Do we have the scientific theory why the click consonants were developed?

Question

Do we have a scientific theory explaining why the click consonants were developed, and why they are used almost exclusivly in praerie regions?

I've watched a BBC documentary about the evolution of humans, and the speaker noticed when hunting with San, that their clicks are good to hear in high grass on short distances, but the speaker was in the same time very hard to locate, so they are perfect adaptation to group hunting in such environment.

From the other way, I can't imagine communicating with clicks on large distances, so the clicks may not be practical in boreal forest during ice age etc.

However, I've failed to google interesting topics, so maybe theses on that topic exist, but only in paper form in some universities libraries?

Answer 1

I don't know of any paper trying to explain why click consonants might have developed in languages in the first place. But something to keep in mind is that most languages I know use clicks as non-segmental signs, for instance the English interjection tsktsk, or the way you call a horse. Germans have a bilabial click that indicates something like "tough question/don't know". Intuitively I have a feeling that clicks are very iconic (for instance the click we use with horses somewhat resembles the sound of a gallop, the disapproving tsktsk that of a slap), but my intuition might be wrong and I don't know of any studies on this. Acoustically clicks are quite distinct in the signal, meaning even in difficult conditions they should offer high recoverability compared to say a fricative. On the other hand, complexity comes with a phonological price tag, so such an argument in phonetics has a counter argument in phonology. I could imagine that acoustic distinctness/recoverability is a good thing under difficult conditions (e.g. noisy environment, dense forestation) or communication over a long distance, but whistled language is generally a lot better for this and the environmental conditions around click-rich languages do not really speak for this being a factor.

There is a paper here which suggests that clicks don't offer any acoustic processing advantage per se in languages where they are not used as regular segments. And this paper has a nice overview of literature on linguistic change involving clicks, which might be of interest, but doesn't offer an answer to "why"--in fact one may see this as partial evidence that because clicks are segmentally complex they might be difficult phonologically.

Regarding the question of whether clicks were part of a hypothetical proto-human language and then lost elsewhere to be only retained as non-segmental signs, see Knight et. al.'s (2003) paper arguing that this is the case, from a genetic perspective authored by geneticists and anthropologists. And then compare this with Tom Güldemann's (2007) paper in ULPA responding to that very paper, from a linguistic perspective, arguing that there isn't really that much support for that hypothesis.

Answer 2

Clicks are used by other animals for echo-location. In an environment with lots of echoing objects, clicks would be hard to use for communication. Because they don't use (pharyngeal) airflow (unlike all other phonemes), they would be easy to skip when making up sounds. {Perhaps there is no research to cite because this is common sense. It's not common sense if it's wrong...}