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A friend in need is a friend indeed: Need-based sharing, rather than cooperative assortment, predicts experimental resource transfers among Agta hunter-gatherers

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)82-89
Number of pages8
JournalEvolution and Human Behavior
Issue number1
Early online date16 Aug 2018
DateAccepted/In press - 13 Aug 2018
DateE-pub ahead of print - 16 Aug 2018
DatePublished (current) - 1 Jan 2019


Despite much theorizing, the evolutionary reasons why humans cooperate extensively with unrelated individuals are still largely unknown. While reciprocity explains many instances of non-kin cooperation, much remains to be understood. A recent suite of models based upon ‘cooperative assortativity’ suggest that non-kin cooperation can evolve if individuals preferentially assort with certain cooperative phenotypes, such as helping those who help others. Here, we test these assortative hypotheses among the Agta, a population of Filipino hunter-gatherers, using an experimental resource allocation game in which individuals divide resources between themselves and camp-mates. Individuals preferentially shared with less cooperative individuals, arguing against cooperative assortativity as a mechanism sustaining resource transfers in this population. Rather, sharing was often based on the recipient's level of need, in addition to kin-based transfers and reciprocal sharing. Contrary to several recent theoretical accounts, in this real-world setting we find no evidence for cooperative assortativity influencing patterns of cooperation. These results may reflect the demands of living in a foraging ecology characterized by high resource stochasticity, necessitating need-based sharing as a system of long-term reciprocity to mitigate repeated subsistence shortfalls.

    Research areas

  • Cooperation, Assortativity, Need-based sharing, Reciprocity, Hunter-gatherers, Experimental games

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Elsevier at . Please refer to any applicable terms of use of the publisher.

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    Licence: CC BY-NC-ND


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