On the origins of human speech: language as an internal trigger of the reward system

This article proposes a neuroevolutionary model of language origins in which the human-specific ability to experience intrinsic reward from symbolic vocal behavior emerged as a major innovation, building upon pre-existing communicative vocalizations found in non-human primates. We suggest that, while vocal communication served essential social and emotional functions in early hominins, a neurobiological shift occurred when self-generated vocalizations that successfully matched symbolic referents,whether perceptual, mnemonic, or affective,began to activate dopaminergic reward circuits. This new capacity for self-reward did not replace communicative functions, but rather enriched them, enabling the stabilization and creative expansion of symbolic behaviors even in the absence of immediate social utility. In Homo sapiens, genetic adaptations further expanded vocal and articulatory capacities and refined the connectivity between reward circuits and cortical language areas, dramatically increasing the range and precision of symbolic matches. The anticipation and achievement of articulatory, lexical, and syntactic success became then intrinsically pleasurable, establishing a self-reinforcing loop of linguistic exploration and innovation. Over time, the social dimension of language learning and use, amplified by group size and cultural complexity, catalyzed the rapid growth of linguistic and cooperative capacities in modern humans. Crucially, we suggest that this self-rewarded symbolic behavior conferred adaptive advantages beyond cognition and sociality, notably by enabling the generation of dopaminergic reward at low energetic cost, potentially supporting stress reduction and immune function. This hypothesis is supported by converging evidence from neuroimaging, neurogenetics, and experimental psychology, which demonstrate that successful symbolic matching and linguistic insight activate dopaminergic reward circuits, and that human-specific neural adaptations may have provided the substrate for these processes.