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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] [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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A cost for signaling: do Hadza hunter-gatherers forgo calories to show-off in an experimental context? EVOL HUM BEHAV 2022. [DOI: 10.1016/j.evolhumbehav.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Affiliation(s)
- Nicole Barbaro
- Department of Psychology Oakland University Rochester Michigan USA
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Hawkes K. The Centrality of Ancestral Grandmothering in Human Evolution. Integr Comp Biol 2020; 60:765-781. [PMID: 32386309 DOI: 10.1093/icb/icaa029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
When Fisher, Williams, and Hamilton laid the foundations of evolutionary life history theory, they recognized elements of what became a grandmother hypothesis to explain the evolution of human postmenopausal longevity. Subsequent study of modern hunter-gatherers, great apes, and the wider mammalian radiation has revealed strong regularities in development and behavior that show additional unexpected consequences that ancestral grandmothering likely had on human evolution, challenging the hypothesis that ancestral males propelled the evolution of our radiation by hunting to provision mates and offspring. Ancestral grandmothering has become a serious contender to explain not only the large fraction of post-fertile years women live and children's prolonged maturation yet early weaning; it also promises to help account for the pair bonding that distinguishes humans from our closest living evolutionary cousins, the great apes (and most other mammals), the evolution of our big human brains, and our distinctive preoccupation with reputations, shared intentionality and persistent cultural learning that begins in infancy.
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Affiliation(s)
- Kristen Hawkes
- Anthropology, University of Utah, 260 South Central Campus Drive, Gardener Commons Suite 4625, Salt Lake City, UT 84112, USA
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5
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Abstract
Paternal provisioning is ubiquitous in human subsistence societies and unique among apes. How could paternal provisioning have emerged from promiscuous or polygynous mating systems that characterize other apes? An anomalous provisioning male would encounter a social dilemma: Since this investment in prospective offspring can be expropriated by other males, this investment is unlikely to increase the provisioner’s fitness. We present an ecological theory of the evolution of human paternal investment. Ecological change favoring reliance on energetically rich, difficult-to-acquire resources increases payoffs to paternal provisioning due to female–male and/or male–male complementarities. Paternal provisioning becomes a viable reproductive strategy when complementarities are strong, even under high paternity uncertainty. This model illuminates additional paths for understanding the evolution of fatherhood. Paternal provisioning among humans is puzzling because it is rare among primates and absent in nonhuman apes and because emergent provisioning would have been subject to paternity theft. A provisioning “dad” loses fitness at the hands of nonprovisioning, mate-seeking “cads.” Recent models require exacting interplay between male provisioning and female choice to overcome this social dilemma. We instead posit that ecological change favored widespread improvements in male provisioning incentives, and we show theoretically how social obstacles to male provisioning can be overcome. Greater availability of energetically rich, difficult-to-acquire foods enhances female–male and male–male complementarities, thus altering the fitness of dads versus cads. We identify a tipping point where gains from provisioning overcome costs from paternity uncertainty and the dad strategy becomes viable. Stable polymorphic states are possible, meaning that dads need not necessarily eliminate cads. Our simulations suggest that with sufficient complementarities, dads can emerge even in the face of high paternity uncertainty. Our theoretical focus on ecological change as a primary factor affecting the trade-off between male mating and parenting effort suggests different possibilities for using paleo-climatic, archaeological, and genomic evidence to establish the timing of and conditions associated with emergence of paternal provisioning in the hominin lineage.
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Schacht R, Kramer KL. Are We Monogamous? A Review of the Evolution of Pair-Bonding in Humans and Its Contemporary Variation Cross-Culturally. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00230] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Rose D, Hawkes K, Kim PS. Adult sex ratio as an index for male strategy in primates. Theor Popul Biol 2019; 126:40-50. [PMID: 30771361 DOI: 10.1016/j.tpb.2019.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 01/18/2019] [Accepted: 02/04/2019] [Indexed: 11/17/2022]
Abstract
The adult sex ratio (ASR) is defined as the number of fertile males divided by the number of fertile females in a population. We build an ODE model with minimal age structure, in which males compete for paternities using either a multiple-mating or searching-then-guarding strategy, to investigate the value of ASR as an index for predicting which strategy males will adopt, with a focus in our investigation on the differences of strategy choice between chimpanzees (Pan troglodytes) and human hunter-gatherers (Homo sapiens). Parameters in the model characterise aspects of life history and behaviour, and determine both dominant strategy and the ASR when the population is at or near equilibrium. Sensitivity analysis on the model parameters informs us that ASR is strongly influenced by parameters characterising life history, while dominant strategy is affected most strongly by the effectiveness of guarding (average length of time a guarded pair persists, and resistance to paternity theft) and moderately by some life history traits. For fixed effectiveness of guarding and other parameters, dominant strategy tends to change from multiple mating to guarding along a curve that aligns well with a contour of constant ASR, under variation of parameters such as longevity and age female fertility ends. This confirms the hypothesis that ASR may be a useful index for predicting the optimal male mating strategy, provided we have some limited information about ecology and behaviour.
