Universals and individuality in facial behavior—past and future of an evolutionary perspective

Multiple dimensions of facial expression research are reviewed with emphasis in the study of species’ homology in both facial action single components and patterns or gestalten. Research over the last 30 years has revealed human universal patterns and some cross-species gestalten that appear as homologies. Recently, researchers are looking into the importance of individuality markers in facial behavior, which can play an important role in the fitness of individuals living in complex social systems and thus might be traceable in their evolutionary path. Chimpanzees, bonobos, and humans were in the center of most of this research with research results pointing toward homologies within the Homo–Pan clade.