1
|
McLean E, Kalobekamo F, Mwiba O, Crampin AC, Slaymaker E, Sear R, Dube A. Family network and household composition: a longitudinal dataset derived from the Karonga Health and Demographic Surveillance System, in rural Malawi. Wellcome Open Res 2024; 8:573. [PMID: 38836071 PMCID: PMC11148530 DOI: 10.12688/wellcomeopenres.20406.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2024] [Indexed: 06/06/2024] Open
Abstract
Proximity to family, household composition, and structure are often studied as outcomes and as explanatory factors in a wide range of scientific disciplines. Here, we describe a large longitudinal dataset (currently including data from over 70,000 individuals from 2004 to 2017), including data on household structure, proximity to kin, population density, and other socio-demographic factors derived from data from the Karonga Health and Demographic Surveillance Site (HDSS) in Northern Malawi. We present how the dataset is generated, list some examples of how it can be used, and provide information on the limitations that affect the types of analyses that can be carried out.
Collapse
Affiliation(s)
- Estelle McLean
- Department of Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
- Malawi Epidemiology and Intervention Research Unit, Chilumba, Karonga District, Malawi
| | - Fredrick Kalobekamo
- Malawi Epidemiology and Intervention Research Unit, Chilumba, Karonga District, Malawi
| | - Oddie Mwiba
- Malawi Epidemiology and Intervention Research Unit, Chilumba, Karonga District, Malawi
| | - Amelia C Crampin
- Department of Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
- Malawi Epidemiology and Intervention Research Unit, Chilumba, Karonga District, Malawi
| | - Emma Slaymaker
- Department of Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Rebecca Sear
- Department of Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Albert Dube
- Malawi Epidemiology and Intervention Research Unit, Chilumba, Karonga District, Malawi
| |
Collapse
|
2
|
Simpson CR, Power EA. Dynamics of cooperative networks associated with gender among South Indian Tamils. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210437. [PMID: 36440558 PMCID: PMC9703249 DOI: 10.1098/rstb.2021.0437] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/16/2022] [Indexed: 11/29/2022] Open
Abstract
Helping behaviour is thought to play a major role in the evolution of group-living animals. Yet, it is unclear to what extent human males and human females use the same strategies to secure support. Accordingly, we investigate help-seeking over a 5-year period in relation to gender using data from virtually all adults in two Tamil villages (N = 782). Simulations of network dynamics (i.e. stochastic actor-oriented models) calibrated to these data broadly indicate that women are more inclined than men to create and maintain supportive bonds via multiple mechanisms of cooperation (e.g. reciprocity, kin bias, friend bias, generalized exchange). However, gender-related differences in the simulated dynamics of help-seeking are modest, vary based on structural position (e.g. out-degree), and do not appear to translate to divergence in the observed structure of respondents' egocentric networks. Findings ultimately suggest that men and women in the two villages are similarly social but channel their sociality differently. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.
Collapse
Affiliation(s)
- Cohen R. Simpson
- Nuffield College, University of Oxford, Oxford OX1 1NF, UK
- Department of Methodology, The London School of Economics and Political Science, London WC2A 2AE, UK
| | - Eleanor A. Power
- Department of Methodology, The London School of Economics and Political Science, London WC2A 2AE, UK
- The Santa Fe Institute, Santa Fe, NM 87501, USA
| |
Collapse
|
3
|
Charpentier MJE, Poirotte C, Roura-Torres B, Amblard-Rambert P, Willaume E, Kappeler PM, Rousset F, Renoult JP. Mandrill mothers associate with infants who look like their own offspring using phenotype matching. eLife 2022; 11:79417. [PMCID: PMC9665846 DOI: 10.7554/elife.79417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 10/03/2022] [Indexed: 11/16/2022] Open
Abstract
Behavioral discrimination of kin is a key process structuring social relationships in animals. In this study, we provide evidence for discrimination towards non-kin by third-parties through a mechanism of phenotype matching. In mandrills, we recently demonstrated increased facial resemblance among paternally related juvenile and adult females indicating adaptive opportunities for paternal kin recognition. Here, we hypothesize that mandrill mothers use offspring’s facial resemblance with other infants to guide offspring’s social opportunities towards similar-looking ones. Using deep learning for face recognition in 80 wild mandrill infants, we first show that infants sired by the same father resemble each other the most, independently of their age, sex or maternal origin, extending previous results to the youngest age class. Using long-term behavioral observations on association patterns, and controlling for matrilineal origin, maternal relatedness and infant age and sex, we then show, as predicted, that mothers are spatially closer to infants that resemble their own offspring more, and that this maternal behavior leads to similar-looking infants being spatially associated. We then discuss the different scenarios explaining this result, arguing that an adaptive maternal behavior is a likely explanation. In support of this mechanism and using theoretical modeling, we finally describe a plausible evolutionary process whereby mothers gain fitness benefits by promoting nepotism among paternally related infants. This mechanism, that we call ‘second-order kin selection’, may extend beyond mother-infant interactions and has the potential to explain cooperative behaviors among non-kin in other social species, including humans.
