I have heard it suggested that the conflict between Cain and Abel illustrates the conflict between life on the move and the settled life. Most early societies were either herding groups living by animal husbandry, and settled agricultural groups. The story of Cain and Abel would suggest that G-d preferred his people to keep on being shepherds and goatherds – Yahweh preferred the animal sacrifice, and disciplined Cain by sending him off to wander.
This preference of G-d for people who weren’t settled shows up again in the dietary laws. When archaeologists discover pig bones at a site, it is a sign that those particular people had settled down and become immobile. It’s hard enough to herd goats and sheep. Herding pigs? That’s right out. Once pigs are on the scene, you’re staying put. Shellfish are also tough to manage for mobile groups; bad clams can kill you.
Even for those of you who don’t believe a deity has anything to do with the directions given to the Jews, it’s still an interesting story, recording the cultural competition between the two ways of life. For believers, it raises another interesting question: why did G-d prefer to keep His people on the move so much of the time?