to our unique capacity for large-scale cooperation and cumulative culture, but its evolutionary origins are understudied. In chimpanzees, one of our closest living relatives, predominantly hostile between-group interactions impede cooperation and information flow across groups. In contrast, in our other closest living relative, the bonobo, tolerant between-group associations are observed. However, as these associations can be frequent and prolonged and involve social interactions that mirror those within groups, it is unclear whether these bonobos really do belong to separate groups. Alternatively, the bonobo grouping patterns may be homologous to observations from the large Ngogo chimpanzee community, where individuals form within-group neighborhoods despite sharing the same membership in the larger group. To characterize bonobo grouping patterns, we compare the social structure of the Kokolopori bonobos with the chimpanzee group of Ngogo. Using cluster analysis, we find temporally stable clusters only in bonobos. Despite the large spatial overlap and frequent interactions between the bonobo clusters, we identified significant association preference within but not between clusters and a unique space use of each cluster. Although bonobo associations are flexible (i.e., fission-fusion dynamics), cluster membership predicted the bonobo fission compositions and the spatial cohesion of individuals during encounters. These findings suggest the presence of a social system that combines clear in-group/out-group distinction and out-group tolerance in bonobos, offering a unique referential model for the evolution of tolerant between-group interactions in humans.
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19
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Lemoine SRT, Samuni L, Crockford C, Wittig RM. Parochial cooperation in wild chimpanzees: a model to explain the evolution of parochial altruism. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210149. [PMID: 35369746 PMCID: PMC8977654 DOI: 10.1098/rstb.2021.0149] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/24/2022] [Indexed: 12/18/2022] Open
Abstract
Parochial altruism, taking individual costs to benefit the in-group and harm the out-group, has been proposed as one of the mechanisms underlying the human ability of large-scale cooperation. How parochial altruism has evolved remains unclear. In this review paper, we formulate a parochial cooperation model in small-scale groups and examine the model in wild chimpanzees. As suggested for human parochial altruism, we review evidence that the oxytocinergic system and in-group cooperation and cohesion during out-group threat are integral parts of chimpanzee collective action during intergroup competition. We expand this model by suggesting that chimpanzee parochial cooperation is supported by the social structure of chimpanzee groups which enables repeated interaction history and established social ties between co-operators. We discuss in detail the role of the oxytocinergic system in supporting parochial cooperation, a pathway that appears integral already in chimpanzees. The reviewed evidence suggests that prerequisites of human parochial altruism were probably present in the last common ancestor between Pan and Homo. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
- Sylvain R. T. Lemoine
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Archaeology, University of Cambridge, Cambridge, UK
| | - Liran Samuni
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Catherine Crockford
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Institute of Cognitive Sciences Marc Jeannerod, UMR 5229, CNRS/University of Lyon, Bron, France
| | - Roman M. Wittig
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Institute of Cognitive Sciences Marc Jeannerod, UMR 5229, CNRS/University of Lyon, Bron, France
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20
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Moscovice LR, Hohmann G, Trumble BC, Fruth B, Jaeggi AV. Dominance or Tolerance? Causes and consequences of a period of increased intercommunity encounters among bonobos (Pan paniscus) at LuiKotale. INT J PRIMATOL 2022. [DOI: 10.1007/s10764-022-00286-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AbstractGroup-living primates exhibit variable reactions to intergroup encounters (or IGEs), reflecting species-specific strategies and individual motivations. In chimpanzees (Pan troglodytes), dominating in IGEs provides fitness benefits. Less is known about responses to IGEs in bonobos (Pan paniscus) despite their equal relevance for understanding the origins of human intergroup relations. We observed the Bompusa West (WBp) bonobo community at LuiKotale during a 2-month shift in ranging resulting in frequent IGEs with the smaller Bompusa East (EBp) community. We tested whether incursions provided ecological benefits, and whether responses to IGEs were consistent with inter-community dominance or tolerance. We measured fruit availability and collected activity scans from 26 mature WBp community members when in their core ranging area, during incursions into the EBp ranging area, and during IGEs. We collected data on sexual interactions and aggression with in-group and out-group members during 19 independent IGEs. During their shift in ranging, fruit availability was greater in the EBp ranging area, and WBp bonobos consumed more fruit during incursions than when in their core ranging area. Coalitionary intergroup aggression occurred during nine IGEs, and outcomes were consistent with imbalances in fighting power, in that larger WBp parties supplanted smaller EBp parties from the immediate area. However, communities reformed associations following 70% of coalitionary conflicts, and prolonged IGEs facilitated out-group sexual interactions and female transfers. The WBp community shift in ranging was likely motivated by ecological factors and responses to increased IGEs reflected a mixture of competitive and tolerant strategies.
