This paper discusses the role of interactional and cognitive mechanisms in the emergence of (proto-)linguistic structures and the evolution of (proto)language(s) from the perspective of usage-based and constructionist approaches. Both the social, interactive nature of human communication and the enchronic, interactional timescale have received increasing attention in investigations of how structure emerges in the complex adaptive system of language, which operates across multiple timescales and is shaped by multiple different factors. This has also led to an increasing focus on the mechanisms involved in the dialogic co-construction of structure and meaning in interaction. These include ad hoc constructionalization, interactive alignment, conceptual pacts, reuse and modification, and local forms of entrenchment, routinisation and schematisation. Interactional and cognitive mechanisms like these not only play a crucial role in the emergence of structure in modern languages. They can also help explain how the first (proto)constructions came into being in hominin interaction. Frequently re-occuring, temporary, local (proto)constructions acquired increasing degrees of entrenchment, which led to their subsequent diffusion throughout hominin communities. They were then subject to processes of conventionalisation and cumulative cultural evolution. This process is hypothesised to eventually have led to the gradual transition from protolanguage to language.