In fact, I had already read Quinn's most famous book, Ishmael, a novel that is structured as a Socratic dialogue between a human and and a gorilla. I must admit, though, that I had mostly forgotten it.
There are a number of essays and other materials on the internet that present Quinn's thoughts about the likely future of our human civilization, and that seem to me to raise interesting questions about when the "human world" separated itself out, as something different from the world of Nature.
Quinn tends to think that the tribal bands depicted in The First Thanksgiving, at a time when they were just about to be displaced, may have had some important information that got lost, with the consequence that we're "lost," now.
Having read some of this free material from the internet, I can now echo the recommendation I got on the "Come Hungry" tour. Here's a sample I thought provocative:
In fact, to the authors of the stories in Genesis, it looked as if their brothers to the north had the bizarre idea that they had eaten at God's own tree of wisdom and had gained the very knowledge God uses to rule the world. And what knowledge is this? It's a knowledge that only God is competent to use, the knowledge that every single action God might take--no matter what it is, no matter how large or small--is good for one but evil for another. If a fox is stalking a pheasant, it's in the hands of God whether she will catch the pheasant or the pheasant will escape. If God gives the fox the pheasant, then this is good for the fox but evil for the pheasant. If God allows the pheasant to escape, then this is good for the pheasant but evil for the fox. There's no outcome that can be good for both. The same is true in every area of the world's governance. If God allows the valley to be flooded, then this is good for some but evil for others. If God holds back the flood then this too will be good for some but evil for others.
Decisions of this kind are clearly at the very root of what it means to rule the world, and the wisdom to make them cannot possibly belong to any mere creature, for any creature making such decisions would inevitably say, "I will make every choice so that it's good for me but evil for all others." And of course this is precisely how the agriculturalist operates, saying, "If I scour this plain to plant food for myself, then this will be evil for all the creatures that inhabit the plain, but it'll be good for me. If I raze this forest to plant food for myself, then this will be evil for all the creatures that inhabit the forest, but it'll be good for me."
What the authors of the stories in Genesis perceived was that their brothers to the north had taken into their own hands the rule of the world; they had usurped the role of God. Those who let God run the world and take the food that he's planted for them have an easy life. But those who want to run the world themselves must necessarily plant their own food, must necessarily make their living by the sweat of the brow. As this makes plain, agriculture was not the crime itself but rather the result of the crime, the punishment that must inevitably follow such a crime. It was wielding the knowledge of good and evil that had turned their brothers in the north into farmers--and into murderers.
But these were not the only consequences to be expected from Adam's act. The fruit of the tree of the knowledge of good and evil is harmless to God but poison to Man. It seemed to these authors that usurping God's role in the world would be the very death of Man.