Collapse
Affiliation(s)
| | - Clémence Poirotte
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute of Primate Research
| | - Berta Roura-Torres
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute of Primate Research
- Projet Mandrillus, SODEPAL
| | | | | | - Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute of Primate Research
| | | | | |
Collapse
|
4
|
Social Support and Network Formation in a Small-Scale Horticulturalist Population. Sci Data 2022; 9:570. [PMID: 36109560 PMCID: PMC9477840 DOI: 10.1038/s41597-022-01516-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/29/2022] [Indexed: 11/11/2022] Open
Abstract
Evolutionary studies of cooperation in traditional human societies suggest that helping family and responding in kind when helped are the primary mechanisms for informally distributing resources vital to day-to-day survival (e.g., food, knowledge, money, childcare). However, these studies generally rely on forms of regression analysis that disregard complex interdependences between aid, resulting in the implicit assumption that kinship and reciprocity drive the emergence of entire networks of supportive social bonds. Here I evaluate this assumption using individual-oriented simulations of network formation (i.e., Stochastic Actor-Oriented Models). Specifically, I test standard predictions of cooperation derived from the evolutionary theories of kin selection and reciprocal altruism alongside well-established sociological predictions around the self-organisation of asymmetric relationships. Simulations are calibrated to exceptional public data on genetic relatedness and the provision of tangible aid amongst all 108 adult residents of a village of indigenous horticulturalists in Nicaragua (11,556 ordered dyads). Results indicate that relatedness and reciprocity are markedly less important to whom one helps compared to the supra-dyadic arrangement of the tangible aid network itself.
Collapse
|
5
|
Witkower Z, Hill AK, Koster J, Tracy JL. Is a downwards head tilt a cross-cultural signal of dominance? Evidence for a universal visual illusion. Sci Rep 2022; 12:365. [PMID: 35013481 PMCID: PMC8748875 DOI: 10.1038/s41598-021-04370-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 12/21/2021] [Indexed: 11/12/2022] Open
Abstract
The present pre-registered research provides the first evidence that a downwards head tilt is sufficient to communicate dominance from a neutral facial expression among the Mayangna, members of an unindustrialized, small-scale traditional society in Nicaragua who have had minimal exposure to North American culture. Consistent with the Action Unit imposter effect observed in North American populations (Witkower and Tracy in Psychol Sci 30:893-906, 2019), changes to the appearance of the upper face caused by a downwards head tilt were sufficient to elicit perceptions of dominance among this population. Given that the Mayangna are unlikely to associate a downwards head tilt or related apparent facial changes with dominance as a result of cross-cultural learning, the present results suggest that perceptions of dominance formed from a downwards head tilt, and the visual illusion shaping these perceptions, are a widely generalizable, and possibly universal, feature of human psychology.
Collapse
Affiliation(s)
- Zachary Witkower
- Department of Psychology, University of Toronto, 100 St. George Street, Toronto, ON, M5S 3G3, Canada.
| | | | | | | |
Collapse
|
6
|
Witkower Z, Hill AK, Koster J, Tracy JL. Beyond Face Value: Evidence for the Universality of Bodily Expressions of Emotion. AFFECTIVE SCIENCE 2021; 2:221-229. [PMID: 36059900 PMCID: PMC9382937 DOI: 10.1007/s42761-021-00052-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 05/19/2021] [Indexed: 02/02/2023]
Abstract
Research on emotion communication typically focuses on facial expressions, yet scientists dating back to Darwin have noted the importance of the body in conveying emotions. In fact, studies have found that the body is reliably used to express and recognize anger, fear, and sadness, by individuals in several industrialized populations. Here, we provide the first evidence that bodily expressions of these three emotions are reliably recognized by members of an isolated small-scale traditional society: the Mayangna of Nicaragua. Specifically, we found that recognition rates for sadness and anger bodily expressions were high, and recognition rates for a fear bodily expression were lower but still significantly greater than chance. Given that the Mayangna are unlikely to have learned these bodily expressions through cross-cultural transmission, their ability to recognize these displays provides strong evidence for the universality of each expression. Supplementary Information The online version contains supplementary material available at 10.1007/s42761-021-00052-y.
