In this essay I shall attempt to show how Darwin's work on, and contribution to, linguistics has often charted a proto-biosemiotic trajectory of thought. While modern linguistic studies have tended to explore Darwin's contribution to linguistics adopting a Saussurean view I argue that such views undermine Darwin's notion of continuity between animals and humans and I propose to look at Darwin's theory of language, which stems from the Romantic thought, by adopting a biosemiotic perspective which clarifies Darwin's own ideas on the origin of language and animal evolution as well as their inter-relations.