Thanks for posting your thoughts Michael.
So there are 2 theories for language:
1. They originated from one same place - a tribe in Africa - where all other humans come from...
2. They originated from different places - but because the brain patterns are same, they sound the same.
We obviously can't go back in time to find the exact answer. But the present can show us light.
New words.
Slangs.
Margaret Magnus did this experiment once. She made up some words that had no meaning. And asked different people to guess what these words meant. And the answers were very similar.
This is very interesting: How do we understand the meaning of made-up words in Dr. Seuss's books?
http://www.conknet.com/~mmagnus/Suess.html
New words originate from their intended phonetic group.
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I understand what you say about ISness Michael. And I'm not trying to find a unified theory that explains everything. More questions will popup for every question we find an answer to.
But its fun - atleast for me - to find out what makes us tick.
Finding such patterns of language or emotions or facial features will help us become better commnicators too.