Geologists believe that 120 million years ago the Atlantic Ocean formed, dividing the Americas from Africa and Eurasia. Over the next several million years in both the Americas and in Afro-Eurasia, biological evolution followed individual paths, creating two primarily separate biological worlds. When Christopher Columbus arrived in the Bahamas in 1492, the two long-separated worlds were reunited. Following his arrival, the animals, plants and diseases began to mix. This process was called the Columbian Exchange.
The Columbian Exchange had dramatic and lasting effects on the world. Diseases were introduced to American populations that had no prior experience of them. The results were devastating. These populations also were introduced to new weeds and pests, livestock, and pets. New food and fiber crops were introduced to Eurasia and Africa, improving diets. The results of this exchange recast the biology of both regions and altered the history of the world.
The flow from east to west: Disease
The most devastating impact of the Columbian Exchange was the introduction of new diseases into the Americas. When the first inhabitants of the Americas arrived between 20,000 and 12,000 years ago, they brought few diseases with them. The first Americans and their descendants, perhaps 40 to 60 million strong by 1492, enjoyed freedom from most of the infectious diseases that plagued populations in Afro-Eurasia. Meanwhile, in Asia and Africa, the domestication of herd animals brought new diseases spread by cattle, sheep, pigs, and fowl.
Soon after 1492, sailors introduced diseases — including smallpox, measles, mumps, whooping cough, influenza, chicken pox, and typhus — to the Americas. Native Americans had no immunities. Adults and children were stricken by many epidemics, which produced catastrophic mortality throughout the Americas. Between 1492 and 1650, perhaps 90 percent of the first Americans had died.
The flow from east to west: Crops and animals
The introduction of new crops and domesticated animals to the Americas upset the region’s biological, economic, and social balance. On his later voyages Columbus brought many crops including food grains of Europe: wheat, barley, and rye. He also brought Mediterranean plantation crops such as sugar, bananas, and citrus fruits. Eventually they all flourished. After 1640, sugar became the mainstay of the Caribbean and Brazilian economies, becoming the foundation for some of the largest slave societies ever known. The production of rice and cotton, both imported in the Columbian Exchange, together with tobacco, formed the basis of slave society in the United States. Wheat eventually became a fundamental food crop for tens of millions of people in the Americas. It is true that the spread of these crops drastically changed the economy of the Americas
The Columbian Exchange brought horses, cattle, sheep, goats, pigs to the Americas. So, while Native Americans had plenty of good food crops available before 1492, they had few domesticated animals; aside from llamas and alpacas, were dogs, turkeys, and guinea pigs.
Of all the animals introduced by the Europeans, the horse held particular attraction. In the North American great plains, the arrival of the horse revolutionized Native American life, permitting tribes to hunt the buffalo far more effectively.
Cattle, sheep, pigs, and goats also proved popular in the Americas. Ranching economies emerged, based variously on cattle, goats, or sheep. Native Americans used the livestock for meat, tallow, hides, transportation, and hauling. Altogether, the suite of domesticated animals from Eurasia brought a biological, economic, and social revolution to the Americas.
The flow from west to east: Disease
In terms of diseases, the Columbian Exchange was an unequal affair, and the Americas got the worst of it. The flow of disease from the Americas eastward into Eurasia and Africa was either trivial or consisted of a single important infection. One controversial theory asserts that the venereal syphilis epidemic that swept Europe beginning in 1494 came from the Americas.
The flow from west to east: Crops and cuisine
America’s contribution to Afro-Eurasia in terms of new plant species, transformed life in places as far apart as Ireland, South Africa, and China. By the time Columbus had arrived, dozens of plants were in regular use, the most important of which were maize (corn), potatoes, cassava, and various beans and squashes. Lesser crops included sweet potato, papaya, pineapple, tomato, avocado, guava, peanuts, chili peppers, and cacao, the raw form of cocoa. Maize gradually spread across Eurasia. It was often used as animal feed, but people ate it too. The potato improved the food supply and promoted population growth in Eurasia.
The animals of the Americas have had very little impact on the rest of the world. One domesticated animal that did have an effect was the turkey.
Source: The Columbian Exchange
By J.R. McNeill.Copyright ©2008. All Rights Reserved.