This study investigated whether earnings inequality is associated with social capital as measured by active membership in organizations and interpersonal trust. Pearson product-moment correlation analysis showed that greater earnings inequality was associated with lower values on both measures...

The scale of violent intergroup conflict in humans is astonishingly large compared to other mammals [1, 2, 3, 4]. This capacity for war is closely linked to our exceptionally cooperative abilities [5, 6]. The parochial altruism model formally describes how within-group cooperation and...