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21
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Love thy neighbour: behavioural and endocrine correlates of male strategies during intergroup encounters in bonobos. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.02.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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22
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Hashimoto C, Ryu H, Mouri K, Shimizu K, Sakamaki T, Furuichi T. Physical, behavioral, and hormonal changes in the resumption of sexual receptivity during postpartum infertility in female bonobos at Wamba. Primates 2022; 63:109-121. [PMID: 35142939 PMCID: PMC9352606 DOI: 10.1007/s10329-021-00968-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 12/01/2021] [Indexed: 11/26/2022]
Abstract
The operational sex ratio (OSR) is used as a predictor for the intensity of mating competition. While many factors affect the OSR, there tends to be a high male bias in primate species with long interbirth intervals and non-seasonal breeding, such as hominid apes. However, the OSR of bonobos (Pan paniscus) is lower than that of chimpanzees (Pan troglodytes), which is thought to reduce competitive and aggressive male behaviors. The low OSR of bonobos is considered to result from the early resumption of female sexual receptivity during postpartum infertility and the receptivity that they continue to show until the late stage of pregnancy. In this study, we aimed to examine the early resumption of sexual receptivity by providing quantitative data on the resumption of maximal swelling (MS) in sexual skin and copulation, and changes in urinary estrone conjugate (E1C) concentrations during postpartum infertility in wild bonobos at Wamba in the Luo Scientific Reserve, Democratic Republic of the Congo. An analysis of 9 years of data revealed that females showed the first MS at 225.4 ± 132.7 days after parturition and performed the first copulation at 186.8 ± 137.5 days after parturition, both of which were in the early stage of postpartum infertility. The proportion of days with MS and the frequency of copulation steadily increased subsequently; however, the rate of increase gradually slowed approximately 42–48 months after parturition. There was a significant correlation between the proportion of days with MS and the frequency of copulation in each period for each female. We confirmed that E1C concentrations were significantly higher during the MS phase than during the non-MS phase. Data collected over 15 months on the E1C concentration during MS showed that it increased linearly from the early stage of lactation to the next conception. These results suggest that, although female bonobos do not usually conceive until 49.7 months after parturition, they resume MS and receptivity at a low level of E1C concentration during an early stage of postpartum infertility. This study of female bonobo receptivity and sex hormone changes during the postpartum non-fertile period provides important insights for examining the evolution of low OSR, which has been considered to contribute to peaceful social relationships among bonobos.
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Affiliation(s)
- Chie Hashimoto
- Primate Research Institute, Kyoto University, Kyoto, Japan.
| | - Heungjin Ryu
- Primate Research Institute, Kyoto University, Kyoto, Japan.
- School of Life Science, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
| | - Keiko Mouri
- Primate Research Institute, Kyoto University, Kyoto, Japan
| | - Keiko Shimizu
- Faculty of Science, Okayama University of Science, Okayama, Japan
| | - Tetsuya Sakamaki
- Primate Research Institute, Kyoto University, Kyoto, Japan
- Antwerp Zoo Foundation, Royal Zoological Society of Antwerp, Antwerp, Belgium
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23
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Do immigrant female bonobos prefer older resident females as important partners when integrating into a new group? Primates 2022; 63:123-136. [PMID: 35119562 DOI: 10.1007/s10329-021-00971-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 12/07/2021] [Indexed: 12/29/2022]
Abstract
Intergroup transfer is a critical part of the life history of group-living species, with considerable variation in its timings and patterns among species. Immigrant female bonobos are documented to smoothly integrate into a new group through forming affiliative relationships with old, high-ranking resident females (Idani, Folia Primatol 57:83-95, 1991). However, only a few studies are available on immigration costs and strategies for female bonobos. Here, we compared social relationships of natal females (known to be 4.5-7.2 years old) and immigrant females (estimated to be 6.8-12.3 years old) from one bonobo group at Wamba in the Luo Scientific Reserve, Democratic Republic of the Congo. Similar to previous studies, resident females did not appear to spatially isolate immigrant females or act aggressively toward them. However, resident males were more frequently aggressive toward immigrant females than toward natal females. Both natal and immigrant females tended to groom high-ranking females more than middle- and low-ranking females, although immigrant females spent more time grooming unrelated females than natal females. Immigrant females did not exhibit rank-related partner preference for genito-genital rubbing and copulation. Although we did not control for age differences because of the small sample size, our results provide partial support for the hypothesis that old female bonobos are important partners for the successful integration of young females into an unfamiliar group. This strategy could explain why female bonobos disperse before reaching sexual maturity, which contrasts with the need for female chimpanzees to display sexual swellings and draw male interest as protection against aggression from resident females.
