Most languages that English speakers have heard "use" clicks — the lips-smack of an irritated parent, the tongue-cluck of disapproval — but use them paralinguistically, outside the phoneme inventory. In southern Africa, by contrast, several language families have made clicks into real consonants: building blocks of ordinary words, indistinguishable in status from p and t in English.
The traditional cluster of "click languages" comprises three completely unrelated lineages:
- Khoe — the family that includes Khoekhoegowab (Nama–Damara) of Namibia, Naro and Gǀui of Botswana, and several smaller languages of the Kalahari fringe.
- Tuu — the southern group that includes Taa (!Xóõ), the consonant-record holder featured elsewhere in this trivia collection, plus the moribund N|uu of South Africa.
- Kx'a — a small family containing Juǀ'hoan and ǂHoan, with elaborate click inventories of their own.
To these three families one usually adds two isolates of East Africa: Hadza, spoken by perhaps a thousand hunter-gatherers around Lake Eyasi in Tanzania, and Sandawe, about 150 km to the south in the rocky uplands of Dodoma Region. Both have clicks, but they sit differently: Hadza has no demonstrated relatives anywhere, while Sandawe may be a distant relative of the Khoe family — a link Tom Güldemann and Edward Elderkin have argued on lexical and pronominal evidence is promising, though short of proven. The old umbrella term "Khoisan" lumped all five together, but Güldemann and others have spent the last twenty years arguing — convincingly — that Khoisan is an areal grouping, not a genetic family.
Phoneticians distinguish five primary click types by where the front closure is made:
- Bilabial ʘ — a kiss-like pop made with the lips. Rarest of all; survives mainly in Taa and a few neighbouring varieties.
- Dental | — the sound English speakers make as "tut-tut".
- Alveolar ! — a sharp pop made by snapping the tongue from the alveolar ridge, rather like a cork leaving a bottle; written q in Xhosa and Zulu.
- Palatal ǂ — a softer release further back on the palate.
- Lateral || — a side-of-tongue click sometimes used by English speakers to urge a horse on; this is the click in Xhosa's own name, written xh.
Each click can then be accompanied by voicing, aspiration, nasalisation, glottalisation, and combined with uvular or ejective releases. Multiplying the parameters out gives some Khoe and Tuu languages click inventories larger than the entire consonant systems of well-known languages elsewhere.
The most striking sociolinguistic fact about clicks is that they jumped families. The Bantu languages Zulu, Xhosa, Southern Sotho and Swati all have phonemic clicks — three click types in Zulu and Xhosa, a single one in Southern Sotho and Swati — even though their nearest Bantu relatives further north have none whatsoever. The explanation, worked out in detail by historians and linguists from Anthony Traill to Rainer Vossen, runs roughly as follows: as Bantu-speaking farmers moved south of the Limpopo in the second millennium CE, they encountered, intermarried with and partly absorbed Khoe and San communities. The bilingual generations who grew up in mixed households brought clicks across the family boundary, especially in respectful and ritual vocabulary. The name isiXhosa carries one itself: straight after the noun-class prefix, the xh is an aspirated lateral click.
If you click Compare above, you'll notice that not one of this map's everyday basic words actually contains a click in Xhosa or Zulu. That's the second half of the story: clicks in Bantu live almost entirely in cultural and respectful vocabulary — names (iXhosa, uXamu), animals (iqaqa "polecat", ixoxo "frog"), greetings, taboo replacements in hlonipha avoidance speech, and Khoekhoe loans (iCawa "Sunday"). Inherited Bantu words for water / fire / sun / hand / eye remain click-free.
The mechanism is now reasonably well reconstructed. Pakendorf, Gunnink, Sands and Bostoen (2017), combining linguistic and genetic evidence, conclude that the copying of clicks accompanied large-scale inmarriage of Khoisan-speaking women into Bantu-speaking communities, with part of the effect attributable to language shift by Khoisan speakers themselves. On that account clicks did not arrive the way a casual loanword arrives: they came through households in which children grew up hearing both languages, and once a generation had them, they were simply native consonants.
Beyond southern Africa, robust documented cases are the East African isolates Hadza and Sandawe, the Cushitic language Dahalo of coastal Kenya, plus the special ritual register Damin in Australia — used by initiated men of Mornington Island rather than as an ordinary spoken language. Dahalo is the odd one out: its clicks survive in only about forty words, several of them basic vocabulary, and are generally read as a substrate relic left behind when its speakers shifted to Cushitic. (Reports of click-like sounds in the ceremonial register of El Molo exist but are not well established.) In southern Africa, clicks have been maintained and exchanged across four language families for at least several thousand years.
Whether clicks are an archaic feature inherited from very early African populations, a regional innovation strengthened through contact, or a combination of both remains debated. Their status as fully functional phonemes does not: children acquire them as part of their ordinary sound system, as they acquire any other consonant.