This article summarizes the major findings from the economic and socio-biological theories of group conflicts and contrasts them with findings from sociology and social psychology, especially the relationship between group size and group success. The predictive power of some of the results of economic group-conflict models for behavior in laboratory experiments is relatively poor if one assumes that individuals are self-interested. One gets systematic overinvestment compared to the theoretical predictions, which points to the fact that other-regarding references may be an important explanatory variable. This conjecture is in line with findings in evolutionary biology, social psychology, and neuroscience that all point to a close link between the structure of individual preferences and group conflicts. In fact, the evidence suggests group conflicts were constitutive for the ability of individuals to cooperate, and that this willingness to cooperate evolved in the form of parochial altruism. Building on this idea, the last part of the essay builds a bridge between parochial altruism and social identities and traces the question how social identities are constructed and what this implies for the structure of group conflicts.
