Upon the arrival of the Europeans to North America in 1492, there began a massive transformation in the global ecosystem resulting from the exchange of flora, fauna, and disease between the Old World and the New. This interchange of native life-forms was called the Columbian Exchange by historian Alfred Crosby in his book of that title. Centuries of geographic isolation had led to the divergent evolution of flora and fauna in North America and Europe.
In the New World, Europeans encountered indigenous plant foods, often cultivated by Native Americans, such as potatoes, beans, squash, and maize (corn), probably the world’s most important cereal crop. These plants carried back to Europe so enriched nutrition in the Old World that they stimulated major population explosions. To America, Europeans introduced crops like wheat, rice, bananas, sugar, and wine grapes, many serving as cash crops for export by the colonists.
Europeans also brought a number of domesticated animals to the New World, including horses, cattle, pigs, sheep, and fowl, producing mixed results for the Indians since the animals destroyed their croplands but also served as valuable sources of food, clothing, and energy. Disease was another dimension of the Columbian Exchange, with catastrophic consequences for Native Americans who for centuries were an isolated population and thus lacked adequate immunities for diseases introduced by Europeans.
Eruptive fevers, like smallpox and measles, proved deadly and often wiped out over half of entire tribes. The European microbe was the ultimate conqueror of America, more than any act of war. In turn, Europeans fell prey to the New World disease of syphilis, generating widespread social and biological effects. The long-term consequences of the Columbian Exchange were mixed. It created enormous increases in food production and human populations, but it also destroyed the ecological stability of vast areas, increased erosion of the land, and led to the extinction of many life-forms.