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Rind B. Same-Sex Sexual Behavior, Age-Class, and Coalitions in Male Rhesus Macaques (Macaca mulatta). ARCHIVES OF SEXUAL BEHAVIOR 2024:10.1007/s10508-024-02983-6. [PMID: 39227500 DOI: 10.1007/s10508-024-02983-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 08/08/2024] [Accepted: 08/09/2024] [Indexed: 09/05/2024]
Abstract
In the present study, relations between same-sex sexual behavior (SSB), age-class, and coalitional behavior in male rhesus macaques were examined in a re-analysis of data first analyzed and reported by Clive et al. (2023). Age-class as a focal variable was indicated in an extensive literature review, which showed that male non-adult (juvenile, adolescent) participation in SSB is extensive in this and related primate species and associated with various benefits. Clive et al. (2023) excluded juveniles from their analysis. In the re-analysis (n = 995 mounting events), it was found that non-adult involvement was substantial (51%). Most dyads contained at least one non-adult (76%). Young and prime adult mounters most often selected non-adults to mount. Mounters were often sexually motivated: most for adolescents (72%); equally for juveniles (57%) and adults (56%). Finally, the highest rate of SSB with coalitional context appeared in adolescent-adult dyads involved in multiple repeated mounts. SSB, age-class, special friendships, bonding, and coalitions were linked, as reported in some other primate species and human societies cross-culturally. Employing age-class in male SSB analysis improved description and explanation.
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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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Clive J, Flintham E, Savolainen V. Same-sex sociosexual behaviour is widespread and heritable in male rhesus macaques. Nat Ecol Evol 2023; 7:1287-1301. [PMID: 37429903 DOI: 10.1038/s41559-023-02111-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/01/2023] [Indexed: 07/12/2023]
Abstract
Numerous reports have documented the occurrence of same-sex sociosexual behaviour (SSB) across animal species. However, the distribution of the behaviour within a species needs to be studied to test hypotheses describing its evolution and maintenance, in particular whether the behaviour is heritable and can therefore evolve by natural selection. Here we collected detailed observations across 3 yr of social and mounting behaviour of 236 male semi-wild rhesus macaques, which we combined with a pedigree dating back to 1938, to show that SSB is both repeatable (19.35%) and heritable (6.4%). Demographic factors (age and group structure) explained SSB variation only marginally. Furthermore, we found a positive genetic correlation between same-sex mounter and mountee activities, indicating a common basis to different forms of SSB. Finally, we found no evidence of fitness costs to SSB, but show instead that the behaviour mediated coalitionary partnerships that have been linked to improved reproductive success. Together, our results demonstrate that SSB is frequent in rhesus macaques, can evolve, and is not costly, indicating that SSB may be a common feature of primate reproductive ecology.
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Affiliation(s)
- Jackson Clive
- Georgina Mace Centre for the Living Planet, Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK
| | - Ewan Flintham
- Georgina Mace Centre for the Living Planet, Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK
| | - Vincent Savolainen
- Georgina Mace Centre for the Living Planet, Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK.
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Tai YM, Chen MM, Zhang YH, Ma AX, Wang H, Wang X. Social Rank or Social Bonds: Which one Facilitates Coalition Formation in Male Tibetan Macaques? BIOLOGY 2022; 11:1269. [PMID: 36138747 PMCID: PMC9495305 DOI: 10.3390/biology11091269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/21/2022] [Accepted: 08/24/2022] [Indexed: 06/16/2023]
Abstract
Previous studies have shown that fierce competition could promote male coalitions. There are two ways for males to choose their allies in the conflict. The first is that supporters choose high-ranking individuals, and the second is that supporters choose affiliated individuals. It is necessary to clarify the factors for forming a coalition and the process of cooperation in primates with complex relationships and strict hierarchies. Thus, we conducted a study on a group of free-ranging Tibetan macaques (Macaca thibetana) in Anhui, China, and recorded the whole process of male macaques forming coalitions once agonistic support occurred. The results showed that a higher intensity of the social bond between males was associated with more frequent coalitions. Dominance rank also significantly influenced male coalitions, showing that high-ranking individuals allied more frequently. Moreover, males with longer residence times formed more stable coalitions. We suggest that male Tibetan macaques form a stable social relationship, where social bond and social rank both promote the formation of a coalition. This study provided some insights into the mechanism by which social cooperation develops in multi-male and multi-female groups.
