[PW] Hypothetical cultural divergence

[Megan Fitzgibbons]

Hello,

I've had a friend ask me a hypothetical, possibly unanswerable question, and I
thought this excellent listserv would be the best shot of giving me direction
toward finding some sort of answer. The question, in my friend's words, is:

If you have a fairly homogeneous group of people that speak a common language
that are then sundered by a cataclysm, following which the different groups
remain fairly insular with little to no communication with each other or
outside cultures, how long would it take the languages to diverge? After, say,
300 years, would they be separate languages or dialects? What types of
differences would one expect? I want fairly pronounced differences of custom
and ritual, but this would no doubt be accompanied by divergence in language as
well.

I believe this is for a book he is writing.

I realize that there are probably not any "real life" anthropological examples
that could provide evidence of this scenario, but it is possible to find
scholarly speculation about the time needed for cultural and linguistic
divergence? I am aware of glottochronology theories, but they are not very
accepted amongst linguists.

Any suggestions will be most appreciated.
Thanks,
Megan Fitzgibbons
MLIS Candidate
megan.fitzgibbons at dal.ca