Re: Ablaut and the Mid IE vowel system

I am tempted to suppose that:-
The original vowel was "e".
It (sometimes or always) changed very early to "o" after the stress,
so long ago that that pattern was much obscured by analogical
levellings even before the IE language area broke up.
Unstressed vowels often dropped, causing zero-grading.
Where analogy tried to force zero-grading in a place where the result
would be unpronounceable, assorted sorts of helping-vowels got in.
The H2 laryngeal tended to change nearby "e" to "a".
The H3 laryngeal tended to change nearby "e" and "a" to "o".
Later, except in Hittite, all laryngeals dropped, often with
compensatory vowel lengthening.
Then more analogical levelling and casual extensions of apparent rules
happened.

To use a metaphor, to those trying to reconstruct old forms of
languages, it is to be regretted when the bulldozer of Analogical
Levelling drags its dirty iron tracks and blade through a language's
internal linguistic "archaeology", destroying evidence, and fogs out
phonetic laws with the blastings of its dirty outsized exhaust pipe,
but it happens.