Still another theory is that the farms were in the lowlands near the oceans and were covered by glacial melt, then revived later on lands of higher elevation which is what we find today. Not a mystery.
There must have been an ancient and relatively high civilization during the last Ice Age that was catastrophically destroyed. That civilization developed farming, bread making, domesticated livestock, dogs, and cheetahs. That civilization is now covered by 300 to 400 feet of ocean.