Risk buffering and resource access shape valuation of out-group strangers

Abstract

Unlike other primates, humans exhibit extensive inter-group tolerance and frequently build relationships with out-group members. Despite its common occurrence, little is known about the conditions leading to out-group relationship building in humans. What are the social and ecological factors promoting valuation of out-group members as potential social partners? Do they differ from those promoting valuation of in-group members? We propose that opportunities for non-local resource access and resource buffering, crucial in the human foraging niche, will increase valuation of out-group strangers. Using survey and experimental data collected among three Bolivian horticultural populations, we find that individuals with fewer non-locally available resources and more information about out-groups demonstrate more generosity toward out-group strangers, but not in-group strangers. The effects are specific to subjective resource access, not objective measures of access, and out-group exposure, not stereotypes. Further, depending on the measure, existing network connections affect both out-group and in-group giving, suggesting that new partnerships from both in-groups and out-groups may bolster one's networks. Our results illustrate how evolved human psychology is sensitive to the costs and benefits of both out-group and in-group relationships, but underscore that the social and ecological factors favoring new relationships with in-group versus out-group strangers may differ.

Figure 1. An example of the non-anonymous giving game (NAGG).

Six photos were arrayed on a table, all of past participants in the experiment. The three men on the left were participants who identify with one ethnic group, for example, and the three on the right with another. Participants were told the name and group affiliation of each individual. Stacks of three one boliviano coins were placed on each photo and in front of the participant. The participant could move any number of coins between photos, from photos to his own stack, or from his stack to the photos. Participants were informed that any coins left on a photo would be given to that person in the participant’s name (unless the participant wished to remain anonymous) and any coins left in front of the participant would be his.

Figure 2

Predicted amounts allocated (with 95% prediction intervals for a and b) to an out-group member (purple, solid line), an in-group member (blue, short-long dash), and the self (orange, long dash) by (A) log subjective socioeconomic status, (B) number of places lived, and (C) availability of cooperative labor partners.