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Saccà T, Gort G, van de Waal E, Hemelrijk CK. Male intrasexual aggression and partial dominance of females over males in vervet monkeys. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.930266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Females dominate a subset of the males in a minority of mammalian species despite male-biased sexual dimorphism. How this may arise is suggested by a computational model, DomWorld. The model represents male-biased sexual dimorphism through the males’ greater initial dominance and higher intensity of aggression, meaning that fights initiated by males have a greater impact than those by females. The model shows that female dominance over males increases with a greater proportion of males in the group. This happens because when males are involved in a larger fraction of fights this results in greater hierarchical differentiation (i.e., steepness). This causes rank overlap between the sexes (i.e., partial female dominance). We test the validity of these processes in vervet monkeys (Cercopithecus pygerythrus), a primate species with partial female dominance. We confirm that the proportion of males in the group is significantly positively correlated with the degree of dominance by females over males and with the steepness of the hierarchy among males exclusively, but not with the steepness of the hierarchy among all adults of the group. The steepness in male hierarchies correlated positively with female dominance over males in these groups. We show that steeper hierarchies among vervet males resulted from male-to-male fights being a larger proportion of the fights among all adults of the group. We conclude that the higher frequency of male intrasexual aggression favors female dominance in vervet monkeys. We also show that females received coalitionary support when they were in conflict with a male, mainly from other females, and that this favors female dominance in this species, but this does not explain why partial female dominance increased with the proportion of males in the group. We advocate further investigation of the influence of male intrasexual aggression on the degree of female dominance over males in other species with partial female dominance.
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Bshary R, Richter XYL, van Schaik C. Male services during between-group conflict: the 'hired gun' hypothesis revisited. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210150. [PMID: 35369754 DOI: 10.1098/rstb.2021.0150] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In many group-living mammals, philopatric females form the stable core of the group and defend food or shelter against other groups of females. Where males are larger, their participation could give their female group the edge. How can females secure the contribution of males that are neither the father of current infants, nor the dominant male expecting to sire the next generation of infants? It has been proposed that females recruit these males as 'hired guns', receiving social support and copulations in exchange for fighting, against the interests of the dominant male. We first develop the logic of this hypothesis in unprecedented detail by considering the potential pay-off consequences for females and males. We then provide empirical evidence for the existence of hired guns in this context in several primate species. The game-theoretical aspects of the phenomenon remain to be studied, as is the distribution across contexts (e.g. predation avoidance) and species of the hired gun phenomenon. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
- Redouan Bshary
- Behavioural Ecology Laboratory, Faculty of Science, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Xiang-Yi Li Richter
- Behavioural Ecology Laboratory, Faculty of Science, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Carel van Schaik
- Department of Anthropology and Anthropological Museum, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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Gareta García M, Farine DR, Brachotte C, Borgeaud C, Bshary R. Wild female vervet monkeys change grooming patterns and partners when freed from feeding constraints. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.08.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Schaik CP, Bshary R, Wagner G, Cunha F. Male anti‐predation services in primates as costly signalling? A comparative analysis and review. Ethology 2021. [DOI: 10.1111/eth.13233] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Carel P. Schaik
- Department of Anthropology University of Zurich Zurich Switzerland
- Center for the Interdisciplinary Study of Language Evolution University of Zurich Zurich Switzerland
| | - Redouan Bshary
- Department of Biology University of Neuchâtel Neuchâtel Switzerland
| | - Gretchen Wagner
- Behavioural Ecology Group Wageningen University & Research Wageningen The Netherlands
| | - Filipe Cunha
- Behavioural Ecology Group Wageningen University & Research Wageningen The Netherlands
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Gareta García M, Lemieux D, Bshary R. Factors affecting tolerance persistence after grooming interactions in wild female vervet monkeys, Chlorocebus pygerythrus. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.04.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Caselli M, Zanoli A, Dagradi C, Gallo A, Yazezew D, Tadesse A, Capasso M, Ianniello D, Rinaldi L, Palagi E, Norscia I. Wild geladas (Theropithecus gelada) in crops-more than in pasture areas-reduce aggression and affiliation. Primates 2021; 62:571-584. [PMID: 34061281 PMCID: PMC8225520 DOI: 10.1007/s10329-021-00916-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 05/05/2021] [Indexed: 10/26/2022]
Abstract