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24
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Migliano AB, Vinicius L. The origins of human cumulative culture: from the foraging niche to collective intelligence. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200317. [PMID: 34894737 PMCID: PMC8666907 DOI: 10.1098/rstb.2020.0317] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 06/28/2021] [Indexed: 12/15/2022] Open
Abstract
Various studies have investigated cognitive mechanisms underlying culture in humans and other great apes. However, the adaptive reasons for the evolution of uniquely sophisticated cumulative culture in our species remain unclear. We propose that the cultural capabilities of humans are the evolutionary result of a stepwise transition from the ape-like lifestyle of earlier hominins to the foraging niche still observed in extant hunter-gatherers. Recent ethnographic, archaeological and genetic studies have provided compelling evidence that the components of the foraging niche (social egalitarianism, sexual and social division of labour, extensive co-residence and cooperation with unrelated individuals, multilocality, fluid sociality and high between-camp mobility) engendered a unique multilevel social structure where the cognitive mechanisms underlying cultural evolution (high-fidelity transmission, innovation, teaching, recombination, ratcheting) evolved as adaptations. Therefore, multilevel sociality underlies a 'social ratchet' or irreversible task specialization splitting the burden of cultural knowledge across individuals, which may explain why human collective intelligence is uniquely able to produce sophisticated cumulative culture. The foraging niche perspective may explain why a complex gene-culture dual inheritance system evolved uniquely in humans and interprets the cultural, morphological and genetic origins of Homo sapiens as a process of recombination of innovations appearing in differentiated but interconnected populations. This article is part of a discussion meeting issue 'The emergence of collective knowledge and cumulative culture in animals, humans and machines'.
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Affiliation(s)
| | - Lucio Vinicius
- Department of Anthropology, University of Zurich, Zurich, ZH, Switzerland
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25
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Canine sexual dimorphism in Ardipithecus ramidus was nearly human-like. Proc Natl Acad Sci U S A 2021; 118:2116630118. [PMID: 34853174 DOI: 10.1073/pnas.2116630118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2021] [Indexed: 11/18/2022] Open
Abstract
Body and canine size dimorphism in fossils inform sociobehavioral hypotheses on human evolution and have been of interest since Darwin's famous reflections on the subject. Here, we assemble a large dataset of fossil canines of the human clade, including all available Ardipithecus ramidus fossils recovered from the Middle Awash and Gona research areas in Ethiopia, and systematically examine canine dimorphism through evolutionary time. In particular, we apply a Bayesian probabilistic method that reduces bias when estimating weak and moderate levels of dimorphism. Our results show that Ar. ramidus canine dimorphism was significantly weaker than in the bonobo, the least dimorphic and behaviorally least aggressive among extant great apes. Average male-to-female size ratios of the canine in Ar. ramidus are estimated as 1.06 and 1.13 in the upper and lower canines, respectively, within modern human population ranges of variation. The slightly greater magnitude of canine size dimorphism in the lower than in the upper canines of Ar. ramidus appears to be shared with early Australopithecus, suggesting that male canine reduction was initially more advanced in the behaviorally important upper canine. The available fossil evidence suggests a drastic size reduction of the male canine prior to Ar. ramidus and the earliest known members of the human clade, with little change in canine dimorphism levels thereafter. This evolutionary pattern indicates a profound behavioral shift associated with comparatively weak levels of male aggression early in human evolution, a pattern that was subsequently shared by Australopithecus and Homo.
