1
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Brown ER, Gettler LT, Rosenbaum S. Effects of social environments on male primate HPG and HPA axis developmental programming. Dev Psychobiol 2024; 66:e22491. [PMID: 38698633 DOI: 10.1002/dev.22491] [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: 09/01/2023] [Revised: 03/05/2024] [Accepted: 04/07/2024] [Indexed: 05/05/2024]
Abstract
Developmental plasticity is particularly important for humans and other primates because of our extended period of growth and maturation, during which our phenotypes adaptively respond to environmental cues. The hypothalamus-pituitary-gonadal (HPG) and hypothalamus-pituitary-adrenal (HPA) axes are likely to be principal targets of developmental "programming" given their roles in coordinating fitness-relevant aspects of the phenotype, including sexual development, adult reproductive and social strategies, and internal responses to the external environment. In social animals, including humans, the social environment is believed to be an important source of cues to which these axes may adaptively respond. The effects of early social environments on the HPA axis have been widely studied in humans, and to some extent, in other primates, but there are still major gaps in knowledge specifically relating to males. There has also been relatively little research examining the role that social environments play in developmental programming of the HPG axis or the HPA/HPG interface, and what does exist disproportionately focuses on females. These topics are likely understudied in males in part due to the difficulty of identifying developmental milestones in males relative to females and the general quiescence of the HPG axis prior to maturation. However, there are clear indicators that early life social environments matter for both sexes. In this review, we examine what is known about the impact of social environments on HPG and HPA axis programming during male development in humans and nonhuman primates, including the role that epigenetic mechanisms may play in this programming. We conclude by highlighting important next steps in this research area.
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Affiliation(s)
- Ella R Brown
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lee T Gettler
- Department of Anthropology, University of Notre Dame, Notre Dame, Indiana, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Stacy Rosenbaum
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan, USA
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2
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Morrison RE, Ndayishimiye E, Stoinski TS, Eckardt W. Multiple mechanisms for inbreeding avoidance used simultaneously in a wild ape. Proc Biol Sci 2023; 290:20231808. [PMID: 37848059 PMCID: PMC10581766 DOI: 10.1098/rspb.2023.1808] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 09/21/2023] [Indexed: 10/19/2023] Open
Abstract
Mating with close kin can have considerable negative fitness consequences, which are expected to result in selective pressure for inbreeding avoidance mechanisms, such as dispersal, mate choice and post-copulatory biases. Captive studies have suggested that inbreeding avoidance through mate choice is far less widespread than expected and may be absent where other mechanisms already limit inbreeding. However, few studies have examined multiple mechanisms of inbreeding avoidance simultaneously, particularly in the wild. We use 13 years of detailed dispersal, copulation and paternity data from mountain gorillas to examine inbreeding avoidance. We find that partial dispersal of both sexes results in high kinship in multimale groups, but that copulations between close kin occur 40% less than expected. We find strong kin discrimination in mate choice, with significant avoidance of maternal kin but more limited avoidance of paternal kin. We find no evidence for post-copulatory inbreeding avoidance. Our analyses support familiarity-based mechanisms of kin identification and age-based avoidance that limits mating between fathers and daughters in their natal group. Our findings demonstrate that multiple complementary mechanisms for inbreeding avoidance can evolve in a single species and suggest that inbreeding avoidance through mate choice may enable more flexible dispersal systems to evolve.
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Affiliation(s)
- Robin E. Morrison
- Dian Fossey Gorilla Fund, Musanze, Rwanda
- Human Evolutionary Ecology Group, Department of Evolutionary Anthropology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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3
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Hawley CR, Patterson SK, Silk JB. Tradeoffs between mating effort and parenting effort in a polygynandrous mammal. iScience 2023; 26:106991. [PMID: 37534148 PMCID: PMC10391602 DOI: 10.1016/j.isci.2023.106991] [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: 12/16/2022] [Revised: 02/09/2023] [Accepted: 05/25/2023] [Indexed: 08/04/2023] Open
Abstract
Reproductive strategies are defined by expenditures of time and energy devoted to mating effort, which increases mating opportunities, and parenting effort, which enhances the survival of offspring. We examine tradeoffs between mating effort and parenting effort in male olive baboons, Papio anubis, a species in which males compete for mating opportunities, but also form ties to lactating females (primary associations) that represent a form of parenting effort. Males that are involved in more primary associations invest less in mating effort than males who are involved in fewer primary associations. Males that are involved in more primary associations play a smaller role in establishing proximity to their primary associates than other males, suggesting that males operate under temporal constraints. There is also some evidence that involvement in primary associations negatively affects paternity success. Taken together, the data suggest that males face tradeoffs between mating effort and parenting effort.
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Affiliation(s)
- Caitlin R. Hawley
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, USA
| | - Sam K. Patterson
- Department of Anthropology, New York University, New York, NY 10003, USA
| | - Joan B. Silk
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, USA
- Institute for Human Origins, Arizona State University, Tempe, AZ 85287, USA
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4
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Morrison RE, Eckardt W, Stoinski TS, Rosenbaum S. Cumulative early-life adversity does not predict reduced adult longevity in wild gorillas. Curr Biol 2023; 33:2307-2314.e4. [PMID: 37192615 PMCID: PMC10264970 DOI: 10.1016/j.cub.2023.04.051] [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: 12/20/2022] [Revised: 02/24/2023] [Accepted: 04/21/2023] [Indexed: 05/18/2023]
Abstract
Extensive research across fields has repeatedly confirmed that early-life adversity (ELA) is a major selective force for many taxa, in part via its ties to adult health and longevity.1,2,3 Negative effects of ELA on adult outcomes have been documented in a wide range of species, from fish to birds to humans.4 We used 55 years of long-term data collected on 253 wild mountain gorillas to examine the effects of six putative sources of ELA on survival, both individually and cumulatively. Although cumulative ELA was associated with high mortality in early life, we found no evidence that it had detrimental consequences for survival later in life. Experiencing three or more forms of ELA was associated with greater longevity, with a 70% reduction in the risk of death across adulthood, driven specifically by greater longevity in males. Although this higher survival in later life is likely a consequence of sex-specific viability selection5 during early life due to the immediate mortality consequences of adverse experiences, patterns in our data also suggest that gorillas have significant resilience to ELA. Our findings demonstrate that the detrimental consequences of ELA on later life survival are not universal, and indeed largely absent in one of humans' closest living relatives. This raises important questions about the biological roots of sensitivity to early experiences and the protective mechanisms that contribute to resiliency in gorillas, which could be critical for understanding how best to encourage similar resiliency to early-life shocks in humans.
