Human Travel and Disease

Ryan McKenna

The relationship between human beings and the environment is constantly changing. As human beings adopt new technologies that alter their lifestyles, the environment adapts to these changes, and this process repeats itself with each new development and invention. The implementation of various modes of human travel to society has had drastic and devastating effects on the environment, many of which turned out to be both irreversible and uncontrollable. In transitioning from a society comprised mostly of hunter-gatherers that lived out their entire lives in one relatively small region to a more mobile society that depended on agriculture and domesticated animals for food, humans developed methods of travel to take them further distances, including steamboats, railroads, and a system of roadways. These advancements in technology made it possible for humans to cover large distances easily, but also created and perpetuated disease. The shift from a hunter-gatherer lifestyle to a farming lifestyle brought about the need for travel, which in turn brought about devastating consequences.

By transitioning from hunter-gatherer societies to agricultural societies, human beings developed a necessity for means of travel. Early humans who lived out the course of their lives as nomadic hunter-gatherers had no need to travel far distances because they never stayed in one place, and were in effect constantly traveling, although they never covered great distances and generally stayed within a bounded region. Human beings eventually shifted their lifestyle from that of the hunter-gather to that of the farmer type once the advent of agriculture came about. Humans then began to live together in societies and settled together in one centralized place, which led to the development of villages and eventually cities. Once humans settled in these various settlements, the necessity and desire to travel among various establishments was born, and new technologies that allowed for traveling far distances were developed. First, boats allowed humans to cross waterways and make contact with other nations. Once humans were able to cross bodies of water, they developed means of traveling across land and smaller waterways such as rivers that were located well within continents, and railroads and steamboats were created. These methods of travel allowed humans to travel from continent to continent, and then to expand inland. This led to the development of more societies as well as the interaction between pre-existing societies, both of which led to the creation and spread of debilitating diseases.

The formation of farming and industrial societies led to the development of new diseases that ravaged the human population. For one, humans that relied on newly developed agricultural methods for sustenance established farms on which they not only grew and harvested plants, but also kept animals. The domestication of animals led to the transmission of numerous diseases from animals to humans, and because these diseases were not native to humans, human immune systems initially lacked the ability to fight them (225). With human beings living in such close quarters with animals, and often in the same buildings, humans acquired such deadly diseases as smallpox, tuberculosis, and influenza, all of which can be traced back to animals (226). Other aspects of the farming lifestyle contributed to the spread of these new diseases; for example, the development of irrigation systems led to the spread of schistosmiasis, a blood fluke that relies on both humans and water snails as hosts at various stages of development – the invention of irrigation systems provided this unique environment and allowed the disease to thrive (226).

After these debilitating illnesses became ingrained in human populations, they spread from person to person, and this spread was aided by the fact that human beings also began living in structured villages and cities once they moved away from the hunter-gatherer lifestyle. Humans living in cities posed two major problems associated with disease. First, so many humans living in the same concentrated area allowed communicable diseases to spread easily, as there were increased instances of human-to-human contact. Some diseases, such as cholera, malaria, and measles, which require a minimum number of human hosts in order to survive, were able to remain in existence because of the dense concentration of people in certain areas (226). Second, many early societies experienced problems keeping human waste out of the water supply. The human excrement in the water supply provided the ideal environment for intestinal parasites such as worms, and because the same water supply that carried away waste was used for drinking water, human beings often contracted these parasites through direct consumption (226).

The transition from hunter-gatherer societies to agricultural and industrial societies led to the development of many deadly diseases, and advancements in technology, particularly the creation of various modes of travel, allowed these diseases to spread among human societies. Colonization by Europeans was a main conduit for disease transmission. Europeans coming to America brought a host of diseases with them that had previously never been seen on the continent. Because there were no domesticated animals in America at the time the first European settlers reached the continent, there was no way in which Native Americans would have the ability to fight these new diseases; as a result, these diseases ravaged Native American populations that came in contact with European settlers (231). This disease transmission was not one-sided however; Europeans also suffered the repercussions of their colonization efforts – syphilis was brought back to Europe from the Americas in the late 1400s, and around the same time typhus was brought to Western Europe from Cyprus (231-232). Aside from colonization, increased trade between nations, which was made possible by innovations in travel, contributed to the spread of disease amongst distant societies. For example, rodents that carried fleas infected with bubonic plague spread the disease into China in the fourteenth century because of the implementation of trade between European countries and the newly established Mongol empire (228).

The creation and spread of disease has been an unfortunate and unavoidable bi-product of human travel. Innovations in travel that allowed humans to cover greater distances aided the development of agricultural societies; these societies in turn led to the development of diseases because of human interaction with animals. These diseases were able to thrive on newly formed societies in which people lived together in close quarters with unsanitary conditions. The spread of disease was also perpetuated by travel, as humans carrying diseases specific to their society were able to interact with humans in societies that had no way of fighting off these alien illnesses, and the results of these interactions were devastating. The development of various methods for humans to travel great distances has undoubtedly had positive effects on the human population as a whole, but these positive outcomes are certainly dulled by disastrous consequences brought about by the spread of disease.


A Green history of the world: the Environment and the Collapse of Great Civilizations. Clive Ponting; St. Martin's Press, 1992. Chapter 11, The
Changing Face of

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last updated 3/27/07