Collapse
Affiliation(s)
- Zachary Witkower
- Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, BC V6K 1Z4 Canada
| | | | | | - Jessica L. Tracy
- Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, BC V6K 1Z4 Canada
| |
Collapse
|
7
|
Abstract
The importance of kin relationships varies with socioecological demands. Among subsistence agriculturalists, people commonly manage fluctuations in food availability by relying on family members to share resources and pool labor. However, the process of market integration may disrupt these support networks, which may begin to carry costs or liabilities in novel market environments. The current study aims to address (1) how kin are distributed in household support networks (2) how kin support varies as households become more engaged in market activities, and (3) how variation in kin support is associated with income disparities within a Yucatec Maya community undergoing rapid market integration. Using long-term census data combined with social networks and detailed household economic data, we find that household support networks are primarily composed of related households. Second, households engaged predominantly in wage labor rely less on kin support than agricultural or mixed economy households. Finally, kin support is associated with lower household net income and income per capita. Understanding how kin support systems shift over the course of market integration and in the face of new opportunities for social and economic production provides a unique window into the social and economic drivers of human family formation.
Collapse
|
8
|
Timing, Initiators, and Causes of Divorce in a Mayangna/Miskito Community in Nicaragua. SOCIAL SCIENCES-BASEL 2021. [DOI: 10.3390/socsci10060212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There exists a paucity of evolution-oriented research focusing on why relationships end, particularly in comparison to the substantial literature centered around individual preferences that define the beginning of relationships. In contrast, there is a long tradition in the fields of sociology and family studies of exploring divorce; however, this body of research is largely limited to studies of Western populations. We address these gaps in the literature with an examination of patterns of divorce among a small-scale horticultural population in Nicaragua. We test a number of hypotheses derived from behavioral ecology perspective regarding the timing and causes of divorce. Results lend support to all but one of the hypotheses. Overall divorce rates are comparable to U.S. rates; however, they tend to occur earlier in marriages. Children appear to provide a slight buffering effect against divorce, although age in marriage does not. Gender differences in the reported causes of divorce fall along the lines that would be expected due to differences in partner preferences reported in previous research. Finally, this population also exhibits a similar peculiar pattern exhibited by Western populations, in which divorce is more costly for women, and yet women are slightly more likely to initiate divorces than husbands.
Collapse
|
9
|
Small-scale utilitarianism: High acceptance of utilitarian solutions to Trolley Problems among a horticultural population in Nicaragua. PLoS One 2021; 16:e0249345. [PMID: 33819284 PMCID: PMC8021155 DOI: 10.1371/journal.pone.0249345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 03/16/2021] [Indexed: 11/25/2022] Open
Abstract
Researchers often use moral dilemmas to investigate the specific factors that influence participants’ judgments of the appropriateness of different actions. A common construction of such a dilemma is the Trolley Problem, which pits an obvious utilitarian solution against a common deontological dictum to not do harm to others. Cross-cultural studies have validated the robustness of numerous contextual biases, such as judging utilitarian decisions more negatively if they require contact with other individuals (contact bias), they force others to serve as a means to an end (means bias), and if they require direct action rather than inaction (omission bias). However, such cross-cultural research is largely limited to studies of industrialized, nation-state populations. Previous research has suggested that the more intimate community relationships that characterize small-scale populations might lead to important differences, such as an absence of an omission bias. Here we contribute to this literature by investigating perceptions of Trolley Problem solutions among a Mayangna/Miskito community, a small-scale indigenous population in Nicaragua. Compared to previously sampled populations, the Mayangna/Miskito participants report higher levels of acceptance of utilitarian solutions and do not exhibit an omission bias. We also examine the justifications participants offered to explore how Mayangna/Miskito culture might influence moral judgments.
Collapse
|
10
|
|
11
|
Sweet T, Adhikari S. A Latent Space Network Model for Social Influence. PSYCHOMETRIKA 2020; 85:251-274. [PMID: 32221792 DOI: 10.1007/s11336-020-09700-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/07/2020] [Indexed: 06/10/2023]
Abstract
Social network data represent interactions and relationships among groups of individuals. One aspect of social interaction is social influence, the idea that beliefs or behaviors change as a result of one's social network. The purpose of this article is to introduce a new model for social influence, the latent space model for influence, which employs latent space positions so that individuals are affected most by those who are "closest" to them in the latent space. We describe this model along with some of the contexts in which it can be used and explore the operating characteristics using a series of simulation studies. We conclude with an example of teacher advice-seeking networks to show that changes in beliefs about teaching mathematics may be attributed to network influence.
