A gene–culture co-evolutionary perspective on the puzzle of human twinship
Natural selection should favour litter sizes that optimise trade-offs between brood-size and offspring viability. Across the primate order, the modal litter size is one, suggesting a deep history of selection favouring minimal litters in primates. Humans, however – despite having the longest juvenil...
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Cambridge University Press
2024-01-01
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| Series: | Evolutionary Human Sciences |
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| Online Access: | https://www.cambridge.org/core/product/identifier/S2513843X24000306/type/journal_article |
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| author | Augusto Dalla Ragione Cody T. Ross Daniel Redhead |
| author_facet | Augusto Dalla Ragione Cody T. Ross Daniel Redhead |
| author_sort | Augusto Dalla Ragione |
| collection | DOAJ |
| description | Natural selection should favour litter sizes that optimise trade-offs between brood-size and offspring viability. Across the primate order, the modal litter size is one, suggesting a deep history of selection favouring minimal litters in primates. Humans, however – despite having the longest juvenile period and slowest life-history of all primates – still produce twin births at appreciable rates, even though such births are costly. This presents an evolutionary puzzle. Why is twinning still expressed in humans despite its cost? More puzzling still is the discordance between the principal explanations for human twinning and extant empirical data. Such explanations propose that twinning is regulated by phenotypic plasticity in polyovulation, permitting the production of larger sib sets if and when resources are abundant. However, comparative data suggest that twinning rates are actually highest in poorer economies and lowest in richer, more developed economies. We propose that a historical dynamic of gene–culture co-evolution might better explain this geographic patterning. Our explanation distinguishes geminophilous and geminophobic cultural contexts, as those celebrating twins (e.g. through material support) and those hostile to twins (e.g. through sanction of twin-infanticide). Geminophilous institutions, in particular, may buffer the fitness cost associated with twinning, potentially reducing selection pressures against polyovulation. We conclude by synthesising a mathematical and empirical research programme that might test our ideas. |
| format | Article |
| id | doaj-art-8b8aa4c38a0f4e00886bde663e70cc90 |
| institution | OA Journals |
| issn | 2513-843X |
| language | English |
| publishDate | 2024-01-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Evolutionary Human Sciences |
| spelling | doaj-art-8b8aa4c38a0f4e00886bde663e70cc902025-08-20T02:13:48ZengCambridge University PressEvolutionary Human Sciences2513-843X2024-01-01610.1017/ehs.2024.30A gene–culture co-evolutionary perspective on the puzzle of human twinshipAugusto Dalla Ragione0https://orcid.org/0009-0008-4472-4242Cody T. Ross1https://orcid.org/0000-0002-0067-4799Daniel Redhead2https://orcid.org/0000-0002-2809-8121Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, GermanyDepartment of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, GermanyDepartment of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany Department of Sociology, University of Groningen, Grote Rozenstraat 31, 9712 TG Groningen, The Netherlands Inter-University Center for Social Science Theory and Methodology, University of Groningen, Groningen, The NetherlandsNatural selection should favour litter sizes that optimise trade-offs between brood-size and offspring viability. Across the primate order, the modal litter size is one, suggesting a deep history of selection favouring minimal litters in primates. Humans, however – despite having the longest juvenile period and slowest life-history of all primates – still produce twin births at appreciable rates, even though such births are costly. This presents an evolutionary puzzle. Why is twinning still expressed in humans despite its cost? More puzzling still is the discordance between the principal explanations for human twinning and extant empirical data. Such explanations propose that twinning is regulated by phenotypic plasticity in polyovulation, permitting the production of larger sib sets if and when resources are abundant. However, comparative data suggest that twinning rates are actually highest in poorer economies and lowest in richer, more developed economies. We propose that a historical dynamic of gene–culture co-evolution might better explain this geographic patterning. Our explanation distinguishes geminophilous and geminophobic cultural contexts, as those celebrating twins (e.g. through material support) and those hostile to twins (e.g. through sanction of twin-infanticide). Geminophilous institutions, in particular, may buffer the fitness cost associated with twinning, potentially reducing selection pressures against polyovulation. We conclude by synthesising a mathematical and empirical research programme that might test our ideas.https://www.cambridge.org/core/product/identifier/S2513843X24000306/type/journal_articleTwinshipcoevolutiontwinsgeminophiliageminophobia |
| spellingShingle | Augusto Dalla Ragione Cody T. Ross Daniel Redhead A gene–culture co-evolutionary perspective on the puzzle of human twinship Evolutionary Human Sciences Twinship coevolution twins geminophilia geminophobia |
| title | A gene–culture co-evolutionary perspective on the puzzle of human twinship |
| title_full | A gene–culture co-evolutionary perspective on the puzzle of human twinship |
| title_fullStr | A gene–culture co-evolutionary perspective on the puzzle of human twinship |
| title_full_unstemmed | A gene–culture co-evolutionary perspective on the puzzle of human twinship |
| title_short | A gene–culture co-evolutionary perspective on the puzzle of human twinship |
| title_sort | gene culture co evolutionary perspective on the puzzle of human twinship |
| topic | Twinship coevolution twins geminophilia geminophobia |
| url | https://www.cambridge.org/core/product/identifier/S2513843X24000306/type/journal_article |
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