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Affiliation(s)
- Robin E Morrison
- Dian Fossey Gorilla Fund, PO Box 105, Musanze, Rwanda; Centre for Research in Animal Behaviour, Department of Psychology, University of Exeter, Exeter EX4 4QG, UK.
| | | | | | - Stacy Rosenbaum
- Department of Anthropology, University of Michigan-Ann Arbor, Ann Arbor, MI 48109, USA.
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5
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Rosenbaum S, Silk JB. Pathways to paternal care in primates. Evol Anthropol 2022; 31:245-262. [PMID: 35289027 DOI: 10.1002/evan.21942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 10/01/2021] [Accepted: 01/21/2022] [Indexed: 11/06/2022]
Abstract
Natural selection will favor male care when males have limited alternative mating opportunities, can invest in their own offspring, and when care enhances males' fitness. These conditions are easiest to fulfill in pair-bonded species, but neither male care nor stable "breeding bonds" that facilitate it are limited to pair-bonded species. We review evidence of paternal care and extended breeding bonds in owl monkeys, baboons, Assamese macaques, mountain gorillas, and chimpanzees. The data, which span social/mating systems and ecologies, suggest that there are multiple pathways by which conditions conducive to male care can arise. This diversity highlights the difficulty of making inferences about the emergence of male care in early hominins based on single traits visible in the fossil record. We discuss what types of data are most needed and the questions yet to be answered about the evolution of male care and extended breeding bonds in the primate order.
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Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan, USA
| | - Joan B Silk
- School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, USA.,Institute of Human Origins, Arizona State University, Tempe, Arizona, USA
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6
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Bray J, Murray CM, Gilby IC, Stanton MA. Immature Male Chimpanzees’ (Pan troglodytes schweinfurthii) Social Relationships with Adult Males, but Not Peers, Persist into Adulthood. INT J PRIMATOL 2021. [DOI: 10.1007/s10764-021-00235-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Rosenbaum S, Eckardt W, Stoinski TS, Umuhoza R, Kuzawa CW, Santymire RM. Group structure, but not dominance rank, predicts fecal androgen metabolite concentrations of wild male mountain gorillas (Gorilla beringei beringei). Am J Primatol 2021; 83:e23295. [PMID: 34223661 DOI: 10.1002/ajp.23295] [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: 01/08/2021] [Revised: 04/24/2021] [Accepted: 06/06/2021] [Indexed: 11/11/2022]
Abstract
Androgens are important mediators of male-male competition in many primate species. Male gorillas' morphology is consistent with a reproductive strategy that relies heavily on androgen-dependent traits (e.g., extreme size and muscle mass). Despite possessing characteristics typical of species with an exclusively single-male group structure, multimale groups with strong dominance hierarchies are common in mountain gorillas. Theory predicts that androgens should mediate their dominance hierarchies, and potentially vary with the type of group males live in. We validated the use of a testosterone enzyme immunoassay (T-EIA R156/7, CJ Munro, UC-Davis) for use with mountain gorilla fecal material by (1) examining individual-level androgen responses to competitive events, and (2) isolating assay-specific hormone metabolites via high-performance liquid chromatography. Males had large (2.6- and 6.5-fold), temporary increases in fecal androgen metabolite (FAM) after competitive events, and most captured metabolites were testosterone or 5α-dihydrotestosterone-like androgens. We then examined the relationship between males' dominance ranks, group type, and FAM concentrations. Males in single-male groups had higher FAM concentrations than males in multimale groups, and a small pool of samples from solitary males suggested they may have lower FAM than group-living peers. However, data from two different time periods (n = 1610 samples) indicated there was no clear relationship between rank and FAM concentrations, confirming results from the larger of two prior studies that measured urinary androgens. These findings highlight the need for additional research to clarify the surprising lack of a dominance hierarchy/androgen relationship in mountain gorillas.
