All Language is Local

When you've studied or researched language contact situations, you are used to thinking of the ways that languages become more similar. They share words, sounds and eventually even word patterns. These ideas are so common, that I had come to think that interactions between speakers of different languages always makes those two languages more alike.

Then there's this, taken from a grammar of the Californian language Cupeño:

The many unusual typological properties of Cupeño, especially when it is
compared to other Uto-Aztecan languages, suggest that it has undergone what
Thurston (1987, 1989, 1992) called “esoterogeny,” a process whereby a language
accumulates strategies for distinction from its neighboring languages.

In other words, small linguistic groups, surrounded by similar languages, may actually start speaking differently in order to distinguish themselves from their neighbors. (The above, by the way, is taken from Jane Hill's Grammar of Cupeño, published online by the forward thinking peeps of the University of California system. You can read it here).

After recovering from the initial deeply-held-belief-detonation, I got to thinking about local language. It does seem that people take pride in their local language idiosyncrasies: odd pronunciations, "pop" versus "soda," "bubbler" versus "water fountain," that sort of thing. People want to distinguish "their" in-group from that of other people, and language is a likely target.

So, I'm appealing to all you language types out there. Anyone else know of examples of "esoterogeny?" This is an exciting flip-side to language contact situations.