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Affiliation(s)
- Danya Rose
- School of Mathematics and Statistics, University of Sydney, Sydney, NSW 2006, Australia.
| | - Kristen Hawkes
- Department of Anthropology, University of Utah, Salt Lake City, UT 84112, USA
| | - Peter S Kim
- School of Mathematics and Statistics, University of Sydney, Sydney, NSW 2006, Australia
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Edlund JE, Buller DJ, Sagarin BJ, Heider JD, Scherer CR, Farc MM, Ojedokun O. Male Sexual Jealousy: Lost Paternity Opportunities? Psychol Rep 2018; 122:575-592. [DOI: 10.1177/0033294118806556] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Numerous studies have shown that men experience relatively greater levels of jealousy in response to the sexual aspects of an infidelity (relative to women), whereas women experience relatively greater levels of jealousy in response to the emotional aspects of an infidelity (relative to men). The traditional explanation for this relationship suggests that men experience this greater level of jealousy due to threats of a loss of paternal certainty. In this article, we present three studies that demonstrate that men’s differentially greater jealousy occurs in response to situations that threaten paternity opportunities. These results suggest that a loss of perceived paternity opportunities is the ultimate origin of men’s increased jealousy in response to sexual infidelity.
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Loo SL, Hawkes K, Kim PS. Evolution of male strategies with sex-ratio-dependent pay-offs: connecting pair bonds with grandmothering. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2017.0041. [PMID: 28760768 DOI: 10.1098/rstb.2017.0041] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2017] [Indexed: 11/12/2022] Open
Abstract
Men's provisioning of mates and offspring has been central to ideas about human evolution because paternal provisioning is absent in our closest evolutionary cousins, the great apes, and is widely assumed to result in pair bonding, which distinguishes us from them. Yet mathematical modelling has shown that paternal care does not readily spread in populations where competition for multiple mates is the common male strategy. Here we add to models that point to the mating sex ratio as an explanation for pairing as pay-offs to mate guarding rise with a male-biased sex ratio. This is of interest for human evolution because our grandmothering life history shifts the mating sex ratio from female- to male-biased. Using a difference equation model, we explore the relative pay-offs for three competing male strategies (dependant care, multiple mating, mate guarding) in response to changing adult sex ratios. When fertile females are abundant, multiple mating prevails. As they become scarce, mate guarding triumphs. The threshold for this shift depends on guarding efficiency. Combined with mating sex ratios of hunter-gatherer and chimpanzee populations, these results strengthen the hypothesis that the evolution of our grandmothering life history propelled the shift to pair bonding in the human lineage.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.
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Affiliation(s)
- Sara L Loo
- School of Mathematics and Statistics, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kristen Hawkes
- Department of Anthropology, University of Utah, Salt Lake City, UT 84112, USA
| | - Peter S Kim
- School of Mathematics and Statistics, University of Sydney, Sydney, New South Wales 2006, Australia
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Hawkes K, O'Connell J, Blurton Jones N. Hunter-gatherer studies and human evolution: A very selective review. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165:777-800. [PMID: 29574845 PMCID: PMC5875731 DOI: 10.1002/ajpa.23403] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 11/07/2022]
Abstract
The century long publication of this journal overlapped major changes in the sciences it covers. We have been eyewitnesses to vast changes during the final third of the last century and beginning of this one, momentous enough to fundamentally alter our work separately and collectively. One (NBJ) from animal ethology, another from western North American archaeology (JOC), and a third (KH) from cultural anthropology came to longtime collaboration as evolutionary ecologists with shared focus on studying modern hunter-gatherers to guide hypotheses about human evolution. Our findings have radically revised hypotheses each of us took for granted when we began. Our (provisional) conclusions are not the consensus among hunter-gatherer specialists; but grateful that personal reflections are invited, we aim to explain how and why we continue to bet on them.
