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Hunt A, Merola GP, Carpenter T, Jaeggi AV. Evolutionary perspectives on substance and behavioural addictions: Distinct and shared pathways to understanding, prediction and prevention. Neurosci Biobehav Rev 2024; 159:105603. [PMID: 38402919 DOI: 10.1016/j.neubiorev.2024.105603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/31/2024] [Accepted: 02/21/2024] [Indexed: 02/27/2024]
Abstract
Addiction poses significant social, health, and criminal issues. Its moderate heritability and early-life impact, affecting reproductive success, poses an evolutionary paradox: why are humans predisposed to addictive behaviours? This paper reviews biological and psychological mechanisms of substance and behavioural addictions, exploring evolutionary explanations for the origin and function of relevant systems. Ancestrally, addiction-related systems promoted fitness through reward-seeking, and possibly self-medication. Today, psychoactive substances disrupt these systems, leading individuals to neglect essential life goals for immediate satisfaction. Behavioural addictions (e.g. video games, social media) often emulate ancestrally beneficial behaviours, making them appealing yet often irrelevant to contemporary success. Evolutionary insights have implications for how addiction is criminalised and stigmatised, propose novel avenues for interventions, anticipate new sources of addiction from emerging technologies such as AI. The emerging potential of glucagon-like peptide 1 (GLP-1) agonists targeting obesity suggest the satiation system may be a natural counter to overactivation of the reward system.
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Affiliation(s)
- Adam Hunt
- Institute of Evolutionary Medicine, University of Zürich, Zürich, Switzerland.
| | | | - Tom Carpenter
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zürich, Zürich, Switzerland
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Schradin C, Jaeggi AV, Criscuolo F. Quick Guide to Evolutionary Medicine in Neuroimmunomodulation: Why "Evolved for the Benefit of the Species" Is Not a Valid Argument. Neuroimmunomodulation 2024; 31:66-77. [PMID: 38471475 DOI: 10.1159/000538294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND Evolutionary medicine builds on evolutionary biology and explains why natural selection has left us vulnerable to disease. Unfortunately, several misunderstandings exist in the medical literature about the levels and mechanisms of evolution. Reasons for these problems start from the lack of teaching evolutionary biology in medical schools. A common mistake is to assume that "traits must benefit the species, as otherwise the species would have gone extinct in the past" confusing evolutionary history (phylogeny) with evolutionary function (fitness). SUMMARY Here we summarise some basic aspects of evolutionary medicine by pointing out: (1) Evolution has no aim. (2) For adaptive evolution to occur, a trait does not have to be beneficial to its carrier throughout its entire life. (3) Not every single individual carrying an adaptive trait needs to have higher than average fitness. (4) Traits do not evolve for the benefit of the species. Using examples from the field of neuroimmunomodulation like sickness behaviour (nervous system), testosterone (hormones), and cytokines (immunity), we show how misconceptions arise from not differentiating between the explanatory categories of phylogeny (evolutionary history) and evolutionary function (fitness). KEY MESSAGES Evolution has no aim but is an automatism that does not function for the benefit of the species. In evolution, successful individuals are those that maximise the transmission of their genes, and health and survival are just strategies to have the opportunity to do so. Thus, a trait enabling survival of the individual until reproductive age will spread even if at later age the same trait leads to disease and death. Natural and sexual selection do not select for traits that benefit the health or happiness of the individual, but for traits that increase inclusive fitness even if this increases human suffering. In contrast, our humane aim is to increase individual well-being. Evolutionary medicine can help us achieve this aim against evolutionary constraints.
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Affiliation(s)
- Carsten Schradin
- IPHC, UNISTRA, CNRS, Strasbourg, France
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adrian V Jaeggi
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Zürich, Switzerland
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Olivier CA, Martin JS, Pilisi C, Agnani P, Kauffmann C, Hayes L, Jaeggi AV, Schradin C. Primate social organization evolved from a flexible pair-living ancestor. Proc Natl Acad Sci U S A 2024; 121:e2215401120. [PMID: 38154063 PMCID: PMC10769843 DOI: 10.1073/pnas.2215401120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/26/2023] [Indexed: 12/30/2023] Open
Abstract
Explaining the evolution of primate social organization has been fundamental to understand human sociality and social evolution more broadly. It has often been suggested that the ancestor of all primates was solitary and that other forms of social organization evolved later, with transitions being driven by various life history traits and ecological factors. However, recent research showed that many understudied primate species previously assumed to be solitary actually live in pairs, and intraspecific variation in social organization is common. We built a detailed database from primary field studies quantifying the number of social units expressing different social organizations in each population. We used Bayesian phylogenetic models to infer the probability of each social organization, conditional on several socioecological and life history predictors. Here, we show that when intraspecific variation is accounted for, the ancestral social organization of primates was inferred to be variable, with the most common social organization being pair-living but with approximately 10 to 20% of social units of the ancestral population deviating from this pattern by being solitary living. Body size and activity patterns had large effects on transitions between types of social organizations. As in other mammalian clades, pair-living is closely linked to small body size and likely more common in ancestral species. Our results challenge the assumption that ancestral primates were solitary and that pair-living evolved afterward emphasizing the importance of focusing on field data and accounting for intraspecific variation, providing a flexible statistical framework for doing so.
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Affiliation(s)
- Charlotte-Anaïs Olivier
- Institut Pluridisciplinaire Hubert Curien, CNRS, Department of Ethology and Evolutionary Physiology, University of Strasbourg, Strasbourg67200, France
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg2050, South Africa
| | - Jordan S. Martin
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, ZurichCH-8057, Switzerland
| | - Camille Pilisi
- Institut Pluridisciplinaire Hubert Curien, CNRS, Department of Ethology and Evolutionary Physiology, University of Strasbourg, Strasbourg67200, France
| | - Paul Agnani
- Institut Pluridisciplinaire Hubert Curien, CNRS, Department of Ethology and Evolutionary Physiology, University of Strasbourg, Strasbourg67200, France
| | - Cécile Kauffmann
- Institut Pluridisciplinaire Hubert Curien, CNRS, Department of Ethology and Evolutionary Physiology, University of Strasbourg, Strasbourg67200, France
| | - Loren Hayes
- Department of Biology, Geology, and Environmental Science, University of Tennessee, Chattanooga37403, TN
| | - Adrian V. Jaeggi
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, ZurichCH-8057, Switzerland
| | - C. Schradin
- Institut Pluridisciplinaire Hubert Curien, CNRS, Department of Ethology and Evolutionary Physiology, University of Strasbourg, Strasbourg67200, France
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg2050, South Africa
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4
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Ross CT, Hooper PL, Smith JE, Jaeggi AV, Smith EA, Gavrilets S, Zohora FT, Ziker J, Xygalatas D, Wroblewski EE, Wood B, Winterhalder B, Willführ KP, Willard AK, Walker K, von Rueden C, Voland E, Valeggia C, Vaitla B, Urlacher S, Towner M, Sum CY, Sugiyama LS, Strier KB, Starkweather K, Major-Smith D, Shenk M, Sear R, Seabright E, Schacht R, Scelza B, Scaggs S, Salerno J, Revilla-Minaya C, Redhead D, Pusey A, Purzycki BG, Power EA, Pisor A, Pettay J, Perry S, Page AE, Pacheco-Cobos L, Oths K, Oh SY, Nolin D, Nettle D, Moya C, Migliano AB, Mertens KJ, McNamara RA, McElreath R, Mattison S, Massengill E, Marlowe F, Madimenos F, Macfarlan S, Lummaa V, Lizarralde R, Liu R, Liebert MA, Lew-Levy S, Leslie P, Lanning J, Kramer K, Koster J, Kaplan HS, Jamsranjav B, Hurtado AM, Hill K, Hewlett B, Helle S, Headland T, Headland J, Gurven M, Grimalda G, Greaves R, Golden CD, Godoy I, Gibson M, Mouden CE, Dyble M, Draper P, Downey S, DeMarco AL, Davis HE, Crabtree S, Cortez C, Colleran H, Cohen E, Clark G, Clark J, Caudell MA, Carminito CE, Bunce J, Boyette A, Bowles S, Blumenfield T, Beheim B, Beckerman S, Atkinson Q, Apicella C, Alam N, Mulder MB. Reproductive inequality in humans and other mammals. Proc Natl Acad Sci U S A 2023; 120:e2220124120. [PMID: 37216525 PMCID: PMC10235947 DOI: 10.1073/pnas.2220124120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 04/16/2023] [Indexed: 05/24/2023] Open
Abstract
To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women's fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species-including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.
