Otdfbt

Paralinguistic clicks are quite common across world's languages. But paralinguistic clicks usually appears as ideophones. But why is Africa the only continent that uses click consonants? Are there any theories/speculation/hypotheses for why click languages are found only in Africa?

Damin

The only non-African language known to have clicks is Damin. But to me, Damin appears to be a constructed language, used as ritual code.

Not even African languages in general: clicks seem to have originated only in the Khoisan language "family" (*), and spread from there into neighboring languages. In other words, clicks don't seem to be an African feature so much as a Khoisan feature.

As for why they're only a Khoisan feature—it really seems to be pure random luck! Clicks appear paralinguistically, as you mention, and also show up in twin-codes, showing that they're not that difficult to come up with.

But for the most part, languages gain new consonants in two different ways: either an existing sound shifts, or bilinguals borrow a sound from one language into another. For example, /ð/ was added to Greek and Germanic when stops lenited, and to Swahili via overlap with Arabic.

Click consonants are borrowed fairly easily, which is why they're found all across southern Africa even though the Khoisan languages are rare and dying. (And why they're steadily moving up the east coast now as well!) But there just aren't any common—or even attested—sound changes that can create clicks where no clicks were before.

How Khoisan got clicks in the first place is lost to the mists of time, farther back than the comparative method can reconstruct. Maybe t → ǁ is a sound shift that happened, but it's so rare and unlikely that it only happened once in a surviving language. Or maybe language was invented independently in several places, and the version created by the pre-Khoisan-speakers just happened to include clicks while others didn't. There's unfortunately no way to know for sure now.

(*) The Khoisan languages don't seem to be a family in the same way that the Germanic languages or the Romance languages are. Rather, they're a collection of scattered languages grouped together for convenience; they all share some features, but there just isn't enough evidence to say if that's due to a genetic relationship, a sprachbund, areal features, or even just coincidence.

This is an example of areal phonetics, where certain phonetic properties are relatively widely exploited in one area, but is rare (or nonexistent) elsewhere. Another example is labiovelars such as [kp], which are almost all in the "Central Sudanic belt" of subsaharan Africa. They are universal and numerous in the "Khoisan" languages of southern Africa, also found to a lesser extent in Zulu and Xhosa (in closes proximity to Khoisan), tapering off to rareness in languages like Chopi (still in Southern Africa, southern Mozambique). They also exist in Hadza and Sandawe in Tanzania, and exist in a few words of Cushitic Dahalo.

They are actually somewhat difficult to produce, compared to other sounds. There is a tendency to open the velum during their production (the velum is normally lowered except for speech and lifting heavy stuff), and people who are not native speakers of e.g. Khoekhoe tend not to be able to integrate their articulation with that of surrounding vowels.

Excluding the more recent adoption of clicks by neighboring Bantu and Cushitic speakers, the languages with clicks have been spoken fairly undisturbed in situ for tens of thousands of years, not being influenced by other phylla. Relative isolation tends to encourage the development / retention of "exotic" phonetic features, since you don't have to accommodate to the phonetic preferences of neighbors that don't have those exotic sounds. The exact phonetic mechanism that would have encouraged these sounds is not clear, but there are parallels involving velarization in southern and eastern African languages, where phonemic /tw, pw/ are often heavily velarized and partially unrounded. In Shona, this can lead to "token clicks", where a given token of intended [tˣʷ] may be produced as a kind of click. If, for example, clicks originated as a phonetic variant of standard velarization, they might have been popular enough that they spread to all of the languages down there, and there wasn't ever any reason to get rid of them.