Languages continue evolving and growing.....building or restructuring based on previous knowledge.  You are on target when you state that the boundary line is arbitrary but so also is the point of origin.  My point is that all languages have attributes which indicate both monogenetic and polygenetic.  We'd be much closer at showing a connection between language and species evolution if we could somehow synthesize both elements.
----- Original Message -----
From: Richard Wordingham
Sent: Thursday, July 22, 2004 12:15 PM
Subject: [Nostratica] Re: Monogenetic vs Polygenetic Language

--- In, "nostradafemme" <waluk@......>

> Humans without human parents?  Are you thinking of Odysseus or
> possibly Romulus and Remus?

No.  Consider the first human.  Either that person had no parents,
or the parents (or mother if parthenogenetic) were not human.  The
boundary line is arbitrary, and I am sure there are sensible
biological criteria by which a human may have had non-human parents
and non-human chlidren.

My point here is that language ability is something that has
developed, so although language may have developed rapidly
(Nicaraguan Sign Langauge is often cited as an example), I find it
hard to believe that spoken language appeared fully developed. 
Actually, if we want to argue for monogenesis, we had better
restrict ourselves to spoken language, or else the various sign
languages will probably demolish the claim!

Incidentally, most private languages turn out on investigation to
have an external ancestor of some sort, so they do not disprove