Dual neurobiological systems underlying language evolution: inferring the ancestral state

The Dual Neurobiological Systems (DNS) framework places the neurobiological and evolutionary origins of language center-stage, and views the communicative and combinatorial capacities of the modern human as a dynamic coalition of two intersecting but evolutionarily and functionally distinguishable sets of systems. Strong evolutionary continuity between humans and their primate relatives is provided by a distributed, bi-hemispheric set of capacities that support the dynamic interpretation of multi-modal sensory inputs, in the context of social communication between members of the same species. Here we use this set of capacities to derive a neurobiologically constrained approach to the evolution of speech-based communication in the modern human lineage. A key challenge for such an approach is to identify the neurocognitive ancestral state from which the modern dual systems framework emerged.