The co-evolution of human intersubjectivity, morality and language

The chapter argues that language, which rests on the sharing of linguistic norms, honest information, and moral norms, evolved through a co-evolutionary process with a pivotal role for intersubjectivity. Mainstream evolutionary models, based only on individual-level and gene-level selection, are argued to be incapable to account for such sharing of care, values and information, thus implying the need to evoke multi-level selection, including (cultural) group selection. Four of the most influential current theories of the evolution of human-scale sociality, those of Dunbar, Deacon, Tomasello and Hrdy, are compared and evaluated on the basis of their answers to five questions: (1) Why we and not others? (2) How: by what mechanisms? (3) When? (4) In what kind of social settings? (5) What are the implications for ontogeny? The conclusions are that the theories are to a large degree complementary, and that they all assume, explicitly or not, a role for group selection. Hrdy’s theory, focusing on the evolution of alloparenting, is argued to provide the best explanation for the onset of the evolution of human intersubjectivity, and can furthermore offer a Darwinian framework for Tomasello’s theory of shared intentionality. Deacon’s theory deals rather with the evolution of morality and its co-evolution with “symbolic reference”, but these are necessarily antecedent to the primary evolution of human intersubjectivity. Dunbar’s theory on the transition from “musical” vocal-grooming to vocal “gossip” can be seen as providing a partial explanation for evolution of spoken language, most likely with Homo heidelbergensis 0.5 MYA, but presupposes the capacities accounted for by the other models