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26
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Heesen R, Zuberbühler K, Bangerter A, Iglesias K, Rossano F, Pajot A, Guéry JP, Genty E. Evidence of joint commitment in great apes' natural joint actions. ROYAL SOCIETY OPEN SCIENCE 2021; 8:211121. [PMID: 34909217 PMCID: PMC8652280 DOI: 10.1098/rsos.211121] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/08/2021] [Indexed: 05/20/2023]
Abstract
Human joint action seems special, as it is grounded in joint commitment-a sense of mutual obligation participants feel towards each other. Comparative research with humans and non-human great apes has typically investigated joint commitment by experimentally interrupting joint actions to study subjects' resumption strategies. However, such experimental interruptions are human-induced, and thus the question remains of how great apes naturally handle interruptions. Here, we focus on naturally occurring interruptions of joint actions, grooming and play, in bonobos and chimpanzees. Similar to humans, both species frequently resumed interrupted joint actions (and the previous behaviours, like grooming the same body part region or playing the same play type) with their previous partners and at the previous location. Yet, the probability of resumption attempts was unaffected by social bonds or rank. Our data suggest that great apes experience something akin to joint commitment, for which we discuss possible evolutionary origins.
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Affiliation(s)
- Raphaela Heesen
- Institute of Work and Organizational Psychology, University of Neuchâtel, Switzerland
- Department of Psychology, Durham University, UK
| | - Klaus Zuberbühler
- Institute of Biology, University of Neuchâtel, Switzerland
- School of Psychology and Neuroscience, University of St Andrews, Scotland
| | - Adrian Bangerter
- Institute of Work and Organizational Psychology, University of Neuchâtel, Switzerland
| | - Katia Iglesias
- School of Health Sciences (HEdS-FR), HES-SO University of Applied Sciences and Arts of WesternSwitzerland
| | - Federico Rossano
- Department of Cognitive Science, University of California, San Diego, CA, USA
| | - Aude Pajot
- Institute of Work and Organizational Psychology, University of Neuchâtel, Switzerland
| | | | - Emilie Genty
- Institute of Work and Organizational Psychology, University of Neuchâtel, Switzerland
- Institute of Biology, University of Neuchâtel, Switzerland
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Tokuyama N, Toda K, Poiret ML, Iyokango B, Bakaa B, Ishizuka S. Two wild female bonobos adopted infants from a different social group at Wamba. Sci Rep 2021; 11:4967. [PMID: 33737517 PMCID: PMC7973529 DOI: 10.1038/s41598-021-83667-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022] Open
Abstract
Adoption, the act of taking another individual's offspring and treating it as one's own, is rare but widely observed in various mammal species and may increase the survival of adoptees. Adoption may also benefit adoptive mothers, for example they might care for close kin to gain indirect fitness or to learn caregiving behaviours. Here, we report two cases of a wild bonobo adopting an infant from a different social group, the first report of cross-group adoption in great apes. In one case, the adoptive mother was already a mother of two dependent offspring. In the other case, the adoptive mother was an old parous female whose own offspring had already emigrated into a different social group. The adoptive mothers provided various maternal care to the adoptees, such as carrying, grooming, nursing, and sharing food. No aggression was observed by group members towards the out-group adoptees. In both cases, adoptees had no maternal kin-relationship with their adoptive mothers. Both adoptive mothers already had experience of rearing their own offspring. Instead, these cases of adoption may have been driven by other evolutionary adaptive traits of bonobos, such as their strong attraction to infants and high tolerance towards immatures and out-group individuals.
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Affiliation(s)
- Nahoko Tokuyama
- Primate Research Institute, Kyoto University, Kanrin 41, Inuyama, Aichi, 484-8506, Japan.
- Wildlife Research Center, Kyoto University, Kyoto, Japan.
