> > And the fact that *ekw-o- is
> > thematic?
>
> Many perfectly native IE nouns are thematic. What's your point?
The thematic inflection is derived from the athematic inflection, thus
historically late, but since had immobile stress, it was the open
category in which you'd expect loans to be placed; conversely, one
would expect words for inherited things and concepts to be represented
by athematic nouns.