I posted this to the Faith and Theology blog's discussion of sin. It sums up ideas I've been working on for several years but never shared with anyone until about a month ago. It doesn't seem to be drawing any responses in its original context, so I'm re-posting it here in a slightly edited form.
I do not think the fall was a matter of mere disobedience. This would suggest that had Adam transgressed any arbitrary command of God it would have had the same effect. Rather, I think the nature of the fall must be found in the particular transgression – eating the fruit of the tree of knowledge of good and evil.
Until the fall, Adam and Eve were naive creatures living in paradise in accordance with their God-given nature (very good, created in the image and likeness of God). Upon eating the fruit, their eyes were opened. At this point, they began to substitute their own judgment, in accordance with their perceived, calculated interests, for the unconscious operation from their God-given nature.
I think the story of Genesis 2-4 can be tied loosely to a real, though not exactly historic (it was more prehistoric) setting. Scholars locate Eden in what is now northern Iraq, southeastern Turkey, or northwestern Iran. This was, not coincidentally, an early locus of the Neolithic Revolution – the shift from the hunter-gatherer mode of subsistence to the more "advanced" lifestyles of agriculture and herding (represented by Cain and Abel).
Evolution suited mankind to be hunter-gatherers – that is our nature. When humans began to manipulate their environments for survival advantages (more for groups than for individuals, as it turned out), they were on their way to adopting new lifestyles at odds with their hunter-gatherer nature.
So Adam and Eve, through their own choices, were forced out of the easy, natural, naive life of Eden, and they had to start working for their living. This complicated their relationships with God, one another, and all of Creation. To the extent that there was a fall within human history, I think this was it, and Genesis records it.
Now I don't really think Genesis 2-4 is about the Neolithic Revolution any more than I think Genesis 12-35 is about the nomadic herding culture of the early second millennium BC. The authors of Genesis were not recording history as an end in itself. But the ancient oral tales on which they based Genesis embodied memories of real settings as the background of their stories.
It would be simplistic to attribute the entire state of human fallenness to the abandonment of hunter-gatherer ways. But this was the "event" that, more than any other, set mankind on a new trajectory that has led to alienation from God, our fellow creatures, and our own nature. It is, then, not surprising that the author of Genesis 2-4 would set the story of the fall of man in that time and place.