Social interdependencies: the deep evolutionary roots of morality and normativity.

We propose that minimal morality (experiencing "ought-thoughts") and minimal normativity (having expectations or "standards") historically emerged in the context of parental care among animals. Subsequently, in animals that formed stable, personalized societies, the moral motivation was functionally extended to enable interdependent social relationships (bonds, with kin, but also with non-kin as same-sex social or pair bonds), whereas the presence of normative expectations for the partner's behavior in social bonds emerged concomitantly because the ever-present risk of shirking requires evaluation of the partner's social actions. This social evaluation is extended toward the actions of other group members whenever individuals can switch to other bonded partners or allies. The spectrum of responses to partners' actions can range from shunning to punishment, depending on the strength of the fitness-augmentation effects of bonds or alliances. We do not expect individuals to socially evaluate the actions of non-group members, except in dispersal situations. This functional hypothesis for the evolution of morality and normativity is supported by extensive behavioral and physiological evidence from various social animals. In sum, we argue that morality and normativity are fundamentally social, both serving to sustain dyadic relationships of interdependence that are inherently threatened by free riding. Human morality and normativity are an extension of this basic dyadic version, by involving group-level interdependencies, and presumably also by involving an awareness of the same motivations and social evaluations in others, which, through language-based negotiation and reflection, permits the explicit formulation of moral prescriptions, which may therefore vary culturally.