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Affiliation(s)
- Cody T. Ross
- Santa Fe Institute, Santa Fe, NM87501
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Paul L. Hooper
- Santa Fe Institute, Santa Fe, NM87501
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | | | - Adrian V. Jaeggi
- Institut für Anthropologie und Anthropologisches Museum, University of Zürich, Zürich8006, Switzerland
| | - Eric Alden Smith
- Department of Anthropology, University of Washington, Seattle, WA98195
| | - Sergey Gavrilets
- Departments of Ecology and Evolutionary Biology and Mathematics, University of Tennessee, Knoxville, TN37996
| | - Fatema tuz Zohora
- International Centre for Diarrheal Disease Research, Dhaka1000, Bangladesh
| | - John Ziker
- Department of Anthropology, Boise State University, Boise, ID83725
| | | | | | - Brian Wood
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Anthropology, University of California, Los Angeles, CA90095
| | | | - Kai P. Willführ
- Institute for Social Science, University of Oldenburg, Oldenburg26129, Germany
| | - Aiyana K. Willard
- Centre for Culture and Evolution, Brunel University, LondonUB8 3PH, United Kingdom
| | - Kara Walker
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC27695
| | | | - Eckart Voland
- Institute for Philosophy, Justus-Liebig University, Giessen35390, Germany
| | | | - Bapu Vaitla
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Samuel Urlacher
- Department of Anthropology, Baylor University, Waco, TX76706
- Canadian Institute for Advanced Research, Toronto, CAM5G 1M1
| | - Mary Towner
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK74078
| | - Chun-Yi Sum
- College of General Studies, Boston University, Boston, MA02215
| | | | - Karen B. Strier
- Department of Zoology, University of Wisconsin, Madison, WI53706
| | | | - Daniel Major-Smith
- Department of Anthropology and Archaeology, University of Bristol, BristolBS8 1QU, United Kingdom
| | - Mary Shenk
- Department of Anthropology, Pennsylvania State University, University Park, PA16802
| | - Rebecca Sear
- Department of Population Health, London School of Hygiene and Tropical Medicine, LondonWC1E 7HT, United Kingdom
| | - Edmond Seabright
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Ryan Schacht
- Department of Anthropology, East Carolina University, Greenville, NC27858
| | - Brooke Scelza
- Department of Anthropology, University of California, Los Angeles, CA90095
| | - Shane Scaggs
- Department of Anthropology, Ohio State University, Columbus, OH43210
| | - Jonathan Salerno
- Department of Human Dimensions of Natural Resources, Colorado State University, Fort Collins, CO80523
| | - Caissa Revilla-Minaya
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Daniel Redhead
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Anne Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC27708
| | - Benjamin Grant Purzycki
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of the Study of Religion, Aarhus University, Aarhus8000, Denmark
| | - Eleanor A. Power
- Santa Fe Institute, Santa Fe, NM87501
- Department of Methodology, London School of Economics and Political Science, LondonWC2A 2AE, United Kingdom
| | - Anne Pisor
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Anthropology, Washington State University, Pullman, WA99164
| | - Jenni Pettay
- Department of Biology, University of Turku, Turku20014, Finland
| | - Susan Perry
- Department of Anthropology, University of California, Los Angeles, CA90095
| | - Abigail E. Page
- Department of Population Health, London School of Hygiene and Tropical Medicine, LondonWC1E 7HT, United Kingdom
| | - Luis Pacheco-Cobos
- Facultad de Ciencias Biológicas y Agropecuarias, Universidad Veracruzana, Veracruz94294, Mexico
| | - Kathryn Oths
- Department of Anthropology, University of Alabama, Tuscaloosa, AL35487
| | - Seung-Yun Oh
- Korea Insurance Research Institute, Seoul150-606, Korea
| | - David Nolin
- Department of Sociology, University of Massachusetts, Amherst, MA01003
| | - Daniel Nettle
- Département d’Etudes Cognitives, Ecole Normale Supérieure, Université PSL, Paris75230, France
| | - Cristina Moya
- Department of Anthropology, University of California, Davis, CA95616
| | - Andrea Bamberg Migliano
- Institut für Anthropologie und Anthropologisches Museum, University of Zürich, Zürich8006, Switzerland
| | - Karl J. Mertens
- Department of Anthropology, Boise State University, Boise, ID83725
| | - Rita A. McNamara
- School of Psychology, Victoria University of Wellington, Wellington6012, New Zealand
| | - Richard McElreath
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Siobhan Mattison
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Eric Massengill
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Frank Marlowe
- Department of Biological Anthropology, University of Cambridge, CambridgeCB2 1TN, United Kingdom
| | - Felicia Madimenos
- Department of Anthropology, Queens College (CUNY), New York, NY11367
| | - Shane Macfarlan
- Department of Anthropology, University of Utah, Salt Lake City, UT84112
| | - Virpi Lummaa
- Department of Biology, University of Turku, Turku20014, Finland
| | - Roberto Lizarralde
- Facultad de Ciencias Económicas y Sociales, Universidad Central de Venezuela, Caracas1010A, Venezuela
| | - Ruizhe Liu
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Melissa A. Liebert
- Department of Anthropology, Northern Arizona University, Flagstaff, AZ86011
| | - Sheina Lew-Levy
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Psychology, Durham University, DurhamDH1 3LE, United Kingdom
| | - Paul Leslie
- Department of Anthropology, University of North Carolina, Chapel Hill, NC27599
| | | | - Karen Kramer
- Department of Anthropology, University of Utah, Salt Lake City, UT84112
| | - Jeremy Koster
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH45221
| | | | | | - A. Magdalena Hurtado
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ85287
| | - Kim Hill
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ85287
| | - Barry Hewlett
- Department of Anthropology, Washington State University, Pullman, WA99164
| | - Samuli Helle
- Department of Biology, University of Turku, Turku20014, Finland
| | | | | | - Michael Gurven
- Department of Anthropology, University of California, Santa Barbara, CA93106
| | | | - Russell Greaves
- Department of Anthropology, University of Utah, Salt Lake City, UT84112
| | - Christopher D. Golden
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Irene Godoy
- Department of Animal Behaviour, Bielefeld University, Bielefeld33615, Germany
| | - Mhairi Gibson
- Department of Anthropology and Archaeology, University of Bristol, BristolBS8 1QU, United Kingdom
| | - Claire El Mouden
- School of Anthropology and Museum Ethnography, University of Oxford, OxfordOX1 2JD, United Kingdom
| | - Mark Dyble
- Department of Anthropology, University College London, LondonWC1E 6BT, United Kingdom
| | - Patricia Draper
- School of Global Integrative Studies, University of Nebraska, Lincoln, NE68588
| | - Sean Downey
- Department of Anthropology, Ohio State University, Columbus, OH43210
| | | | | | - Stefani Crabtree
- Santa Fe Institute, Santa Fe, NM87501
- Department of Environment and Society, Utah State University, Logan, UT84322
| | - Carmen Cortez
- Department of Anthropology, University of California, Davis, CA95616
| | - Heidi Colleran
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Emma Cohen
- School of Anthropology and Museum Ethnography, University of Oxford, OxfordOX1 2JD, United Kingdom
| | - Gregory Clark
- Department of Economics, University of California, Davis, CA95616
| | | | - Mark A. Caudell
- Department of Anthropology, Washington State University, Pullman, WA99164
| | - Chelsea E. Carminito
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH45221
| | - John Bunce
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Adam Boyette
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | | | - Tami Blumenfield
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
- School of Ethnology and Sociology, Yunnan University, Yunnan650106, China
| | - Bret Beheim
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Stephen Beckerman
- Department of Anthropology, Pennsylvania State University, University Park, PA16802
| | - Quentin Atkinson
- School of Psychology, University of Auckland, Auckland1010, New Zealand
| | - Coren Apicella
- Department of Psychology, University of Pennsylvania, Philadelphia, PA19104
| | - Nurul Alam
- International Centre for Diarrheal Disease Research, Dhaka1000, Bangladesh
| | - Monique Borgerhoff Mulder
- Santa Fe Institute, Santa Fe, NM87501
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Anthropology, University of California, Davis, CA95616
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Furtwängler A, Baumann C, Majander K, Wilkin S, Tomoum N, Rühli F, Jaeggi AV, Eppenberger P, Bender N, Schuenemann VJ. The Mummy Explorer-a self-regulated open-access online teaching tool. Evol Med Public Health 2023; 11:129-138. [PMID: 37252429 PMCID: PMC10224693 DOI: 10.1093/emph/eoad009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 03/27/2023] [Indexed: 05/31/2023] Open
Abstract
Background and objectives Virtual teaching tools have gained increasing importance in recent years. In particular, the COVID-19 pandemic has reinforced the need for media-based and self-regulated tools. What is missing are tools that allow us to interlink highly interdisciplinary fields such as evolutionary medicine and, at the same time, allow us to adapt content to different lectures. Methodology We designed an interactive online teaching tool, namely, the Mummy Explorer, using open-access software (Google Web Designer), and we provided a freely downloadable template. We tested the tool on students and lecturers of evolutionary medicine using questionnaires and improved the tool according to their feedback. Results The tool has a modular design and provides an overview of a virtual mummy excavation, including the subfields of palaeopathology, paleoradiology, cultural and ethnographic context, provenance studies, paleogenetics, and physiological analyses. The template allows lecturers to generate their own versions of the tool for any topic of interest by simply changing the text and pictures. Tests undertaken with students of evolutionary medicine showed that the tool was helpful during their studies. Lecturers commented that they appreciated having a similar tool in other fields. Conclusions and implications Mummy Explorer fills a gap in the virtual teaching landscape of highly interdisciplinary fields such as evolutionary medicine. It will be offered for free download and can be adapted to any educational topic. Translations into German and possibly other languages are in progress.