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Affiliation(s)
- Kristen Hawkes
- Department of Anthropology, University of Utah, Salt Lake City, Utah
| | - James O'Connell
- Department of Anthropology, University of Utah, Salt Lake City, Utah
| | - Nicholas Blurton Jones
- Department of Anthropology, University of California at Los Angeles, Los Angeles, California
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Further Mathematical Modelling of Mating Sex Ratios & Male Strategies with Special Relevance to Human Life History. Bull Math Biol 2017; 79:1907-1922. [PMID: 28660545 DOI: 10.1007/s11538-017-0313-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 06/16/2017] [Indexed: 10/19/2022]
Abstract
Influential models of male reproductive strategies have often ignored the importance of mate guarding, focusing instead on trade-offs between fitness gained through care for dependants in a pair bond versus fitness from continued competition for additional mates. Here we follow suggestions that mate guarding is a distinct alternative strategy that plays a crucial role, with special relevance to the evolution of our own lineage. Human pair bonding may have evolved in concert with the evolution of our grandmothering life history, which entails a shift to male-biased sex ratios in the fertile ages. As that sex ratio becomes more male biased, payoffs for mate-guarding increase due to partner scarcity. We present an ordinary differential equation model of mutually exclusive strategies (dependant care, multiple mating, and mate guarding), calculate steady-state frequencies and perform bifurcation analysis on parameters of care and guarding efficiency. Mate guarding triumphs over alternate strategies when populations are male biased, and guarding is fully efficient. When guarding does not ensure complete certainty of paternity, and multiple maters are able to gain some paternity from guarders, multiple mating can coexist with guarding. At female-biased sex ratios, multiple mating takes over, unless the benefit of care to the number of surviving offspring produced by the mates of carers is large.
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12
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Barbaro N, Shackelford TK, Weekes-Shackelford VA. Mothers and Fathers Perform More Mate Retention Behaviors than Individuals without Children. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2017; 27:316-33. [PMID: 27147537 DOI: 10.1007/s12110-016-9261-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Human life history is unique among primates, most notably the extraordinary length of infant dependency and the formation of long-term pair-bonds. Men and women are motivated to remain pair-bonded to maintain the distribution of male-provisioned resources to a woman and her offspring, or to protect offspring from infanticide. Men and women can employ several strategies to retain their mate and prevent their partner from defecting from the relationship, including individual mate retention (behaviors performed alone) and coalitional mate retention (behaviors performed by a close ally). The current research investigates whether men and women with children perform more frequent mate retention behaviors than men and women without children. Participants (n = 1003) currently in a heterosexual romantic relationship completed a survey, reporting whether they had genetic children with their current romantic partner and how frequently they performed various mate retention behaviors. The results indicate that men (n = 262) and women (n = 234) who share genetic children with their current partner performed more frequent individual mate retention behaviors and requested more frequent coalitional mate retention behaviors than men (n = 280) and women (n = 227) who do not share genetic children with their current partner. The results are interpreted as they relate to hypotheses concerning the evolution of pair-bonding in humans, and mate retention behaviors more generally. Limitations of the current research are discussed, and profitable avenues for future research in this domain are suggested.
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Affiliation(s)
- Nicole Barbaro
- Department of Psychology, Oakland University, 108 Pryale Hall, Rochester, MI, 48309, USA.
| | - Todd K Shackelford
- Department of Psychology, Oakland University, 108 Pryale Hall, Rochester, MI, 48309, USA
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13
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Edlund J, Sagarin B. Sex Differences in Jealousy. ADVANCES IN EXPERIMENTAL SOCIAL PSYCHOLOGY 2017. [DOI: 10.1016/bs.aesp.2016.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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14
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Lawson DW, Borgerhoff Mulder M. The offspring quantity-quality trade-off and human fertility variation. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150145. [PMID: 27022072 PMCID: PMC4822425 DOI: 10.1098/rstb.2015.0145] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2016] [Indexed: 11/12/2022] Open
Abstract
The idea that trade-offs between offspring quantity and quality shape reproductive behaviour has long been central to economic perspectives on fertility. It also has a parallel and richer theoretical foundation in evolutionary ecology. We review the application of the quantity–quality trade-off concept to human reproduction, emphasizing distinctions between clutch size and lifetime fertility, and the wider set of forces contributing to fertility variation in iteroparous and sexually reproducing species like our own. We then argue that in settings approximating human evolutionary history, several factors limit costly sibling competition. Consequently, while the optimization of quantity–quality trade-offs undoubtedly shaped the evolution of human physiology setting the upper limits of reproduction, we argue it plays a modest role in accounting for socio-ecological and individual variation in fertility. Only upon entering the demographic transition can fertility limitation be clearly interpreted as strategically orientated to advancing offspring quality via increased parental investment per child, with low fertility increasing descendant socio-economic success, although not reproductive success. We conclude that existing economic and evolutionary literature has often overemphasized the centrality of quantity–quality trade-offs to human fertility variation and advocate for the development of more holistic frameworks encompassing alternative life-history trade-offs and the evolved mechanisms guiding their resolution.
