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Smit N, Dezeure J, Sauvadet L, Huchard E, Charpentier MJ. Socially bonded females face more sexual coercion in a female-philopatric primate. iScience 2023; 26:107358. [PMID: 37766985 PMCID: PMC10520811 DOI: 10.1016/j.isci.2023.107358] [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: 01/19/2023] [Revised: 05/09/2023] [Accepted: 07/07/2023] [Indexed: 09/29/2023] Open
Abstract
Sexual coercion is a manifestation of sexual conflict increasing male mating success while inflicting costs to females. Although previous work has examined inter-individual variation in male sexually coercive tactics, little is known about female counter-strategies. We investigated whether social bonding mitigates the extent of sexual coercion faced by female mandrills (Mandrillus sphinx), as a putative mechanism linking sociality to fitness. Surprisingly, females faced the most coercion from those males with whom they formed the strongest bonds, while the strength of a female-male bond was also positively correlated with coercion from all other males. Finally, greater social integration in the female network was positively correlated with coercion, through a direct 'public exposure' mechanism and not mediated by female reproductive success or retaliation potential. Altogether, this study shows that neither between- nor within-sex bonds are protective against sexual coercion and identifies, instead, a hidden cost of social bonding.
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Affiliation(s)
- Nikolaos Smit
- Institute of Evolutionary Sciences of Montpellier (ISEM), University of Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | | | | | - Elise Huchard
- Institute of Evolutionary Sciences of Montpellier (ISEM), University of Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Marie J.E. Charpentier
- Institute of Evolutionary Sciences of Montpellier (ISEM), University of Montpellier, CNRS, IRD, EPHE, Montpellier, France
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Bücklestrasse 5, 78467 Konstanz, Germany
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2
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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 DOI: 10.1098/rstb.2022.0301] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [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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3
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Thierry B, Rebout N, Heistermann M. Hormonal responses to mating competition in male Tonkean macaques. Horm Behav 2023; 154:105395. [PMID: 37390781 DOI: 10.1016/j.yhbeh.2023.105395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/30/2023] [Accepted: 06/17/2023] [Indexed: 07/02/2023]
Abstract
Glucocorticoid and androgen hormones play a prominent role in male reproductive effort. Their production usually increases in non-human primates during mating competition, which may include rivalry for access to receptive females, struggles for high dominance rank, or social pressure on low-ranking individuals. It is generally assumed that glucocorticoids and androgens are associated with mating challenges rather than dominance status, but the involvement of multiple factors makes it difficult to disentangle the two. In this regard, Tonkean macaques provide a suitable model because they are characterized by relaxed dominance and year-round breeding, meaning that there is typically no more than one receptive female in a group, and thus first-ranking males can easily monopolize her. We studied two captive groups of Tonkean macaques over an 80-month period, recording the reproductive status of females, collecting urine from males and sampling behaviors in both sexes. Male urinary hormone concentrations could be affected by increased competition caused by the mating period, the number of males and the degree of female attractiveness. The highest increases in androgens were recorded in males performing female mate-guarding. Despite the importance of dominance status in determining which males can mate, we found no significant effect of male rank on glucocorticoids and only a marginal effect on androgens during mate-guarding. Both types of hormones were more directly involved in the mating effort of males than in their dominance status. Our results show that their function can be understood in light of the particular competitive needs generated by the species-specific social system.
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Affiliation(s)
- Bernard Thierry
- Laboratoire de Psychologie Sociale et Cognitive, CNRS, Université Clermont Auvergne, Clermont-Ferrand, France.
| | - Nancy Rebout
- UMR Herbivores, INRAE, VetAgro Sup, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Michael Heistermann
- Endocrinology Laboratory, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
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4
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Sandel AA. Male-male relationships in chimpanzees and the evolution of human pair bonds. Evol Anthropol 2023; 32:185-194. [PMID: 37269494 DOI: 10.1002/evan.21986] [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: 08/23/2022] [Revised: 12/27/2022] [Accepted: 05/12/2023] [Indexed: 06/05/2023]
Abstract
The evolution of monogamy has been a central question in biological anthropology. An important avenue of research has been comparisons across "socially monogamous" mammals, but such comparisons are inappropriate for understanding human behavior because humans are not "pair living" and are only sometimes "monogamous." It is the "pair bond" between reproductive partners that is characteristic of humans and has been considered unique to our lineage. I argue that pair bonds have been overlooked in one of our closest living relatives, chimpanzees. These pair bonds are not between mates but between male "friends" who exhibit enduring and emotional social bonds. The presence of such bonds in male-male chimpanzees raises the possibility that pair bonds emerged earlier in our evolutionary history. I suggest pair bonds first arose as "friendships" and only later, in the human lineage, were present between mates. The mechanisms for these bonds were co-opted for male-female bonds in humans.
