Nostratic has been a topic under discussion for a long time
and
presently is an active topic on many discussion groups.
Your point
about people who evolved in different places speaking
a different language is
as plausible as the antithesis which amounts
to people evolving in one
specific area (say OoA) and then
dispersing.
I like to think of
languages as different dialects whereby the speaker
of a definite "down
Maine" accent cannot understand someone speaking
Creole from New
Orleans. Both languages are considered to be
indigenous to America yet
both New Orleans and Maine were settled
by immigrants who came from the
continent.
Hope this helps.
Gerry Reinhart-Waller
www.home.earthlink.net/~waluk