realmachiavelli-blog asked:

I love this blog! Since I love linguistics and culture/kinship, one of my professors recommended reading Dravidian kinship (which is amazing!) Anyway, in the beginning, Trautman mentions that languages in the same region may adopt innovations from one language, so they may have similar features even if they are in different language families. I was wondering how this actually works. If say click consonants become a feature of one language, what prompts its neighbours to also start using them?

linguisten answered:

Thank you for your kind words! ♥

I do have a slight issue with the claim that languages take over “innovations”. The things adopted are innovations in the recipient languages’ perspectives, but in most cases they are not really new in the source languages. So I suggest we stick with “features” which is neutral in this respect.

So, in most cases features do get borrowed along with words (or “material”, if we want to include units of other sizes). If a language borrows enough words from a language, sooner or later sounds from the donor or source language are entering minimal pair contrasts with native recipient language sounds, thus adding to the distinctions made in it. In some speaker communities, people also prefer to keep the phonological shape of loanwords unadapted, so as to keep the foreign material visibly foreign. 

With the click sounds of southern Africa, there is also another story to be told: Many languages in the region have some kind of avoidance speech style or avoidance lexicon (google ”mother-in-law-language” or “Hlonipha”). In general, such special registers draw their material from neigboring languages, whether these are dialects of the same language or genealogically unrelated, as with Bantoid lgs. like isiXhosa and iziZulu, taking over material from languages of the Khoi-San families. 

If languages are spoken in areal proximity over extended periods of time and there is widespread bilingualism, these languages can enter a sprachbund and become more similar to each other. This is not limited to phonology or lexicon, it also extends to typological features, perhaps even discourse structures and pragmatic rules.