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Affiliation(s)
- Aaron A Sandel
- Department of Anthropology, University of Texas at Austin, Austin, Texas, USA
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Weiss A, Feldblum JT, Altschul DM, Collins DA, Kamenya S, Mjungu D, Foerster S, Gilby IC, Wilson ML, Pusey AE. Personality traits, rank attainment, and siring success throughout the lives of male chimpanzees of Gombe National Park. PeerJ 2023; 11:e15083. [PMID: 37123001 PMCID: PMC10135409 DOI: 10.7717/peerj.15083] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 02/25/2023] [Indexed: 05/02/2023] Open
Abstract
Personality traits in many taxa correlate with fitness. Several models have been developed to try to explain how variation in these traits is maintained. One model proposes that variation persists because it is linked to trade-offs between current and future adaptive benefits. Tests of this model's predictions, however, are scant in long-lived species. To test this model, we studied male chimpanzees living in Gombe National Park, Tanzania. We operationalized six personality traits using ratings on 19 items. We used 37 years of behavioral and genetic data to assemble (1) daily rank scores generated from submissive vocalizations and (2) records of male siring success. We tested whether the association between two personality traits, Dominance and Conscientiousness, and either rank or reproductive success, varied over the life course. Higher Dominance and lower Conscientiousness were associated with higher rank, but the size and direction of these relationships did not vary over the life course. In addition, independent of rank at the time of siring, higher Dominance and lower Conscientiousness were related to higher siring success. Again, the size and direction of these relationships did not vary over the life course. The trade-off model, therefore, may not hold in long-lived and/or slowly reproducing species. These findings also demonstrate that ratings are a valid way to measure animal personality; they are related to rank and reproductive success. These traits could therefore be used to test alternative models, including one that posits that personality variation is maintained by environmental heterogeneity, in studies of multiple chimpanzee communities.
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Affiliation(s)
- Alexander Weiss
- National Evolutionary Synthesis Center, Durham, NC, United States of America
- School of Philosophy, Psychology and Language Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Wildlife Research Center, Kyoto University, Kyoto, Japan
- Scottish Primate Research Group, United Kingdom
| | - Joseph T. Feldblum
- Department of Anthropology, University of Michigan - Ann Arbor, Ann Arbor, MI, United States of America
- Society of Fellows, University of Michigan - Ann Arbor, Ann Arbor, MI, United States of America
- Department of Evolutionary Anthropology, Duke University, Durham, NC, United States of America
| | - Drew M. Altschul
- School of Philosophy, Psychology and Language Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Scottish Primate Research Group, United Kingdom
- Mental Health Data Science, Edinburgh, United Kingdom
| | | | - Shadrack Kamenya
- Gombe Stream Research Centre, Jane Goodall Institute, Kigoma, Tanzania
| | - Deus Mjungu
- Gombe Stream Research Centre, Jane Goodall Institute, Kigoma, Tanzania
| | - Steffen Foerster
- Department of Evolutionary Anthropology, Duke University, Durham, NC, United States of America
| | - Ian C. Gilby
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, United States of America
- Institute of Human Origins, Arizona State University, Tempe, AZ, United States of America
| | - Michael L. Wilson
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, United States of America
- Institute on the Environment, University of Minnesota, St. Paul, MN, United States of America
| | - Anne E. Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC, United States of America
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Puberty initiates a unique stage of social learning and development prior to adulthood: Insights from studies of adolescence in wild chimpanzees. Dev Cogn Neurosci 2022; 58:101176. [PMID: 36427434 PMCID: PMC9699942 DOI: 10.1016/j.dcn.2022.101176] [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: 06/28/2022] [Revised: 10/28/2022] [Accepted: 11/15/2022] [Indexed: 11/18/2022] Open
Abstract
In humans, puberty initiates a period of rapid growth, change, and formative neurobehavioral development. Brain and behavior changes during this maturational window contribute to opportunities for social learning. Here we provide new insights into adolescence as a unique period of social learning and development by describing field studies of our closest living relatives, chimpanzees. Like humans, chimpanzees have a multiyear juvenile life stage between weaning and puberty onset followed by a multiyear adolescent life stage after pubertal onset but prior to socially-recognized adulthood. As they develop increasing autonomy from caregivers, adolescent chimpanzees explore and develop many different types of social relationships with a wide range of individuals in a highly flexible social environment. We describe how adolescent social motivations and experiences differ from those of juveniles and adults and expose adolescents to high levels of uncertainty, risk, and vulnerability, as well as opportunities for adaptive social learning. We discuss how these adolescent learning experiences may be shaped by early life and in turn shape varied adult social outcomes. We outline how future chimpanzee field research can contribute in new ways to a more integrative interdisciplinary understanding of adolescence as a developmental window of adaptive social learning and resilience.