| | - Kazuya Toda
- Primate Research Institute, Kyoto University, Kanrin 41, Inuyama, Aichi, 484-8506, Japan
| | | | - Bahanande Iyokango
- Research Center for Ecology and Forestry, Mabali, Mbandaka, Democratic Republic of the Congo
| | - Batuafe Bakaa
- Research Center for Ecology and Forestry, Mabali, Mbandaka, Democratic Republic of the Congo
| | - Shintaro Ishizuka
- Primate Research Institute, Kyoto University, Kanrin 41, Inuyama, Aichi, 484-8506, Japan
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Brooks J, Kano F, Sato Y, Yeow H, Morimura N, Nagasawa M, Kikusui T, Yamamoto S. Divergent effects of oxytocin on eye contact in bonobos and chimpanzees. Psychoneuroendocrinology 2021; 125:105119. [PMID: 33388536 DOI: 10.1016/j.psyneuen.2020.105119] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 12/08/2020] [Accepted: 12/18/2020] [Indexed: 10/22/2022]
Abstract
Oxytocin has drawn significant research attention for its role in modulating mammalian social behavior. Despite generally conserved roles, oxytocin can function differently even in closely related species. Previous studies have shown that bonobos and chimpanzees, humans' two closest relatives, demonstrate considerable behavioral differences, including that bonobos look more at others' eyes than chimpanzees. Oxytocin is known to increase attention to another's eyes in many mammalian species (e.g. dogs, monkeys, and humans), yet this effect has not been tested in any nonhuman great ape species. This study examined how intranasally-administered oxytocin affects eye contact in bonobos and chimpanzees using eye tracking. Following administration of either oxytocin or saline control with a nebulizer, chimpanzees (n = 6) and bonobos (n = 5) were shown images of conspecific faces while their eye movement was recorded. Oxytocin changed the eye-looking behavior of bonobos and chimpanzees differently. We found that oxytocin increased eye contact in bonobos but not chimpanzees; while one chimpanzee showed an increase, interestingly, 5 out of 6 chimpanzees showed decreased looking to the eyes compared to the mouth, suggesting moderate eye avoidance. Given the importance of eye contact in their social interactions, our results suggest that oxytocin may play modulatory roles in bonobos' and chimpanzees' species-specific social behavior and underscore the importance of oxytocin in hominid social evolution.
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Affiliation(s)
- James Brooks
- Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan.
| | - Fumihiro Kano
- Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan.
| | - Yutaro Sato
- Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan
| | - Hanling Yeow
- Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan
| | - Naruki Morimura
- Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan
| | - Miho Nagasawa
- School of Veterinary Medicine, Azabu University, Japan
| | | | - Shinya Yamamoto
- Wildlife Research Center, Kyoto University, Japan; Institute for Advanced Study, Kyoto University, Japan
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Cheng L, Lucchesi S, Mundry R, Samuni L, Deschner T, Surbeck M. Variation in aggression rates and urinary cortisol levels indicates intergroup competition in wild bonobos. Horm Behav 2021; 128:104914. [PMID: 33373622 DOI: 10.1016/j.yhbeh.2020.104914] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 01/08/2023]
Abstract
Intergroup competition is a widespread phenomenon across taxa and groups typically compete over access to limited resources, such as food and mates. Such competition may be quantified by changes in individuals' behavioral and physiological status in response to intergroup encounters (IGEs). Bonobos, one of our closest living relatives, are often regarded as xenophilic and exhibit high tolerance towards out-group individuals. This tolerance between groups may still be accompanied by intergroup competition over resources. We hereby compared variation in aggression rates and urinary cortisol levels of bonobos during and outside contexts of IGEs in the Kokolopori Bonobo Reserve and investigated whether food and mate availability influenced males' and females' aggression and cortisol levels, when controlling for dominance rank and the number of individuals present. We found that although females had higher aggression rates and urinary cortisol levels during than outside contexts of IGEs, these increases were not related to food availability or changes in between-group dynamics when maximally tumescent females were present, rather than absent. Furthermore, males showed higher aggression rates and urinary cortisol levels during than outside contexts of IGEs. However, males' responses during IGEs were not related to the presence of maximally tumescent females and food availability. Taken together, while competition intensified during seemingly tolerant IGEs in bonobos, such competition was unrelated to short-term changes in food and mate availability. Despite physical and physiological costs of aggression, bonobos associate with out-group individuals frequently and for extended periods. This suggests potential benefits of bonobo intergroup associations.
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Affiliation(s)
- Leveda Cheng
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
| | - Stefano Lucchesi
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Roger Mundry
- Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Liran Samuni
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Tobias Deschner
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
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Better together? How intergroup associations affect energy balance and feeding behavior in wild bonobos. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02943-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Abstract
When the benefits of interacting with out-group members exceed the associated costs, social groups may be expected to be tolerant towards each other. However, in many species exhibiting intergroup tolerance, the nature of benefits gained from intergroup encounters remains unclear. We investigated the potential costs and benefits associated with intergroup associations in bonobos, a species with varying degrees of intergroup tolerance, by testing whether these associations conferred energetic benefits to participants under different socioecological contexts and whether the consequences of these associations substantially differed from within-group competition. We used measures of socioecological factors (fruit abundance and group size), feeding and ranging behaviors, and a physiological marker of energy balance (urinary c-peptide of insulin) collected over a 19-month period from two neighboring wild communities in the Kokolopori Bonobo Reserve, Democratic Republic of the Congo. We found that intergroup associations were not related to individuals’ energy balance, but they were related to variations in individuals’ ranging and feeding behavior. Specifically, bonobos traveled longer distances, visited larger fruit patches, and increased the time spent feeding on fruits on days they associated with the neighboring group. These adaptations in feeding behavior may be strategies to offset the energetic costs of increased travel distances. In the absence of obvious energetic benefits and with clear strategies employed to offset energetic costs, it is likely that intergroup associations in bonobos provide benefits unrelated to energy acquisition, such as social benefits. Our study sheds light on the potential incentives promoting social networks to extend beyond and across groups in a tolerant species.