Human-primate interfaces are expanding and, despite recent studies on primates from peri-urban environments, little research exists on the impact of agriculture and/or pasture areas on primate social behavior and health. We assessed how crop/pasture areas potentially alter social behavior and health of wild geladas (Theropithecus gelada) frequenting the unprotected area of Kundi (Ethiopia). We predicted that compared to pasture areas, crop areas (i) would be more challenging for geladas (prediction 1) and (ii) would have a greater impact on both aggressive and affiliative behavior, by reducing grooming time and enhancing competition (prediction 2). During January-May 2019 and December 2019-February 2020, we collected data (via scan, focal animal sampling, and video analyses) on direct human disturbance, external signs of pathologies and social behavior of 140 individuals from 14 one-male units and two all-male units. Animals experienced the highest level of human disturbance in crop areas (in line with prediction 1). Individuals from the groups preferentially frequenting crop areas showed the highest prevalence of external signs of pathologies consistent with chemical and biological contamination (alopecia/abnormally swollen parts). We collected 48 fecal samples. Samples from frequent crop users contained the highest rates of parasitic elements/gram (egg/larva/oocyst/cyst) from Entamoeba histolytica/dispar, a parasite common in human settlements of the Amhara region. In crop areas, subjects spent less time grooming but engaged in lower rates of intense aggression (in partial agreement with prediction 2). We speculate that the reduction in social behavior may be a tactic adopted by geladas to minimize the likelihood of detection and maximize food intake while foraging in crops.
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Affiliation(s)
- Marta Caselli
- Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123, Torino, Italy
| | - Anna Zanoli
- Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123, Torino, Italy
| | - Carlo Dagradi
- Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123, Torino, Italy
| | - Alessandro Gallo
- Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123, Torino, Italy
| | - Dereje Yazezew
- Department of Biology, Debre Behran University, Debre Berhan, Ethiopia
| | - Abebe Tadesse
- Department of Biology, Debre Behran University, Debre Berhan, Ethiopia
| | - Michele Capasso
- Department of Veterinary Medicine and Animal Production, University of Napoli Federico II, Naples, Italy
| | - Davide Ianniello
- Department of Veterinary Medicine and Animal Production, University of Napoli Federico II, Naples, Italy
| | - Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Napoli Federico II, Naples, Italy
| | - Elisabetta Palagi
- Unit of Ethology, Department of Biology, University of Pisa, via Volta 6, 56126, Pisa, Italy.
- University of Pisa, Natural History Museum, Pisa, Italy.
| | - Ivan Norscia
- Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123, Torino, Italy.
- University of Pisa, Natural History Museum, Pisa, Italy.
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Gokcekus S, Cole EF, Sheldon BC, Firth JA. Exploring the causes and consequences of cooperative behaviour in wild animal populations using a social network approach. Biol Rev Camb Philos Soc 2021; 96:2355-2372. [DOI: 10.1111/brv.12757] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 12/26/2022]
Affiliation(s)
- Samin Gokcekus
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
| | - Ella F. Cole
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
| | - Ben C. Sheldon
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
| | - Josh A. Firth
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
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Primates are living links to our past: The contribution of comparative studies with wild vervet monkeys to the field of social cognition. Cortex 2019; 118:65-81. [DOI: 10.1016/j.cortex.2019.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 10/29/2018] [Accepted: 03/13/2019] [Indexed: 01/14/2023]
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Mercier S, Déaux EC, van de Waal E, Bono AEJ, Zuberbühler K. Correlates of social role and conflict severity in wild vervet monkey agonistic screams. PLoS One 2019; 14:e0214640. [PMID: 31042731 PMCID: PMC6493722 DOI: 10.1371/journal.pone.0214640] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 03/18/2019] [Indexed: 11/29/2022] Open
Abstract
Screams are acoustically distinct, high-pitched and high-amplitude calls, produced by many social species. Despite a wide range of production contexts, screams are characterised by an acoustic structure that appears to serve in altering the behaviour of targeted receivers during agonistic encounters. In chimpanzees, this can be achieved by callers producing acoustic variants that correlate with their identity, social role, relationship with the targeted recipient, the composition of the audience and the nature of the event. Although vervet monkeys (Chlorocebus pygerythrus) have been studied for decades, not much is known about their agonistic screams. Here, we examined agonistic screams produced by wild vervet monkeys to investigate the degree to which caller identity, social role and conflict severity affected call structure. We found that screams were both individually distinctive and dependent of the agonistic events. In particular, victim screams were longer and higher-pitched than aggressor screams, while screams produced in severe conflicts (chases, physical contact) had higher entropy than those in mild conflicts. We discuss these findings in terms of their evolutionary significance and suggest that acoustic variation might serve to reduce the aggression level of opponents, while simultaneously attracting potential helpers.
