Tribe: On Homecoming and Belonging

by Sebastian Junger

Not only are bad actions punished, but good actions are rewarded. When a person does something for another person—a prosocial act, as it’s called—they are rewarded not only by group approval but also by an increase of dopamine and other pleasurable hormones in their blood. Group cooperation triggers higher levels of oxytocin, for example, which promotes everything from breast-feeding in women to higher levels of trust and group bonding in men. Both reactions impart a powerful sensation of well-being. Oxytocin creates a feedback loop of good-feeling and group loyalty that ultimately leads members to “self-sacrifice to promote group welfare,” in the words of one study. Hominids that cooperated with one another—and punished those who didn’t—must have outfought, outhunted, and outbred everyone else. These are the hominids that modern humans are descended from.