Significance statement
Intergroup encounters can be energetically costly due to increased competition over resources. Yet, some species associate with out-group individuals for extended periods of time when the benefits of participating in these associations exceed the potential costs. Bonobos, a species exhibiting intergroup tolerance, modified their feeding behavior during intergroup associations by feeding on larger fruit patches and increasing their time spent feeding on fruits, likely to offset energetic costs of increased travel distances. As results, individuals’ energy balance was not related with intergroup associations. The employment of such strategies in addition to the absence of clear energetic benefits suggests that intergroup associations in bonobos provide social rather than ecological benefits.
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Consistent differences in a virtual world model of ape societies. Sci Rep 2020; 10:14075. [PMID: 32826938 PMCID: PMC7442632 DOI: 10.1038/s41598-020-70955-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/06/2020] [Indexed: 11/20/2022] Open
Abstract
Practical and ethical constraints limit our ability to experimentally test socioecological theory in wild primates. We took an alternate approach to model this, allowing groups of humans to interact in a virtual world in which they had to find food and interact with both ingroup and outgroup avatars to earn rewards. We altered ratios and distributions of high- and low-value foods to test the hypothesis that hominoids vary with regards to social cohesion and intergroup tolerance due to their feeding ecology. We found larger nesting clusters and decreased attacks on outgroup competitors in the Bonobo condition versus the Chimpanzee condition, suggesting a significant effect of feeding competition alone on social structure. We also demonstrate that virtual worlds are a robust mechanism for testing hypotheses that are impossible to study in the wild.
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Age and sex differences in juvenile bonobos in party associations with their mothers at Wamba. Primates 2020; 62:19-27. [PMID: 32785867 DOI: 10.1007/s10329-020-00853-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 07/26/2020] [Indexed: 10/23/2022]
Abstract
Mothers are the most fundamental individuals for the survival and development of their immature offspring. Sex-biased dispersal has an effect on strong and long-lasting social bonding between mothers and their philopatric offspring. Nepotistic relationships are often seen in species with male-biased dispersal but less frequently in species with female-biased dispersal. Bonobos are unique among female-biased dispersal primates in that the females are codominant with males, exert influence on the mating opportunities of their mature sons, and tolerate each other regardless of relatedness. Few studies on bonobos have examined sex differences in social relationships between juveniles and their mothers, and how this relates to mother-son and female-female cooperative relationships amongst adults. We investigated whether the association index of juveniles with their mothers changed with age depending on the sex of the juveniles in parties of bonobos at Wamba, the Democratic Republic of the Congo. We found that female bonobos had decreased party associations with their mothers prior to their emigration from the natal group, while male bonobos maintained relatively high party associations with their mothers. These results indicate that sex differences that emerge during the juvenile period in bonobos in their spatial relationships with their mothers differ from previous findings on chimpanzees, spider monkeys, and muriquis, in which philopatric sons tend to spend less time in proximity to their mothers and disperse earlier than, or at a similar age to, daughters. The contrasts between bonobos and other primate species suggest that the high social status of female bonobos relative to that of males may facilitate the extension of maternal support for their philopatric sons, and that high tolerance among unrelated females may enable the spatial independence of daughters from their mothers at an earlier stage.