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Affiliation(s)
- Stéphanie Mercier
- Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu-Natal, Vryheid, South Africa
| | - Eloïse C. Déaux
- Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Erica van de Waal
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu-Natal, Vryheid, South Africa
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Anthropological Institute and Museum, University of Zürich, Zürich, Switzerland
| | - Axelle E. J. Bono
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu-Natal, Vryheid, South Africa
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Klaus Zuberbühler
- Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu-Natal, Vryheid, South Africa
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Scotland, United Kingdom
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Arseneau-Robar TJM, Müller E, Taucher AL, van Schaik CP, Bshary R, Willems EP. Male monkeys use punishment and coercion to de-escalate costly intergroup fights. Proc Biol Sci 2018; 285:20172323. [PMID: 29875293 PMCID: PMC6015864 DOI: 10.1098/rspb.2017.2323] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 05/10/2018] [Indexed: 11/12/2022] Open
Abstract
In numerous social species, males direct aggression towards female group members during intergroup fights, and this behaviour is commonly thought to function as mate guarding, even though males often target non-receptive females. In studying intergroup fights in a wild population of vervet monkeys, we found that male intragroup aggression was primarily directed towards individuals who had either just finished exhibiting, or were currently attempting to instigate intergroup aggression. Targeted females were less likely to instigate intergroup aggression in the future, indicating that male intragroup aggression functioned as coercion (when directed towards those who were currently trying to instigate a fight) and punishment (when directed towards those who had recently fought). These manipulative tactics effectively prevented intergroup encounters from escalating into fights and often de-escalated ongoing conflicts. Males who were likely sires were those most likely to use punishment/coercion, particularly when they were wounded, and, therefore, less able to protect vulnerable offspring should a risky intergroup fight erupt. This work, along with our previous finding that females use punishment and rewards to recruit males into participating in intergroup fights, highlights the inherent conflict of interest that exists between the sexes, as well as the role that social incentives can play in resolving this conflict. Furthermore, unlike other studies which have found punishment to be used asymmetrically between partners, these works represent a novel example of reciprocal punishment in a non-human animal.
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Affiliation(s)
- T Jean M Arseneau-Robar
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal, South Africa
| | - Eliane Müller
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal, South Africa
| | - Anouk L Taucher
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal, South Africa
| | - Carel P van Schaik
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal, South Africa
| | - Redouan Bshary
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal, South Africa
- Department of Zoology, University of Neuchâtel, Rue Emile-Argand 11, 2007 Neuchâtel, Switzerland
| | - Erik P Willems
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal, South Africa
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Kappeler PM. Sex roles and adult sex ratios: insights from mammalian biology and consequences for primate behaviour. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160321. [PMID: 28760762 PMCID: PMC5540861 DOI: 10.1098/rstb.2016.0321] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2017] [Indexed: 12/23/2022] Open
Abstract
Theoretical models and empirical studies in various taxa have identified important links between variation in sex roles and the number of adult males and females (adult sex ratio (ASR)) in a population. In this review, I examine these relationships in non-human primates. Because most existing theoretical models of the evolution of sex roles focus on the evolutionary origins of sex-biased behaviour, they offer only a general scaffold for predicting variation in sex roles among and within species. I argue that studies examining sex role variation at these more specific levels need to take social organization into account to identify meaningful levels for the measurement of ASR and to account for the fact that ASR and sex roles mutually influence each other. Moreover, taxon-specific life-history traits can constrain sex role flexibility and impact the operational sex ratio (OSR) by specifying the minimum length of female time outs from reproduction. Using examples from the primate literature, I highlight practical problems in estimating ASR and OSR. I then argue that interspecific variation in the occurrence of indirect forms of paternal care might indeed be linked to variation in ASR. Some studies also indicate that female aggression and bonding, as well as components of inter-sexual relationships, are sensitive to variation in ASR. Thus, links between primate sex roles and sex ratios merit further study, and such studies could prompt the development of more specific theoretical models that make realistic assumptions about taxon-specific life history and social organization.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.
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Affiliation(s)
- Peter M Kappeler
- Wissenschaftskolleg zu Berlin, Wallotstrasse 19, 14193 Berlin, Germany
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
- Department of Sociobiology/Anthropology, University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany
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