“The argument depends on the differences between how grains and tubers are grown. Crops like wheat are harvested once or twice a year, yielding piles of small, dry grains. These can be stored for long periods of time and are easily transported — or stolen.

Root crops, on the other hand, don’t store well at all. They’re heavy, full of water, and rot quickly once taken out of the ground. Yuca, for instance, grows year-round and in ancient times, people only dug it up right before it was eaten. This provided some protection against theft in ancient times. It’s hard for bandits to make off with your harvest when most of it is in the ground, instead of stockpiled in a granary somewhere.”