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Affiliation(s)
- David W Lawson
- Department of Population Health, London School of Hygiene and Tropical Medicine, London, UK
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15
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The evolution of monogamy in response to partner scarcity. Sci Rep 2016; 6:32472. [PMID: 27600189 PMCID: PMC5013280 DOI: 10.1038/srep32472] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 07/26/2016] [Indexed: 11/29/2022] Open
Abstract
The evolution of monogamy and paternal care in humans is often argued to have resulted from the needs of our expensive offspring. Recent research challenges this claim, however, contending that promiscuous male competitors and the risk of cuckoldry limit the scope for the evolution of male investment. So how did monogamy first evolve? Links between mating strategies and partner availability may offer resolution. While studies of sex roles commonly assume that optimal mating rates for males are higher, fitness payoffs to monogamy and the maintenance of a single partner can be greater when partners are rare. Thus, partner availability is increasingly recognized as a key variable structuring mating behavior. To apply these recent insights to human evolution, we model three male strategies – multiple mating, mate guarding and paternal care – in response to partner availability. Under assumed ancestral human conditions, we find that male mate guarding, rather than paternal care, drives the evolution of monogamy, as it secures a partner and ensures paternity certainty in the face of more promiscuous competitors. Accordingly, we argue that while paternal investment may be common across human societies, current patterns should not be confused with the reason pairing first evolved.
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Gavrilets S. Collective action problem in heterogeneous groups. Philos Trans R Soc Lond B Biol Sci 2015; 370:20150016. [PMID: 26503689 PMCID: PMC4633852 DOI: 10.1098/rstb.2015.0016] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2015] [Indexed: 11/12/2022] Open
Abstract
I review the theoretical and experimental literature on the collective action problem in groups whose members differ in various characteristics affecting individual costs, benefits and preferences in collective actions. I focus on evolutionary models that predict how individual efforts and fitnesses, group efforts and the amount of produced collective goods depend on the group's size and heterogeneity, as well as on the benefit and cost functions and parameters. I consider collective actions that aim to overcome the challenges from nature or win competition with neighbouring groups of co-specifics. I show that the largest contributors towards production of collective goods will typically be group members with the highest stake in it or for whom the effort is least costly, or those who have the largest capability or initial endowment. Under some conditions, such group members end up with smaller net pay-offs than the rest of the group. That is, they effectively behave as altruists. With weak nonlinearity in benefit and cost functions, the group effort typically decreases with group size and increases with within-group heterogeneity. With strong nonlinearity in benefit and cost functions, these patterns are reversed. I discuss the implications of theoretical results for animal behaviour, human origins and psychology.
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Affiliation(s)
- Sergey Gavrilets
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA Department of Mathematics, University of Tennessee, Knoxville, TN 37996, USA National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN 37996, USA
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Abstract
The evolution of distinctively human life history and social organization is generally attributed to paternal provisioning based on pair bonds. Here we develop an alternative argument that connects the evolution of human pair bonds to the male-biased mating sex ratios that accompanied the evolution of human life history. We simulate an agent-based model of the grandmother hypothesis, compare simulated sex ratios to data on great apes and human hunter-gatherers, and note associations between a preponderance of males and mate guarding across taxa. Then we explore a recent model that highlights the importance of mating sex ratios for differences between birds and mammals and conclude that lessons for human evolution cannot ignore mammalian reproductive constraints. In contradiction to our claim that male-biased sex ratios are characteristically human, female-biased ratios are reported in some populations. We consider the likelihood that fertile men are undercounted and conclude that the mate-guarding hypothesis for human pair bonds gains strength from explicit links with our grandmothering life history.
