[This is a practice run of a talk to be presented at CASTL in Tromso in December.]
Dediu and Ladd (2007) showed that the geographical distribution of tone languages is correlated with the distribution of older and newer alleles of two genes apparently involved in brain development, and argued that there might be a causal relation. The causal relation would be based on some sort of genetically induced "cognitive bias" that would influence the direction of language change over many generations. In this talk I will discuss three topics related to Dediu and Ladd's work. First, I will summarise the original paper and attempt to answer some common objections and clear up some common misunderstandings about what it did and didn't claim. Second, I will briefly describe my current investigations of substantial individual differences in pitch perception, which might be the source of the hypothesised cognitive bias. Finally, I will talk about the linguistics of tonogenesis and its relevance to the idea that different populations might be differently disposed to develop and/or maintain tone languages. In particular, I will talk about the distinction between tonogenesis based on consonant distinctions and tonogenesis based on syllable structure, and about the question of whether there is an inherent connection between tone and lexical or morphosyntactic monosyllabicity.
Reference: Dan Dediu and D. Robert Ladd, 2007. Linguistic tone is related to the population frequency of the adaptive haplogroups of two brain size genes, ASPM and Microcephalin. Proceedings of the National Academy of Sciences 104: 10944-10949 (online reference 10.1073/pnas.0610848104).