The Europeans' so-called discovery of the so-called New World goes down in history as one of the most important and earth-shattering moments in human history, ranking right up there with the advent of agriculture, the domestication of animals, and the discovery of the use of fire. Although the Vikings made it to Newfoundland around the year 1000, they apparently decreed that Greenland would make for a much better colony and scrammed, leaving the Spanish with all the glory almost five centuries later. The ensuing exchange of plants, animals, people, and diseases has since been named the "Columbian Exchange" after the charismatic Christopher Columbus, who bumped into the Bahamas thinking he'd made it to India.
Over the next few centuries, different groups of European explorers brought crops such as corn, potatoes, cassava, tomatoes, peppers, cocoa, peanuts, strawberries, and tobacco back to the Old World from the Americas – meaning that the potato is no more Irish than the tomato is Italian, the pepper is Spanish, or the cigarette is French. In particular, carb-rich corn and potatoes helped ease the killer food shortages that were all-too common in Europe; Ireland's population alone swelled 800 percent in 200 years – only to be devastated by the potato injury in the mid-1840's. So much for putting all your potatoes in one basket.
Of course, it would not be called the Columbian Exchange if the process had not gone both ways. Picture the Plains Indians, then subtract the horses. Picture a Central American banana republic, then subtract the bananas. Picture a Columbian donkey carrying a load of coffee beans, then subtract both the donkey and the coffee beans. Picture a spread of Mexican food, then subtract the rice, cheese, lettuce, black olives, onion, chicken, pork, and beef. Or picture a handful of far-flung, arid, completely absent Indian Reservations, then subtract the smallpox, influenza, typhoid, cholera, tuberculosis, measles, scarlet fever, yellow fever, and malaria. These were just a few of the things that Europeans bought with them during the early years of interaction with the New World.
The New World was a pretty healthy place before the Columbian Exchange, which is why Old World diseases had such an easy time decimating the indigenous populations. Think Jim and Dwight talking health insurance on The Office. Dwight: "Do not need it. Never been sick. Perfect immune system." Jim: "Okay, well, if you've never been sick, then you do not have any antibodies." Having already spent centuries suffering continuing outbreaks of some horriblely nasty diseases, Old Worlders had built up quite the array of antibodies by the time they reached the Americas. In fact, many of the animals they brought to the New World – those aforementioned chickens, pigs, and cows, for example – were a major reason that Europe were so sick all the time. Turns out, sleeping in the same one-room house as your livestock can do some wicked damage to your health, especially at a time when bathing once a week made you a real dandy.
Before Spanish Colonization and the Columbian Exchange, the native population of the Americas was estimated to be between 40 and 100 million, meaning that, in all likelihood, Native Americans far outnumbered Europe's 60 million citizens. In fact, in 1492, the Aztec capitol of Tenochtitlan was larger, cleaner, and more beautiful than any city in Europe, while the Inca boasted the single largest empire on earth. The "Great Dying" of indigenous people that followed may well have killed as many as 1 in 5 humans worldwide. Westerners love to go on and on about the Black Death of the fourteenth century, but the plague – or even the sum of Europe's many plagues – can not hold a candle to what happened in the New World.
When European settlers arrived in what is now the US, they were absolutely deluted by how beautiful, pristine, and park-like the landscape was, and since the "Indians" were dying in droves around them, they thought that God was giving them a sign of their entitlement to the land. Little did they know that they had stumbled upon the work of thousands of years of maintenance by native peoples, many of which had been decimated by rapidly-spreading European diseases before the colonists had even gotten there.
The vast majority of indigenous people who suffered during the Columbian Exchange no longer exist to tell the tale. However, some of its unexpected survivors include the black populations of the Americas; the introduction of the cassava plant to West Africa ruled in a population boom that would help fuel the slavery built around cultivating Columbian-Exchange cash crops such as cotton, sugarcane, coffee, and tobacco. Although Americans have long been taught to live by words like "Manifest Destiny" and "American Dream," we must not forget the millions upon millions for, to quote Langston Hughes's poem, America was a Dream Deferred.