Collapse
Affiliation(s)
- Tracy Sweet
- Department of Human Development and Quantitative Methodology, University of Maryland, College Park, USA.
| | - Samrachana Adhikari
- Department of Population Health, New York University School of Medicine, New York, USA
| |
Collapse
|
12
|
Lew-Levy S, Kissler SM, Boyette AH, Crittenden AN, Mabulla IA, Hewlett BS. Who teaches children to forage? Exploring the primacy of child-to-child teaching among Hadza and BaYaka Hunter-Gatherers of Tanzania and Congo. EVOL HUM BEHAV 2020. [DOI: 10.1016/j.evolhumbehav.2019.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
13
|
Koster J, Lukas D, Nolin D, Power E, Alvergne A, Mace R, Ross CT, Kramer K, Greaves R, Caudell M, MacFarlan S, Schniter E, Quinlan R, Mattison S, Reynolds A, Yi-Sum C, Massengill E. Kinship ties across the lifespan in human communities. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180069. [PMID: 31303163 DOI: 10.1098/rstb.2018.0069] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A hypothesis for the evolution of long post-reproductive lifespans in the human lineage involves asymmetries in relatedness between young immigrant females and the older females in their new groups. In these circumstances, inter-generational reproductive conflicts between younger and older females are predicted to resolve in favour of the younger females, who realize fewer inclusive fitness benefits from ceding reproduction to others. This conceptual model anticipates that immigrants to a community initially have few kin ties to others in the group, gradually showing greater relatedness to group members as they have descendants who remain with them in the group. We examine this prediction in a cross-cultural sample of communities, which vary in their sex-biased dispersal patterns and other aspects of social organization. Drawing on genealogical and demographic data, the analysis provides general but not comprehensive support for the prediction that average relatedness of immigrants to other group members increases as they age. In rare cases, natal members of the community also exhibit age-related increases in relatedness. We also find large variation in the proportion of female group members who are immigrants, beyond simple traditional considerations of patrilocality or matrilocality, which raises questions about the circumstances under which this hypothesis of female competition are met. We consider possible explanations for these heterogenous results, and we address methodological considerations that merit increased attention for research on kinship and reproductive conflict in human societies. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.
Collapse
Affiliation(s)
- Jeremy Koster
- 1 Department of Anthropology, University of Cincinnati , Cincinnati, OH 45221-0380 , USA.,2 Department of Human Behavior, Ecology, and Culture, Max Planck Institute of Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany
| | - Dieter Lukas
- 2 Department of Human Behavior, Ecology, and Culture, Max Planck Institute of Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany
| | - David Nolin
- 3 Department of Anthropology and Population Research Institute, Penn State University , University Park, PA 16802 , USA
| | - Eleanor Power
- 4 Department of Methodology, The London School of Economics and Political Science , Houghton Street, London WC2A 2AE , UK
| | - Alexandra Alvergne
- 5 School of Anthropology and Museum Ethnography, University of Oxford , 51 Banbury Road, Oxford OX2 6PE , UK
| | - Ruth Mace
- 6 Department of Anthropology, University College London , 14 Taviton St, London WC1H 0BW , UK.,7 School of Life Sciences, Lanzhou University , 222 Tianshui NanLu, Lanzhou, Gansu 73000 , People's Republic of China
| | - Cody T Ross
- 2 Department of Human Behavior, Ecology, and Culture, Max Planck Institute of Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany
| | - Karen Kramer
- 8 Department of Anthropology, University of Utah , Salt Lake City, UT 84112 , USA
| | - Russell Greaves
- 8 Department of Anthropology, University of Utah , Salt Lake City, UT 84112 , USA
| | - Mark Caudell
- 9 Paul G. Allen School for Global Animal Health, Washington State University , Pullman, WA 99164 , USA
| | - Shane MacFarlan
- 8 Department of Anthropology, University of Utah , Salt Lake City, UT 84112 , USA
| | - Eric Schniter
- 10 Economic Sciences Institute, Chapman University , Orange, CA 92866 , USA
| | - Robert Quinlan
- 11 Department of Anthropology, Washington State University , Pullman, WA 99164 , USA
| | - Siobhan Mattison
- 12 Department of Anthropology, University of New Mexico , Albuquerque, NM 87131 , USA
| | - Adam Reynolds
