Travel and Disease

Travel and Disease: The Implications of Domestication

            The domestication of animals helped humans to evolve into complex societies with large populations.  However, the domestication also helped to strengthen and spread an assortment of deadly diseases.  “The adoption of agriculture and the transition to settled societies exposed humans to a range of diseases they had never encountered before.” The proximity of farmers in Europe to their livestock allowed for infectious diseases to spread to them.  After long periods of time, the diseases spread and killed many people in Europe.  However, antibodies began to develop to protect many Europeans from these diseases.  When exploration began in the 15th century, Europeans brought these deadly diseases to the Native peoples.  Unlike the Europeans, the Natives did not have these antibodies and the spread of these diseases caused mass deaths.

              Most of the deadly diseases that affected Europeans were picked up from animals.  “The major killers of humanity through our recent history- smallpox, flu, tuberculosis, malaria, plague, measles, and cholera- are infectious diseases that evolved from diseases of animals.”  Because of the close quarters of animals and human beings, infectious diseases were able to evolve and infect humans. Bestiality, some people’s use of animals sexually, also led to the rapid spread of disease from animals to humans. 

As more diseases began to affect humans, the growth of large cities also contributed to their spread: “Towns and cities, because of their lack of sanitation and the crowding together of larger numbers of people, were extremely unhealthy places where diseases flourished.” Unclean water systems spread microbes and infectious diseases.  Feces that contaminated the water supply could lead to “snails carrying schistosomiasis and … flukes that borough through our skin.” Poor diets also weakened people’s immune system and made them more susceptible to infectious diseases.  The most developed cities in Europe became breeding ground for infection, which led to large-scale deaths from infection and plagues.  Eventually, antibodies developed in certain individuals so that the populations gradually built up immunity.  This immunity slowed down the diseases and “death rates fell as the diseases became endemic, but less virulent in their impact.”

As disease was spreading throughout Europe, so was the desire to explore the world.  Europeans who desired great wealth started exploring the economic opportunities overseas.  Although many of these explorers justified their explorations religiously, Cipolla points out that “religion supplied the pretext and gold the motive.”  He goes further to point out that technological progress of the fourteenth and fifteenth centuries provided the means for exploration.  The motives for exploration had developed long before the fifteenth century, however the Industrial Revolution, which led to the invention of the gun boat, allowed for European explorers to control ports and benefit from overseas trade. 

When contact between Europeans and Natives was established for trade purposes, the major consequence for the Natives was the spread of infectious disease.  When contact was established, “diseases spread with a terrible impact on the people who had acquired no natural immunity or resistance to the infection.” The large-scale deaths that had once occurred in Europe started occurring in the Americas.  By 1540 Indian populations in the Mississippi Valley had been destroyed by epidemics transmitted from coastal Indians infected by Spaniards visiting the coast.  The major killers in the New World were smallpox, measles, influenza, and typhus.  Most of these diseases were no longer large threats in Europe due to immunity.  “For the New World as a whole, the Indian population decline in the century or two following Columbus’ arrival is estimated to have been as large as 95 percent.”    A lot more Native Americans died from the spread of European disease than from battles with Europeans.

            While a plethora of deadly infectious diseases spread to the Americas from Europe, very few diseases spread to Europe from America.  Why?  The answer brings me back to the title of the paper: Implications of Domestication.  Since only a small number of animals were domesticated in the Americas: “The turkey in Mexico, the llama and the guinea pig in the Andes, the Muscovy Duck in tropical south America, and the dog throughout the Americas,” the chance of any diseases spreading from animals to humans was very small.  Also, the idea that a llama is not as appealing sexually as a sheep prevented the spread of disease through bestiality.  The domestication of animals helped humans to evolve into complex societies.  However there was a downside, as exemplified by the spread of disease and death first in Europe and then in the Americas.


Ponting, Clive.  A Green History of the World, 225

Diamond, Jared.  Guns, Germs, and Steel, 196

Ponting, Clive.  A Green History of the World, 227

Diamond, Jared.  Guns, Germs, and Steel, 205

Ponting, Clive.  A Green History of the World, 228

Cipolla, Carlo M.  Guns, Sails and Empires, 133

Ponting, Clive.  A Green History of the World, 228

Diamond, Jared.  Guns, Germs, and Steel, 211

Ibid, 213

Return to ENVS2 homepage

Send message to Swarthmore College Environmental Studies

last updated 3/28/06