I know of Sechelt having /e/, /a/, /o/, [log in to unmask]
[i] and [u] are allophones of /@/

>>> Paul Bennett <[log in to unmask]> 11/18 4:28  >>>
Barry Garcia wrote:
> Is there a reason for /i u a/ being most likely in a three vowel system?

Look at where they are on the vowel chart - at the extreme edges.  The
further apart two vowels are from each other, the easier they are to
distinguish.  /E a O/ would be inefficient because they are too close to
each other, /E/ and /O/ would tend to rise to higher levels to be more
easily distinguished.  Remember, clarity and lack of confusion are
important factors in language design.  Features which can create
confusion tend to be eliminated.

I'm a bit out of my depth here, but doesn't PIE have a two-vowel system =
with /E/
and /O/? (or is it /e/ and /o/?)

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