- 12 Department of Anthropology, University of New Mexico , Albuquerque, NM 87131 , USA
| | - Chun Yi-Sum
- 12 Department of Anthropology, University of New Mexico , Albuquerque, NM 87131 , USA.,13 Harvard-Yenching Institute , Vanserg Hall, Suite 20, 25 Francis Avenue, Cambridge, MA 02138 , USA
| | - Eric Massengill
- 12 Department of Anthropology, University of New Mexico , Albuquerque, NM 87131 , USA
| |
Collapse
|
14
|
Mattison SM, Shenk MK, Thompson ME, Borgerhoff Mulder M, Fortunato L. The evolution of female-biased kinship in humans and other mammals. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190007. [PMID: 31303170 DOI: 10.1098/rstb.2019.0007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Female-biased kinship (FBK) arises in numerous species and in diverse human cultures, suggesting deep evolutionary roots to female-oriented social structures. The significance of FBK has been debated for centuries in human studies, where it has often been described as difficult to explain. At the same time, studies of FBK in non-human animals point to its apparent benefits for longevity, social complexity and reproduction. Are female-biased social systems evolutionarily stable and under what circumstances? What are the causes and consequences of FBK? The purpose of this theme issue is to consolidate efforts towards understanding the evolutionary significance and stability of FBK in humans and other mammals. The issue includes broad theoretical and empirical reviews as well as specific case studies addressing the social and ecological correlates of FBK across taxa, time and space. It leverages a comparative approach to test existing hypotheses and presents novel arguments that aim to expand our understanding of how males and females negotiate kinship across diverse contexts in ways that lead to the expression of female biases in kinship behaviour and social structure. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.
Collapse
Affiliation(s)
- Siobhán M Mattison
- 1 Department of Anthropology, University of New Mexico, Albuquerque, NM 87131 , USA
| | - Mary K Shenk
- 2 Department of Anthropology, Pennsylvania State University , University Park, PA 16802 , USA
| | | | | | - Laura Fortunato
- 4 Department of Anthropology, Magdalen College, University of Oxford , Oxford, OX1 4AU , UK.,5 Santa Fe Institute , Santa Fe, NM 87501 , USA
| |
Collapse
|
15
|
Martin MA. Biological Anthropology in 2018: Grounded in Theory, Questioning Contexts, Embracing Innovation. AMERICAN ANTHROPOLOGIST 2019. [DOI: 10.1111/aman.13233] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
16
|
Dyble M, Gardner A, Vinicius L, Migliano AB. Inclusive fitness for in-laws. Biol Lett 2018; 14:20180515. [PMID: 30305461 PMCID: PMC6227869 DOI: 10.1098/rsbl.2018.0515] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 09/11/2018] [Indexed: 11/12/2022] Open
Abstract
Cooperation among kin is common across the natural world and can be explained in terms of inclusive fitness theory, which holds that individuals can derive indirect fitness benefits from aiding genetically related individuals. However, human kinship includes not only genetic kin but also kin by marriage: our affines (in-laws) and spouses. Can cooperation between these genetically unrelated kin be reconciled with inclusive fitness theory? Here, we argue that although affinal kin and spouses do not necessarily share genetic ancestry, they may have shared genetic interests in future reproduction and, as such, can derive indirect fitness benefits though cooperating. We use standard inclusive fitness theory to derive a coefficient of shared reproductive interest (s) that predicts altruistic investment both in genetic kin and in spouses and affines. Specifically, a behaviour that reduces the fitness of the actor by c and increases the fitness of the recipient by b will be favoured by natural selection when sb > c We suggest that the coefficient of shared reproductive interest may provide a valuable tool for understanding not only the evolution of human kinship but also cooperation and conflict across the natural world more generally.
Collapse
Affiliation(s)
- M Dyble
- Jesus College, University of Cambridge, Jesus Lane, Cambridge CB5 8BL, UK
- Deparment of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - A Gardner
- School of Biology, University of St Andrews, St Andrews KY16 9TH, UK
| | - L Vinicius
- Department of Anthropology, University College London, 14 Taviton Street, London WC1H 0BW, UK
| | - A B Migliano
- Department of Anthropology, University College London, 14 Taviton Street, London WC1H 0BW, UK
- Department of Anthropology, University of Zurich, Winterthurerstrasse, Zürich, Switzerland
| |
Collapse
|