Ethnocentrism denotes behaviour and beliefs that are positive towards those who share the same ethnicity and negative towards others. The model considers short-term cultural evolution, where agents may interact in a population and do not die or give birth but imitate and innovate their behaviours. While agents retain a fixed ethnicity they have the ability to form and join cultural groups and to change how they define their in-group based on both ethnic and cultural markers (or tags).
Over a range of parameters cultural identity rather than ethnocentrism becomes the dominant way that agents identify their in-group producing high levels of positive interaction both within and between ethnicities.
However, in some circumstances, cultural markers of group preference are supplemented by ethnic markers. In other words, whilst pure ethnocentrism (based only on ethnic identity) is not sustained, groups that discriminate in terms of a combination of cultural and ethnic identities do occur.
In these less common cases, high levels of ethnocentric behaviours evolve and persist – even though the ethnic markers are arbitrary and fixed. Furthermore, cooperative ethnocentric groups do not emerge in the absence of cultural processes. The latter suggests the hypothesis that observed ethnocentrism in observed societies need not be the result of long-term historical processes based upon ethnic markers but could be more dependent upon short run cultural ones.
Full details can be found at: http://cfpm.org/discussionpapers/152 (by Nov. 2015)