New Guinea remained on my radar: a horizon of maximum difference, a test bed for linguistics and for linguists. Elsewhere, linguistic differences usually stem from geographic isolation. But in much of New Guinea the diversity is actually deepest in places where travel is easiest. Instead of using religion, clothing, or food, Papua New Guineas have distinguished themselves above all through language. Call it tribalism or, as linguists do, the “constructive fostering of variegation” through “intentional language change.”