title: Impartial institutions, pathogen stress and the expanding social network.
abstract: 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.
authors.affiliation: School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA, Daniel.Hruschka@asu.edu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hruschka
authors.forename: Charles
authors.initials: C
authors.lastname: Efferson
authors.forename: Ting
authors.initials: T
authors.lastname: Jiang
authors.forename: Ashlan
authors.initials: A
authors.lastname: Falletta-Cowden
authors.forename: Sveinn
authors.initials: S
authors.lastname: Sigurdsson
authors.forename: Rita
authors.initials: R
authors.lastname: McNamara
authors.forename: Madeline
authors.initials: M
authors.lastname: Sands
authors.forename: Shirajum
authors.initials: S
authors.lastname: Munira
authors.forename: Edward
authors.initials: E
authors.lastname: Slingerland
authors.forename: Joseph
authors.initials: J
authors.lastname: Henrich
mesh_terms: D003431:Cross-Cultural Comparison; D006076:Government; D006801:Humans; D012111:Residence Characteristics; D060756:Social Networking; D012944:Social Support; D013312:Stress, Physiological