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Affiliation(s)
- Anja Furtwängler
- Corresponding authors. Anja Furtwängler, Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. E-mail:
| | - Chris Baumann
- Faculty of Science, University of Helsinki, Gustaf Hällströmin katu 2, 00014, Finland
- Biogeology, Department of Geosciences, University of Tübingen, Hölderlinstraße 12, 72074 Tübingen, Germany
| | - Kerttu Majander
- Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department of Evolutionary Anthropology, University of Vienna, 1030 Vienna, Austria
| | - Shevan Wilkin
- Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Australian Research Centre for Human Evolution (ARCHE), Griffith University, Brisbane 4111, Australia
- Max Planck Institute for Geoanthropology, 07745 Jena, Germany
| | - Nadja Tomoum
- Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Frank Rühli
- Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Adrian V Jaeggi
- Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Patrick Eppenberger
- Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Nicole Bender
- Nicole Bender, Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. Tel: +41 44 635 05 31; E-mail:
| | - Verena J Schuenemann
- Verena Schuenemann, Institute for Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. E-mail:
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Delton AW, Jaeggi AV, Lim J, Sznycer D, Gurven M, Robertson TE, Sugiyama LS, Cosmides L, Tooby J. Cognitive foundations for helping and harming others: Making welfare tradeoffs in industrialized and small-scale societies. EVOL HUM BEHAV 2023. [DOI: 10.1016/j.evolhumbehav.2023.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Smith JE, Jaeggi AV, Holmes RK, Silk JB. Sex differences in cooperative coalitions: a mammalian perspective. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210426. [PMID: 36440559 PMCID: PMC9703251 DOI: 10.1098/rstb.2021.0426] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 08/09/2022] [Indexed: 11/29/2022] Open
Abstract
In group-living species, cooperative tactics can offset asymmetries in resource-holding potential between individuals and alter the outcome of intragroup conflicts. Differences in the kinds of competitive pressures that males and females face might influence the benefits they gain from forming intragroup coalitions. We predicted that there would be a female bias in intragroup coalitions because females (1) are more like to live with kin than males are, and (2) compete over resources that are more readily shared than resources males compete over. We tested this main prediction using information about coalition formation across mammalian species and phylogenetic comparative analyses. We found that for nearly all species in which intragroup coalitions occur, members of both sexes participate, making this the typical mammalian pattern. The presence and frequency of female or male coalitions were not strongly associated with key socio-ecological factors like resource defensibility, sexual dimorphism or philopatry. This suggests that once the ability to form intragroup coalitions emerges in one sex, it is likely to emerge in the other sex as well and that there is no strong phylogenetic legacy of sex differences in this form of cooperation. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.
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Affiliation(s)
- Jennifer E. Smith
- Biology Department, University of Wisconsin Eau Claire, 105 Garfield Avenue, Eau Claire, WI 54702, USA
- Biology Department, Mills College, 5000 MacArthur Boulevard, Oakland, CA 94631, USA
| | - Adrian V. Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich 8057, Switzerland
| | - Rose K. Holmes
- Biology Department, University of Wisconsin Eau Claire, 105 Garfield Avenue, Eau Claire, WI 54702, USA
| | - Joan B. Silk
- School of Human Evolution and Social Change, Institute of Human Origins, Arizona State University, Tempe, AZ 85287-2402, USA
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Martin JS, Jaeggi AV, Koski SE. The social evolution of individual differences: Future directions for a comparative science of personality in social behavior. Neurosci Biobehav Rev 2023; 144:104980. [PMID: 36463970 DOI: 10.1016/j.neubiorev.2022.104980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022]
Abstract
Personality is essential for understanding the evolution of cooperation and conflict in behavior. However, personality science remains disconnected from the field of social evolution, limiting our ability to explain how personality and plasticity shape phenotypic adaptation in social behavior. Researchers also lack an integrative framework for comparing personality in the contextualized and multifaceted behaviors central to social interactions among humans and other animals. Here we address these challenges by developing a social evolutionary approach to personality, synthesizing theory, methods, and organizing questions in the study of individuality and sociality in behavior. We critically review current measurement practices and introduce social reaction norm models for comparative research on the evolution of personality in social environments. These models demonstrate that social plasticity affects the heritable variance of personality, and that individual differences in social plasticity can further modify the rate and direction of adaptive social evolution. Future empirical studies of frequency- and density-dependent social selection on personality are crucial for further developing this framework and testing adaptive theory of social niche specialization.
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Affiliation(s)
- Jordan S Martin
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Switzerland.
| | - Adrian V Jaeggi
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Switzerland.
| | - Sonja E Koski
- Organismal and Evolutionary Biology, University of Helsinki, Finland.
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9
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Abstract
Traditional evolutionary theory invoked natural and sexual selection to explain species- and sex-typical traits. However, some heritable inter-individual variability in behaviour and psychology - personality - is probably adaptive. Here we extend this insight to common psychopathological traits. Reviewing key findings from three background areas of importance - theoretical models, non-human personality and evolved human social dynamics - we propose that a combination of social niche specialisation, negative frequency-dependency, balancing selection and adaptive developmental plasticity should explain adaptation for individual differences in psychology - 'specialised minds' - explaining some variance in personality and psychopathology trait dimensions, which share various characteristics. We suggest that anthropological research of behavioural differences should be extended past broad demographic factors (age and sex) to include individual specialisations. As a first step towards grounding psychopathology in ancestral social structure, we propose a minimum plausible prevalence, given likely ancestral group sizes, for negatively frequency-dependent phenotypes to be maintained as specialised tails of adaptive distributions - below the calculated prevalence, specialisation is highly unlikely. For instance, chronic highly debilitating forms of autism or schizophrenia are too rare for such explanations, whereas attention-deficit-hyperactivity disorder and broad autism phenotypes are common enough to have existed in most hunter-gatherer bands, making adaptive explanations more plausible.
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Affiliation(s)
- Adam D. Hunt
- Institute of Evolutionary Medicine, University of Zürich, Switzerland
| | - Adrian V. Jaeggi
- Institute of Evolutionary Medicine, University of Zürich, Switzerland
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10
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Smith JE, Fichtel C, Holmes RK, Kappeler PM, van Vugt M, Jaeggi AV. Sex bias in intergroup conflict and collective movements among social mammals: male warriors and female guides. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210142. [PMID: 35369756 DOI: 10.1098/rstb.2021.0142] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Intergroup conflict is a major evolutionary force shaping animal and human societies. Males and females should, on average, experience different costs and benefits for participating in collective action. Specifically, among mammals, male fitness is generally limited by access to mates whereas females are limited by access to food and safety. Here we analyse sex biases among 72 species of group-living mammals in two contexts: intergroup conflict and collective movements. Our comparative phylogenetic analyses show that the modal mammalian pattern is male-biased participation in intergroup conflict and female-biased leadership in collective movements. However, the probability of male-biased participation in intergroup conflicts decreased and female-biased participation increased with female-biased leadership in movements. Thus, female-biased participation in intergroup conflict only emerged in species with female-biased leadership in collective movements, such as in spotted hyenas and some lemurs. Sex differences are probably attributable to costs and benefits of participating in collective movements (e.g. towards food, water, safety) and intergroup conflict (e.g. access to mates or resources, risk of injury). Our comparative review offers new insights into the factors shaping sex bias in leadership across social mammals and is consistent with the 'male warrior hypothesis' which posits evolved sex differences in human intergroup psychology. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
- Jennifer E Smith
- Biology Department, Mills College, 5000 MacArthur Boulevard, Oakland, CA 94631, USA
| | - Claudia Fichtel
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
| | - Rose K Holmes
- Biology Department, Mills College, 5000 MacArthur Boulevard, Oakland, CA 94631, USA
| | - Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany.,Department Anthropology/Sociobiology, University of Göttingen, Göttingen, Germany
| | - Mark van Vugt
- Department of Experimental and Applied Psychology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
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11
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Moscovice LR, Hohmann G, Trumble BC, Fruth B, Jaeggi AV. Dominance or Tolerance? Causes and consequences of a period of increased intercommunity encounters among bonobos (Pan paniscus) at LuiKotale. INT J PRIMATOL 2022. [DOI: 10.1007/s10764-022-00286-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AbstractGroup-living primates exhibit variable reactions to intergroup encounters (or IGEs), reflecting species-specific strategies and individual motivations. In chimpanzees (Pan troglodytes), dominating in IGEs provides fitness benefits. Less is known about responses to IGEs in bonobos (Pan paniscus) despite their equal relevance for understanding the origins of human intergroup relations. We observed the Bompusa West (WBp) bonobo community at LuiKotale during a 2-month shift in ranging resulting in frequent IGEs with the smaller Bompusa East (EBp) community. We tested whether incursions provided ecological benefits, and whether responses to IGEs were consistent with inter-community dominance or tolerance. We measured fruit availability and collected activity scans from 26 mature WBp community members when in their core ranging area, during incursions into the EBp ranging area, and during IGEs. We collected data on sexual interactions and aggression with in-group and out-group members during 19 independent IGEs. During their shift in ranging, fruit availability was greater in the EBp ranging area, and WBp bonobos consumed more fruit during incursions than when in their core ranging area. Coalitionary intergroup aggression occurred during nine IGEs, and outcomes were consistent with imbalances in fighting power, in that larger WBp parties supplanted smaller EBp parties from the immediate area. However, communities reformed associations following 70% of coalitionary conflicts, and prolonged IGEs facilitated out-group sexual interactions and female transfers. The WBp community shift in ranging was likely motivated by ecological factors and responses to increased IGEs reflected a mixture of competitive and tolerant strategies.
