The Columbian Exchange was the process of transferring various biota—livestock, germs, and plants—between the Old World and the New, setting in motion massive ecological and demographic changes in both hemispheres, particularly in the Americas.
Historians have only recently begun to unravel the story of what the scholar Alfred Crosby labeled the “Columbian Exchange,” a stage in what he later described as “ecological imperialism.” This story replaces an older version, which explained Europe’s successful invasion of the Americas as the result of supposedly more advanced cultures and superior technologies. The idea of the Columbian Exchange, however, takes into account how the age of exploration remade the environment of the planet, particularly in exposing the Americas to new plants, livestock, and DISEASE. For example, on the second voyage of CHRISTOPHER CoLUMBUS to HISPANIOLA in 1493, the shipping records list the variety of plants, animals, and colonists that he brought with him: “seventeen ships, 1200 men; seeds, cuttings, and stones for wheat, chick-peas, melons, onions, radishes, salad greens, grapevines, sugarcane, and fruit trees; and horses, dogs, pigs, cattle, chickens, sheep, and goats.” Unintentionally, the expedition also brought weeds, rats, and germs. The story of the Columbian Exchange explores how these biological factors— many unintended and their consequences often ignored— were significant, even pivotal, in Europe’s success in the New World. And while the Columbian Exchange refers primarily to exchanges between Old World and New, this global interaction also had important consequences for Africa as well, especially for its burgeoning Atlantic SLAVE TRADE.
One important component of the Columbian Exchange was the transfer of plants between the global hemispheres, both food crops and weeds. Root vegetables from the Americas were especially significant for agriculture: The potato, from South America, spread through northern Europe; the cassava, also from South America, spread through Africa and Asia; and sweet potatoes from the Americas became important crops in Africa as well. This exchange also involved grains. Maize (see CORN) from the New World continues to be a vital crop grown all over the world today. Europeans also introduced wheat and other grains of African and Eurasian origins. In addition, Europeans brought peach, pear, orange, and lemon trees as well as chick peas, grapevines, melons, onions, radishes, and various other fruits and vegetables. One unintentional consequence of this exchange of plants was the introduction of new weeds. On the whole, European weeds and grasses invaded the Americas, rather than vice versa. Only a few American weeds, such as horseweed and burn-weed, have managed to survive in Europe, and not in great numbers. In contrast, in the Americas aggressive European weeds, including clover, plantain, and the dandelion spread rapidly, outcompeting the native plants and modifying many ecosystems.
One reason that weeds and nonnative grasses spread so widely in the Americas was the simultaneous introduction of livestock, another important component of the Columbian Exchange. Cattle, HoRSEs, and pigs adapted very quickly to New World grasslands and soon experienced population explosions. Upon arriving on islands in the Caribbean and South America, the Spaniards, for example, simply set the livestock loose to multiply and to provide protein and labor resources for their further invasions into the northern Americas. This intensive overgrazing destroyed native ground covers, making it possible for imported European grasses and weeds to establish themselves in place of native plants. European weeds and grasses quickly gained strong footholds in these endangered ecosystems. The omnivorous tusked European swine, especially, ate everything in sight, not just the plants, and quickly adapted to almost every ecological niche in the Americas. In the Antilles the swine devoured the local Indians crops of manioc roots, sweet potato, and fruit. They also decimated the populations of lizards and various small wildlife. Eventually, from Brazil to Virginia to New England, wild pigs ranged everywhere, creating havoc among local flora, fauna, and indigenous peoples’ crops as they went.
Not only did Europeans introduce domestic livestock to the New World, they brought rats from Old World seaports as well. Rats devoured many of the grains and other stores on board ships on the passage across the Atlantic. Upon landing these rats came ashore with the remaining supplies and then swarmed through the New World. Rats fed on and competed with various small animal populations and also spread disease, such as the bubonic PLAGUE, a devastating parasite carried through the bite of the rats’ accompanying fleas. Cats, dogs, and European rabbits went wild in the Americas as well as all sorts of insects, including the honeybee.
By far, the most devastating result of the Columbian Exchange was a dramatic reduction in the Native American population throughout the Americas. When the first humans crossed the Bering land bridge into North America, probably between 12,000 and 14,000 years ago, the freezing temperatures destroyed many Old World microorganisms that had traveled with them. This “cold funnel” removed diseases such as measles, smallpox, and influenza from the human population that migrated into North and South
America. In addition, Europeans living in close contact with domesticated animals evolved new diseases. These processes turned out to be a mixed blessing; while precontact Native Americans never had to experience anything like the 14th-century bubonic plague epidemic that killed between 60 and 90 percent of the population in some areas of Europe, they also did not develop the natural immunities to Old World diseases. Frequent exposure to disease microorganisms serves to boost the immune systems of the humans who survive epidemics, offering at least some protection from future outbreaks of the same illness. Without a history of exposures, Native Americans were left biologically defenseless when Europeans arrived and, usually unintentionally, began spreading disease. Many scholars have argued that the disease exchange was to some extent two-sided, with the New World sending syphilis to the Old World. There is no clear consensus as to the origin of syphilis, however, and more research needs to be completed before we can determine whether this venereal disease existed in Europe before the first sailors began returning from the Americas.
