The Evolution and
Development of Morality
Melanie Killen & Frans B. M. de Waal
What are the origins of morality, both phylogenetically and ontogenetically? Phylogeny deals with possible homologies between species and with stages of evolution over millions of years. Naturally, evolution also deals with the issue of adaptive function. After all, how could we have evolved moral tendencies if such tendencies lacked positive effects on survival and reproduction? The ontogenetic question, however, focuses on the development over a much more limited time, between infancy and adulthood, within a single species. In this chapter, we make two fundamental assertions regarding the evolution of morality: (1) there are specific types of behavior demonstrated by both human and nonhuman primates that hint at a shared evolutionary background to morality; and (2) there are theoretical and actual connections between morality and conflict resolution in both nonhuman primates and human development.
In our analysis of the literature we make several points that apply to both human and nonhuman primates. First, the transition from nonmoral or premoral to moral is more gradual than commonly assumed. No magic point appears in either evolutionary history or human development at which morality suddenly comes into existence. In both early childhood and in animals closely related to us, we can recognize behaviors (and, in the case of children, judgments) that are essential building blocks of the morality of the human adult. Second, we theorize that the phylogenetic origins of human morality can be detected in the social interactions of nonhuman primates, our closest biological relatives, and the ontogenetic origins of morality can be observed in the early social