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Affiliation(s)
- Yi-Mei Tai
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
- International Collaborative Research Center for Huangshan Biodiversity and Tibetan Macaque Behavioral Ecology, Hefei 230601, China
| | - Meng-Meng Chen
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
- International Collaborative Research Center for Huangshan Biodiversity and Tibetan Macaque Behavioral Ecology, Hefei 230601, China
| | - Yu-Heng Zhang
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
- International Collaborative Research Center for Huangshan Biodiversity and Tibetan Macaque Behavioral Ecology, Hefei 230601, China
| | - An-Xiang Ma
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
| | - Huan Wang
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
| | - Xi Wang
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
- International Collaborative Research Center for Huangshan Biodiversity and Tibetan Macaque Behavioral Ecology, Hefei 230601, China
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Neumann C, Kulik L, Agil M, Engelhardt A, Widdig A. Temporal dynamics and fitness consequences of coalition formation in male primates. Proc Biol Sci 2022; 289:20212626. [PMID: 35673873 PMCID: PMC9174735 DOI: 10.1098/rspb.2021.2626] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Coalition formation is one of the most striking forms of cooperation found in animals. Yet, there is substantial variation between taxa regarding the mechanisms by which coalitions can result in fitness consequences. Here, we investigate the influence of coalitions on dominance rank trajectories and subsequently on reproductive success in wild male crested macaques (Macaca nigra) at Tangkoko Nature Reserve (Sulawesi, Indonesia). We observed 128 coalition events involving 28 males and tested how a variety of coalition properties and factors related to the social environment influenced future male rank. We further used genetic paternity analysis of 19 infants conceived during the study to assess male reproductive success. Our results show that males participating in coalitions achieved higher-than-expected future ranks, while coalition targets had lower-than-expected future ranks. Additionally, all-up coalitions had stronger effects on rank than all-down and bridging coalitions, and these were modulated by the relative strength of coalition partners versus targets. Finally, higher ranking males were more likely to sire infants than lower ranking males. These results provide important insights regarding the mechanisms underlying coalition formation and support the idea that one major path by which coalitions can affect fitness is through influencing male dominance trajectories.
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Affiliation(s)
- Christof Neumann
- Research Group of Primate Behavioural Ecology, Department of Human Behaviour, Ecology and Culture, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany,Research Group of Behavioural Ecology, Institute of Biology, Faculty of Life Sciences, University of Leipzig, Germany,Junior Research Group of Primate Sexual Selection, Department of Reproductive Biology, German Primate Center, Göttingen, Germany,Courant Research Centre ‘Evolution of Social Behaviour’, Georg-August-Universität, Göttingen, Germany
| | - Lars Kulik
- Research Group of Primate Behavioural Ecology, Department of Human Behaviour, Ecology and Culture, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany,Research Group of Behavioural Ecology, Institute of Biology, Faculty of Life Sciences, University of Leipzig, Germany
| | - Muhammad Agil
- Faculty of Veterinary Medicine, Bogor Agricultural University, Bogor, Indonesia
| | - Antje Engelhardt
- Research Group of Primate Behavioural Ecology, Department of Human Behaviour, Ecology and Culture, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany,Research Group of Behavioural Ecology, Institute of Biology, Faculty of Life Sciences, University of Leipzig, Germany,Junior Research Group of Primate Sexual Selection, Department of Reproductive Biology, German Primate Center, Göttingen, Germany,Courant Research Centre ‘Evolution of Social Behaviour’, Georg-August-Universität, Göttingen, Germany
| | - Anja Widdig
- Research Group of Primate Behavioural Ecology, Department of Human Behaviour, Ecology and Culture, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany,Research Group of Behavioural Ecology, Institute of Biology, Faculty of Life Sciences, University of Leipzig, Germany
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