Just a couple of afterthoughts:
At the time the Greek alphabetic spelling conventions were developed
(say, ca. the 8th BC) the pronunciation of <u> must have been back.
The diphthongs <eu> and <au> were pronounced [eu] and [au] even after
[u] had shifted to [y] (the IPA transcription of the rounded front
vowel, as in French lune [lyn]) in other positions, and the diphthong
<ou> underwent smoothing and then raising to [u:] during the
Hellenistic times, but was never fronted.
The fronting took place in the Attic/Ionic group of dialects and was
inherited by the Hellenistic koine, which had mostly Attic features,
and subsequently (with eventual unrounding of [y] to [i]) by
Byzantine and Modern Greek (so that "upsilon" and "iota" are now both
pronounced as /i/), but there is evidence that other dialects
retained a back quality of <u>.
Piotr
--- In cybalist@..., "caraculiambro" <gpiotr@...> wrote:
> Greek <u> "upsilon" (short and long alike) became fronted (like
Latin
> <u> in French) and eventually unrounded, merging with /i/. The
merger
> proves that the fronting was complete at the time. Of course the
> change was gradual, and the first step was the centralisation of
> former /u/, whose slot in the vowel system was taken by the former
> diphthong /ou/, which developed into close /o:/ and eventually
> into /u:/. In a diachronic perpective (written records of Ancient
> Greek span a period of about two millennia), Greek vowels are not
> nailed down to their "ideal" positions but move to and fro in the
> vowel space as the system evolves.