FROM THE OCTOBER 1992 ISSUE
The Arrow of Disease
When Columbus and his successors invaded the Americas, the most potent weapon they carried was their germs. But why didn't deadly disease flow in the other direction, from the New World to the Old? By Jared Diamond|Thursday, October 01, 1992
The three people talking in the hospital room were already stressed out from having to cope with a mysterious illness, and it didn’t help at all that they were having trouble communicating. One of them was the patient, a small, timid man, sick with pneumonia caused by an unidentified microbe and with only a limited command of the English language. The second, acting as translator, was his wife, worried about her husband’s condition and frightened by the hospital environment. The third person in the trio was an inexperienced young doctor, trying to figure out what might have brought on the strange illness. Under the stress, the doctor was forgetting everything he had been taught about patient confidentiality. He committed the awful blunder of requesting the woman to ask her husband whether he’d had any sexual experiences that might have caused the infection.
As the young doctor watched, the husband turned red, pulled himself together so that he seemed even smaller, tried to disappear under his bed sheets, and stammered in a barely audible voice. His wife suddenly screamed in rage and drew herself up to tower over him. Before the doctor could stop her, she grabbed a heavy metal bottle, slammed it onto her husband’s head, and stormed out of the room. It took a while for the doctor to elicit, through the man’s broken English, what he had said to so enrage his wife. The answer slowly emerged: he had admitted to repeated intercourse with sheep on a recent visit to the family farm; perhaps that was how he had contracted the mysterious microbe.
This episode, related to me by a physician friend involved in the case, sounds so bizarrely one of a kind as to be of no possible broader significance. But in fact it illustrates a subject of great importance: human diseases of animal origins. Very few of us may love sheep in the carnal sense. But most of us platonically love our pet animals, like our dogs and cats; and as a society, we certainly appear to have an inordinate fondness for sheep and other livestock, to judge from the vast numbers of them that we keep.
Some of us--most often our children--pick up infectious diseases from our pets. Usually these illnesses remain no more than a nuisance, but a few have evolved into far more. The major killers of humanity throughout our recent history--smallpox, flu, tuberculosis, malaria, plague, measles, and cholera--are all infectious diseases that arose from diseases of animals. Until World War II more victims of war died of microbes than of gunshot or sword wounds. All those military histories glorifying Alexander the Great and Napoleon ignore the ego-deflating truth: the winners of past wars were not necessarily those armies with the best generals and weapons, but those bearing the worst germs with which to smite their enemies.
The grimmest example of the role of germs in history is much on our minds this month, as we recall the European conquest of the Americas that began with Columbus’s voyage of 1492. Numerous as the Indian victims of the murderous Spanish conquistadores were, they were dwarfed in number by the victims of murderous Spanish microbes. These formidable conquerors killed an estimated 95 percent of the New World’s pre-Columbian Indian population.
Why was the exchange of nasty germs between the Americas and Europe so unequal? Why didn’t the reverse happen instead, with Indian diseases decimating the Spanish invaders, spreading back across the Atlantic, and causing a 95 percent decline in Europe’s human population? Similar questions arise regarding the decimation of many other native peoples by European germs, and regarding the decimation of would-be European...
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