before human could talk, they expressed themselves to each other telepathically. thought is really a feeling. like the most ancient "thought" is when you want to eat something, but don't feel hunger, when you KNOW (feeling-based knowing) that etc:
you want chocolate, and you don't have to have a reason for it, cause your body knows that in this, there's something you need, but you don't have to know it, important part is that you don't think about it with words "i want chocolate", you just KNOW you want it.

when you're having a conversation, logical, philosophical or sth like that, and the other person is talking something, and you have an idea you need to say, which you forget the next moment. you forget it, because you couldn't say it out the moment you knew what to say. that was feeling in which was your idea. if you would have had thought it clearly out by words, you've hadn't forgotten the idea, but you did, because emotions, molecules, won't last long, especially this kind of.

and people read each other's thoughts because it's like an ancient gene opening, which is long ago closed genetically. so some people are open to the brain waves and other send them out.
so words were created, because it allowed complex conversation and it took less energy on thinking...

and it's simpler to understand, what other person is meaning, when talking to them in real life, then mind waves reach to people who have to catch them. like in school, when the teacher is thinking the stuff over, logically, while teaching it, students understand it better. i believe the thought transmission ability is hidden, but exists in every one of us.
that went a bit crazy...

if there was something not logical, let me know.

a few comments would be nice