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12
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Olivier C, Jaeggi AV, Hayes LD, Schradin C. Revisiting the components of Macroscelidea social systems: Evidence for variable social organization, including pair‐living, but not for a monogamous mating system. Ethology 2022. [DOI: 10.1111/eth.13271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Charlotte‐Anaïs Olivier
- IPHC UNISTRA CNRS Strasbourg France
- School of Animal, Plant & Environmental Sciences University of the Witwatersrand Johannesburg South Africa
| | - Adrian V. Jaeggi
- Institute of Evolutionary Medicine University of Zurich Zurich Switzerland
| | - Loren D. Hayes
- Department of Biology, Geology, and Environmental Science University of Tennessee at Chattanooga Tennessee USA
| | - Carsten Schradin
- IPHC UNISTRA CNRS Strasbourg France
- School of Animal, Plant & Environmental Sciences University of the Witwatersrand Johannesburg South Africa
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13
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Abstract
LAY ABSTRACT Oxytocin is a hormone that mediates interpersonal relationships through enhancing social recognition, social memory, and reducing stress. It is released centrally into the cerebrospinal fluid, as well as peripherally into the blood, where it can easily be measured. Some studies indicate that the oxytocin system with its social implications might be different in people with autism spectrum disorder. With summarizing evidence of 31 studies, this meta-analysis suggests that children with autism spectrum disorder have lower blood oxytocin levels compared to neurotypical individuals. This might not be the case for adults with autism spectrum disorder, where we could not find a difference. Our findings motivate further exploration of the oxytocin system in children with autism spectrum disorder. This could lead to therapeutic options in treating autism spectrum disorder in childhood.
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14
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Martin JS, Jaeggi AV. Social animal models for quantifying plasticity, assortment, and selection on interacting phenotypes. J Evol Biol 2021; 35:520-538. [PMID: 34233047 PMCID: PMC9292565 DOI: 10.1111/jeb.13900] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 05/14/2021] [Accepted: 06/24/2021] [Indexed: 11/29/2022]
Abstract
Both assortment and plasticity can facilitate social evolution, as each may generate heritable associations between the phenotypes and fitness of individuals and their social partners. However, it currently remains difficult to empirically disentangle these distinct mechanisms in the wild, particularly for complex and environmentally responsive phenotypes subject to measurement error. To address this challenge, we extend the widely used animal model to facilitate unbiased estimation of plasticity, assortment and selection on social traits, for both phenotypic and quantitative genetic (QG) analysis. Our social animal models (SAMs) estimate key evolutionary parameters for the latent reaction norms underlying repeatable patterns of phenotypic interaction across social environments. As a consequence of this approach, SAMs avoid inferential biases caused by various forms of measurement error in the raw phenotypic associations between social partners. We conducted a simulation study to demonstrate the application of SAMs and investigate their performance for both phenotypic and QG analyses. With sufficient repeated measurements, we found desirably high power, low bias and low uncertainty across model parameters using modest sample and effect sizes, leading to robust predictions of selection and adaptation. Our results suggest that SAMs will readily enhance social evolutionary research on a variety of phenotypes in the wild. We provide detailed coding tutorials and worked examples for implementing SAMs in the Stan statistical programming language.
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Affiliation(s)
- Jordan S Martin
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
| | - Adrian V Jaeggi
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
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15
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Hooper PL, Kaplan HS, Jaeggi AV. Gains to cooperation drive the evolution of egalitarianism. Nat Hum Behav 2021; 5:847-856. [PMID: 33649461 DOI: 10.1038/s41562-021-01059-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 01/21/2021] [Indexed: 01/30/2023]
Abstract
What conditions favour egalitarianism, that is, muted hierarchies with relatively equal distributions of resources? Here, we combine the hawk-dove and prisoner's dilemma games to model the effects of economic defensibility, costs of competition and gains from cooperation on egalitarianism, operationalized as the absence of hawks. We show that a 'leveller' strategy, which punishes hawkishness in the hawk-dove game with defection in the prisoner's dilemma, can be evolutionarily stable provided that the gains from cooperation are high relative to the benefits of hawkishness. Under these conditions, rare mutant levellers select for hawks that acquiesce to punishment by playing dove. If these 'acquiescent hawks' become common, levellers outperform hawks and establish a new egalitarian equilibrium. An analysis of human foraging groups corroborates these results, as groups with a greater reliance on cooperation are more egalitarian. Cooperation fosters greater equality when individuals can withhold its benefits from would-be dominant individuals.
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Affiliation(s)
- Paul L Hooper
- Department of Anthropology, University of New Mexico, Albuquerque, NM, USA. .,Economic Science Institute, Chapman University, Orange, CA, USA.
| | | | - Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
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16
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Jaeggi AV, Blackwell AD, von Rueden C, Trumble BC, Stieglitz J, Garcia AR, Kraft TS, Beheim BA, Hooper PL, Kaplan H, Gurven M. Do wealth and inequality associate with health in a small-scale subsistence society? eLife 2021; 10:59437. [PMID: 33988506 PMCID: PMC8225390 DOI: 10.7554/elife.59437] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 05/10/2021] [Indexed: 12/11/2022] Open
Abstract
In high-income countries, one’s relative socio-economic position and economic inequality may affect health and well-being, arguably via psychosocial stress. We tested this in a small-scale subsistence society, the Tsimane, by associating relative household wealth (n = 871) and community-level wealth inequality (n = 40, Gini = 0.15–0.53) with a range of psychological variables, stressors, and health outcomes (depressive symptoms [n = 670], social conflicts [n = 401], non-social problems [n = 398], social support [n = 399], cortisol [n = 811], body mass index [n = 9,926], blood pressure [n = 3,195], self-rated health [n = 2523], morbidities [n = 1542]) controlling for community-average wealth, age, sex, household size, community size, and distance to markets. Wealthier people largely had better outcomes while inequality associated with more respiratory disease, a leading cause of mortality. Greater inequality and lower wealth were associated with higher blood pressure. Psychosocial factors did not mediate wealth-health associations. Thus, relative socio-economic position and inequality may affect health across diverse societies, though this is likely exacerbated in high-income countries. Poverty is bad for health. People living in poverty are more likely to struggle to afford nutritious food, lack access to health care, or be overworked or stressed. This may make them susceptible to chronic diseases, contribute to faster aging, and shorten their lifespans. In high-income countries, there is growing evidence to suggest that a person’s ‘rank’ in society also impacts their health. For example, individuals who have a lower position in the social hierarchy report worse health outcomes, regardless of their incomes. But it is unclear why living in an unequal society or having a lower social status contributes to poorer health. One possibility is that inequalities in society are creating a stressful environment that leads to worse physical and mental outcomes. It is thought that this stress largely comes from how humans evolved to prioritize reaching a higher social status over having a long and healthy life. If this is the case, this would mean that the link between social status and health would also be present in non-industrialized communities where social hierarchies tend to be less pronounced. To test this, Jaeggi, Blackwell et al. studied the Indigenous Tsimane population in Bolivia who live in small communities and forage and farm their own food. The income and relative wealth of 870 households from 40 Tsimane communities were compared against various outcomes, including symptoms associated with depression, stress hormone levels, blood pressure, self-rated health and several diseases. Jaeggi, Blackwell et al. found poverty and inequality did not negatively impact all of the health outcomes measured as has been previously reported for industrialized societies. However, blood pressure was higher among people with lower incomes or those who lived in more unequal communities. But because the Tsimane people generally have low blood pressure, the differences were too small to have much effect on their health. People who lived in more unequal communities were also three times more likely to have respiratory infections, but the reason for this was unclear. This shows that social determinants such as a person’s wealth or inequality can affect health, even in communities with less rigid social hierarchies. In industrial societies the effect may be worse in part because they are compounded by lifestyle factors, such as diets rich in fat and sugar, and physical inactivity which can also increase blood pressure. This information may help policy makers reduce health disparities by addressing some of the social determinants of health and the lifestyle factors that cause them.
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Affiliation(s)
- Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland.,Department of Anthropology, Emory University, Atlanta, United States
| | - Aaron D Blackwell
- Department of Anthropology, Washington State University, Pulman, United States
| | | | - Benjamin C Trumble
- School of Human Evolution and Social Change, Arizona State University, Tempe, United States.,Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, United States
| | | | - Angela R Garcia
- Department of Anthropology, Emory University, Atlanta, United States.,School of Human Evolution and Social Change, Arizona State University, Tempe, United States.,Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, United States
| | - Thomas S Kraft
- Department of Anthropology, University of California, Santa Barbara, Santa Barbara, United States
| | - Bret A Beheim
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Paul L Hooper
- Economic Science Institute, Chapman University, Irvine, United States.,Department of Anthropology, University of New Mexico, Albuquerque, United States
| | - Hillard Kaplan
- Economic Science Institute, Chapman University, Irvine, United States
| | - Michael Gurven
- Department of Anthropology, University of California, Santa Barbara, Santa Barbara, United States
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17
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Abstract
Inequality or skew in reproductive success (RS) is common across many animal species and is of long-standing interest to the study of social evolution. However, the measurement of inequality in RS in natural populations has been challenging because existing quantitative measures are highly sensitive to variation in group/sample size, mean RS, and age-structure. This makes comparisons across multiple groups and/or species vulnerable to statistical artefacts and hinders empirical and theoretical progress. Here, we present a new measure of reproductive skew, the multinomial index, M, that is unaffected by many of the structural biases affecting existing indices. M is analytically related to Nonacs’ binomial index, B, and comparably accounts for heterogeneity in age across individuals; in addition, M allows for the possibility of diminishing or even highly nonlinear RS returns to age. Unlike B, however, M is not biased by differences in sample/group size. To demonstrate the value of our index for cross-population comparisons, we conduct a reanalysis of male reproductive skew in 31 primate species. We show that a previously reported negative effect of group size on mating skew was an artefact of structural biases in existing skew measures, which inevitably decline with group size; this bias disappears when using M. Applying phylogenetically controlled, mixed-effects models to the same dataset, we identify key similarities and differences in the inferred within- and between-species predictors of reproductive skew across metrics. Finally, we provide an R package, SkewCalc, to estimate M from empirical data.