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The social modes of men : Toward an ecological model of human male relationships. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2015; 11:335-66. [PMID: 26193657 DOI: 10.1007/s12110-000-1007-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/1999] [Revised: 04/10/2000] [Accepted: 05/22/2000] [Indexed: 10/23/2022]
Abstract
Here we attempt to define a specifically human ecology within which male reproductive strategies are formulated. By treating the domestic and public spheres of social life as "ecological niches" that men have been forced to compete within or to avoid as best they can, we generate a typology of four "social modes" of human male behavior. We then attempt to explain the broad distribution of social modes within and between human groups based on the relative intensity of scramble and contest competition.
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Apicella CL, Marlowe FW. Men's reproductive investment decisions : Mating, Parenting, and Self-perceived Mate Value. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2015; 18:22-34. [PMID: 26181742 DOI: 10.1007/bf02820844] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 05/15/2005] [Accepted: 12/26/2005] [Indexed: 11/29/2022]
Abstract
Using questionnaire data completed by 170 men, we examine variation in paternal investment in relation to the trade-off between mating and parenting. We found that as men's self-perceived mate value increases, so does their mating effort, and in turn, as mating effort increases, paternal investment decreases. This study also simultaneously examined the influence on parental investment of men's mating effort, men's perception of their mates' fidelity, and their perceived resemblance to their offspring. All predicted investment. The predictors of investment are also tested independently for men who are still in a relationship with the mother of their children and those that are separated from her. Finally we examine how self-perceived mate value affects how men respond to variation in paternity confidence. Men with a self-perceived low mate value were less likely to respond to lowered mate fidelity by reducing their parental investment compared with men with a self-perceived high mate value.
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Affiliation(s)
- Coren L Apicella
- Department of Anthropology, Harvard University, Peabody Museum, 02138, Cambridge, MA, USA.
| | - Frank W Marlowe
- Department of Anthropology, Harvard University, Peabody Museum, 02138, Cambridge, MA, USA
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Abstract
The evolutionary emergence of the egalitarian syndrome is one of the most intriguing unsolved puzzles related to the origins of modern humans. Standard explanations and models for cooperation and altruism--reciprocity, kin and group selection, and punishment--are not directly applicable to the emergence of egalitarian behavior in hierarchically organized groups that characterized the social life of our ancestors. Here I study an evolutionary model of group-living individuals competing for resources and reproductive success. In the model, the differences in fighting abilities lead to the emergence of hierarchies where stronger individuals take away resources from weaker individuals and, as a result, have higher reproductive success. First, I show that the logic of within-group competition implies under rather general conditions that each individual benefits if the transfer of the resource from a weaker group member to a stronger one is prevented. This effect is especially strong in small groups. Then I demonstrate that this effect can result in the evolution of a particular, genetically controlled psychology causing individuals to interfere in a bully-victim conflict on the side of the victim. A necessary condition is a high efficiency of coalitions in conflicts against the bullies. The egalitarian drive leads to a dramatic reduction in within-group inequality. Simultaneously it creates the conditions for the emergence of inequity aversion, empathy, compassion, and egalitarian moral values via the internalization of behavioral rules imposed by natural selection. It also promotes widespread cooperation via coalition formation.
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Abstract
A crucial step in recent theories of human origins is the emergence of strong pair-bonding between males and females accompanied by a dramatic reduction in the male-to-male conflict over mating and an increased investment in offspring. How such a transition from promiscuity to pair-bonding could be achieved is puzzling. Many species would, indeed, be much better off evolutionarily if the effort spent on male competition over mating was redirected to increasing female fertility or survivorship of offspring. Males, however, are locked in a "social dilemma," where shifting one's effort from "appropriation" to "production" would give an advantage to free-riding competitors and therefore, should not happen. Here, I first consider simple models for four prominent scenarios of the human transition to pair-bonding: communal care, mate guarding, food for mating, and mate provisioning. I show that the transition is not feasible under biologically relevant conditions in any of these models. Then, I show that the transition can happen if one accounts for male heterogeneity, assortative pair formation, and evolution of female choice and faithfulness. This process is started when low-ranked males begin using an alternative strategy of female provisioning. At the end, except for the top-ranked individuals, males invest exclusively in provisioning females who have evolved very high fidelity to their mates. My results point to the crucial importance of female choice and emphasize the need for incorporating between-individual variation in theoretical and empirical studies of social dilemmas and behaviors.
