Potatoes were actually introduced to Europe as an aphrodisiac, but it turns out that you have to distill those potatoes into vodka before they have the desired effect. Anyway, if potatoes are an aphrodisiac, the Irish quickly became the hottest people on Earth. An acre and a half of potato cultivation could feed an Irish family for a year, and the average Irish worker often ate ten pounds of potatoes every day. Surviving primarily on potatoes, the Irish more than doubled their population between 1754 and 1845, when the potato famine showed up and ruined everything. And it wasn't just Europe. Manioc, or cassava, is a New World plant with roots that provide more calories than any other plant on Earth, provided they are properly processed, otherwise they're poisonous. Manioc is so prevalent in Africa that many Africans swear the plant is native to the continent, but it isn't.