Peripheral promotes "common innovation" ?

[JoatSimeon at aol.com]

>ECOLING at aol.com writes:

>if major changes are taken as going through a number of stages
>in the process of "drift".

-- that's often the case.  Eg., when two sounds collapse into a single one,
it often creates lexical or morphological ambiguities, which in turn require
other changes.

>BECAUSE WE CAN DETECT THE TIME THEY TAKE FROM THEIR ORIGIN AT THEIR CORE
>UNTIL THEY REACH THEIR FARTHEST EXTENTS

-- actually, it's rare to be able to precisely date this sort of thing --
relatively, yes, precisely, no.  Satemization is a classic example.  One of
the rare instances when we _can_ date sound shifts is the first bunch
distinguishing proto-Germanic, which occurred after the borrowing of some
technical vocabulary to do with ironworking from an early form of Celtic
(which means it had to be after about 700 BCE).  That's valuable because it's
surprising those changes were so late; without that information, they would
have been assumed to be much earlier.

>That is, because the groups at the edges do not have genetically
>related dialects on all sides of them, matters which were really
>dialect-area phenomena, interpreted as common innovations on
>nodes on a tree, will tend to segment off the outermost areas first?

-- what happens is that the peripheral dialects, especially if the
language-group is expanding rapidly, tend to become isolated from
developments in the core.  The archaism of say, Baltic, vs. a vs. say,
Indo-Iranian, is partly due to this.  Or for that matter, in a much milder
way, American vs. British Standard English.