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Winking J, Gurven M. The total cost of father desertion. Am J Hum Biol 2011; 23:755-63. [PMID: 21932418 DOI: 10.1002/ajhb.21207] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 06/04/2011] [Accepted: 06/20/2011] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES The benefits of paternal investment have long been explored by assessing the impact of father's presence on child wellbeing. Previous studies, however, have only examined the average effect of father's presence on child survivorship. Here we assess the total fitness cost to men of deserting (or the benefit of staying), by considering effects on the entire progeny. We estimate the total number of children that a deserting father can expect to lose due to reduced survivorship over the life course in five populations, and compare this loss to the benefit gains from remarrying a younger wife. METHODS We compiled the observed impacts of father's absence, as well as mortality and fertility schedules, for five foraging or foraging/horticultural populations. We calculate how many additional children a man can expect to lose due to father's absence throughout a marriage. We then calculate the minimum age difference between a first and second spouse that would be necessary to overcome this cost. RESULTS Because child mortality rates drop so rapidly, the costs that men experience from desertion due to augmented child mortality are modest throughout marriage. Even hypothetically inflated father effects can be overcome with modest age differences between first and second spouses. CONCLUSIONS Returns to paternal investment in terms of increased child survival are not substantial compared to those received by successfully practicing a serial mating strategy. This suggests that factors other than the ability to enhance child survival, such as female choice, are important to the evolutionary history and continued adaptive functioning of men's unique reproductive strategies.
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Affiliation(s)
- Jeffrey Winking
- Department of Anthropology, Texas A&M University, College Station, 77843-4352, USA.
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Winking J, Gurven M, Kaplan H. Father Death and Adult Success among the Tsimane: Implications for Marriage and Divorce. EVOL HUM BEHAV 2011; 32:79-89. [PMID: 21516217 PMCID: PMC3079911 DOI: 10.1016/j.evolhumbehav.2010.08.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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LAHDENPERÄ M, LUMMAA V, RUSSELL AF. Selection on male longevity in a monogamous human population: late-life survival brings no additional grandchildren. J Evol Biol 2011; 24:1053-63. [DOI: 10.1111/j.1420-9101.2011.02237.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Winking J, Gurven M, Kaplan H, Stieglitz J. The goals of direct paternal care among a South Amerindian population. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2009; 139:295-304. [PMID: 19140194 DOI: 10.1002/ajpa.20981] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human males are remarkable among mammals in the level of investment they provide to their wives and children. However, there has been debate as to the degree to which men actually invest and through which fitness pathways the benefits of familial investment are realized. Much of the previous research exploring these issues has focused on men's roles as providers, but few have explored correlates of men's direct parental care. Although this is reasonable given men's parental emphasis on provisioning, the providing of direct care is more straightforward with a clear provider and recipient and little ambiguity as to the care-giver's intent. Here, we explore contextual correlates of men's direct care among the Tsimane of Bolivia to determine the extent to which such care is patterned to enhance its effectiveness in increasing child wellbeing and the efficient functioning of the family. We also explore whether Tsimane fathers provide care in ways that enhance the positive effect it has on the wife's perception of the care provider. Overall, we find that Tsimane men appear responsive to the needs of children and the family, but show that there is little evidence that men respond to factors expected to increase the impact that men's care has on their reputations with their wives.
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Affiliation(s)
- Jeffrey Winking
- Department of Anthropology, Texas A&M University, 4352 TAMU, College Station, TX 77843-4352, United States.
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Brunson EK, Shell-Duncan B, Steele M. Women's autonomy and its relationship to children's nutrition among the Rendille of northern Kenya. Am J Hum Biol 2009; 21:55-64. [PMID: 18792063 PMCID: PMC3962675 DOI: 10.1002/ajhb.20815] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This study explores the effect of women's autonomy on children's health. Research was conducted among the Rendille, a traditionally nomadic pastoralist population living in northern Kenya. Using data collected from 435 women and 934 of their children, we tested the hypothesis that women with higher levels of autonomy would have children with better nutrition. Results of our study indicated that while women's autonomy had no effect on younger-ages 0-35 months-children's nutrition as measured by WHZ scores, greater levels of women's autonomy were significantly associated with improved nutrition among older-ages 3-10 years-children. These results suggest that women's autonomy is an important factor in relation to children's health in some circumstances. In addition to exploring the applied aspects of our findings, we also suggest how considering the concept of women's autonomy may add to the existing literature on parental investment.
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Affiliation(s)
- Emily K Brunson
- Department of Anthropology, University of Washington, Seattle, WA 98195-3100, USA.