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Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan, USA.,Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, Illinois, USA
| | - Winnie Eckardt
- Karisoke Research Center, Musanze, Rwanda.,The Dian Fossey Gorilla Fund, Atlanta, Georgia, USA
| | | | | | - Christopher W Kuzawa
- Department of Anthropology, Northwestern University, Evanston, Illinois, USA.,Institute for Policy Research, Northwestern University, Evanston, Illinois, USA
| | - Rachel M Santymire
- Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, Illinois, USA
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8
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Miller CM, Snyder-Mackler N, Nguyen N, Fashing PJ, Tung J, Wroblewski EE, Gustison ML, Wilson ML. Extragroup paternity in gelada monkeys, Theropithecus gelada, at Guassa, Ethiopia and a comparison with other primates. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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9
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Gartland KN, Biggs N, Shreeve CM, White FJ. Dominance rank, female choice, and reproductive success in semi-free ranging adult male Japanese macaques (Macaca fuscata). Am J Primatol 2021; 83:e23294. [PMID: 34157137 DOI: 10.1002/ajp.23294] [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: 04/09/2021] [Revised: 06/07/2021] [Accepted: 06/15/2021] [Indexed: 11/07/2022]
Abstract
The assumed evolutionary advantage of dominance is increased reproductive success. However, the efficacy of dominance as a mating strategy may be interrupted by any number of variables including female choice, estrous synchrony, and mating by non-troop males. In Japanese macaques (Macaca fuscata), there is evidence both for and against dominance as conferring reproductive success for adult males, with many discussions pointing to the importance of female choice in governing reproductive success in certain populations. In this study, we aimed to evaluate dominance-based versus female choice-based male behavioral strategies and their impact on reproductive success. This study was conducted on a group of Japanese macaques at the Oregon National Primate Research Center. We collected a total of 512 h of behavioral data across two summer study periods in 2018 and 2019. We conducted 15-min focal follows with 1-min instantaneous scans on 17 adult males. Reproductive data were available from genetic records. Using principal components analysis (PCA), we identified males that cluster according to similar behavioral strategies. We then used analysis of variance (ANOVA) and non-parametric ANOVA on ranks to ascertain significant variation in rank and reproductive success between clusters. We found that males that clustered based on high directed aggression held higher rank than less-aggressive male clusters (F = 27.21, df = 4, p < .0001). However, less aggressive male clusters had higher reproductive success (F = 3.50, df = 4, p = .04). There was no variation between affiliative clusters in reproductive success (F = 1.77, df = 3, p = .15). The highly aggressive strategy is effective for attaining high rank, but only resulted in high reproductive success for a single male which likely necessitates alternative strategies. We suggest the operation of female choice within this population, with females preferentially mating with males who are not only affiliative but also less aggressive.
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Affiliation(s)
- Kylen N Gartland
- Department of Anthropology, University of Oregon, Eugene, Oregon, USA
| | - Nichole Biggs
- Department of Anthropology, University of Oregon, Eugene, Oregon, USA
| | - Caitlin M Shreeve
- Department of Anthropology, University of Oregon, Eugene, Oregon, USA
| | - Frances J White
- Department of Anthropology, University of Oregon, Eugene, Oregon, USA
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10
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Städele V, Vigilant L, Strum SC, Silk JB. Extended male–female bonds and potential for prolonged paternal investment in a polygynandrous primate (Papio anubis). Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.01.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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11
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Colchero F, Eckardt W, Stoinski T. Evidence of demographic buffering in an endangered great ape: Social buffering on immature survival and the role of refined sex-age classes on population growth rate. J Anim Ecol 2021; 90:1701-1713. [PMID: 33759185 DOI: 10.1111/1365-2656.13486] [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: 08/31/2020] [Accepted: 03/16/2021] [Indexed: 11/29/2022]
Abstract
Theoretical and empirical research has shown that increased variability in demographic rates often results in a decline in the population growth rate. In order to reduce the adverse effects of increased variability, life-history theory predicts that demographic rates that contribute disproportionately to population growth should be buffered against environmental variation. To date, evidence of demographic buffering is still equivocal and limited to analyses on a reduced number of age classes (e.g. juveniles and adults), and on single sex models. Here we used Bayesian inference models for age-specific survival and fecundity on a long-term dataset of wild mountain gorillas. We used these estimates to parameterize two-sex, age-specific stochastic population projection models that accounted for the yearly covariation between demographic rates. We estimated the sensitivity of the long-run stochastic population growth rate to reductions in survival and fecundity on ages belonging to nine sex-age classes for survival and three age classes for female fecundity. We found a statistically significant negative linear relationship between the sensitivities and variances of demographic rates, with strong demographic buffering on young adult female survival and low buffering on older female and silverback survival and female fecundity. We found moderate buffering on all immature stages and on prime-age females. Previous research on long-lived slow species has found high buffering of prime-age female survival and low buffering on immature survival and fecundity. Our results suggest that the moderate buffering of the immature stages can be partially due to the mountain gorilla social system and the relative stability of their environment. Our results provide clear support for the demographic buffering hypothesis and its predicted effects on species at the slow end of the slow-fast life-history continuum, but with the surprising outcome of moderate social buffering on the survival of immature stages. We also demonstrate how increasing the number of sex-age classes can greatly improve the detection of demographic buffering in wild populations.
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Affiliation(s)
- Fernando Colchero
- Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark.,Interdisciplinary Center on Population Dynamics, University of Southern Denmark, Odense, Denmark
| | - Winnie Eckardt
- The Dian Fossey Gorilla Fund International, Atlanta, GA, USA
| | - Tara Stoinski
- The Dian Fossey Gorilla Fund International, Atlanta, GA, USA
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12
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Morrison RE, Eckardt W, Colchero F, Vecellio V, Stoinski TS. Social groups buffer maternal loss in mountain gorillas. eLife 2021; 10:62939. [PMID: 33752800 PMCID: PMC7987338 DOI: 10.7554/elife.62939] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
Mothers are crucial for mammals’ survival before nutritional independence, but many social mammals reside with their mothers long after. In these species the social adversity caused by maternal loss later in life can dramatically reduce fitness. However, in some human populations these negative consequences can be overcome by care from other group members. We investigated the consequences of maternal loss in mountain gorillas and found no discernible fitness costs to maternal loss through survival, age at first birth, or survival of first offspring through infancy. Social network analysis revealed that relationships with other group members, particularly dominant males and those close in age, strengthened following maternal loss. In contrast to most social mammals, where maternal loss causes considerable social adversity, in mountain gorillas, as in certain human populations, this may be buffered by relationships within cohesive social groups, breaking the link between maternal loss, increased social adversity, and decreased fitness. Most mammals depend entirely upon their mothers when they are born. In these species, losing a mother at a young age has dramatic consequences for survival. In cases where orphaned individuals do reach adulthood, they often suffer negative effects, like reduced reproductive success or lower social status. But this is not the case for humans. If a child loses their mother, relatives, friends and the wider community can take over. This does not tend to happen in nature. Even our closest relatives, chimpanzees, are much less likely to survive if their mothers die before they reach adolescence. Although orphan survival is not the norm for mammals, humans may not be entirely unique. Mountain gorillas also live in stable family groups, usually with a dominant male and one or more females who care for their offspring for between 8 and 15 years. It is possible that gorillas may also be able to provide community support to orphans, which could buffer the costs of losing a mother, just as it does in humans. To answer this question, Morrison et al. examined 53 years of data collected by the Dian Fossey Gorilla Fund to assess the effects of maternal loss in mountain gorillas. The analysis examined survival, reproduction and changes in social relationships. This revealed that, like humans, young gorillas that lose their mothers are not at a greater risk of dying. There is also no clear long-term effect on their ability to reproduce. In fact, gorillas who lost their mothers ended up with stronger social relationships, especially with the dominant male of the group and young gorillas around the same age. It seems that gorilla social groups, like human families, provide support to young group members that lose their mothers. These findings suggest that the human ability to care for others in times of need may not be unique. It is possible that the tendency to care for orphaned young has its origins in our evolutionary past. Understanding this in more depth could provide clues into the social mechanisms that help to overcome early life adversity, and have a positive impact on future health and survival.
