@star damn, I fell asleep halfways through this (time zones...), so here's a very late question:
I've read that the form of corn that they grew was very different to what exists today. Much like wheat and spelt/dinkel - we bred a different kind of wheat, that's much less healthy. Spelt/dinkel wheat has more fibre, more vitamins, but is less... like candy. So we don't grow it that much.
The difference, as I've heard, is that while spelt still exists, the older forms of corn has been lost. There's an obvious possibility of racism in this neglect, but I don't know much about this...
Is this anything you know more about?