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28
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Abstract
Humans are quite unusual compared to other great apes in that reproduction typically takes place within long-term, iteroparous pairings--social arrangements that have been culturally reified as the institution of marriage. With respect to male behaviour, explanations of marriage fall into two major schools of thought. One holds that marriage facilitates a sexual division of labour and paternal investment, both important to the rearing of offspring that are born helpless and remain dependent for remarkably long periods (provisioning model). And the other suggests that the main benefits which men receive from entering into marriage derive from monopolizing access to women's fertility (mating effort model). In this paper, we explore extramarital sexual relationships and the conditions under which they occur as a means of testing predictions derived from these two models. Using data on men's extramarital sexual relationships among Tsimane forager-horticulturists in lowland Bolivia, we tested whether infidelity was more common when men had less of an opportunity to invest in their children or when they risked losing less fertility. We found that Tsimane men appear to be biasing the timing of their affairs to when they are younger and have fewer children, supporting the provisioning model.
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Affiliation(s)
- Jeffrey Winking
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA.
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30
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Zhao Q, Pan W. Male–immature interactions seem to depend on group composition in white-headed langur (Trachypithecus leucocephalus). Acta Ethol 2006. [DOI: 10.1007/s10211-006-0019-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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31
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Abstract
Human pair-bonding and paternal involvement have long been attributed to the need for biparental rearing of altricial offspring with extended periods of dependency. More recently, researchers have focused on the fertility benefits that pair-bonding offers men and have re-conceptualized paternal care as a stratagem designed to curry favor with the recipient children's mother. These models, however, fail to explain a number of puzzling empirical findings, namely the lack of a significant and robust effect of father-presence cross-culturally, despite what appears to be true paternal involvement. I argue that the record is better explained by conceptualizing reproduction within unions as a joint venture, in which men's contributions are not simply lumped onto women's invariant levels of parental investment, but one in which men's involvement allows wives to reduce their own allocations to parental investment and increase those to fertility (fertility model), thereby maximizing the production of the union, not simply child survivorship.
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Affiliation(s)
- Jeffrey Winking
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA.
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GOOD LAMALERA WHALE HUNTERS ACCRUE REPRODUCTIVE BENEFITS. SOCIOECONOMIC ASPECTS OF HUMAN BEHAVIORAL ECOLOGY 2004. [DOI: 10.1016/s0190-1281(04)23009-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Shropshire WO. An economic approach to the evolution of male-female exchange. HUMAN NATURE (HAWTHORNE, N.Y.) 2003; 14:235-266. [PMID: 26190209 DOI: 10.1007/s12110-003-1005-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2001] [Revised: 10/30/2002] [Indexed: 06/04/2023]
Abstract
Males and females of a number of animal species divide labor and provide jointly for offspring. Males may provide food, for example, while females protect defenseless young. This exchange is unlikely, however, unless a prior partnership has been established in which a female practices fidelity in exchange for a male's provisioning activity. The formation of the trading partnership is itself an exchange, and economic theory can help explain when and why there are mutual gains from trading fidelity for resources. Environmental factors determine the potential gains from trade while evolved psychological mechanisms influence the extent to which gains are realized.
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Abstract
Body size is one of the most important characteristics of any animal because it affects a range of behavioral, ecological, and physiological traits including energy requirements, choice of food, reproductive strategies, predation risk, range size, and locomotor style. This article focuses on the implications of being large bodied for Homo erectus females, estimated to have been over 50% heavier than average australopithecine females. The energy requirements of these hominins are modeled using data on activity patterns, body mass, and life history from living primates. Particular attention is given to the inferred energetic costs of reproduction for Homo erectus females based on chimpanzee and human reproductive scheduling. Daily energy requirements during gestation and lactation would have been significantly higher for Homo erectus females, as would total energetic cost per offspring if the australopithecines and Homo erectus had similar reproductive schedules (gestation and lactation lengths and interbirth intervals). Shortening the interbirth interval could considerably reduce the costs per offspring to Homo erectus and have the added advantage of increasing reproductive output. The mother would, however, incur additional daily costs of caring for the dependent offspring. If Homo erectus females adopted this reproductive strategy, it would necessarily imply a revolution in the way in which females obtained and utilized energy to support their increased energetic requirements. This transformation is likely to have occurred on several levels involving cooperative economic division of labor, locomotor energetics, menopause, organ size, and other physiological mechanisms for reducing the energetic load on females.
