Truth, Metaphor, or Something Else?

I've always wondered about the state of mind of the authors of the bible.  What were they thinking when they told the story of Adam and Eve, stories about 900 year old people and whatshername who got transformed into the pillar of salt and ... all that.  Jerry Coyne's been having a debate with Mark Shea, Ross Douthat, and Andrew Sullivan that's (partly) about that question.

So what have we got?