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Affiliation(s)
- Cody T Ross
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
| | - Monique Borgerhoff Mulder
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Department of Anthropology, University of California, Davis, CA, USA
| | | | - Eric Alden Smith
- Department of Anthropology, University of Washington, Seattle, WA, USA
| | - Sergey Gavrilets
- Departments of Mathematics and Ecology & Evolutionary Biology, Center for the Dynamics of Social Complexity, and National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN, USA
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18
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Gurven M, Kraft TS, Alami S, Adrian JC, Linares EC, Cummings D, Rodriguez DE, Hooper PL, Jaeggi AV, Gutierrez RQ, Suarez IM, Seabright E, Kaplan H, Stieglitz J, Trumble B. Rapidly declining body temperature in a tropical human population. Sci Adv 2020; 6:6/44/eabc6599. [PMID: 33115745 PMCID: PMC7608783 DOI: 10.1126/sciadv.abc6599] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/10/2020] [Indexed: 05/11/2023]
Abstract
Normal human body temperature (BT) has long been considered to be 37.0°C. Yet, BTs have declined over the past two centuries in the United States, coinciding with reductions in infection and increasing life expectancy. The generality of and reasons behind this phenomenon have not yet been well studied. Here, we show that Bolivian forager-farmers (n = 17,958 observations of 5481 adults age 15+ years) inhabiting a pathogen-rich environment exhibited higher BT when first examined in the early 21st century (~37.0°C). BT subsequently declined by ~0.05°C/year over 16 years of socioeconomic and epidemiological change to ~36.5°C by 2018. As predicted, infections and other lifestyle factors explain variation in BT, but these factors do not account for the temporal declines. Changes in physical activity, body composition, antibiotic usage, and thermal environment are potential causes of the temporal decline.
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Affiliation(s)
- Michael Gurven
- Department of Anthropology, University of California Santa Barbara, CA, USA.
| | - Thomas S Kraft
- Department of Anthropology, University of California Santa Barbara, CA, USA
| | - Sarah Alami
- Department of Anthropology, University of California Santa Barbara, CA, USA
| | | | | | - Daniel Cummings
- Department of Anthropology, University of New Mexico, Albuquerque, NM, USA
| | | | - Paul L Hooper
- Department of Anthropology, University of New Mexico, Albuquerque, NM, USA
- Economic Science Institute, Chapman University, Orange, CA, USA
| | - Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
| | | | | | - Edmond Seabright
- Department of Anthropology, University of New Mexico, Albuquerque, NM, USA
| | - Hillard Kaplan
- Economic Science Institute, Chapman University, Orange, CA, USA
| | | | - Benjamin Trumble
- School of Human Evolution and Social Change, Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
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19
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Abstract
Alloparental care is central to human life history, which integrates exceptionally short interbirth intervals and large birth size with an extended period of juvenile dependency and increased longevity. Formal models, previous comparative research, and palaeoanthropological evidence suggest that humans evolved higher levels of cooperative childcare in response to increasingly harsh environments. Although this hypothesis remains difficult to test directly, the relative importance of alloparental care varies across human societies, providing an opportunity to assess how local social and ecological factors influence the expression of this behaviour. We therefore, investigated associations between alloparental infant care and socioecology across 141 non-industrialized societies. We predicted increased alloparental care in harsher environments, due to the fitness benefits of cooperation in response to shared ecological challenges. We also predicted that starvation would decrease alloparental care, due to prohibitive energetic costs. Using Bayesian phylogenetic multilevel models, we tested these predictions while accounting for potential confounds as well as for population history. Consistent with our hypotheses, we found increased alloparental infant care in regions characterized by both reduced climate predictability and relatively lower average temperatures and precipitation. We also observed reduced alloparental care under conditions of high starvation. These results provide evidence of plasticity in human alloparenting in response to ecological contexts, comparable to previously observed patterns across avian and mammalian cooperative breeders. This suggests convergent social evolutionary processes may underlie both inter- and intraspecific variation in alloparental care.
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Affiliation(s)
- J S Martin
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland.,Department of Anthropology, Emory University, Atlanta, GA, USA
| | - E J Ringen
- Department of Anthropology, Emory University, Atlanta, GA, USA
| | - P Duda
- Department of Zoology, University of South Bohemia, Ceske Budejovice, Jihočeský, Czechia
| | - A V Jaeggi
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland.,Department of Anthropology, Emory University, Atlanta, GA, USA
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20
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Moscovice LR, Surbeck M, Fruth B, Hohmann G, Jaeggi AV, Deschner T. The cooperative sex: Sexual interactions among female bonobos are linked to increases in oxytocin, proximity and coalitions. Horm Behav 2019; 116:104581. [PMID: 31449811 DOI: 10.1016/j.yhbeh.2019.104581] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/15/2019] [Accepted: 08/20/2019] [Indexed: 10/26/2022]
Abstract
In some species habitual same-sex sexual behavior co-occurs with high levels of intra-sexual alliance formation, suggesting that these behaviors may be linked. We tested for such a link by comparing behavioral and physiological outcomes of sex with unrelated same- and opposite-sex partners in female bonobos (Pan paniscus). We analyzed behavioral outcomes following 971 sexual events involving n = 19 female and n = 8 male adult and sub-adult members of a wild, habituated bonobo community. We additionally collected n = 143 urine samples before and after sexual interactions to non-invasively measure oxytocin (OT), which modulates female sexual behavior and facilitates cooperation in other species. The majority of sexual events (65%) consisted of female same-sex genito-genital rubbing (or GG-rubbing). Female dyads engaged in significantly more sexual interactions than did inter-sexual dyads, and females were more likely to remain within close proximity to their partners following GG-rubbing. Females also exhibited greater increases in urinary OT following GG-rubbing compared with copulations, indicating a physiological basis for increased motivation to cooperate among females. The frequency of coalitionary support among non-kin was positively predicted by the frequency of sexual interactions for female as well opposite-sex dyads, although coalitionary support tended to be more frequent among females. The emergence of habitual same-sex sexual behavior may have been an important step in the evolution of cooperation outside of kinship and pair-bonds in one of our closest phylogenetic relatives.
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Affiliation(s)
- Liza R Moscovice
- Institute of Behavioural Physiology, Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany; Anthropology Department, Emory University, 1557 Dickey Drive, Atlanta, GA 30322, USA.
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, Peabody Museum, 5(th) Floor, 11 Divinity Avenue, Cambridge, MA 02138, USA; Primatology Department, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
| | - Barbara Fruth
- Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, United Kingdom; Centre for Research and Conservation, Royal Zoological Society of Antwerp, Koningin Astridplein 20-26, 2018 Antwerp, Belgium.
| | - Gottfried Hohmann
- Primatology Department, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
| | - Adrian V Jaeggi
- Anthropology Department, Emory University, 1557 Dickey Drive, Atlanta, GA 30322, USA; Institute of Evolutionary Medicine, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Tobias Deschner
- Primatology Department, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
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21
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Martin JS, Staes N, Weiss A, Stevens JMG, Jaeggi AV. Facial width-to-height ratio is associated with agonistic and affiliative dominance in bonobos (Pan paniscus). Biol Lett 2019; 15:20190232. [PMID: 31455170 DOI: 10.1098/rsbl.2019.0232] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Facial width-to-height ratio (fWHR) is associated with social dominance in human and non-human primates, which may reflect the effects of testosterone on facial morphology and behaviour. Given that testosterone facilitates status-seeking motivation, the association between fWHR and behaviour should be contingent on the relative costs and benefits of particular dominance strategies across species and socioecological contexts. We tested this hypothesis in bonobos (Pan paniscus), who exhibit female dominance and rely on both affiliation and aggression to achieve status. We measured fWHR from facial photographs, affiliative dominance with Assertiveness personality scores and agonistic dominance with behavioural data. Consistent with our hypothesis, agonistic and affiliative dominance predicted fWHR in both sexes independent of age and body weight, supporting the role of status-seeking motivation in producing the link between fWHR and socioecologically relevant dominance behaviour across primates.
