Although definitional details vary somewhat, the central tendency of ethnicity is how people define themselves vis-à-vis others, how distinctions are made between "we" and "they." 1 Any number of criteria can be used, either singly or in combination, in arriving at such distinctions, but the important point is that they create a feeling of sameness among people, a feeling that subordinates other possible forms of stratification such as age, sex, and class. 2 Ethnic groups are "whole" societies from a biological perspective, in that they have the necessary age-sex structures for reproducing themselves; and, in a very real sense, ethnicity can be thought of as a "living" concept because it comes out of the world of interaction, competition, and conflict among people as they attempt to survive and prosper.