Eric Christopherson wrote:

> I've wondered many times, so I guess I might as well ask, in case anyone 
> knows:

> 1. Do any languages have their 1st-/2nd-/3rd-person pronouns 
> transparently related to their proximal/medial/distal demonstratives?

My loglang, Cenyaci, has a phonosemantic foundation where there is a 
relationship between them.

SASXSEK doesn't relate them to demonstratives but there is a 
relationship between basic prepositions, pronouns and adverbs of 
time.  It's something I started early in the development but it's no 
entirely complete because it proved to be impractical, though the 
legacy of it still exists.

	M = orgin
	mo	= I, me
	mu	= from
	mi	= former, previous
	ma	= because

	F = destination
	fo	= you
	fu	= to(ward)
	fi	= later, future
	fa	= then

The third person is "lo", but it was a late addition.  Originally I 
had no third-person and instead relied on demonstratives.  I still 
recommend using demonstratives instead of "lo" in situations where 
there may be some ambiguity.

> 2. Do personal pronouns ever derive historically from demonstratives, or 
> vice versa?

ISTR quite a few examples of natlangs that have 3rd persons 
orginating from demonstratives, likewise for definite articles.

> 3. Does person/number/gender agreement marking on verbs, or possessive 
> marking on nouns, ever derive from demonstratives?

I can't think of any example off hand.