Ian Maddieson: What accounts for the geographical distribution of tone languages?

“Languages without tone occur widely distributed throughout the world with the notable exception of sub-Saharan Africa, whereas languages with tone are concentrated in regions relatively close to the equator where generally warm and humid conditions prevail, apart from (primarily western) North America and some marginal cases in Europe. Everett et al (2015, 2016) suggest that low ambient humidity leads to loss of tone distinctions, since precise control of phonation is impeded by dry air. An implicit assumption here is that tonality is the ‘natural’ state of language, and its absence is derived (as is claimed by Brown 2017, among others). Comparative evidence suggests that tone is neither predominant nor original, it can nearly always be shown to be derived through documentable phonological change (Maddieson 2023). Hence, if the claimed correlation between the distribution of tone and humidity is valid (see Roberts 2018 for discussion) motivation to encourage tonality in warm wet climates rather than to discourage it in cold dry ones is required as the explanation. Our analyses suggest that it is worth further pursuing the hypothesis that differences in transmission conditions, rather than concerns with production, influence such design features of languages. Tone contrasts concern steady to slow-moving changes in the acoustic signal, which are less disrupted by ambient factors affecting fidelity of transmission, such as dense vegetation and high temperature, as found in tropical regions, compared to distinctions between consonants, especially obstruents. Thus, for example, transferring contrasts between consonant types to distinctions of tone on the following vowel —  the most frequent route to tonogenesis — provides a more robust acoustic identity for the intended message under the prevailing conditions.”

Prof Ian Maddieson is adjunct research professor of linguistics at University of New Mexico.