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Ehmann B, van Schaik CP, Ashbury AM, Mörchen J, Musdarlia H, Utami Atmoko S, van Noordwijk MA, Schuppli C. Immature wild orangutans acquire relevant ecological knowledge through sex-specific attentional biases during social learning. PLoS Biol 2021; 19:e3001173. [PMID: 34010339 PMCID: PMC8133475 DOI: 10.1371/journal.pbio.3001173] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 03/05/2021] [Indexed: 11/22/2022] Open
Abstract
As a part of growing up, immature orangutans must acquire vast repertoires of skills and knowledge, a process that takes several years of observational social learning and subsequent practice. Adult female and male orangutans show behavioral differences including sex-specific foraging patterns and male-biased dispersal. We investigated how these differing life trajectories affect social interest and emerging ecological knowledge in immatures. We analyzed 15 years of detailed observational data on social learning, associations, and diet repertoires of 50 immatures (16 females and 34 males), from 2 orangutan populations. Specific to the feeding context, we found sex differences in the development of social interest: Throughout the dependency period, immature females direct most of their social attention at their mothers, whereas immature males show an increasing attentional preference for individuals other than their mothers. When attending to non-mother individuals, males show a significant bias toward immigrant individuals and a trend for a bias toward adult males. In contrast, females preferentially attend to neighboring residents. Accordingly, by the end of the dependency period, immature females show a larger dietary overlap with their mothers than do immature males. These results suggest that immature orangutans show attentional biases through which they learn from individuals with the most relevant ecological knowledge. Diversifying their skills and knowledge likely helps males when they move to a new area. In sum, our findings underline the importance of fine-grained social inputs for the acquisition of ecological knowledge and skills in orangutans and likely in other apes as well.
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Affiliation(s)
- Beatrice Ehmann
- Department of Anthropology, University of Zürich, Zürich, Switzerland
| | | | - Alison M. Ashbury
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Julia Mörchen
- Behavioral Ecology Research Group, Institute of Biology, Faculty of Life Science, Leipzig University, Leipzig, Germany
- Research Group Primate Behavioural Ecology, Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Helvi Musdarlia
- Department of Biology, Graduate School, Universitas Nasional, Jakarta, Indonesia
| | - Suci Utami Atmoko
- Faculty of Biology and Primate Research Center, Universitas Nasional, Jakarta, Indonesia
| | | | - Caroline Schuppli
- Department of Anthropology, University of Zürich, Zürich, Switzerland
- Leipzig Research Center for Early Child Development, Leipzig University, Leipzig, Germany
- Development and Evolution of Cognition Research Group, Max Planck Institute of Animal Behavior, Konstanz, Germany
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Lonsdorf EV, Stanton MA, Murray CM. Sex differences in maternal sibling-infant interactions in wild chimpanzees. Behav Ecol Sociobiol 2018. [DOI: 10.1007/s00265-018-2531-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Stanton MA, Lonsdorf EV, Pusey AE, Murray CM. Do juveniles help or hinder? Influence of juvenile offspring on maternal behavior and reproductive outcomes in wild chimpanzees (Pan troglodytes). J Hum Evol 2017; 111:152-162. [PMID: 28874268 PMCID: PMC5659293 DOI: 10.1016/j.jhevol.2017.07.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 07/24/2017] [Accepted: 07/26/2017] [Indexed: 01/10/2023]
Abstract
Compared to great apes, humans maintain a relatively rapid reproductive pace despite long periods of dependency. This seemingly contradictory set of traits is made possible by weaning offspring before nutritional independence and alloparents who help provide care. In traditional societies, this help may be provided to mothers in part by their juvenile offspring who carry, supervise, or provision younger siblings. In contrast to humans, chimpanzees (Pan troglodytes) are nutritionally independent after weaning, yet juveniles continue to travel with their mother and younger sibling for an additional 4-5 years. This continued association could be costly to the mother if she continues to invest in weaned offspring. Alternately, while juvenile chimpanzees do not typically provision younger siblings, their presence and social interaction with infants may allow mothers to focus on other tasks. In this study, we investigate the costs and benefits to mothers of continued association with juveniles in wild chimpanzees. Using 26 years of long-term behavioral data we examined how maternal activity budgets varied based on the presence of a dependent juvenile offspring. We found that continued social interaction between mothers and juveniles does not influence the mother's time allocated to interacting with the younger infant, her feeding, resting, or travel time, or time socializing with other community members. Instead, mothers may benefit from the additional social interaction and/or relationship with their older offspring. Using 45 years of demographic data we found that those offspring who had an older sibling tended to be more likely to survive each year from birth to 8 years than those without an older sibling. Additionally, interbirth intervals were more likely to end when the female had an older offspring present. A mutually beneficial mother-juvenile dynamic in great apes provides insight into continued association between mothers and offspring after nutritional independence and the emergence of juvenile helping during hominin evolution.
