In summary, the conversation discusses the idea of artificial adaptations outpacing natural adaptations. The participants agree that there is no such thing as "de-evolution" and that artificial adaptations, such as agriculture, have already greatly outpaced natural selectional pressures. They also discuss the potential consequences of this, including dependence on artificial supports and potential harm to the health of crops and humans.
None of them. You can't reverse natural adaptation. You can have continued adaptation in the opposite direction (like if it suddenly became desirable to be a lump of primordial slime) but there is no such thing as deevolution.
But that is not deevolution. Evolution is movement towards local highs of survivability. All you do is change the landscape of survivability. You do not reverse the process itself. Do you see the difference?
Not quite. I am saying that the discovery of agriculture itself has already greatly outpaced natural selectional pressures. With agriculture, man is immediately freed from the typical requirement to evolve lean, mean hunters, and with time, the high sense of reliability agriculture provides lessens the requirement for tolerant physiques. If after a few million years of agriculture, we decide to suddenly stop, we would not be able to survive in the same competitive niche that we once did, that we would still be in if we didn't begin farming.
It seems ironic that agriculture, an immediate adaptation toward man's prosperous civilizations and increased survival, would cause him to alienate natural competition, the health of his crops and eventually his own well being.