>My question is how verb ablaut in Germanic started in
>Does it have any congeners in other IE branches?
I'm sure Piotr will give a fuller answer, but in brief, yes. They reflect
the old PIE ablaut on different kinds of roots, but messed around with
analogy, simplification, phonological changes and so on, and the vowel
apophony after things like the causative -jan suffix don't help either.
The pattern is best seen in modern German, rather than English. Roughly:
*CiC roots (ei, oi, i) give Modern German ei / i,ie, / i, ie
e.g. beissen, biss, gebissed (short i)
leihen, lieh, geliehen (long i)
English bite, bit
*CuC roots (eu, ou, u) gie Modern German au, ie / o / o
e.g. giessen, goss, gegossen (short o)
fliegen, flog, geflogen (long o)
English fly, flew, flown
*CRC roots (eR, oR, R) give Modern German e, i / a / u, o
e.g. binden, band, gebunden
werfen, warf, geworfen
English swim, swam swum (and sing goes here too)
*CeR roots (eR#, oR#, R) give Modern German ah, eh, i, ie / ah / o
e.g. nehmen, nahm, genommen (short o)
stehlen, stahl, gestohlen (long o)
English steal, stole, stolen
*CeC roots (CeC, CoC, CC) give Modern German e, i / ah / e
Verbs with the suffix -jan show a present in -i-.
e.g. geben (gibt), gab, gegeben (long e)
essen (isst), ass, gegessen (short e)
English eat, ate, eaten
*CHC roots (eH, oH, H) give Modern German a, e, o / u / a, o.
Verbs with the suffix -jan show a present in -e-.
e.g. fahren, fuhr, gefahren
heben, hob, gehoben
English swear, swore, sworn
The class seven verbs were originally reduplicating, but they have been
messed around a bit. They give Modern German a, o, au etc / i, ie /
ge+present
e.g. fallen, fiel, gefallen
heissen, hiess, geheissen
English fall, fell, fallen, hang, hung
Peter