By some definition, I imagine you could call any group a tribe if they share a common interest or some other shared condition that promotes communication and cooperation. As far as a hierarchy goes, all of life sorts itself into hierarchies. Big fish eat the little fish. Big guys tell the little guys what to do. Guys with the big ideas organize the working stiffs to build things the rest of us are willing to pay for. In the context of this site, some members earn greater credibility by posting accurate, worthwhile reviews and making other contributions the rest of us find useful.