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Affiliation(s)
- Robin E Morrison
- Dian Fossey Gorilla Fund, Musanze, Rwanda.,Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom
| | | | - Fernando Colchero
- Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark.,Interdisciplinary Center on Population Dynamics, University of Southern Denmark, Odense, Denmark
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13
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Gettler LT, Boyette AH, Rosenbaum S. Broadening Perspectives on the Evolution of Human Paternal Care and Fathers’ Effects on Children. ANNUAL REVIEW OF ANTHROPOLOGY 2020. [DOI: 10.1146/annurev-anthro-102218-011216] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Unlike most mammals, human fathers cooperate with mothers to care for young to an extraordinary degree. Human paternal care likely evolved alongside our unique life history strategy of raising slow-developing, energetically costly children, often in rapid succession. Adaptive frameworks generally assume that paternal provisioning played a critical role in this pattern's emergence. We draw on nonhuman primate data to propose that nonprovisioning forms of low-cost hominin male care were potentially foundational and ratcheted up through evolutionary time, helping facilitate social contexts for later subsistence specialization and sharing. We then argue for expanding the breadth of anthropological research on paternal effects in families, particularly in three domains: direct care and teaching;social capital cultivation; and reduction of family conflict. Anthropologists can greatly contribute to conversations about the determinants of children's development across contexts, but we need to ask more expansive questions about the pathways through which caregivers (including fathers) affect child outcomes.
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Affiliation(s)
- Lee T. Gettler
- Department of Anthropology, and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Adam H. Boyette
- Department of Human Behavior, Ecology, and Culture, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
| | - Stacy Rosenbaum
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
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14
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Sandel AA, Langergraber KE, Mitani JC. Adolescent male chimpanzees (Pan troglodytes) form social bonds with their brothers and others during the transition to adulthood. Am J Primatol 2020; 82:e23091. [PMID: 31903634 DOI: 10.1002/ajp.23091] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 12/15/2019] [Accepted: 12/20/2019] [Indexed: 12/29/2022]
Abstract
Social relationships play an important role in animal behavior. Bonds with kin provide indirect fitness benefits, and those with nonkin may furnish direct benefits. Adult male chimpanzees (Pan troglodytes) exhibit social bonds with maternal brothers as well as unrelated adult males, facilitating cooperative behavior, but it is unclear when these bonds develop. Prior studies suggest that social bonds emerge during adolescence. Alternatively, bonds may develop during adulthood when male chimpanzees can gain fitness benefits through alliances used to compete for dominance status. To investigate these possibilities and to determine who formed bonds, we studied the social relationships of adolescent and young adult male chimpanzees (N = 18) at Ngogo in Kibale National Park, Uganda. Adolescent male chimpanzees displayed social bonds with other males, and they did so as often as did young adult males. Adolescent and young adult males frequently joined subgroups with old males. They spent time in proximity to and grooming with old males, although they also did so with their age peers. Controlling for age and age difference, males formed strong association and proximity relationships with their maternal brothers and grooming relationships with their fathers. Grooming bonds between chimpanzee fathers and their adolescent and young adult sons have not been documented before and are unexpected because female chimpanzees mate with multiple males. How fathers recognize their sons and vice versa remains unclear but may be due to familiarity created by relationships earlier in development.
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Affiliation(s)
- Aaron A Sandel
- Department of Anthropology, University of Texas, Austin, Texas.,Department of Anthropology, University of Michigan, Ann Arbor, Michigan
| | - Kevin E Langergraber
- School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona.,Institute of Human Origins, Arizona State University, Tempe, Arizona
| | - John C Mitani
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan
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15
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Emery Thompson M. How can non-human primates inform evolutionary perspectives on female-biased kinship in humans? Philos Trans R Soc Lond B Biol Sci 2019; 374:20180074. [PMID: 31303156 PMCID: PMC6664131 DOI: 10.1098/rstb.2018.0074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2018] [Indexed: 11/12/2022] Open
Abstract
The rarity of female-biased kinship organization in human societies raises questions about ancestral hominin family structures. Such questions require grounding in the form and function of kin relationships in our close phylogenetic relatives, the non-human primates. Common features of primate societies, such as low paternity certainty and lack of material wealth, are consistent with features that promote matriliny in humans. In this review, I examine the role of kinship in three primate study systems (socially monogamous species, female-bonded cercopithecines and great apes) that, each for different reasons, offer insights into the evolutionary roots of matriliny. Using these and other examples, I address potential analogues to features of female-biased kinship organization, including residence, descent and inheritance. Social relationships are biased towards matrilineal kin across primates, even where female dispersal limits access to them. In contrast to the strongly intergenerational nature of human kinship, most primate kin relationships function laterally as the basis for cooperative networks and require active reinforcement. There is little evidence that matrilineal kin relationships in primates are functionally equivalent to descent or true inheritance, but further research is needed to understand whether human cultural constructs of kinship produce fundamentally different biological outcomes from their antecedents in primates. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.
