Résumé
Animals discriminate among familiar and unfamiliar conspecifics probably to avoid wasting time and energy during social interactions. Individual recognition may reduce the chance of expensive fights among territorial neighbors during resource defense, or allow mates, kin, or parents and offspring to find each other where familiar individuals intermingle with unfamiliar ones. Because individual recognition may involve a time-consuming learning process, or because it may be costly in some other way, individual recognition will probably only evolve when benefits outweigh these costs (e.g., Beer, 1970; Wilson, 1975; Falls, 1982, Beecher and Stoddard, 1990).