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Affiliation(s)
- Margaret A Stanton
- Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC 20052, USA.
| | - Elizabeth V Lonsdorf
- Department of Psychology and Biological Foundations of Behavior Program, Franklin & Marshall College, Lancaster, PA 17603, USA.
| | - Anne E Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA.
| | - Carson M Murray
- Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC 20052, USA.
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Stanton MA, Lonsdorf EV, Pusey AE, Goodall J, Murray CM. Maternal Behavior by Birth Order in Wild Chimpanzees ( Pan troglodytes): Increased Investment by First-Time Mothers. CURRENT ANTHROPOLOGY 2014; 55:483-489. [PMID: 25328164 DOI: 10.1086/677053] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Parental investment theory predicts that maternal resources are finite and allocated among offspring based on factors including maternal age and condition, and offspring sex and parity. Among humans, firstborn children are often considered to have an advantage and receive greater investment than their younger siblings. However, conflicting evidence for this "firstborn advantage" between modern and hunter-gatherer societies raises questions about the evolutionary history of differential parental investment and birth order. In contrast to humans, most non-human primate firstborns belong to young, inexperienced mothers and exhibit higher mortality than laterborns. In this study, we investigated differences in maternal investment and offspring outcomes based on birth order (firstborn vs. later-born) among wild chimpanzees (Pan troglodyte schweinfurthii). During the critical first year of life, primiparous mothers nursed, groomed, and played with their infants more than did multiparous mothers. Furthermore, this pattern of increased investment in firstborns appeared to be compensatory, as probability of survival did not differ by birth order. Our study did not find evidence for a firstborn advantage as observed in modern humans but does suggest that unlike many other primates, differences in maternal behavior help afford chimpanzee first-borns an equal chance of survival.
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Affiliation(s)
- Margaret A Stanton
- Postdoctoral Scientist, Center for the Advanced Study of Hominid Paleobiology, George Washington University, 2110 G Street NW, Washington, DC 20052, U.S.A
| | - Elizabeth V Lonsdorf
- Assistant Professor of Psychology, Department of Psychology and Biological Foundations of Behavior Program, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604, U.S.A
| | - Anne E Pusey
- Professor, Chair, and James B. Duke Professor at the Department of Evolutionary Anthropology, Duke University, P.O. Box 90383, Durham, NC 27708, U.S.A
| | - Jane Goodall
- Founder of The Jane Goodall Institute, 1595 Spring Hill Road, Suite 550, Vienna, VA 22182, U.S.A
| | - Carson M Murray
- Assistant Professor of Anthropology at the Center for the Advanced Study of Hominid Paleobiology, George Washington University, 2110 G Street NW, Washington, DC 20052, U.S.A
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Lonsdorf EV, Markham AC, Heintz MR, Anderson KE, Ciuk DJ, Goodall J, Murray CM. Sex differences in wild chimpanzee behavior emerge during infancy. PLoS One 2014; 9:e99099. [PMID: 24911160 PMCID: PMC4049619 DOI: 10.1371/journal.pone.0099099] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 05/09/2014] [Indexed: 11/19/2022] Open
Abstract
The role of biological and social influences on sex differences in human child development is a persistent topic of discussion and debate. Given their many similarities to humans, chimpanzees are an important study species for understanding the biological and evolutionary roots of sex differences in human development. In this study, we present the most detailed analyses of wild chimpanzee infant development to date, encompassing data from 40 infants from the long-term study of chimpanzees at Gombe National Park, Tanzania. Our goal was to characterize age-related changes, from birth to five years of age, in the percent of observation time spent performing behaviors that represent important benchmarks in nutritional, motor, and social development, and to determine whether and in which behaviors sex differences occur. Sex differences were found for indicators of social behavior, motor development and spatial independence with males being more physically precocious and peaking in play earlier than females. These results demonstrate early sex differentiation that may reflect adult reproductive strategies. Our findings also resemble those found in humans, which suggests that biologically-based sex differences may have been present in the common ancestor and operated independently from the influences of modern sex-biased parental behavior and gender socialization.