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16
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Rosenbaum S, Gettler LT. With a little help from her friends (and family) part I: the ecology and evolution of non-maternal care in mammals. Physiol Behav 2019; 193:1-11. [PMID: 29933836 DOI: 10.1016/j.physbeh.2017.12.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 11/27/2017] [Accepted: 12/20/2017] [Indexed: 10/28/2022]
Abstract
In the class Mammalia, most young are cared for exclusively by their mothers. In species where mothers receive help, however, non-maternal caregivers may play a crucial role in development and life history trajectories. In turn, recipients of such care may have important impacts on caregivers of all types. In Part I of this overview, we briefly review the evolutionary barriers to widespread non-maternal care in mammals, and explain why the exceptions are of particular theoretical importance. We also summarize the current understanding of the selective forces leading to non-maternal care, and the taxa and types of caretakers amongst which it occurs. Finally, we argue for a fresh look at the categorization schemes that have traditionally been used to separate various types of mammalian non-maternal caregivers. This two-part introduction is aimed at scientists from multiple disciplines who study diverse organismal systems. It draws from the social and biological sciences literatures to provide an overview of this special issue of Physiology and Behavior's suite of methodological offerings and theoretical underpinnings.
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Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, Northwestern University, Evanston, IL, United States; Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, IL, United States.
| | - Lee T Gettler
- Department of Anthropology, University of Notre Dame, Notre Dame, IN, United States; The Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
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17
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Mirville MO, Ridley AR, Samedi JPM, Vecellio V, Ndagijimana F, Stoinski TS, Grueter CC. Low familiarity and similar ‘group strength’ between opponents increase the intensity of intergroup interactions in mountain gorillas (Gorilla beringei beringei). Behav Ecol Sociobiol 2018. [DOI: 10.1007/s00265-018-2592-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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18
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Robbins MM, Robbins AM. Variation in the social organization of gorillas: Life history and socioecological perspectives. Evol Anthropol 2018; 27:218-233. [PMID: 30325554 DOI: 10.1002/evan.21721] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 07/18/2018] [Accepted: 08/06/2018] [Indexed: 01/29/2023]
Abstract
A focus of socioecological research is to understand how ecological, social, and life history factors influence the variability of social organization within and between species. The genus Gorilla exhibits variability in social organization with western gorilla groups being almost exclusively one-male, yet approximately 40% of mountain gorilla groups are multimale. We review five ultimate causes for the variability in social organization within and among gorilla populations: human disturbance, ecological constraints on group size, risk of infanticide, life history patterns, and population density. We find the most evidence for the ecological constraints and life history hypotheses, but an over-riding explanation remains elusive. The variability may hinge on variation in female dispersal patterns, as females seek a group of optimal size and with a good protector male. Our review illustrates the challenges of understanding why the social organization of closely related species may deviate from predictions based on socioecological and life history theory.
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Affiliation(s)
- Martha M Robbins
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Andrew M Robbins
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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19
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Rosenbaum S, Vigilant L, Kuzawa CW, Stoinski TS. Caring for infants is associated with increased reproductive success for male mountain gorillas. Sci Rep 2018; 8:15223. [PMID: 30323256 PMCID: PMC6189178 DOI: 10.1038/s41598-018-33380-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/27/2018] [Indexed: 11/09/2022] Open
Abstract
Socioecological theory predicts that male parenting among mammals should be rare due to the large payoffs of prioritizing mating effort over parenting. Although these predictions are generally met, in some promiscuous primate species males overcome this by identifying their offspring, and providing benefits such as protection and resource access. Mountain gorillas, which often organize into multi-male groups, are an intriguing exception. Males frequently affiliate with infants despite not discriminating their own from other males' offspring, raising questions about the function of this behavior. Here we demonstrate that, independent of multiple controls for rank, age, and siring opportunities, male gorillas who affiliated more with all infants, not only their own, sired more offspring than males who affiliated less with young. Predictive margins indicate males in the top affiliation tertile can expect to sire approximately five times more infants than males in the bottom tertile, across the course of their reproductive careers. These findings establish a link between males' fitness and their associations with infants in the absence of kin discrimination or high paternity certainty, and suggest a strategy by which selection could generate more involved male parenting among non-monogamous species.
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Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, Northwestern University, Evanston, IL, USA.
- Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, IL, USA.
| | - Linda Vigilant
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Christopher W Kuzawa
- Department of Anthropology, Northwestern University, Evanston, IL, USA
- Institute for Policy Research, Northwestern University, Evanston, IL, USA
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20
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Mirville MO, Ridley AR, Samedi J, Vecellio V, Ndagijimana F, Stoinski TS, Grueter CC. Factors influencing individual participation during intergroup interactions in mountain gorillas. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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21
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Affiliation(s)
- Stephanie L Canington
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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22
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Boose K, White F, Brand C, Meinelt A, Snodgrass J. Infant handling in bonobos (Pan paniscus): Exploring functional hypotheses and the relationship to oxytocin. Physiol Behav 2018; 193:154-166. [DOI: 10.1016/j.physbeh.2018.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 04/08/2018] [Accepted: 04/09/2018] [Indexed: 12/26/2022]
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23
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Baker RR, Shackelford TK. A comparison of paternity data and relative testes size as measures of level of sperm competition in the Hominoidea. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017; 165:421-443. [DOI: 10.1002/ajpa.23360] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/30/2017] [Accepted: 10/31/2017] [Indexed: 02/06/2023]
Affiliation(s)
- R. Robin Baker
- School of Biological Sciences; University of Manchester; Manchester United Kingdom
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24
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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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25
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Chagnon NA, Lynch RF, Shenk MK, Hames R, Flinn MV. Cross-cousin marriage among the Yanomamö shows evidence of parent-offspring conflict and mate competition between brothers. Proc Natl Acad Sci U S A 2017; 114:E2590-E2607. [PMID: 28289230 PMCID: PMC5380100 DOI: 10.1073/pnas.1618655114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Marriage in many traditional societies often concerns the institutionalized exchange of reproductive partners among groups of kin. Such exchanges most often involve cross-cousins-marriage with the child of a parent's opposite-sex sibling-but it is unclear who benefits from these exchanges. Here we analyze the fitness consequences of marrying relatives among the Yanomamö from the Amazon. When individuals marry close kin, we find that (i) both husbands and wives have slightly lower fertility; (ii) offspring suffer from inbreeding depression; (iii) parents have more grandchildren; and (iv) siblings, especially brothers, benefit when their opposite-sex siblings marry relatives but not when their same-sex siblings do. Therefore, individuals seem to benefit when their children or opposite-sex siblings marry relatives but suffer costs when they, their parents, or same-sex siblings do. These asymmetric fitness outcomes suggest conflicts between parents and offspring and among siblings over optimal mating strategies. Parental control of marriages is reinforced by cultural norms prescribing cross-cousin marriage. We posit that local mate competition combined with parental control over marriages may escalate conflict between same-sex siblings who compete over mates, while simultaneously forging alliances between opposite-sex siblings. If these relationships are carried forward to subsequent generations, they may drive bilateral cross-cousin marriage rules. This study provides insights into the evolutionary importance of how kinship and reciprocity underlie conflicts over who controls mate choice and the origins of cross-cousin marriage prescriptions.
