The Origins of Faith Healing

So, I was watching a few clips of James Randi today, and I heard him say something rather interesting--in particular, that part of the reason that faux-psychics are so successful is because of the media. In retrospect, I think he might've been referring to the very specific programs of the psychics, but there's a more general cultural appreciation of these ideas, too. In fantasy and also in the Bible, and even earlier than that in ancient cultures.

So, my questions, then, are these:

1. In these ancient cultures, before there were any previous mythoses to build upon, how did spiritualism emerge?

2. How was it maintained--did the ancient shamans who probably grew up believing in these things have to be let in on the big secret that it was all a lie, and taught the appropriate techniques to fake it? Or was confirmation bias all that was necessary to maintain the illusion?

Thanks in advance for the input.