Inclusive fitness for in-laws
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.
Citation
Dyble , M , Gardner , A , Vinicius , L & Migliano , A 2018 , ' Inclusive fitness for in-laws ' , Biology Letters , vol. 14 , no. 10 . https://doi.org/10.1098/rsbl.2018.0515
Publication
Biology Letters
Status
Peer reviewed
ISSN
1744-9561Type
Journal article
Rights
Copyright 2018 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited
Description
A.G. is supported by a Natural Environment Research Council Independent Research Fellowship (NE/K009524/1) and a European Research Council Consolidator Grant (771387)Collections
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