Commentary: As humans, instinct holds us back and carries us forward

For the many animal species that live in small, independent social networks (apes, wolves, whales, etc.), outsiders are typically dangerous, feared adversaries. Survival for such animals, therefore, requires not just the relative safety of one’s own group, but also a well-tuned ability to identify nonmembers.Likewise, for millions of years beginning with humankind’s earliest communal framework — isolated, close-knit clans of hunter-gatherers — contact with strangers often