Finite state syntax in Bengalese finches: From birdsong to the origin of language

Kazuo Okanoya

Chiba University and PRESTO, JST, Japan

In passerine birds, song is a learned behavior used by males to attract females. Generally, a song is composed of several types of song notes and the order of these notes is stereotyped. However, unlike most songbirds studied to date, Bengalese finches sing non-deterministic songs that may be described by a finite-state syntax. Why do Bengalese finches sing such complex songs? First, to answer from the mechanical point of view, we found that the finite-state syntax is expressed in hierarchically organized brain nuclei in this species. Next, to answer from the functional point of view, we showed that a song with syntax is more attractive to female birds, and therefore the song syntax in Bengalese finches may have evolved through sexual selection. Furthermore, to answer from the evolutionary point of view, we found that song syntax was absent in the ancestor species of the Bengalese finch yet females of the ancestor species preferred syntactically complex songs. Based on these results, we discuss the evolution of complex behavior and associated changes in the brain. Bengalese finches developed finite-state syntax presumably through the process of sexual selection. However, each token in the Bengalese finch song does not have any associated semantics, and the finite-state syntax in Bengalese finch song does not produce any meanings. Thus, a finite state syntax could evolve without meaning. Most authors arguing the origin of language assume that proto-language that had symbolic contents but no syntactical structure evolved first, then the proto-language somehow evolved into true language with the syntax. However, how the proto-language acquired the syntax is always the hardest question in the origin of language. Through the analyses of Bengalese finch songs, we showed a syntactical behavior could evolve without a need of semantics. We propose that the symbolic and the syntactical aspects of human language could also have evolved independently.

Honda, E., & Okanoya, K. (1999). Acoustical and syntactical comparisons between songs of the white-backed munias and its domesticated strain, the Bengalese finch. Zoological Science, 16, 319-326.

Okanoya, K., & Yamaguchi, A. (1997). Adult Bengalese finches (Lonchura striata var. domestica) require real-time auditory feedback to produce normal song syntax. Journal of Neurobiology, 33, 343-356.

Okanoya, K. Tsumaki, S., & Honda, E. (in press). Perception of temporal structures in self-generated songs by Bengalese finches. Journal of Comparative Psychology.

Okanoya, Kazuo

Department of Cognitive and Information Sciences, Chiba University

1-33 Yayoi-cho, Inage-ku, Chiba, Chiba, 263-8522, Japan

okanoya@cogsci.l.chiba-u.ac.jp