I know these sort of threads can be very speculative but can I throw out something that I've been wondering about since I moved to Ireland and started struggling through a few Irish lessons?
It's about the origin of the word "yes". I was amazed to be told that there is no real Irish word for yes other than the repetion of the verb of the preceeding question , thus: "An bhuil tu thirstig? " meaning   "are you thirsty ?" is answered in the affirmative by "ta im " meaning "I am" .The abbrieviated "ta" is used for "yes". As I say, I was surprised by this ,but then I thought about how my father , a non - Irish speaking Irishman , constructed his replies in English. If you asked him if he was thirsty (which he invariably was) he would say "I am" .You'd never hear him say the word "yes" .
So, I wonder whether other languages might have come to the word "yes" in the same way . Does "aye" come from abbreviating " I am"? What about "Yes" itself ? Does it come from "Je suis" perhaps. And would the French who tend to accentuate the last syllable have got their "Oui" that way?
Or is this just a load of bull?
P.S. Does anyone want to hear my theorey on the origin of the word Bullshite?
Alright,I'll tell youse all anyway. My theorey is that it comes from the Gaelic Beal (pronounced bale) shite. Beal is the Irish for mouth. You used to often hear Irish people talk about gobshite which means the same thing -Mouth shite.