The Exchange of Plant and Animal Species Between the New World and Old World

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The Exchange of Plant and Animal Species Between the New World and Old World

Overview

When Europeans reached North America's shorelines in the late 1400s and began to explore the continent's interior in the 1500s, they saw the vast land as a source of new plants, animals, and minerals for them to use and to transport back to Europe. As they colonized this New World, they also brought with them many familiar plants and animals for food, farming, and other purposes. This exchange of species between the two continents had positive and negative effects, and they continue today. On the positive side, the exchange introduced what would become important agricultural crops and beneficial animals to both continents. It also, however, expanded the range of species that carried disease and competed with beneficial native species, and it also permanently changed the face of each continent.

Background

When the Europeans landed in the New World in the late 1400s and early 1500s, North America was an untamed wilderness filled with mysterious flowers, trees, birds, and mammals. Christopher Columbus wrote of the scent of a breeze from the shores of North America as "the sweetest thing in the world." Other explorers similarly reported of the biological wealth of this unknown continent: flocks of birds so thick they blocked out the noonday sun; fishes so large and numerous that they sometimes hampered river navigation; enormous stands of pines, oaks and chestnuts; and meadows so vast that their boundaries were beyond sight.

The explorers were in the New World to find items of economic benefit to their countries and saw the new land as a resource to be exploited and a wilderness to be tamed. The first explorers to North America came with hopes of finding a passageway to the East Indies, and eventually opening a lucrative trade route with the spice-rich islands. Although they were unsuccessful in this regard, they were able to discover many new and useful plants and animals, which they were only too happy to transport back to their homelands.

One successful transplant was corn. It was first cultivated in the Americas more than 5,000 years ago, by the Maya, Aztec, and Inca. Called ma-hiz by the Indians of Central America, its name was later corrupted to "maize" in Europe. By the time the New World was discovered in 1492, corn had spread across the continent as far north as Canada. Columbus is credited with bringing corn back to Europe from his first voyage, where it quickly became a popular crop.

It is believed that the native Indians also offered Columbus tobacco, but he discarded the gift as no more than fragrant dried leaves. Shortly thereafter, explorers Rodrigo de Jerez and Luis de Torres witnessed the actual smoking of tobacco while they were in Cuba. Jerez became a smoker himself, but when he returned to Europe and engaged in his habit, he was imprisoned by religious zealots for what was seen as an unholy activity. Nonetheless, smoking caught on in Spain while Jerez was serving his seven years of incarceration.

Potatoes were actually imported to both North America and to Europe from their native South America. In the late 1500s, European explorers discovered potatoes in South America and transported them to Spain, where the plants spread throughout Europe. Within about 50 years, Europeans transported the spuds back across the ocean to North America.

Other plants moved from Europe to the New World. On Columbus's second voyage to the Americas, he brought with him seeds for such plants as wheat, salad greens, grapes and sugarcane. Each grew well in the fertile American soil. Other explorers introduced additional agricultural plants, and settlers followed with European plants that served to remind them of their faraway homes.

Along with plant transportation, the Old World and New World exchanged many animal species. Europeans introduced such domestic animals as cattle, pigs, chickens, goats, and sheep to North America, with the intent of using the animal meat for food, and hides or wool for clothing. They also inadvertently brought pest animals and plants, such as rats and assorted weeds. Many of these pest species had disastrous consequences for endemic plants and animals in the New World.

Impact

Some of the plants introduced from the New World to the Old World had obvious beneficial aspects. When corn made its way to Europe, Spanish farmers began to plant the kernels. Their success of these crops prompted corn's quick spread throughout Europe and to other continents, where it became an important dietary component.

