Cultural differences in the ways homosexuality is categorized or conceived may be explained by differences in the ways hierarchies are organized. Where age brings greater prestige, homosexuality takes the form of "master/ apprentice" relationships, as among ancient Greeks, Japanese Samurais, the African Azande and several New Guinea societies. Where hierarchies are based on impersonal criteria (like curriculum vitae), rather than personal connections, homosexual relations are generally discouraged, and those at the homosexual extreme of the continuum resort to sex with similar males (giving the North European "gay" system). Where social positions depend more on personal ties, male/male alliances continue to be important and "mediterranean systems" (such as the Brazilian bicha/bofe system) arise, in which ordinary heterosexually identified males typically maintain sexual relationships (active role) with homosexually identified males (assuming a passive role). In these systems ordinary adolescent males may also typically have homosexual relationships with each other.