Abstract
Inclusive fitness theory provides a compelling explanation for the evolution of altruism among kin. However, a completely satisfactory account of non-kin altruism is still lacking. The present study compared the level of altruism found among siblings with that found among friends and mates and sought to reconcile the findings with an evolutionary explanation for human altruism. Participants (163 males and 156 females) completed a questionnaire about help given to a sibling, friend, or mate. Overall, participants gave friends and mates as much or more help than they gave siblings. However, as the cost of help increased, siblings received a progressively larger share of the help, whereas friends and mates received a progressively smaller share, despite the fact that participants were closer emotionally to friends and mates than they were to siblings. These findings help to explain the relative standing of friends and mates as recipients of altruistic aid.
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Acknowledgments
This research was reviewed and approved by the McMaster University Ethics Review Board (MERB), Project 2005 023, and was supported by a New Zealand Science and Technology Post-Doctoral Fellowship, Contract MMST0401, administered by the Foundation for Research, Science, and Technology (FRST). Thanks go to Martin Daly, Greg Dingle, Trina Hancock, Toko Kiyonari, Danny Krupp, Jane Stewart-Williams, Sandra Thomson, and Margo Wilson. Thanks also to Darwin and India for regular surprise visits throughout the period in which this article was written.
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Stewart-Williams, S. Human Beings as Evolved Nepotists. Hum Nat 19, 414–425 (2008). https://doi.org/10.1007/s12110-008-9048-y
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DOI: https://doi.org/10.1007/s12110-008-9048-y