Potatoes likewise radiated throughout Europe. Following their initial journey from South America to Spain, the plant spread to England. English discoverers then shipped them back across the Atlantic to North America in the early seventeenth century. In both continents, potatoes thrived and became a nutritional staple on both sides of the Atlantic. The importance of the potato to European nations became dramatically apparent during the great potato famine of Ireland in the 1840s. Introduced to the country in the 1700s, potatoes had become so important—providing more than three-quarters of the calories in a commoner's diet—that when the crop fell to a fungus in the 1840s, more than one million people died of starvation and at least a million others left the country.

Tobacco's spread throughout Europe was similarly quick. Explorers introduced it to Spain in about 1500, smoking became popular shortly thereafter, and farmers began to cultivate the plant in 1531. By 1556, the plant appeared in France, and within a decade, it was present in England. Its use spread both as a recreational pastime and as an important medicinal herb. Its supposed curative properties ranged from headaches to toothaches, and lockjaw to cancer. By the end of the century, tobacco use had spread nearly around the globe despite mainly religious-based attempts to ban or control its cultivation and/or use.

The introduction of the new crop plants from Europe, along with the invasive European agricultural practices, changed the North American landscape. Native Americans planted corn and other crops sparingly and with little long-term effect on the environment. Europeans were more likely to plant large farm fields, often burning acres of forest and meadows to make way for agricultural plots. Where forests once stood and animals thrived, farm fields fragmented the land. Europeans systematically removed native plants to make way for the introduced crops. Animals that weren't killed outright by farmers often found the new cropland unsuitable, and were forced to move into smaller and smaller areas, facing increased competition and fewer resources. In addition, explorers and settlers unwittingly brought seeds from undesirable "weed" plants with them to the New World. These included dandelions, stinging nettle and crabgrass, which spread through fields and woodlands, and vied with the native vegetation for nutrients, sunlight and space to grow. Overall, the American ecosystem suffered, but the European settlers thrived.

Often the success of the European settlers also spelled misery for the American Indians. As Europeans came to rely more and more on the introduced crops and their productive but invasive agricultural practices, they began to see the Indians as either hindrances to the expansion of agriculture or as potential farm workers. The Indians were thus forced to work the land for the benefit of the Europeans or were pushed—sometimes violently—from land that Europeans began to claim as their own.

European explorers and settlers also obliviously or carelessly transported pest animals to the New World. An example is the European rat, which likely came to North America as a stowaway on Old World ships. The rats flourished. By 1609, for instance, records indicate the rats had become so numerous in Virginia that they devoured nearly the entire stored food supply in Jamestown, destroyed acres of crops and gnawed through the bark on the trunks of fruit trees.

Even the domestic animal introductions to North America weren't without detriment. On the positive side, settlers had a growing supply of meat, along with hides and wool for clothing. On the other hand, many of the domestic animals became feral. This new land had plenty of resources for them, but not the natural predators to keep their populations in check. These now-wild animals swiftly multiplied and competed with native animals, such as bear, deer and beaver, for dwindling resources. In turn, plant communities became devastated by the increased demand of more and more herbivores. In addition, indigenous animals found themselves fighting previously unknown diseases that were carried to the continent by the new domestic animals.

The exchange of plant and animal species brought change to the New World and the Old World. People on both continents gained much, including animal-produced clothing materials and bountiful new agricultural crops that would become dietary mainstays. They also lost a great deal. Author Frederick Turner (1993) wrote: "There is something mythical about the New World described in the old travelers' tales. So much of it has vanished that it seems we are being told of some other, lost continent."

LESLIE A. MERTZ

Books

Crosby, A. The Columbian Exchange. Durham, NC: Duke University Press, 1967.

Cronon, W. Changes in the Land. New York, NY: Hill and Wang, 1983.

Drake, J., et al., eds. Biological Invasions: A Global Perspective. Chichester, U.K.: Wiley, 1989.

McKnight, B., ed. Biological Pollution: The Control and Impact of Invasive Exotic Species. Indianapolis: Indiana Academy of Science, 1993.

U.S. Congress, Office of Technology Assessment. Harmful Non-Indigenous Species in the United States. Washington, DC: U.S. Government Printing Office, 1993.