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Affiliation(s)
- Napoleon A Chagnon
- Department of Anthropology, University of Missouri, Columbia, MO 65211-1440;
| | - Robert F Lynch
- Department of Anthropology, University of Missouri, Columbia, MO 65211-1440
| | - Mary K Shenk
- Department of Anthropology, University of Missouri, Columbia, MO 65211-1440
| | - Raymond Hames
- Department of Anthropology, University of Nebraska, Lincoln, NE 68588-0368
| | - Mark V Flinn
- Department of Anthropology, University of Missouri, Columbia, MO 65211-1440
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26
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Rosenbaum S, Vecellio V, Stoinski T. Observations of severe and lethal coalitionary attacks in wild mountain gorillas. Sci Rep 2016; 6:37018. [PMID: 27849056 PMCID: PMC5111119 DOI: 10.1038/srep37018] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 10/24/2016] [Indexed: 11/09/2022] Open
Abstract
In humans and chimpanzees, most intraspecific killing occurs during coalitionary intergroup conflict. In the closely related genus Gorilla, such behavior has not been described. We report three cases of multi-male, multi-female wild mountain gorilla (G. beringei) groups attacking extra-group males. The behavior was strikingly similar to reports in chimpanzees, but was never observed in gorillas until after a demographic transition left ~25% of the population living in large social groups with multiple (3+) males. Resource competition is generally considered a motivator of great apes' (including humans) violent intergroup conflict, but mountain gorillas are non-territorial herbivores with low feeding competition. While adult male gorillas have a defensible resource (i.e. females) and nursing/pregnant females are likely motivated to drive off potentially infanticidal intruders, the participation of others (e.g. juveniles, sub-adults, cycling females) is harder to explain. We speculate that the potential for severe group disruption when current alpha males are severely injured or killed may provide sufficient motivation when the costs to participants are low. These observations suggest that the gorilla population's recent increase in multi-male groups facilitated the emergence of such behavior, and indicates social structure is a key predictor of coalitionary aggression even in the absence of meaningful resource stress.
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Affiliation(s)
- Stacy Rosenbaum
- Institute for Mind and Biology, University of Chicago, Chicago, Illinois, USA
- Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, Illinois, USA
| | - Veronica Vecellio
- Karisoke Research Center, Musanze Rwanda
- Dian Fossey Gorilla Fund International, Atlanta, Georgia, USA
| | - Tara Stoinski
- Dian Fossey Gorilla Fund International, Atlanta, Georgia, USA
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27
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Murray CM, Stanton MA, Lonsdorf EV, Wroblewski EE, Pusey AE. Chimpanzee fathers bias their behaviour towards their offspring. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160441. [PMID: 28018626 PMCID: PMC5180124 DOI: 10.1098/rsos.160441] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 10/05/2016] [Indexed: 05/05/2023]
Abstract
Promiscuous mating was traditionally thought to curtail paternal investment owing to the potential costs of providing care to unrelated infants. However, mounting evidence suggests that males in some promiscuous species can recognize offspring. In primates, evidence for paternal care exists in promiscuous Cercopithecines, but less is known about these patterns in other taxa. Here, we examine two hypotheses for paternal associations with lactating mothers in eastern chimpanzees (Pan troglodytes schweinfurthii): paternal effort, whereby males associate and interact more with their own infants, and mating effort, whereby males invest in mothers and offspring for mating privileges. We found that fathers associated more with their offspring than they did with non-kin infants, particularly early in life when infanticide risk is highest. Additionally, fathers and their infant offspring interacted more than expected. Notably, association between fathers and mother-infant pairs did not predict the probability of siring the mother's next offspring. Our results support the paternal effort, but not the mating effort hypothesis in this species. Chimpanzees are one of the most salient models for the last common ancestor between Pan and Homo, thus our results suggest that a capacity for paternal care, possibly independent of long-term mother-father bonds, existed early in hominin evolution.
