Tonogenesis

Tonogenesis is the development of distinctive tone from earlier non-tonal contrasts. A well-understood case is Vietnamese (similar in its essentials to that of Chinese and many languages of the Tai-Kadai and Hmong-Mien language families), where the loss of final laryngeal consonants led to the creation of three tones, and the tones later multiplied as voicing oppositions on initial consonants waned. This is by no means the only attested diachronic scenario, however. Besides well-known cases of tonogenesis in East Asia, this survey includes discussions of less well-known cases of tonogenesis from language families including Athabaskan, Chadic, Khoe and Niger-Congo. There is tonogenetic potential in various series of phonemes: glottalized versus plain consonants, unvoiced versus voiced, aspirated versus unaspirated, geminates versus simple (and, more generally, tense versus lax), and even among vowels, whose intrinsic fundamental frequency can transphonologize to tone. We draw attention to tonogenetic triggers that are not so well-known, such as [+ATR] vowels, aspirates and morphotonological alternations. The ways in which these common phonetic precursors to tone play out in a given language depend on phonological factors, as well as on other dimensions of a language’s structure and on patterns of language contact, resulting in a great diversity of evolutionary paths in tone systems. In some language families (such as Niger-Congo and Khoe), recent tonal developments are increasingly well understood, but working out the origin of the earliest tonal contrasts (which are likely to date back thousands of years earlier than tonogenesis among Sino-Tibetan languages, for instance) remains a mid- to long-term research goal for comparative-historical research.