CaoimhínSF wrote:
Actually, what you say may be correct, and I misstated how umlaut works/worked (at least in German). Using the German example, when Mann was pluralized as "Manner" (or something like that, originally), the "e" sound was "anticipated" by speakers, and came to color the "a" sound and result in the umlaut. So, as with séimhiú and urú in Irish, the sound changes came first, as simply a result of (rapid) everyday speech, and only acquired a grammatical aspect much later, once the Germanic speaking peoples had settled down and acquired writing and the concept that they even had a grammar. One interesting aspect of the Germanic languages is that, while the West Germanic (German, Dutch, English, etc.) and North Germanic (Scandinavian) languages all developed umlaut sounds, it apparently never happened in the (now extinct) Gothic branch of the family.
It has nothing to do with the acquisition of writing and everything to do with the loss of the conditioning environment. Take Old English, for example. It's the first West Germanic vernacular to be written and we find umlaut alternations already in place in the earliest texts. The plural of Old English
fót "foot", for instance, is written
fét, with no trace of the second syllable responsible for the change. (The reconstructed Common Germanic forms are, respectively, *fōts and *fōtiz.) Remember that at the time, the vast majority of English-speakers were completely illiterate. They had no more notion of how these nouns were being rendered in writing that you would have of what they look like in binary.
Confusingly, the Old High German plural of
man was actually
man. It wasn't until later that it was treated like an i-stem and pluralised
men and later still that it adopted the
-er plural ending from the neuter z-declension. (An example of noun which etymologically belongs to this declension is
lamb, plural
lembir. [Mod. Ger.
Lamm,
Lämmer.]) That's one of the fun things about umlaut in Germanic: it goes rapidly from being a phonetic peculiarity of certain declensions to a grammatical alternation which gets extended by analogy. It's also fun to compare what happens in different branches. Swedish, for instance, didn't get nearly as carried away in this respect as German.
Man pluralises to
män and
fot to
fötter, but the plural of
lamm is
lamm, not *
lämmer.