August Schleicher

August Schleicher (1821–1868) was a German linguist who helped establish the field of Indo-European studies. He is best known for proposing the family-tree model, or Stammbaumtheorie, to visually represent the historical relationships among related languages.

While he didn't invent the concept, he was the first to systematically reconstruct a fable in the Proto-Indo-European language. In 1868 he published 'The Sheep and the Horses' (Avis akvāsas ka), demonstrating what the ancestral language might have sounded like based on comparative linguistics.

The Stammbaumtheorie, or family-tree theory, suggested that languages evolve and split into distinct branches much like a biological family tree. Schleicher applied Darwinian evolutionary concepts to linguistics, illustrating how languages like Latin, Greek, and Sanskrit descended from a common ancestor.

Schleicher viewed languages as natural organisms that are born, grow, develop, and eventually die. This biological perspective heavily influenced his methodology, leading him to believe that language evolution followed strict, natural laws that could be mapped out systematically.