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Affiliation(s)
- Elizabeth V. Lonsdorf
- Department of Psychology and Biological Foundations of Behavior Program, Franklin & Marshall College, Lancaster, Pennsylvania, United States of America
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois, United States of America
| | - A. Catherine Markham
- Center for the Advanced Study of Hominid Paleobiology, The George Washington University, Washington, DC, United States of America
| | - Matthew R. Heintz
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois, United States of America
- Committee on Evolutionary Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Karen E. Anderson
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois, United States of America
| | - David J. Ciuk
- Department of Government, Franklin & Marshall College, Lancaster, Pennsylvania, United States of America
| | - Jane Goodall
- The Jane Goodall Institute, Vienna, Virginia, United States of America
| | - Carson M. Murray
- Center for the Advanced Study of Hominid Paleobiology, The George Washington University, Washington, DC, United States of America
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Lonsdorf EV, Anderson KE, Stanton MA, Shender M, Heintz MR, Goodall J, Murray CM. Boy will be boys: sex differences in wild infant chimpanzee social interactions. Anim Behav 2014; 88:79-83. [PMID: 24489384 DOI: 10.1016/j.anbehav.2013.11.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Sex differences in the behaviour of human children are a hotly debated and often controversial topic. However, several recent studies have documented a biological basis to key aspects of child social behaviour. To further explore the evolutionary basis of such differences, we investigated sex differences in sociability in wild chimpanzee, Pan troglodytes schweinfurthii, infants at Gombe National Park, Tanzania. We used a long-term data set on mother-infant behaviour to analyse the diversity of infant chimpanzee social partners from age 30 to 36 months. Male infants (N = 12) interacted with significantly more individuals than female infants did (N = 8), even when maternal sociability was controlled for. Furthermore, male infants interacted with significantly more adult males than female infants did. Our data indicate that the well-documented sex differences in adult chimpanzee social tendencies begin to appear quite early in development. Furthermore, these data suggest that the behavioural sex differences of human children are fundamentally rooted in our biological and evolutionary heritage.
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Affiliation(s)
- Elizabeth V Lonsdorf
- Department of Psychology and Biological Foundations of Behavior Program, Franklin & Marshall College, Lancaster, PA, U.S.A ; Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, IL, U.S.A
| | - Karen E Anderson
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, IL, U.S.A
| | - Margaret A Stanton
- Center for the Advanced Study of Hominid Paleobiology, The George Washington University, Washington, D.C., U.S.A
| | - Marisa Shender
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, IL, U.S.A
| | - Matthew R Heintz
- Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, IL, U.S.A ; Committee on Evolutionary Biology, University of Chicago, Chicago, IL, U.S.A
| | | | - Carson M Murray
- Center for the Advanced Study of Hominid Paleobiology, The George Washington University, Washington, D.C., U.S.A
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Bashaw MJ, Gullott RL, Gill EC. What defines successful integration into a social group for hand-reared chimpanzee infants? Primates 2009; 51:139-47. [PMID: 19916071 DOI: 10.1007/s10329-009-0176-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 10/14/2009] [Indexed: 11/28/2022]
Abstract
Hand-rearing of captive great ape infants is sometimes necessary but can have negative behavioral consequences. Modern hand-rearing protocols, including early integration into a diverse group of conspecifics, appear to reduce the negative consequences of hand-rearing, but the process of integration is not well studied. We investigated six potential metrics of success during the introduction of two hand-reared chimpanzee infants into a troop of nine other chimpanzees at the Maryland Zoo in Baltimore. Little aggression was observed and the infants continue to be maintained in the troop at publication. As we predicted, during the introduction the hand-reared infants showed consistent levels of stress-related behaviors, participated in affiliative interactions with all available partners, and acted, received, and mutually engaged in these interactions. Solitary behaviors by these infants were similar to a mother-reared infant in the same group. Each infant also formed a relationship with a specific female that involved nest-sharing, carrying, retrieval, and intervening to reduce risk to the infant; these relationships could be classified as allomothering because they involved maternal behavior but occupied significantly less of the infants' time than a maternal relationship. Contrary to our prediction, the hand-reared infants therefore spent significantly less time in social behavior than a mother-reared infant of the same age. In addition, the hand-reared infants continued to show strong social preferences for each other as introductions progressed and to direct a low but consistent number of nonfeeding social behaviors to humans. The successful introduction of hand-reared infants appeared to involve adding conspecific social relationships to the infants' social repertoire, but not eliminating social interactions directed at humans.
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Affiliation(s)
- Meredith J Bashaw
- Department of Psychology, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA, 17604-3003, USA.
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Why chimpanzee (Pan troglodytes schweinfurthii) mothers are less gregarious than nonmothers and males: the infant safety hypothesis. Behav Ecol Sociobiol 2005. [DOI: 10.1007/s00265-005-0081-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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