Linguistic KB (was Re: Original Dravidian Homeland)

[Das Devaraj]

On Tue, 15 Jun 1999, Ferenc Ruzsa wrote:
> considering the speed of linguistic change, we cannot meaningfully talk of
> any language family before ca. 8 000 BCE. (I joust doubled the period we
> have some knowledge of.)

So that puts 4000 BCE (or 6000 years ago) as the upper limit
of the currently known linguistic knowledge base. Is there a
way to quantify the level of certainty (mentioned in the email
quoted as "some knowledge") of this knowledge base?

I have noticed an _apparent 6000 year bias_ in Indology,
Egyptology and in other areas as well, in dating monuments,
events, activities etc. Is the above mentioned upper limit
the reason?

das devaraj