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Ryu H, Hill DA, Sakamaki T, Garai C, Tokuyama N, Furuichi T. Occurrence and transmission of flu-like illness among neighboring bonobo groups at Wamba. Primates 2020; 61:775-784. [PMID: 32562165 DOI: 10.1007/s10329-020-00832-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 05/29/2020] [Indexed: 10/24/2022]
Abstract
Infectious diseases constitute one of the major threats to African great apes. Bonobos (Pan paniscus) may be particularly vulnerable to the transmission of infectious diseases because of their cohesive grouping and frequent social and sexual interactions between groups. Here we report two cases of a flu-like illness and possible transmission of the illness among neighboring wild bonobo groups at Wamba, DR Congo. The first flu-like outbreak started in the PE group on July 28, 2013, 2 days after they had encounters with the BI and PW groups. All PE members, except for one infant, subsequently developed flu-like symptoms, including coughing and running nose. The second flu-like outbreak occurred in the E1 group on October 14, 2013, after E1 had encountered the PE group and the two groups stayed together from October 7 to 11. Eleven out of the 15 observed party members developed symptoms over the next 4 days. The pathogens underlying the two outbreaks may have been related as two temporary immigrant females, who had previously shown symptoms while in the PE group, stayed briefly in the E1 group during the second outbreak, but did not show any symptoms.
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Affiliation(s)
- Heungjin Ryu
- Primate Research Institute of Kyoto University, Kanrin 41-2 Inuyama, Aichi, 484-8506, Japan. .,Ulsan National Institute of Science and Technology, UNIST-Gil 50, Eonyang-eup, Ulju-gun, Ulsan, 44919, Republic of Korea.
| | - David A Hill
- Wildlife Research Center of Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto, 606-8203, Japan
| | - Tetsuya Sakamaki
- Primate Research Institute of Kyoto University, Kanrin 41-2 Inuyama, Aichi, 484-8506, Japan.,The Antwerp Zoo Foundation of the VZW Royal Zoological Society Antwerp, Koningin Astridplein 26, 2018, Antwerpen, Belgium
| | - Cintia Garai
- Primate Research Institute of Kyoto University, Kanrin 41-2 Inuyama, Aichi, 484-8506, Japan.,Wildlife Messengers, 5645 Hard Rock Place, Richmond, VA, 23230, USA
| | - Nahoko Tokuyama
- Primate Research Institute of Kyoto University, Kanrin 41-2 Inuyama, Aichi, 484-8506, Japan.,Wildlife Research Center of Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto, 606-8203, Japan
| | - Takeshi Furuichi
- Primate Research Institute of Kyoto University, Kanrin 41-2 Inuyama, Aichi, 484-8506, Japan
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34
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Furuichi T. Variation in Intergroup Relationships Among Species and Among and Within Local Populations of African Apes. INT J PRIMATOL 2020. [DOI: 10.1007/s10764-020-00134-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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35
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Barragan RC, Brooks R, Meltzoff AN. Altruistic food sharing behavior by human infants after a hunger manipulation. Sci Rep 2020; 10:1785. [PMID: 32019998 PMCID: PMC7000707 DOI: 10.1038/s41598-020-58645-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/17/2020] [Indexed: 02/04/2023] Open
Abstract
Altruistic behavior entails giving valuable benefits to others while incurring a personal cost. A distinctively human form of altruistic behavior involves handing nutritious food to needy strangers, even when one desires the food. Engaging in altruistic food transfer, instead of keeping the food, is costly, because it reduces the caloric intake of the benefactor vis-à-vis the beneficiary. Human adults engage in this form of altruistic behavior during times of war and famine, when giving food to others threatens one's own survival. Our closest living primate relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), exhibit notable constraints on the proclivity to engage in such food transfer (particularly chimpanzees), although they share many social-cognitive commonalities with humans. Here we show that in a nonverbal test, 19-month-old human infants repeatedly and spontaneously transferred high-value, nutritious natural food to a stranger (Experiment 1) and more critically, did so after an experimental manipulation that imposed a feeding delay (Experiment 2), which increased their own motivation to eat the food. Social experience variables moderated the expression of this infant altruistic behavior, suggesting malleability.
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Affiliation(s)
- Rodolfo Cortes Barragan
- Institute for Learning & Brain Sciences, University of Washington, Seattle, USA.
- Department of Psychology, University of Washington, Seattle, USA.
| | - Rechele Brooks
- Institute for Learning & Brain Sciences, University of Washington, Seattle, USA
| | - Andrew N Meltzoff
- Institute for Learning & Brain Sciences, University of Washington, Seattle, USA.
- Department of Psychology, University of Washington, Seattle, USA.