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Affiliation(s)
- Carson M. Murray
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, USA
- Author for correspondence: Carson M. Murray e-mail:
| | - Margaret A. Stanton
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, USA
| | | | - Emily E. Wroblewski
- Department of Structural Biology and Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Anne E. Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
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28
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Godoy I, Vigilant L, Perry SE. Cues to kinship and close relatedness during infancy in white-faced capuchin monkeys, Cebus capucinus. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.03.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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29
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Minge C, Berghänel A, Schülke O, Ostner J. Patterns and Consequences of Male-Infant Relationships in Wild Assamese Macaques ( Macaca assamensis). INT J PRIMATOL 2016; 37:350-370. [PMID: 27546937 PMCID: PMC4978776 DOI: 10.1007/s10764-016-9904-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/26/2016] [Indexed: 12/05/2022]
Abstract
Male care for offspring is unexpected in polygynandrous mammals. Evidence from nonhuman primates, however, indicates not only the existence of stable male-immature associations in multimale-multifemale groups, but also male care in the form of protection from infanticidal attacks and conspecific harassment. Here, we investigate the relationship characteristics, dynamics, and consequences of male-immature associations in wild Assamese macaques, Macaca assamensis, at Phu Khieo Wildlife Sanctuary, Thailand, to inform hypotheses of their evolutionary origins. Female Assamese macaques reproduce seasonally and do not signal ovulation, resulting in low mating and paternity skew. However, male-immature associations are predicted by paternity, and male behavior potentially reflects paternal effort. We present focal animal data on 12 immatures followed from birth beyond weaning into their juvenile life (1188 focal hours). The distribution of composite sociality indices suggests that male-immature relationships were highly differentiated. Association patterns and the degree of differentiation remained stable from 6 mo well into the juvenile phase, suggesting that male protection extends beyond the phase of high infanticide risk. Based on Hinde indices, immatures were responsible for maintaining the relationships. The likelihood that an infant was associated with its preferred male increased if the mother was absent and if other males were present in proximity, suggesting that immatures sought protection. The presence of the preferred male did not decrease the rate of mild aggression immatures received from group members, but the stronger the relationship between an immature and a male, the more often it received agonistic support from him. Future studies will have to assess whether this agonistic support translates into improved fitness and represents true paternal care.
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Affiliation(s)
- Christin Minge
- Department for Behavioral Ecology, Georg-August University Göttingen, 37077 Göttingen, Germany
| | - Andreas Berghänel
- Department for Behavioral Ecology, Georg-August University Göttingen, 37077 Göttingen, Germany
| | - Oliver Schülke
- Department for Behavioral Ecology, Georg-August University Göttingen, 37077 Göttingen, Germany
- Research Group Primate Social Evolution, German Primate Center Göttingen, 37077 Göttingen, Germany
| | - Julia Ostner
- Department for Behavioral Ecology, Georg-August University Göttingen, 37077 Göttingen, Germany
- Research Group Primate Social Evolution, German Primate Center Göttingen, 37077 Göttingen, Germany
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30
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Mother-male bond, but not paternity, influences male-infant affiliation in wild crested macaques. Behav Ecol Sociobiol 2016; 70:1117-1130. [PMID: 27478299 PMCID: PMC4954837 DOI: 10.1007/s00265-016-2116-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 03/29/2016] [Accepted: 03/30/2016] [Indexed: 11/16/2022]
Abstract
Abstract In promiscuous primates, interactions between adult males and infants have rarely been investigated. However, recent evidence suggests that male affiliation towards infants has an influence on several aspects of the infants’ life. Furthermore, affiliations may be associated with male reproductive strategy. In this study, we examined which social factors influenced male-infant affiliation initiated by either male or infant, in wild crested macaques (Macaca nigra). We combined behavioral data and genetic paternity analysis from 30 infants living in three wild groups in Tangkoko Reserve, Indonesia. Our results indicate that adult males and infants do not interact at random, but rather form preferential associations. The social factors with the highest influence on infant-initiated interactions were male rank and male association with the infant’s mother. While infants initiated affiliations with males more often in the absence of their mothers, adult males initiated more affiliations with infants when their mothers were present. Furthermore, males initiated affiliations more often when they were in the same group at the time the infant was conceived, when they held a high dominance rank, or when they had a close relationship with the mother. Interestingly, paternity did not affect male-infant affiliation despite being highly skewed in this species. Overall, our results suggest that adult males potentially associate with an infant to secure future mating with the mother. Infants are more likely to associate with a male to receive better support, suggesting a strategy to increase the chance of infant survival in a primate society with high infant mortality. Significance statement We explore social relationships between males and infants in a promiscuous primate, the wild crested macaque. Our novel approach addresses the nature of affiliations both from males’ and infants’ perspectives. The results show that males and infants form preferential associations. Male-female affiliation, but not paternity, was a significant predictor of interactions initiated both by males and infants. Males initiated more interactions towards infants when the mother was in proximity, while infants initiated more interactions in her absence. Finally, high-ranking males were more likely to initiate interactions towards infants. We demonstrated that paternity is not a good predictor of male-infant affiliations, even in a species with a high reproductive skew and a relatively high confidence of paternity. Our paper is one of the first to show that infants are active agents in establishing and maintaining preferential relationships with males. Electronic supplementary material The online version of this article (doi:10.1007/s00265-016-2116-0) contains supplementary material, which is available to authorized users.
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31
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Rosenbaum S, Hirwa JP, Silk JB, Vigilant L, Stoinski TS. Infant Mortality Risk and Paternity Certainty Are Associated with Postnatal Maternal Behavior toward Adult Male Mountain Gorillas (Gorilla beringei beringei). PLoS One 2016; 11:e0147441. [PMID: 26863300 PMCID: PMC4749219 DOI: 10.1371/journal.pone.0147441] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 01/03/2016] [Indexed: 11/28/2022] Open
Abstract
Sexually selected infanticide is an important source of infant mortality in many mammalian species. In species with long-term male-female associations, females may benefit from male protection against infanticidal outsiders. We tested whether mountain gorilla (Gorilla beringei beringei) mothers in single and multi-male groups monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center actively facilitated interactions between their infants and a potentially protective male. We also evaluated the criteria mothers in multi-male groups used to choose a preferred male social partner. In single male groups, where infanticide risk and paternity certainty are high, females with infants <1 year old spent more time near and affiliated more with males than females without young infants. In multi-male groups, where infanticide rates and paternity certainty are lower, mothers with new infants exhibited few behavioral changes toward males. The sole notable change was that females with young infants proportionally increased their time near males they previously spent little time near when compared to males they had previously preferred, perhaps to encourage paternity uncertainty and deter aggression. Rank was a much better predictor of females' social partner choice than paternity. Older infants (2-3 years) in multi-male groups mirrored their mothers' preferences for individual male social partners; 89% spent the most time in close proximity to the male their mother had spent the most time near when they were <1 year old. Observed discrepancies between female behavior in single and multi-male groups likely reflect different levels of postpartum intersexual conflict; in groups where paternity certainty and infanticide risk are both high, male-female interests align and females behave accordingly. This highlights the importance of considering individual and group-level variation when evaluating intersexual conflict across the reproductive cycle.
