Phoneme inventory size and the transition from monoplanar to dually patterned speech

Abstract

Atkinson (2011) shows that phoneme inventories are largest in Africa and smaller elsewhere, and suggests that this clinal distribution reflects a serial founder effect of human migrations out of Africa. Because of the way in which velaric ingressive and pulmonic egressive airstream mechanisms combine to create extra-large consonant inventories, click languages have the largest phoneme inventories of all. Critics question why phoneme inventory size, but not other properties of language, should leave a trace of the origin and dispersal of natural language. This article argues that the first modern human languages would likely have had very large phoneme inventories if we assume, following Hockett's work (1960), that duality of patterning was the last 'design feature' of language to emerge. The diachronic trajectories of sign languages and writing systems illustrate that dually patterned phonologies are often preceded by a stage in which minimal units of form map directly onto semantic functions. Following Hjelmslev (1961), I label such linguistic systems, 'monoplanar'. The article critiques language origins theories that have claimed that click consonants were sounds employed in the development of human speech because of their putatively iconic or sound symbolic properties. Focusing on the structural effects of velaric ingressives for phoneme inventory size, I argue that clicks would have been essential in elaborating large inventories, and thus large vocabularies, in monoplanar spoken languages not because of any inherently iconic properties, but because of their capacity to multiply phonemic distinctions by combining with accompaniments produced via the pulmonic egressive airstream mechanism. The contemporary distribution of phonemic clicks offers support for the hypothesis, as genetic studies increasingly point to an Eastern or Southern African origin for modern humans, while phonemic clicks have an areal but non-genetically restricted distribution in overlapping vicinities.