--- In nostratic@yahoogroups.com, "Richard Wordingham"
<richard.wordingham@...> wrote:

> 1) For the thematic vowel, /o/ before voiced consonants, /e/ before
> voiceless consonants, so the nominative singular animate ending
> should be *z.

I was giving this a bit more thought and I kinda like the idea. It's
not necessary to assume a *z, just that word finally *s is voiced.
Also the e~o alternation may occur only in certain unstressed
positions. This would mean that stress was perhaps originally fixed
on the initial syllable.