Abstract
<p>Humans possess two elaborate, culturally transmitted communication systems: music and language. In cognitive science, the evolution of these capacities has been studied through two main approaches: identifying and analysing either features conserved across cultures or traits conserved across species. Both approaches leave key questions unanswered: which ancestral stages corresponded to which features, in what order traits evolved, and whether and how music and language diverged from a common precursor system. We propose adapting an evolutionary systems biology (ESB) framework, originally intended to identify causal interactions in evolving systems and specify their possible evolutionary trajectories. This approach provides mechanistic explanations for phenotypic development and evolutionary transitions. In transferring it to evolutionary cognition, we link recent insights into neurodevelopment and niche construction to processes of active inference, processes mediating between cognitive traits and spectrotemporal features present in the niche. We consider the free-energy landscape over belief states as the cognitive analogue of the ESB epigenotype. We reason that social interaction creates conditions so that cognitive traits and niche-structuring features can mutually shape each other over developmental and evolutionary timescales. For music and language evolution, we argue that these processes can be quantified using our framework, and that recently developed computational models provide the infrastructure for evolutionary simulations to this end. Our evolutionary cognitive systems biology framework thus offers a novel approach to analysing the biocultural evolution of music and language.</p>