While estimates on the precise population decline are still hotly debated, it is clear that the impact of European diseases was a crucial component in the success of early colonization efforts. Studies of archaeological remains suggest that there was a total indigenous population of at least 40 million or 50 million people in the Americas before contact. Whatever the precise numbers, the interloping Europeans were vastly outnumbered as they began their conquest of the New World. But shortly after Columbus arrived, diseases devastated the most populous regions of the Americas, allowing hundreds of Europeans to defeat millions of Indians. Hernan CoRTES was able to conquer the city of Tenochtitlan in 1521 in large part due to an epidemic that decimated the Aztec capital. In Virginia, the Algonquian Indians expressed their fear of the “invisible bullets” that seemed to strike down the Native population while the English visitors were mysteriously unaffected. The physical destruction was matched by an immeasurable psychological toll as Native Americans struggled to explain the debilitating diseases that had suddenly appeared. Some fragmented Native American groups sought new alliances with the Europeans, who appeared to be able to control the deadly diseases. For their part, the English were convinced that the epidemics were a sign from God that the lands were intended for their use. The population decline in many areas was enormous—those that did not die from disease often fled their native lands in a desperate attempt to avoid the illnesses. Unfortunately, these efforts at escape only served to spread disease microorganisms into regions the Europeans had yet to visit. In Mexico alone, the population declined from approximately 30 million in 1519 to 3 million by 1568.
In addition to the transfer of plants, livestock, and diseases, the Columbian Exchange also set the foundations for a new global market. Europeans extracted raw materials from the Americas and then used the New World to expand their markets for manufactured goods. This new pattern of business had global effects. Europeans took GOLD and SILVER from mines in the Western Hemisphere that boosted their economies and increased Europeans’ trade with Asia. The specific effects of this cycle are not yet totally clear, but at the least it seems likely that this transfer of raw materials eventually influenced the rise of certain families and classes in Europe’s economic and social structures. These manufactured goods were also important in European exchanges for African slaves, forming the roots of the Atlantic slave trade that would flourish especially in the late 17th and 18th centuries. This increased trade and exchange of wealth particularly worked to the benefit of Europe, even providing the basis for the later Industrial Revolution.
The model of the Columbian Exchange as it is commonly used can, according to some scholars, reduce the responsibility of European colonizers for the demographic catastrophe in the Western Hemisphere. That is, since the model hinges on the spread of new pathogens to populations where the diseases they produced did not exist, it is unethical to fault the newcomers for introducing infectious agents that they themselves did not know they carried. While it is true that early modern Europeans were unaware that they unwittingly transported ailments to American peoples, a new way of understanding disease transfers, based on advances in the clinical understanding of infection, now reopens the question of the relationship between demographic crisis and European actions. (See the entry on DISEASE for an explanation of the new theory.)
This story of the Columbian Exchange, then, revises much of our previous understandings of the interactions between Europe, Africa, and the Americas during the 16th century. Without question, the transfer of plants, livestock, and especially diseases facilitated the European conquest and colonization of the Western Hemisphere. Yet while the biological and demographic consequences of the Columbian Exchange devastated Native Americans, Europe’s population grew as a result of the cultivation of American foods, especially the potato, the tomato, and maize. Scholars are continuing their efforts to understand how the transfer of these nonhuman entities shaped the history of the Atlantic basin during the early modern age.
Further reading: Alfred W. Crosby, Ecological Imperialism: The Biological Expansion of Europe, 900-1900 (New York: Cambridge University Press, 1986); David S. Jones, Rationalizing Epidemics: Meanings and Uses of American Indian Mortality since 1600 (Cambridge, Mass.: Harvard University Press, 2004); Kenneth F. Kiple and Stephen V Beck, eds., Biological Consequences of the European Expansion, 1450-1800, An Expanding World, vol. 6 (Aldershot, U. K.: Ashgate Publishing, 1997); John W. Verano and Douglas H. Ubelaker, eds., Disease and Demography in the Americas (Washington, D. C.: Smithsonian Institution Press, 1992); Herman J. Viola and Carolyn Margolis, eds., Seeds of Change: Five Hundred Years since Columbus (Washington, D. C.: Smithsonian Institution Press, 1991); Sheldon Watts, Epidemics and History: Disease, Power, and Imperialism (New Haven, Conn.: Yale University Press, 1997).
—Maril Hazlett —Melanie Perreault
World History
