Human Nature

, Volume 25, Issue 4, pp 567–579

Impartial Institutions, Pathogen Stress and the Expanding Social Network


    • School of Human Evolution and Social ChangeArizona State University
  • Charles Efferson
    • Department of EconomicsUniversity of Zurich
  • Ting Jiang
    • University of Pennsylvania
  • Ashlan Falletta-Cowden
    • The Field Museum
  • Sveinn Sigurdsson
    • Yale New Haven Hospital
  • Rita McNamara
    • University of British Columbia
  • Madeline Sands
    • School of Human Evolution and Social ChangeArizona State University
  • Shirajum Munira
    • LAMB Project for Integrated Health and Development
  • Edward Slingerland
    • University of British Columbia
  • Joseph Henrich
    • University of British Columbia

DOI: 10.1007/s12110-014-9217-0

Cite this article as:
Hruschka, D., Efferson, C., Jiang, T. et al. Hum Nat (2014) 25: 567. doi:10.1007/s12110-014-9217-0


Anthropologists have documented substantial cross-society variation in people’s willingness to treat strangers with impartial, universal norms versus favoring members of their local community. Researchers have proposed several adaptive accounts for these differences. One variant of the pathogen stress hypothesis predicts that people will be more likely to favor local in-group members when they are under greater infectious disease threat. The material security hypothesis instead proposes that institutions that permit people to meet their basic needs through impartial interactions with strangers reinforce a tendency toward impartiality, whereas people lacking such institutions must rely on local community members to meet their basic needs. Some studies have examined these hypotheses using self-reported preferences, but not with behavioral measures. We conducted behavioral experiments in eight diverse societies that measure individuals’ willingness to favor in-group members by ignoring an impartial rule. Consistent with the material security hypothesis, members of societies enjoying better-quality government services and food security show a stronger preference for following an impartial rule over investing in their local in-group. Our data show no support for the pathogen stress hypothesis as applied to favoring in-groups and instead suggest that favoring in-group members more closely reflects a general adaptive fit with social institutions that have arisen in each society.


InstitutionsParochialismInsecurityParasitePathogenCross-cultural analysis

Supplementary material

12110_2014_9217_MOESM1_ESM.docx (782 kb)
ESM 1(DOCX 782 KB)

Copyright information

© Springer Science+Business Media New York 2014