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Sonnweber R, Stevens JMG, Hohmann G, Deschner T, Behringer V. Blood testosterone levels in sickness and in health: Male chimpanzee testosterone levels decrease in face of an immune challenge. Am J Primatol 2021; 84:e23334. [PMID: 34662432 DOI: 10.1002/ajp.23334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 09/11/2021] [Accepted: 09/25/2021] [Indexed: 11/08/2022]
Abstract
As an integral part of the immune response, testosterone secretion is inhibited when an individual is confronted with an immune challenge. Testosterone-mediated physiological, morphological, and behavioral traits are compromised at times of impaired health. Nevertheless, males of some species seem to maintain high levels of testosterone when confronted with an immune challenge, upholding competitive strength but compromising their immune response. It has been argued that this phenomenon will occur only in species living in social systems with high degrees of male-male competition over mating opportunities. Male chimpanzees contest over access to fertile females and dominants sire the majority of offspring. This male mating pattern makes chimpanzees a candidate species where we could expect males to maintain high testosterone levels, compromising their immune response, to ensure immediate reproductive success. We measured blood testosterone levels in male and female chimpanzees, who expressed clinical symptoms (symptomatic) or showed no evidence of clinical disease on assessment (asymptomatic). For females, we expected to find lower testosterone levels in symptomatic individuals than in asymptomatic subjects. In males, we would predict lower testosterone levels in symptomatic individuals than in asymptomatic males, if the immune response leads to a decrease in testosterone secretion. Alternatively, males could have equal levels of testosterone when symptomatic and asymptomatic, upholding competitive strength. Our results show that male chimpanzees exhibit lower levels of testosterone when confronted with an immune challenge than when being asymptomatic. This suggests that male testosterone secretion is suppressed as part of the immune response, which potentially increases survival and lifetime reproductive success. It will, however, negatively impact momentary competitive ability. Also, males may employ different mating strategies, some of which are less testosterone-driven (e.g., affiliative strategies). Consequently, in some individuals, the costs of maintaining high testosterone levels may not outweigh the potential gain in reproductive success.
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Affiliation(s)
- Ruth Sonnweber
- Department of Behavioral and Cognitive Biology, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Jeroen M G Stevens
- Department of Biology, Behavioral Ecology and Ecophysiology, University of Antwerp, Wilrijk, Belgium.,SALTO, Agro- and Biotechnology, Odisee University College, Brussels, Belgium
| | - Gottfried Hohmann
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Tobias Deschner
- Interim Group Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Verena Behringer
- Interim Group Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Endocrinology Laboratory, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
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8
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Enigk DK, Emery Thompson M, Machanda ZP, Wrangham RW, Muller MN. Female-directed aggression by adolescent male chimpanzees primarily constitutes dominance striving, not sexual coercion. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 176:66-79. [PMID: 33938563 DOI: 10.1002/ajpa.24296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 04/06/2021] [Accepted: 04/17/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Chimpanzees (Pan troglodytes) are notable for exhibiting high levels of male-to-female aggression. Much of this aggression from adult males serves sexually coercive functions. Despite being smaller and lower-ranking than adult males, adolescent males also engage in regular aggression against adult females. Here, we test whether the primary function of this aggression is sexual coercion, as in adult males, or, alternatively, whether adolescent males use aggression to establish social dominance over females. MATERIALS AND METHODS We analyzed 1771 copulations and 1812 instances of male-initiated aggression between adolescent males (aged nine through 14 years) and adult females across 21 years of observation of the Kanyawara chimpanzee community in Kibale National Park, Uganda. RESULTS Our test of the sexual coercion hypothesis revealed that adolescent males did not selectively target cycling females for aggression, nor did aggression against cycling females predict rates of copulation with those females. Our test of the social dominance hypothesis showed that males succeeded in dominating all adult females before, or soon after, dominating their first adult male. Additionally, we found that adolescent males dominated females approximately in the order of the females' own ranks, from the bottom to the top of the female hierarchy. DISCUSSION Our data illustrate that the establishment of social dominance was more important than sexual coercion in explaining patterns of adolescent male aggression toward females. In comparison, evidence for sexual coercion was clear and compelling in adult males. These findings highlight that the primary function of male-to-female aggression differs between adolescent and adult males.
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Affiliation(s)
- Drew K Enigk
- Department of Anthropology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Melissa Emery Thompson
- Department of Anthropology, University of New Mexico, Albuquerque, New Mexico, USA.,Kibale Chimpanzee Project, Fort Portal, Uganda
| | - Zarin P Machanda
- Kibale Chimpanzee Project, Fort Portal, Uganda.,Department of Anthropology, Tufts University, Medford, USA
| | - Richard W Wrangham
- Kibale Chimpanzee Project, Fort Portal, Uganda.,Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Martin N Muller
- Department of Anthropology, University of New Mexico, Albuquerque, New Mexico, USA.,Kibale Chimpanzee Project, Fort Portal, Uganda
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