In an interview with Tom Collins , the great(est) mythologist, Joseph Campbell, made some compelling comments on the Cain and Abel story. He saw the Genesis tale of sibling rivalry as symbolic of the tribal competition between farming societies and shepherding ones.
In JC’s words:
There’s a very amusing Sumerian dialogue that appeared about 1500 years earlier than the Cain and Abel story. It’s about a herder and an agriculturalist competing for the favor of the goddess. The goddess chooses to prefer the agriculturalist and his offering. Well, the Jews come into this area, and they’re not agriculturalists, they’re herders. And they don’t have a goddess, they have a god. So they turn the whole thing upside down, and make God favor the herder against the agriculturalist.
The interesting thing is that throughout the Old Testament, it’s the younger brother who overturns the older brother in God’s favor. It happens time and time again. This is simply a function of the fact that the Jews come in as younger brothers. They come in as barbaric Bedouins from the desert, into highly sophisticated agricultural areas, and they’re declaring that although the others are the elders – as Cain was, the founder of cities and all that – they are God’s favorite. It’s just another form of sanctified chauvinism. You understand the view of exclusive religion, don’t you – “You worship God in your way, I’ll worship God in his.”
This is basically an idea of the Bible as political propaganda, a way of positioning one version of God as superior to another. It makes sense that Campbell was so antagonistic towards the Bible and Christianity. He saw both the book and the religion as devoted to a form of spiritual and religious warfare that undermined a basic truth: God is everyone’s.
Campbell’s work centered on the universal experience of the transcendent; that the human capacity and need to experience God is woven into every person’s DNA. Religion, he felt, was more often an obstacle to that experience than a vehicle to it.
 For the entire interview transcript, see here: http://www.context.org/iclib/ic12/campbell/