A Historical Appraisal of Clicks: A Linguistic and Genetic Population Perspective

Abstract

Clicks are often considered an exotic feature of languages, and the fact that certain African “Khoisan” groups share the use of clicks as consonants and exhibit deep genetic divergences has been argued to indicate that clicks trace back to an early common ancestral language ( Knight et al. 2003 ). Here, we review the linguistic evidence concerning the use of click sounds in languages and the genetic evidence concerning the relationships of African click-speaking groups. The linguistic evidence suggests that genealogical inheritance and contact-induced transmission are equally relevant for the distribution of clicks in African languages. The genetic evidence indicates that there has been substantial genetic drift in some groups, obscuring their genetic relationships. Overall, the presence of clicks in human languages may in fact not trace back to the dawn of human language, but instead reflect a much later episode in the diversification of human speech.

Hunter-gatherer genomic diversity suggests a southern African origin for modern humans

“…The Hadza and Sandawe of Tanzania are the only Khoisan-speaking populations to reside outside of southern Africa. However, inclusion of the Hadza and Sandawe in the Khoisan language family is highly contentious among linguists (16,17). Despite their small population sizes (the Hadza number only ≈1,000 individuals), the Khoisanspeakers exhibit a large amount of Y-chromosomal and mitochondrial genetic diversity.…”

Laryngeal stop systems in contact

“…The clicks later spread from this marked speech register to the 'normal' lexicon, and even replaced native segments in native Nguni words. Güldemann & Stoneking (2008) point out that clicks, once borrowed, have "a life of their own", as evidenced by the observation that some originally non-click Bantu languages now have more complex click systems that the languages they borrowed from or have click sounds not attested in any of the original languages (Güldemann & Stoneking 2008: 99). While borrowing in the domain of, for instance, vocabulary is known to be highly common, there is thus also considerable evidence that it can also occur in the domain of phonology.…”

Prehistoric Bantu-Khoisan language contact

“…Güldemann and Stoneking, 2008), nor are they always due to contact with Khoisan peoples, but they might be the result of independent innovations or contact with a Bantu click language (cf. Section 2).…”

“…One of the salient characteristics of all the languages belonging to the three Khoisan families is the presence of click consonants that generally have a high functional load; that is, they tend to occur in a high proportion of lexical items (Güldemann and Stoneking, 2008;Sands and Güldemann, 2009). Although clicks are extremely rare crosslinguistically, they are found in some Bantu languages of southern Africa in addition to the Khoisan languages.…”

“…In Bantu languages outside the area in which Khoisan languages are distributed, these consonants are absent. They have therefore not been reconstructed to ProtoBantu (Meeussen, 1967: 83), and it is widely accepted that they were transferred to these Bantu languages from some Khoisan language(s) via contact (Voßen, 1997;Herbert, 2002;Maddieson, 2003;Güldemann and Stoneking, 2008;Sands and Güldemann, 2009). In this paper, we attempt to elucidate the possible prehistoric sociocultural contact situations that led to the copying1 of these highly rare and salient phonemes into Bantu languages by looking at both linguistic and molecular genetic data.…”