A study published by economists at the United Kingdom and Israel noticed that history's more advanced societies cultivated more grain crops like wheat and barley, while less advanced society's depended on root crops like potatoes and manioc. Root crops aren't any more difficult to grow, and tubers have a much shorter lifespan than grains, which can be stored for long periods of time. This, however, allowed grains to be transported very easily, and they were often at risk of being stolen. Researchers believe this is what caused the politics of grain-central societies to develop.

But the fact that grains posed a security risk may have been a blessing in disguise. The economists believe that societies cultivating crops like wheat and barley may have experienced extra pressure to protect their harvests, galvanizing the creation of warrior classes and the development of complex hierarchies and taxation schemes.

In ancient Africa, Asia and Europe, for instance, societies had access to a large catalog of different grains, including barley, sorghum, wheat and rice. They also had access to one root crop, the yam. And in the ancient Americas, societies had access to one kind of grain, corn and three different kinds of root crops — white potatoes, sweet potatoes and cassava.

When the economists examined that agricultural data, they found that more fertile regions did not necessarily yield more complex societies. The crucial factor wasn't the amount of food that a society could produce; it was the type of food they chose as their main crop — grain or tuber.

Head over to The Washington Post to read more.