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36
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Belfer-Cohen A, Hovers E. Prehistoric Perspectives on "Others" and "Strangers". Front Psychol 2020; 10:3063. [PMID: 32038416 PMCID: PMC6985552 DOI: 10.3389/fpsyg.2019.03063] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 12/26/2019] [Indexed: 01/19/2023] Open
Abstract
Social "connectivity" through time is currently considered as one of the major drivers of cultural transmission and cultural evolution. Within this framework, the interactions within and between groups are impacted by individuals' distinction of social relationships. In this paper, we focus on changes in a major aspect of social perceptions, "other" and "stranger." As inferred from the archaeological record, this perception among human groups gained importance during the course of the Pleistocene. These changes would have occurred due to the plasticity of cognitive mechanisms, in response to the demands on behavior along the trajectory of human social evolution. The concepts of "other" and "stranger" have received little attention in the archaeological discourse, yet they are fundamental in the perception of social standing. The property of being an "other" is defined by one's perception and is inherent to one's view of the world around oneself; when shared by a group it becomes a social cognitive construct. Allocating an individual the status of a "stranger" is a socially-defined state that is potentially transient. We hypothesize that, while possibly entrenched in deep evolutionary origins, the latter is a relatively late addition to socio-cognitive categorization, associated with increased sedentism, larger groups and reduced territorial extent as part of the process of Neolithization. We posit that "others" and "strangers" can be approached from contextual archaeological data, with inferences as regards the evolution of cognitive social categories. Our analysis focused on raw material studies, observations on style, and evidence for craft specialization. We find that contrary to the null hypothesis the archaeological record implies earlier emergence of complex socio-cognitive categorization. The cognitive, cultural and social processes involved in the maintenance and distinction between "others" and "strangers" can be defined as "self-domestication" that is still an on-going process.
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Affiliation(s)
- Anna Belfer-Cohen
- The Institute of Archaeology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Erella Hovers
- The Institute of Archaeology, The Hebrew University of Jerusalem, Jerusalem, Israel
- Institute of Human Origins, Arizona State University, Tempe, AZ, United States
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37
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Ishizuka S, Takemoto H, Sakamaki T, Tokuyama N, Toda K, Hashimoto C, Furuichi T. Comparisons of between-group differentiation in male kinship between bonobos and chimpanzees. Sci Rep 2020; 10:251. [PMID: 31937864 PMCID: PMC6959343 DOI: 10.1038/s41598-019-57133-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/23/2019] [Indexed: 11/13/2022] Open
Abstract
Patterns of kinship among individuals in different groups have been rarely examined in animals. Two closest living relatives of humans, bonobos and chimpanzees share many characteristics of social systems including male philopatry, whereas one major difference between the two species is the nature of intergroup relationship. Intergroup relationship is basically antagonistic and males sometimes kill individuals of other groups in chimpanzees, whereas it is much more moderate in bonobos and copulations between individuals of different groups are often observed during intergroup encounters. Such behavioural differences may facilitate more frequent between-group male gene flow and greater between-group differentiation in male kinship in bonobos than in chimpanzees. Here we compared differences between average relatedness among males within groups and that among males of neighbouring groups, and between-group male genetic distance between bonobos and chimpanzees. Contrary to expectation, the differences between average relatedness among males within groups and that among males of neighbouring groups were significantly greater in bonobos than in chimpanzees. There were no significant differences in autosomal and Y-chromosomal between-group male genetic distance between the two species. Our results showed that intergroup male kinship is similarly or more differentiated in bonobos than in chimpanzees.
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Affiliation(s)
- Shintaro Ishizuka
- Primate Research Institute, Kyoto University, Inuyama, Japan.
- Japan Society for the Promotion of Science, Chiyoda-ku, Japan.
| | | | - Tetsuya Sakamaki
- Primate Research Institute, Kyoto University, Inuyama, Japan
- Antwerp Zoo Foundation, Antwerp, Belgium
| | - Nahoko Tokuyama
- Primate Research Institute, Kyoto University, Inuyama, Japan
- Japan Society for the Promotion of Science, Chiyoda-ku, Japan
- Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, Yokosuka, Japan
| | - Kazuya Toda
- Primate Research Institute, Kyoto University, Inuyama, Japan
- Japan Society for the Promotion of Science, Chiyoda-ku, Japan
| | - Chie Hashimoto
- Primate Research Institute, Kyoto University, Inuyama, Japan
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38
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Low Resistance of Senior Resident Females Toward Female Immigration in Bonobos (Pan paniscus) at Wamba, Democratic Republic of the Congo. INT J PRIMATOL 2020. [DOI: 10.1007/s10764-019-00126-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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