I've recently been informed about the belief that the Genesis account of Adam is not speaking about the literal first man and woman, but a metaphorical retelling about the beginning of the nation of Israel.
One of the proofs that they use is when Cain kills Abel and is forced to leave. He is concerned about a posse coming after him to avenge Abel's death. Since there were only a few children of Adam and Eve at this time, who would he have been afraid of? So God puts a mark on Cain and exiles him to Nod, a populated city to the east. There he takes a wife and they have a child, Enoch, and Cain proceeds to build a city, named after his son, in which others can live.
If the Adam story is about the first humans, the presence of other humans outside of Eden is out of place. We are quite justified in concluding that the Adam story is not about absolute human origins but the beginning of one smaller subset, one particular people.
Has anyone else heard of this theory? It does attempt an answer to the problem of 6000 years of human history in the Bible and the dating of older cultures. It answers the gap between the Bible and evolution. I do see a lot of issues with this view, but it was a new POV that I'd never considered. Here's a link to a detailed article about it on biologos:
http://biologos.org/uploads/projects/enns_adam_white_paper.pdf