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Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, University of California Los Angeles, Los Angeles, California, United States of America
| | | | - Joan B. Silk
- School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, United States of America
- Institute for Human Origins, Arizona State University, Tempe, Arizona, United States of America
| | - Linda Vigilant
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Tara S. Stoinski
- Dian Fossey Gorilla Fund International, Atlanta, Georgia, United States of America
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32
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Sargeant EJ, Wikberg EC, Kawamura S, Jack KM, Fedigan LM. Paternal kin recognition and infant care in white-faced capuchins (Cebus capucinus). Am J Primatol 2016; 78:659-68. [PMID: 26815856 DOI: 10.1002/ajp.22530] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/24/2015] [Accepted: 01/17/2016] [Indexed: 11/05/2022]
Abstract
Evidence for paternal kin recognition and paternally biased behaviors is mixed among primates. We investigate whether infant handling behaviors exhibit paternal kin biases in wild white-faced capuchins monkeys (Cebus capucinus) by comparing interactions between infants and genetic sires, potential sires, siblings (full sibling, maternal, and paternal half-siblings) and unrelated handlers. We used a linear mixed model approach to analyze data collected on 21 focal infants from six groups in Sector Santa Rosa, Costa Rica. Our analyses suggest that the best predictor of adult and subadult male interactions with an infant is the male's dominance status, not his paternity status. We found that maternal siblings but not paternal siblings handled infants more than did unrelated individuals. We conclude that maternal but not paternal kinship influence patterns of infant handling in white-faced capuchins, regardless of whether or not they can recognize paternal kin. Am. J. Primatol. 78:659-668, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Elizabeth J Sargeant
- Department of Anthropology and Archaeology, University of Calgary, Alberta, Canada
| | - Eva C Wikberg
- Department of Anthropology and Archaeology, University of Calgary, Alberta, Canada
| | - Shoji Kawamura
- Department of Integrated Biosciences, University of Tokyo, Kashiwa, Chiba, Japan
| | - Katharine M Jack
- Department of Anthropology, Tulane University, New Orleans, Louisiana
| | - Linda M Fedigan
- Department of Anthropology and Archaeology, University of Calgary, Alberta, Canada
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33
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Rosenbaum S, Hirwa JP, Silk JB, Stoinski TS. Relationships Between Adult Male and Maturing Mountain Gorillas (
Gorilla beringei beringei
) Persist Across Developmental Stages and Social Upheaval. Ethology 2015. [DOI: 10.1111/eth.12457] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology University of California‐Los Angeles Los Angeles CA USA
| | | | - Joan B. Silk
- School of Human Evolution and Social Change Arizona State University Tempe AZ USA
- Institute of Human Origins Arizona State University Tempe AZ USA
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34
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Rosenbaum S, Maldonado-Chaparro AA, Stoinski TS. Group structure predicts variation in proximity relationships between male-female and male-infant pairs of mountain gorillas (Gorilla beringei beringei). Primates 2015; 57:17-28. [PMID: 26386711 DOI: 10.1007/s10329-015-0490-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/30/2015] [Indexed: 11/29/2022]
Abstract
Relationships between conspecifics are influenced by both ecological factors and the social organization they live in. Systematic variation of both--consistent with predictions derived from socioecology models--is well documented, but there is considerable variation within species and populations that is poorly understood. The mountain gorilla (Gorilla beringei) is unusual because, despite possessing morphology associated with male contest competition (e.g., extreme sexual dimorphism), they are regularly observed in both single-male and multimale groups. Both male-female and male-infant bonds are strong because males provide protection against infanticide and/or predation. Risk of these threats varies with social structure, which may influence the strength of social relationships among group members (including females and offspring, if females with lower infant mortality risk are less protective of infants). Here, we investigate the relationship between group structure and the strength of proximity relationships between males and females, males and infants, and females and offspring. Data come from 10 social groups containing 1-7 adult males, monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center in Volcanoes National Park, Rwanda. After controlling for group size and infant age, association strength was similar for male-female pairs across group types with both dominant and nondominant males, but male-infant relationships were strongest in single-male groups where paternity certainty was high and animals had fewer social partners to choose from. The male:female and male:infant ratios better predicted both male-female and male-infant associations than the absolute number of males, females, or infants did. The fewer the number of males per female or infant, the more both pair types associated. Dominant males in groups containing fewer males had higher eigenvector centrality (a measure of importance in a social network) than dominant males in groups with more males. Results indicate that nondominant males are an important influence on relationships between dominant males and females/infants despite their peripheral social positions, and that relationships between males and infants must be considered an important foundation of gorilla social structure.
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Affiliation(s)
- S Rosenbaum
- Department of Anthropology, University of California-Los Angeles, Los Angeles, CA, USA. .,Institute for Mind and Biology, University of Chicago, 940 East 57th Street, Chicago, IL, 60637, USA.
| | - A A Maldonado-Chaparro
- Department of Ecology and Evolutionary Biology, University of California-Los Angeles, Los Angeles, CA, USA
| | - T S Stoinski
- The Dian Fossey Gorilla Fund International, Atlanta, GA, USA
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