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Affiliation(s)
- J S Martin
- Behavioral Ecology Lab, Department of Anthropology, Emory University, Atlanta, GA, USA.,Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland.,Department of Anthropology, Miami University, Oxford, OH, USA
| | - N Staes
- Centre for Research and Conservation, Royal Zoological Society of Antwerp, Antwerp, Belgium.,Behavioural Ecology and Ecophysiology Group, Department of Biology, University of Antwerp, Antwerp, Belgium.,Center for Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, Washington, DC, USA
| | - A Weiss
- Department of Psychology, School of Philosophy, Psychology and Language Sciences, The University of Edinburgh, Edinburgh, UK.,The Scottish Primate Research Group, UK
| | - J M G Stevens
- Centre for Research and Conservation, Royal Zoological Society of Antwerp, Antwerp, Belgium.,Behavioural Ecology and Ecophysiology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - A V Jaeggi
- Behavioral Ecology Lab, Department of Anthropology, Emory University, Atlanta, GA, USA.,Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
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Stout D, Rogers MJ, Jaeggi AV, Semaw S. Archaeology and the Origins of Human Cumulative Culture: A Case Study from the Earliest Oldowan at Gona, Ethiopia. Current Anthropology 2019. [DOI: 10.1086/703173] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Minocher R, Duda P, Jaeggi AV. Explaining marriage patterns in a globally representative sample through socio-ecology and population history: A Bayesian phylogenetic analysis using a new supertree. EVOL HUM BEHAV 2019. [DOI: 10.1016/j.evolhumbehav.2018.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jaeggi AV. J.S. Torday, N.W. Blackstone, and V.K. Rehan, A Cell-Centered Alternative to Mainstream Evolutionary Medicine? Review of “Evidence-Based Evolutionary Medicine”. Evol Med Public Health 2019. [PMCID: PMC6442493 DOI: 10.1093/emph/eoz010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Adrian V Jaeggi
- Institute of Evolutionary Medicine University of Zurich Zurich, Switzerland
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Martin JS, Massen JJM, Šlipogor V, Bugnyar T, Jaeggi AV, Koski SE. The
EGA
+
GNM
framework: An integrative approach to modelling behavioural syndromes. Methods Ecol Evol 2018. [DOI: 10.1111/2041-210x.13100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Jordan S. Martin
- Behavioural Ecology LabDepartment of AnthropologyEmory University Atlanta Georgia
- Department of Cognitive BiologyUniversity of Vienna Vienna Austria
- Department of AnthropologyMiami University Oxford Ohio
| | - Jorg J. M. Massen
- Department of Cognitive BiologyUniversity of Vienna Vienna Austria
- Cognitive Psychology UnitInstitute of PsychologyLeiden University Leiden The Netherlands
| | - Vedrana Šlipogor
- Department of Cognitive BiologyUniversity of Vienna Vienna Austria
| | - Thomas Bugnyar
- Department of Cognitive BiologyUniversity of Vienna Vienna Austria
| | - Adrian V. Jaeggi
- Behavioural Ecology LabDepartment of AnthropologyEmory University Atlanta Georgia
| | - Sonja E. Koski
- Faculty of Social SciencesUniversity of Helsinki Helsinki Finland
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Jaeggi AV, Trumble BC, Brown M. Group-level competition influences urinary steroid hormones among wild red-tailed monkeys, indicating energetic costs. Am J Primatol 2018; 80:e22757. [PMID: 29635811 DOI: 10.1002/ajp.22757] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 03/22/2018] [Accepted: 03/22/2018] [Indexed: 02/28/2024]
Abstract
Various theories emphasize that intergroup competition should affect intragroup cooperation and social relationships, especially if the cost of intergroup competition outweighs that of intragroup competition. This cost of intergroup competition may be quantified by changes in physiological status, such as in the steroid hormones cortisol (C) and testosterone (T), which rise or are depressed during periods of energetic stress, respectively. Here we tested for changes in urinary C and T after intergroup encounters (IGEs) among wild red-tailed monkeys (Cercopithecus ascanius), a species that experiences frequent intergroup feeding competition, at the Ngogo station in Kibale National Park, Uganda. We assayed 108 urine samples, of which 36 were collected after IGEs, from 23 individuals in four social groups. Bayesian multilevel models controlling for various confounds revealed that IGEs increased C and decreased T relative to baseline, consistent with an energetic cost to IGEs. The C change was more apparent in samples collected early after IGEs, suggesting an anticipatory increase, whereas the T change was stronger in later samples, suggesting sustained energetic trade-offs. Hormone responses were not affected by the IGE outcome. This cost to intergroup competition, together with little evidence for intragroup competition in redtails and other guenons, establishes an interesting test case for theories emphasizing the effect of intergroup competition on intragroup cooperation.
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Affiliation(s)
- Adrian V Jaeggi
- Departmentof Anthropology, Emory University, Atlanta, Georgia
| | - Benjamin C Trumble
- Center for Evolution and Medicine, Arizona State University, Tempe, Arizona
- School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona
| | - Michelle Brown
- Department of Anthropology, University of California, Santa Barbara, California
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Thayer ZM, Wilson MA, Kim AW, Jaeggi AV. Impact of prenatal stress on offspring glucocorticoid levels: A phylogenetic meta-analysis across 14 vertebrate species. Sci Rep 2018; 8:4942. [PMID: 29563562 PMCID: PMC5862967 DOI: 10.1038/s41598-018-23169-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 03/07/2018] [Indexed: 01/06/2023] Open
Abstract
Prenatal exposure to maternal stress is commonly associated with variation in Hypothalamic Pituitary Adrenal (HPA)-axis functioning in offspring. However, the strength or consistency of this response has never been empirically evaluated across vertebrate species. Here we meta-analyzed 114 results from 39 studies across 14 vertebrate species using Bayesian phylogenetic mixed-effects models. We found a positive overall effect of prenatal stress on offspring glucocorticoids (d' = 0.43) though the 95% Highest Posterior Density Interval overlapped with 0 (-0.16-0.95). Meta-regressions of potential moderators highlighted that phylogeny and life history variables predicted relatively little variation in effect size. Experimental studies (d' = 0.64) produced stronger effects than observational ones (d' = -0.01), while prenatal stress affected glucocorticoid recovery following offspring stress exposure more strongly (d' = 0.75) than baseline levels (d' = 0.48) or glucocorticoid peak response (d' = 0.36). These findings are consistent with the argument that HPA-axis sensitivity to prenatal stress is evolutionarily ancient and occurs regardless of a species' overall life history strategy. These effects may therefore be especially important for mediating intra-specific life-history variation. In addition, these findings suggest that animal models of prenatal HPA-axis programming may be appropriate for studying similar effects in humans.
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Affiliation(s)
- Zaneta M Thayer
- Department of Anthropology, Dartmouth College, New Hampshire, USA.
| | - Meredith A Wilson
- Department of Anthropology, University of Illinois Urbana-Champaign, Illinois, USA
| | - Andrew W Kim
- Department of Anthropology, Northwestern University, Illinois, USA
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Jaeggi AV. Nothing but Mammals? Review of Tim Clutton-Brock's Mammal Societies : (Wiley, 2016). Hum Nat 2017; 28:355-360. [PMID: 28497400 DOI: 10.1007/s12110-017-9288-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Affiliation(s)
- Adrian V Jaeggi
- Department of Anthropology, Emory University, 1557 Dickey Drive, Atlanta, GA, 30322, USA.
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Jaeggi AV, Kramer KL, Hames R, Kiely EJ, Gomes C, Kaplan H, Gurven M. Human grooming in comparative perspective: People in six small-scale societies groom less but socialize just as much as expected for a typical primate. Am J Phys Anthropol 2017; 162:810-816. [PMID: 28164267 DOI: 10.1002/ajpa.23164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 12/15/2016] [Accepted: 12/18/2016] [Indexed: 12/30/2022]
Abstract
OBJECTIVES Grooming has important utilitarian and social functions in primates but little is known about grooming and its functional analogues in traditional human societies. We compare human grooming to typical primate patterns to test its hygienic and social functions. MATERIALS AND METHODS Bayesian phylogenetic analyses were used to derive expected human grooming time given the potential associations between grooming, group size, body size, terrestriality, and several climatic variables across 69 primate species. This was compared against observed times dedicated to grooming, other hygienic behavior, and conversation among the Maya, Pumé, Sanöma, Tsimane', Yanomamö, and Ye'kwana (mean number of behavioral scans = 23,514). RESULTS Expected grooming time for humans was 4% (95% Credible Interval = 0.07%-14%), similar to values observed in primates, based largely on terrestriality and phylogenetic signal (mean λ = 0.56). No other covariates strongly associated with grooming across primates. Observed grooming time across societies was 0.8%, lower than 89% of the expected values. However, the observed times dedicated to any hygienic behavior (3.0%) or "vocal grooming," that is conversation (7.3%), fell within the expected range. CONCLUSIONS We found (i) that human grooming may be a (recent) phylogenetic outlier when defined narrowly as parasite removal but not defined broadly as personal hygiene, (ii) there was no support for thermoregulatory functions of grooming, and (iii) no support for the "vocal grooming" hypothesis of language having evolved as a less time-consuming means of bonding. Thus, human grooming reflects decreased hygienic needs, but similar social needs compared to primate grooming.
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Affiliation(s)
- Adrian V Jaeggi
- Department of Anthropology, Emory University, Atlanta, Georgia, 30322
| | - Karen L Kramer
- Department of Anthropology, University of Utah, Salt Lake City, Utah, 84112
| | - Raymond Hames
- Department of Anthropology, University of Nebraska Lincoln, Lincoln, Nebraska, 68588
| | - Evan J Kiely
- Department of Anthropology, Emory University, Atlanta, Georgia, 30322
| | - Cristina Gomes
- Department of Psychology, University of Miami, Coral Gables, Florida, 33124
| | - Hillard Kaplan
- Department of Anthropology, University of New Mexico, Albuquerque, New Mexico, 87131
| | - Michael Gurven
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, California, 93106
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von Rueden CR, Jaeggi AV. Men's status and reproductive success in 33 nonindustrial societies: Effects of subsistence, marriage system, and reproductive strategy. Proc Natl Acad Sci U S A 2016; 113:10824-9. [PMID: 27601650 PMCID: PMC5047206 DOI: 10.1073/pnas.1606800113] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Social status motivates much of human behavior. However, status may have been a relatively weak target of selection for much of human evolution if ancestral foragers tended to be more egalitarian. We test the "egalitarianism hypothesis" that status has a significantly smaller effect on reproductive success (RS) in foragers compared with nonforagers. We also test between alternative male reproductive strategies, in particular whether reproductive benefits of status are due to lower offspring mortality (parental investment) or increased fertility (mating effort). We performed a phylogenetic multilevel metaanalysis of 288 statistical associations between measures of male status (physical formidability, hunting ability, material wealth, political influence) and RS (mating success, wife quality, fertility, offspring mortality, and number of surviving offspring) from 46 studies in 33 nonindustrial societies. We found a significant overall effect of status on RS (r = 0.19), though this effect was significantly lower than for nonhuman primates (r = 0.80). There was substantial variation due to marriage system and measure of RS, in particular status associated with offspring mortality only in polygynous societies (r = -0.08), and with wife quality only in monogamous societies (r = 0.15). However, the effects of status on RS did not differ significantly by status measure or subsistence type: foraging, horticulture, pastoralism, and agriculture. These results suggest that traits that facilitate status acquisition were not subject to substantially greater selection with domestication of plants and animals, and are part of reproductive strategies that enhance fertility more than offspring well-being.
