As you fill your grocery cart with food for Thanksgiving, pause for a minute and think about where that food came from. I don’t mean is it local or organic or hormone/pesticide /gluten-free—I mean is it Old World or New World? On what continent did that food evolve?
During the age of exploration, Europe was called the Old World, along with its continental neighbors in the Eastern Hemisphere, Africa and Asia. The Americas, North and South, were the New World. Australia is sometimes lumped with the New World, too. This is a geographical and historical division. But the Old World/New World distinction also speaks to the biology of the regions. Organisms that originated on one continent are different from those that evolved halfway around the world. And for the most part, living things—animals, plants, microbes—didn’t travel from one hemisphere to the other without human help.
The sweet potato/yam mash-up is my favorite example of an Old World/New World confusion. Sweet potatoes originated in Central or South America, and are the starch-filled roots of plants related to morning glories. Yams, however, are completely different. They originated in Africa, and are actually the stem tissue of a monocot plant. Most of what we see labeled as “yams” in our grocery stores are actually sweet potatoes. The common name confusion started centuries ago, when African slaves brought the name—but not the vegetable—to the Americas with them. Yams don’t grow in temperate North America; they need a tropical climate, like Africa, Asia, or the Caribbean (where they’ve been imported).
So let’s go through your grocery cart. Your soon-to-be-mashed potatoes? New World—they originated in South America. (And the Irish Potato Famine occurred long after potatoes were imported to Europe.) The corn in your cornmeal stuffing originated in the New World, too. Your turkey is from the New World, but the soy in your tofurkey is native to Asia. And the apple in your apple pie is not at all American—it originated in Europe.