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Affiliation(s)
- Leslie C Aiello
- Department of Anthropology, University College London, London WC1E 6BT England.
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Houston AI, McNamara JM. A self-consistent approach to paternity and parental effort. Philos Trans R Soc Lond B Biol Sci 2002; 357:351-62. [PMID: 11958703 PMCID: PMC1692954 DOI: 10.1098/rstb.2001.0925] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We review the relationship between optimal parental effort and paternity, and emphasize the need for a self-consistent approach. A fundamental consistency condition is what we refer to as the conservation of paternity. Every offspring has exactly one father. If a male has a paternity of less than unity, then another male or other males must have gained the lost paternity. Our approach also emphasizes that paternity emerges as the result of interactions between males and females. From this viewpoint, if paternity changes it is because some aspect of the interaction changes, and the correlation between effort and paternity depends on the aspect that has changed. This has implications for comparative analyses of paternity. The conclusions that are drawn about the correlation between effort and paternity within a population depend on, for example, the types of male in the population and how their abilities are correlated. It is easy to construct models that predict negative correlations between effort and paternity.
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Affiliation(s)
- Alasdair I Houston
- School of Biological Sciences, University of Bristol, Woodland Road, BS8 1UG, UK.
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38
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Alvard MS, Kuznar L. Deferred Harvests: The Transition from Hunting to Animal Husbandry. AMERICAN ANTHROPOLOGIST 2001. [DOI: 10.1525/aa.2001.103.2.295] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
The adaptive significance of midlife menopause in human females has long engaged the attention of evolutionary anthropologists. In spite of extensive debate, the problem has only recently been examined in the context of primate life histories. Here I extend those investigations by comparing life history traits in 16 primate species to test predictions generated from life history theory. In humans, late ages of maturity and higher than expected birth rates are systematically associated with extended postmenopausal longevity. Links among these adjustments on the primate pattern can explain how selection could slow somatic senescence without favoring extension of the fertile span. This conclusion is consistent with the observation that our fertile spans are similar to those of other pongids. The shape of the argument herein demonstrates the utility of life history theory for solving problems of adaptive evolution in female life history traits, with consequences for broader arguments regarding human evolution.
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Affiliation(s)
- H P Alvarez
- Department of Anthropology, University of Utah, Salt Lake City, Utah 84112, USA.
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40
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Abstract
Paternal investment has long been considered responsible for the evolution of predominantly monogamous marriage in humans. However, male-male competition resulting in mate-guarding and male coercion could be equally important. In this review, I use a comparative approach to examine the effect of variation in human paternal investment on our mating system. I conclude paternal investment is important but so too is mate-guarding. I propose a model of our mating system incorporating both factors. Variation in the mating system is explained by variation in male resource control and contribution, resulting in ecologically imposed monogamy or polygyny, as predicted by the polygyny threshold model, as well as variation in male-male competition for status, resulting in socially imposed monogamy or polygyny.
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Affiliation(s)
- F Marlowe
- Department of Anthropology, Harvard University, Peabody Museum, 02138, Cambridge, MA, USA
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Wrangham R, Jones J, Laden G, Pilbeam D, Conklin‐Brittain N. The Raw and the Stolen. CURRENT ANTHROPOLOGY 1999. [DOI: 10.1086/300083] [Citation(s) in RCA: 432] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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46
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Hawkes K, O'Connell JF, Jones NG, Alvarez H, Charnov EL. Grandmothering, menopause, and the evolution of human life histories. Proc Natl Acad Sci U S A 1998; 95:1336-9. [PMID: 9448332 PMCID: PMC18762 DOI: 10.1073/pnas.95.3.1336] [Citation(s) in RCA: 628] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Long postmenopausal lifespans distinguish humans from all other primates. This pattern may have evolved with mother-child food sharing, a practice that allowed aging females to enhance their daughters' fertility, thereby increasing selection against senescence. Combined with Charnov's dimensionless assembly rules for mammalian life histories, this hypothesis also accounts for our late maturity, small size at weaning, and high fertility. It has implications for past human habitat choice and social organization and for ideas about the importance of extended learning and paternal provisioning in human evolution.
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Affiliation(s)
- K Hawkes
- Department of Anthropology, University of Utah, Salt Lake City, UT 84112, USA
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Matrilateral biases in the investment of aunts and uncles. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 1997. [DOI: 10.1007/s12110-997-1008-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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48
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