IN 1492 COLUMBUS BROUGHT DISEASES

In 1492, Columbus sailed the ocean blue, bringing to the New World a bounty of wonder: coffee, horses, turnips, grapes, wine. But Columbus and his fellow explorers, in addition to bringing crops and animals we now take for granted, were also the Typhoid Marys of their time. The New World before Columbus: no typhoid, no flu, no smallpox, no measles. The New World after Columbus: epidemics of death.

For Native Americans, the problem was a lesson in basic virology. Because these microbes were as new to society as horses and coffee, nobody had built any immunity to them. Without immunity, wide swaths of people were quickly infected and killed.

Modern medicine is helping most sufferers to recover. Centuries ago, most cases ended in death.

“Indigenous peoples suffered from white brutality, alcoholism, the killing and driving off of game, and the expropriation of farmland, but all these together are insufficient to explain the degree of their defeat,” wrote the late Alfred W. Crosby, a University of Texas historian considered the preeminent expert on the Columbian Exchange. “The crucial factor was not people, plants, or animals, but germs.”