>Why did all IE branches except Hittite drop the laryngeals, leaving only
traces in the
>vowels?
That's a fascinating question. But there are more traces than just in the
vowels - sufficient for us to know that each dialect dropped the laryngeals
independently.
(a) Skt needs laryngeals early on to explain various things (eg aspiration,
scansion, present tense formations, vowel length);
(b) Latin needs laryngeals early on to explain the apparently irregular
perfects in -ui (all of which without exception [I think!] are on stems with
laryngeals - but the -u- perfects are not even proto-Italic!
(c) Greek needs them likewise.
So why did they all decide that laryngeals were just for Christmas?
Peter