>...bread calls some resonant cord deep within that goes far beyond basic
food.

What you are referring to is cultural--not biological--programming. Marvin
Harris showed in CANNIBALS AND KINGS that the forms of the classic religions
(Christianity, Hinduism, etc.) are directly affected by the kinds of staple
foods eaten by the people adhering to those religions. If you don't come
from a culture in which grain is a staple food, why would grain "call some
resonant cord deep within?" If I cheat by eating a piece of bread or a piece
of pizza, I don't do it because I crave the food physically but out of
nostalgic longing for a favorite food. This is obviously learned behavior.
When I truly crave a food, it's always a food that is natural. I doubt that
bread would call out to an Arctic Inuit or an aboriginal Australian who'd
never considered it as a possible food source.

Troy G.