PS: The article at the head of this thread invokes the church fathers for the literal interpretation of John 6. If the church fathers were wrong about Genesis 1-11 and subject to correction by "new knowledge," then certainly they are subject to correction on all matters and not just some.
Genesis and John are not the same forms of literature. John is quasi-biography; Genesis is world history, not unlike reading Toynbee, with all kinds of theory thrown in. So what is literal in one is not literal in another.