| Abstract | In the current research, I combined insights from the evolutionary sciences, experimental economics, and psychoneuroimmunology to examine the relationship between inflammation and cooperation at the individual, group, and population levels. I hypothesized that cooperation would decrease in the context of heightened inflammation because inflammation delineates a bodily context in which an individual¿s immediate resource needs are relatively high and the likelihood of realizing returns on investment in building social capital is diminished. Further ¿ because previous research finds that early life stress increases sensitivity to the psychological and behavioral sequelae of inflammation ¿ I predicted that the impact of inflammation on cooperation would be greatest for those from more stressful early life environments. Consistent with these predictions, Studies 1-2 both found that for individuals reporting a lower childhood socioeconomic status (SES) ¿ a proxy measure of early life stress exposure ¿ higher inflammation predicted less cooperation. These differences were not found for those reporting a higher childhood SES. Additionally, Study 2 also found that groups with higher collective levels of inflammation cooperated less, regardless of collective exposure to early life stress. Finally, the results of Study 3 revealed that countries with higher infectious disease prevalence ¿ an environmental context that is linked to elevated inflammatory activity ¿ invested less in public goods and were less sociopolitically stable than countries with lower infectious disease burden. Together, these results provide evidence for the immune system playing a role in regulating cooperative behavior, which may have broader implications for social cohesion and the distribution of public goods. |