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Affiliation(s)
| | - Adrian V Jaeggi
- Department of Anthropology, Emory University, Atlanta, GA 30316
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Trumble BC, Jaeggi AV, Gurven M. Evolving the neuroendocrine physiology of human and primate cooperation and collective action. Philos Trans R Soc Lond B Biol Sci 2016; 370:20150014. [PMID: 26503687 DOI: 10.1098/rstb.2015.0014] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
While many hormones play vital roles in facilitating or reinforcing cooperative behaviour, the neurohormones underlying competitive and cooperative behaviours are largely conserved across all mammals. This raises the question of how endocrine mechanisms have been shaped by selection to produce different levels of cooperation in different species. Multiple components of endocrine physiology--from baseline hormone concentrations, to binding proteins, to the receptor sensitivity and specificity--can evolve independently and be impacted by current socio-ecological conditions or individual status, thus potentially generating a wide range of variation within and between species. Here, we highlight several neurohormones and variation in hormone receptor genes associated with cooperation, focusing on the role of oxytocin and testosterone in contexts ranging from parenting and pair-bonding to reciprocity and territorial defence. While the studies reviewed herein describe the current state of the literature with regard to hormonal modulators of cooperation and collective action, there is still a paucity of research on hormonal mechanisms that help facilitate large-scale collective action. We end by discussing several potential areas for future research.
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Affiliation(s)
- Benjamin C Trumble
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Adrian V Jaeggi
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Michael Gurven
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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Jaeggi AV, Hooper PL, Beheim BA, Kaplan H, Gurven M. Reciprocal Exchange Patterned by Market Forces Helps Explain Cooperation in a Small-Scale Society. Curr Biol 2016; 26:2180-7. [PMID: 27451903 DOI: 10.1016/j.cub.2016.06.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/12/2016] [Accepted: 06/09/2016] [Indexed: 10/21/2022]
Abstract
Social organisms sometimes depend on help from reciprocating partners to solve adaptive problems [1], and individual cooperation strategies should aim to offer high supply commodities at low cost to the donor in exchange for high-demand commodities with large return benefits [2, 3]. Although such market dynamics have been documented in some animals [4-7], naturalistic studies of human cooperation are often limited by focusing on single commodities [8]. We analyzed cooperation in five domains (meat sharing, produce sharing, field labor, childcare, and sick care) among 2,161 household dyads of Tsimane' horticulturalists, using Bayesian multilevel models and information-theoretic model comparison. Across domains, the best-fit models included kinship and residential proximity, exchanges in kind and across domains, measures of supply and demand and their interactions with exchange, and household-specific exchange slopes. In these best models, giving, receiving, and reciprocating were to some extent shaped by market forces, and reciprocal exchange across domains had a strong partial effect on cooperation independent of more exogenous factors like kinship and proximity. Our results support the view that reciprocal exchange can provide a reliable solution to adaptive problems [8-11]. Although individual strategies patterned by market forces may generate gains from trade in any species [3], humans' slow life history and skill-intensive foraging niche favor specialization and create interdependence [12, 13], thus stabilizing cooperation and fostering divisions of labor even in informal economies [14, 15].
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Affiliation(s)
- Adrian V Jaeggi
- Department of Anthropology, Emory University, 1557 Dickey Drive, Atlanta, GA 30322, USA; Department of Anthropology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Paul L Hooper
- Department of Anthropology, Emory University, 1557 Dickey Drive, Atlanta, GA 30322, USA
| | - Bret A Beheim
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Hillard Kaplan
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Michael Gurven
- Department of Anthropology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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Jaeggi AV, Boose KJ, White FJ, Gurven M. Obstacles and catalysts of cooperation in humans, bonobos, and chimpanzees: behavioural reaction norms can help explain variation in sex roles, inequality, war and peace. BEHAVIOUR 2016. [DOI: 10.1163/1568539x-00003347] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Our closest living relatives, bonobos and chimpanzees, along with small-scale human societies figure prominently in debates about human nature. Here we emphasize and explain behavioural variation within and among these three species. In the logic of behavioural ecology, individuals have been selected to adjust their behaviour along evolved reaction norms that maximize fitness given current socio-ecological conditions. We discuss variation in three behavioural contexts: relationships between the sexes, hierarchy and inequality, and intergroup interactions. In each context, behavioural variation can be related to two broad socio-ecological conditions: (i) the defensibility of contested resources, and (ii) differences in bargaining power. When defensibility of resources and differences in bargaining power are great, interactions are rife with conflict; when they are minimal, interactions are more harmonious. These socio-ecological conditions therefore constitute key catalysts and obstacles of cooperation. We conclude that human nature should be seen as consisting of evolved reaction norms.
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Affiliation(s)
- Adrian V. Jaeggi
- aDepartment of Anthropology, University of California Santa Barbara, Humanities and Social Sciences Building (HSSB) 2001, Santa Barbara, CA 93106-3210, USA
| | - Klaree J. Boose
- bDepartment of Anthropology, University of Oregon, 308 Condon Hall, 1321 Kincaid Street, Eugene, OR 97403, USA
| | - Frances J. White
- bDepartment of Anthropology, University of Oregon, 308 Condon Hall, 1321 Kincaid Street, Eugene, OR 97403, USA
| | - Michael Gurven
- aDepartment of Anthropology, University of California Santa Barbara, Humanities and Social Sciences Building (HSSB) 2001, Santa Barbara, CA 93106-3210, USA
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Jaeggi AV, Trumble BC, Kaplan HS, Gurven M. Salivary oxytocin increases concurrently with testosterone and time away from home among returning Tsimane' hunters. Biol Lett 2015; 11:rsbl.2015.0058. [PMID: 25788487 DOI: 10.1098/rsbl.2015.0058] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Oxytocin, testosterone and cortisol can have opposing effects on social behaviour, yet few studies have examined their interactions. We measured changes in salivary oxytocin, testosterone and cortisol among Tsimane' men returning home after hunting, an ancient context of male status competition, parental investment and cooperation. Contra normal diurnal rhythm, oxytocin increased relative to baseline and this increase was positively associated with duration of the hunt and change in testosterone, but not cortisol, social context, hunting outcome or physical activity. The concurrent increase in endogenous peripheral oxytocin and testosterone is unexpected given their opposing independent effects on social cognition and behaviour, and has not been observed before. We discuss the potential significance of these effects for the biology of pair-bonding, parenting and social foraging in humans and other species.
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Affiliation(s)
- Adrian V Jaeggi
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Benjamin C Trumble
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Hillard S Kaplan
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Michael Gurven
- Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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Gurven M, Jaeggi AV, von Rueden C, Hooper PL, Kaplan H. Does market integration buffer risk, erode traditional sharing practices and increase inequality? A test among Bolivian forager-farmers. Hum Ecol Interdiscip J 2015; 43:515-30. [PMID: 26526638 PMCID: PMC4624453 DOI: 10.1007/s10745-015-9764-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital.
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Affiliation(s)
- Michael Gurven
- Department of Anthropology, University of California-Santa Barbara, Santa Barbara, CA 93106
- Corresponding author, , 805-893-2202
| | - Adrian V. Jaeggi
- Department of Anthropology, University of California-Santa Barbara, Santa Barbara, CA 93106
| | - Chris von Rueden
- Jepson School of Leadership Studies, University of Richmond, Richmond VA 23173
| | - Paul L. Hooper
- Department of Anthropology, Emory University, Atlanta, GA 30322
| | - Hillard Kaplan
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131
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Abstract
The study of cooperation is rich with theoretical models and laboratory experiments that have greatly advanced our knowledge of human uniqueness, but have sometimes lacked ecological validity. We therefore emphasize the need to tie discussions of human cooperation to the natural history of our species and its closest relatives, focusing on behavioral contexts best suited to reveal underlying selection pressures and evolved decision rules. Food sharing is a fundamental form of cooperation that is well-studied across primates and is particularly noteworthy because of its central role in shaping evolved human life history, social organization, and cooperative psychology. Here we synthesize available evidence on food sharing in humans and other primates, tracing the origins of offspring provisioning, mutualism, trade, and reciprocity throughout the primate order. While primates may gain some benefits from sharing, humans, faced with more collective action problems in a risky foraging niche, expanded on primate patterns to buffer risk and recruit mates and allies through reciprocity and signaling, and established co-evolving social norms of production and sharing. Differences in the necessity for sharing are reflected in differences in sharing psychology across species, thus helping to explain unique aspects of our evolved cooperative psychology.
