Human Nature

pp 1–26 | Cite as

Does Kin-Selection Theory Help to Explain Support Networks among Farmers in South-Central Ethiopia?

  • Lucie ClechEmail author
  • Ashley Hazel
  • Mhairi A. Gibson


Social support networks play a key role in human livelihood security, especially in vulnerable communities. Here we explore how evolutionary ideas of kin selection and intrahousehold resource competition can explain individual variation in daily support network size and composition in a south-central Ethiopian agricultural community. We consider both domestic and agricultural help across two generations with different wealth-transfer norms that yield different contexts for sibling competition. For farmers who inherited land rights from family, firstborns were more likely to report daily support from parents and to have larger nonparental kin networks (n = 180). Compared with other farmers, firstborns were also more likely to reciprocate their parents’ support, and to help nonparental kin without reciprocity. For farmers who received land rights from the government (n = 151), middle-born farmers reported more nonparental kin in their support networks compared with other farmers; nonreciprocal interactions were particularly common in both directions. This suggests a diversification of adult support networks to nonparental kin, possibly in response to a long-term parental investment disadvantage of being middle-born sons. In all instances, regardless of inheritance, lastborn farmers were the most disadvantaged in terms of kin support. Overall, we found that nonreciprocal interactions among farmers followed kin selection predictions. Direct reciprocity explained a substantial part of the support received from kin, suggesting the importance of the combined effects of kin selection and reciprocity for investment from kin.


Support network Social capital Birth order Kin selection Reciprocity Inequalities 



This work was funded by a Leverhulme Trust Research Grant F/00182/BI. Logistical support was provided in part by the Centre Français d’Etude Ethiopienne. We are particularly grateful to the people of the Hitoya and Tiyo districts, Arsi zone, Oromia region, for their warm welcome and for facilitating this research. We thank the field team for many months of hard work in the field on data collection. Suggestions provided by James Holland Jones, Aurelie Cailleau, and Sid Karunaratne are greatly appreciated. Finally, we thank the anonymous reviewers for their helpful comments and feedback.

Supplementary material

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Authors and Affiliations

  1. 1.Department of Anthropology and ArchaeologyUniversity of BristolBristolUK
  2. 2.Department of AnthropologyStanford UniversityStanfordUSA
  3. 3.Department of Earth System ScienceStanford UniversityStanfordUSA

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