The analogy of languages to living organisms and the concept of natural evolution are already found before the publication of Darwin's Evolution in 1857. Humboldt, who wasn't a historical linguist, already saw language as a living organism. He emphasized that each language lives in the speaker's mind as a vital process and that is only fixed in a steady state when a grammarian writes down its structures and forms at a particular time. Furthermore, he thought that languages are continually seeking perfection and used the term "evolution" alongside with "development".
Later on, Schleicher turned Humboldt's abstract perfectionist evolution into Darwinian survival evolution, which is a historical process taking place in real time. In his short treatise on Darwinian theory and linguistics (1863) he stated that what he had already written on the history and prehistory of languages tallied with Darwin's own evolutionary theory. …