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Jaeggi AV, Gurven M. Reciprocity explains food sharing in humans and other primates independent of kin selection and tolerated scrounging: a phylogenetic meta-analysis. Proc Biol Sci 2013; 280:20131615. [PMID: 23945693 PMCID: PMC3757985 DOI: 10.1098/rspb.2013.1615] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 07/17/2013] [Indexed: 12/20/2022] Open
Abstract
Helping, i.e. behaviour increasing the fitness of others, can evolve when directed towards kin or reciprocating partners. These predictions have been tested in the context of food sharing both in human foragers and non-human primates. Here, we performed quantitative meta-analyses on 32 independent study populations to (i) test for overall effects of reciprocity on food sharing while controlling for alternative explanations, methodological biases, publication bias and phylogeny and (ii) compare the relative effects of reciprocity, kinship and tolerated scrounging, i.e. sharing owing to costs imposed by others. We found a significant overall weighted effect size for reciprocity of r = 0.20-0.48 for the most and least conservative measure, respectively. Effect sizes did not differ between humans and other primates, although there were species differences in in-kind reciprocity and trade. The relative effect of reciprocity in sharing was similar to those of kinship and tolerated scrounging. These results indicate a significant independent contribution of reciprocity to human and primate helping behaviour. Furthermore, similar effect sizes in humans and primates speak against cognitive constraints on reciprocity. This study is the first to use meta-analyses to quantify these effects on human helping and to directly compare humans and other primates.
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Affiliation(s)
- Adrian V Jaeggi
- Integrative Anthropological Sciences, Department of Anthropology, University of California Santa Barbara, Santa Barbara, CA 93106-3210, USA.
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Abstract
BACKGROUND Physical inactivity is a growing public health problem, and the fourth leading risk factor for global mortality. Conversely, indigenous populations living traditional lifestyles reportedly engage in vigorous daily activity that is protective against non-communicable diseases. Here we analyze physical activity patterns among the Tsimane, forager-horticulturalists of Amazonian Bolivia with minimal heart disease and diabetes. We assess age patterns of adult activity among men and women, test whether modernization affects activity levels, and examine whether nascent obesity is associated with reduced activity. METHODS AND FINDINGS A factorial method based on a large sample of behavioral observations was employed to estimate effects of age, sex, body mass index, and modernization variables on physical activity ratio (PAR), the ratio of total energy expenditure to basal metabolic rate. Accelerometry combined with heart rate monitoring was compared to the factorial method and used for nighttime sampling. Tsimane men and women display 24 hr physical activity level (PAL) of 2.02-2.15 and 1.73-1.85, respectively. Little time was spent "sedentary", whereas most activity was light to moderate, rather than vigorous. Activity peaks by the late twenties in men, and declines thereafter, but remains constant among women after the early teens. Neither BMI, fat free mass or body fat percentage are associated with PAR. There was no negative effect of modernization on physical activity. CONCLUSIONS Tsimane display relatively high PALs typical of other subsistence populations, but of moderate intensity, and not outside the range of developed populations. Despite rapidly increasing socioeconomic change, there is little evidence that total activity has yet been affected. Overweight and obesity are more prevalent among women than men, and Spanish fluency is associated with greater obesity in women. The lack of cardiovascular disease among Tsimane is unlikely caused by activity alone; further study of diet, food intake and infectious disease is needed.
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Affiliation(s)
- Michael Gurven
- Integrative Anthropological Sciences Unit, Department of Anthropology, University of California Santa Barbara, Santa Barbara, California, United States of America.
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Jaeggi AV, Stevens JMG, Van Schaik CP. Tolerant food sharing and reciprocity is precluded by despotism among bonobos but not chimpanzees. Am J Phys Anthropol 2010; 143:41-51. [PMID: 20310060 DOI: 10.1002/ajpa.21288] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tolerant food sharing among human foragers can largely be explained by reciprocity. In contrast, food sharing among chimpanzees and bonobos may not always reflect reciprocity, which could be explained by different dominance styles: in egalitarian societies reciprocity is expressed freely, while in more despotic groups dominants may hinder reciprocity. We tested the degree of reciprocity and the influence of dominance on food sharing among chimpanzees and bonobos in two captive groups. First, we found that chimpanzees shared more frequently, more tolerantly, and more actively than bonobos. Second, among chimpanzees, food received was the best predictor of food shared, indicating reciprocal exchange, whereas among bonobos transfers were mostly unidirectional. Third, chimpanzees had a shallower and less linear dominance hierarchy, indicating that they were less despotic than bonobos. This suggests that the tolerant and reciprocal sharing found in chimpanzees, but not bonobos, was made possible by the absence of despotism. To investigate this further, we tested the relationship between despotism and reciprocity in grooming using data from an additional five groups and five different study periods on the main groups. The results showed that i) all chimpanzee groups were less despotic and groomed more reciprocally than bonobo groups, and ii) there was a general negative correlation between despotism and grooming reciprocity across species. This indicates that an egalitarian hierarchy may be more common in chimpanzees, at least in captivity, thus fostering reciprocal exchange. We conclude that a shallow dominance hierarchy was a necessary precondition for the evolution of human-like reciprocal food sharing.
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Affiliation(s)
- Adrian V Jaeggi
- Anthropological Institute and Museum, University of Zurich, Winterthurerstr. 190, Zürich 8057, Switzerland.
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Jaeggi AV, Burkart JM, Van Schaik CP. On the psychology of cooperation in humans and other primates: combining the natural history and experimental evidence of prosociality. Philos Trans R Soc Lond B Biol Sci 2010; 365:2723-35. [PMID: 20679115 DOI: 10.1098/rstb.2010.0118] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In any given species, cooperation involves prosocial acts that usually return a fitness benefit to the actor. These acts are produced by a set of psychological rules, which will be similar in related species if they have a similar natural history of cooperation. Prosocial acts can be (i) reactive, i.e. in response to specific stimuli, or (ii) proactive, i.e. occur in the absence of such stimuli. We propose that reactive prosocial acts reflect sensitivity to (i) signals or signs of need and (ii) the presence and size of an audience, as modified by (iii) social distance to the partner or partners. We examine the evidence for these elements in humans and other animals, especially non-human primates, based on the natural history of cooperation, quantified in the context of food sharing, and various experimental paradigms. The comparison suggests that humans share with their closest living relatives reactive responses to signals of need, but differ in sensitivity to signs of need and cues of being watched, as well as in the presence of proactive prosociality. We discuss ultimate explanations for these derived features, in particular the adoption of cooperative breeding as well as concern for reputation and costly signalling during human evolution.
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Affiliation(s)
- Adrian V Jaeggi
- Anthropological Institute and Museum, University of Zurich, 8057 Zürich, Switzerland.
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Jaeggi AV, Dunkel LP, Van Noordwijk MA, Wich SA, Sura AAL, Van Schaik CP. Social learning of diet and foraging skills by wild immature Bornean orangutans: implications for culture. Am J Primatol 2010; 72:62-71. [PMID: 19790189 DOI: 10.1002/ajp.20752] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Studies of social learning in the wild are important to complement findings from experiments in captivity. In this field study, immature Bornean orangutans rarely foraged independently but consistently followed their mothers' choices. Their diets were essentially identical to their mothers' even though not all mothers had the same diet. This suggests vertical transmission of diet by enhancement. Also, immatures selectively observed their mothers during extractive foraging, which increased goal-directed practice but not general manipulation of similar objects, suggesting observational forms of learning of complex skills. Teaching was not observed. These results are consistent with the reported presence of food traditions and skill cultures in wild orangutans. We suggest that food traditions can develop wherever association commonly allows for social learning. However, the capacity for observational learning, and thus more complex culture, is more likely to evolve among extractive foragers with prolonged association between adults and immatures.
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Affiliation(s)
- Adrian V Jaeggi
- Anthropological Institute & Museum, University of Zurich, Zurich, Switzerland.
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Abstract
Transfer of solid food from mothers or other adults to dependent offspring is commonly observed in various primate species and both nutritional and informational benefits have been proposed to explain the function of such food sharing. Predictions from these hypotheses are tested using observational data on wild orangutans (Pongo pygmaeus wurmbii) at Tuanan, Central Borneo, Indonesia. In 1,145 hr of focal observation and 458 recorded food interactions between four pairs of females with offspring it was found that virtually all transfers were initiated by the offspring and that younger infants solicited food more often and did so for a greater variety of items than older offspring. All offspring primarily solicited food that was difficult to process, i.e., inaccessible to them. Furthermore, the amount of food solicitation was negatively correlated with ecological competence. Hence food sharing seemed to be related to an offspring's skill level, as suggested by the informational hypothesis. In contrast, offspring did not solicit high-quality items more than low-quality items and food sharing did not peak around the age of weaning, as predicted by the nutritional hypothesis. Mothers were usually passively tolerant, allowing offspring to take food but hardly ever provisioned. Parent-offspring conflict concerning food sharing was only observed well after weaning. Thus, by taking food directly from the mother, young orangutans were able to obtain information about the affordances and nutritional value of food items that were otherwise out of their reach and could familiarize themselves with the mother's diet. In species such as orangutans or other apes, characterized by a broad diet that requires extractive foraging, informational food transfer may be vital for an immature to acquire complex feeding skills and adult diet.
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Affiliation(s)
- Adrian V Jaeggi
- Anthropological Institute & Museum, University of Zurich, Zurich, Switzerland.
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