Baldwinian Accounts of Language Evolution

Since Hinton & Nowlan published their seminal paper (Hinton & Nowlan 1987), the neglected evolutionary process of the Baldwin effect has been widely acknowledged. Especially in the field of language evolution, the Baldwin effect (Baldwin 1896d, Simpson 1953) has been expected to salvage the long-lasting deadlocked situation of modern linguistics: i.e., it may shed light on the relationship between environment and innateness in the formation of language. However, as intense research of this evolutionary theory goes on, certain robust difficulties have become apparent. One example is genotype-phenotype correlation. By computer simulations, both Yamauchi (1999, 2001) and Mayley (1996b) show that for the Baldwin effect to work legitimately, correlation between genotypes and phenotypes is the most essential underpinning. This is due to the fact that this type of the Baldwin effect adopts as its core mechanism Waddington’s (1975) “genetic assimilation”. In this mechanism, phenocopies have to be genetically closer to the innately predisposed genotype. Unfortunately this is an overly näıive assumption for the theory of language evolution. As a highly complex cognitive ability, the possibility that this type of genotype-phenotype correlation exists in the domain of linguistic ability is vanishingly small. In this thesis, we develop a new type of mechanism, called “Baldwinian Niche Construction (BNC), that has a rich explanatory power and can potentially overcome this bewildering problem of the Baldwin effect. BNC is based on the theory of niche construction that has been developed by Odling-Smee et al. (2003). The incorporation of the theory into the Baldwin effect was first suggested by Deacon (1997) and briefly introduced by Godfrey-Smith (2003). However, its formulation is yet incomplete. In the thesis, first, we review the studies of the Baldwin effect in both biology and the study of language evolution. Then the theory of BNC is more rigorously developed. Linguistic communication has an intrinsic property that is fundamentally described in the theory of niche construction. This naturally leads us to the theoretical necessity of BNC in language evolution. By creating a new linguistic niche, learning discloses a previously hidden genetic variance on which the Baldwin