Evolution of Birdsong Grammars

Recent studies on song birds reveal that their vocal communication has some common features with human language. In particular, a songbird called Bengalese finch has interesting vocal communication in which courtship song is arranged by finite-state grammar [6]. It has been hypothesized that the song grammar may have evolved as a result of sexual selection [10]. In order to explore the evolution of the song grammars, we model the co-evolution of male and female finches by asymmetric finite-state automata. In this paper, we demonstrate that song grammars could evolve by simple communication. We observe that a transition from lower complexity to higher complexity song grammars is driven by the changing of male birds' courting strategy.