The Travel of Disease

Jackie Kahn

Human mobility, in terms of European transcontinental exploration and colonization, began to truly flourish after the 1400s. This travel, inspired by financial motives and justified by religious goals, resulted in the European dominance and decimation of countless cultures in both the Americas and Eurasia. While at first glance it seems as though this dominance was achieved through mainly military means - European militias, like Spanish conquistadors, rolling over native tribes with their technologically advanced weapons - the reality is significantly more complex. The Europeans, most likely unknowingly, employed another, equally deadly weapon during their exploits. With their travel, they brought with them the infectious diseases of their homelands, exposing the defenseless natives to foreign malady that their bodies had no hope of developing immunities against. Because of the nature of disease and their limited knowledge about its modes of infection, the Europeans were able to dispense highly contagious and mortal illnesses while limiting their contraction of any native ones to the new territories. In short, they were able to kill without being killed. In this way, the travel of disease in conjunction with the travel of humans in a search for exotic commodities was able to limit or even halt the development of some cultures while allowing others to flourish at exponential rates.

Before discussing how disease has shaped history and altered cultures, it is important to understand how they themselves have developed and changed throughout history. Disease, in the broadest definition of the word, has been present since the beginning of humanity. Even hunter and gathering societies have been documented as being effected by parasites and intestinal worms (Ponting, 225). However, disease on the epidemic scale did not appear till certain conditions existed, conditions created namely by the Agricultural Revolution. As communities became more sedentary and developed a more stable means of food production through the domestication of animals and irrigation processes, populations were able to increase at exponential rates, one of the fundamental prerequisites for an epidemic outbreak. An increased population translated into closer living conditions, less sanitary means of waste disposal due to sheer volume, and typically, poorer nutrition, making people more susceptible to a breakdown of the immune system. A higher population, in comparison to that of their hunting and gathering predecessors, meant a greater chance for contracting an illness. Equally important, the Agricultural Revolution demanded the domestication of animals. In living in close proximity to cattle, hogs, and other useful livestock, a phenomenon known as species cross-over took place. This species cross-over refers to the mutation of diseases typically found in livestock to a new form that seeks out a human host. The most classic and devastating example is small pox, a highly fatal disease that causes sores to form on the body and known in cattle as cowpox (Ponting, 225-226). This, coupled with irrigation, providing a host for water-born diseases like malaria and schistosomiasis, sheds a bit of light on the magnitude of the influence of the Agricultural Revolution on the evolution of disease. Whereas previously disease consisted of small, easily contained outbreaks that killed a small portion of a tribe at most, post- Agricultural Revolution, the world became exposed to epidemics that had the capabilities to take out nearly 1/3 of a population without even the possibility of finding a cure or hoping for containment.

Once species cross-over had taken place, there was a significant period of time where no new diseases appeared. Smallpox, measles, and other diseases continued to reek their havoc, but for the most part Europe would not be introduced to many new forms of illness. That is, not until travel and trade began to become a major source of business for the rising middle class of European society. After being ravaged by the Black Plague, the people of Europe found themselves with a readily available capital – from the deaths of so many in power – and a developing taste for the finer things in life – as reflected in the sumptuary laws passed throughout Europe. The entrepreneurs emerging in the middle class were quick to act on these new desires, resulting in the development of a merchant class. Beginning simply with trade mainly amongst the European nations, the lucrative prospect of spices in Asia, silks and ivories in Africa, and gold in the Americas, these merchants organized more elaborate excursions with more elaborate means. Once in the Eastern Oceans, the European merchants did not limit themselves to Western trade. The truly business-minded from Portugal, the Netherlands, and England began to serve as middlemen, facilitating trade between Asian nations (Cippola, 136). This new attitude toward trade was not inevitable. It was made possible only after certain shifts in both demographic construct – the Malthusian relief of the Black Death – and in popular thought about trade and exploration. Since medieval times, there has been an attempt "to reconcile the antithesis between business and religion (Cippola, 132)," a search for a moral motive for the exploitative practices of colonization. The best means for this reconciliation, as determined by the leaders and thinkers of the Renaissance, was to liken colonization to an extension of the Crusades, an attempt to right "the heathen ways" of these "pagan tribes" and bring about their "salvation." It is clear that kings sent explorers to new lands to fill their coffers, but what is also apparent is that once in these new lands, "religious convictions nourished boldness in battle, endurance through ordeals, truculence after victory (Cippola, 132)." Whatever the religious guise that these motive may be operating under, the economic prospects of spices, gold, and a new world of global trade made exploration to these new places a priority. With the advent of new technology that made these long sea excursions more economically feasible, European strongholds like Portugal and Spain began to look to Asia, Africa, and the Americas for new sources of wealth. This intense lure of wealth coupled with a nationally funded sense of patriotism resulted in a decimation of the natives in the exotic lands.

The Spanish conquistadors and other empirically funded expeditions to the New Worlds were not strictly interested in financial gains. A certain amount of national pride had begun to support the shift from strictly business to exploration. With this national pride came the spirit of conquest, an attitude that would lead to the merciless exploitation of the native peoples in their paths. It has been argued that the people native to the Americas were virtually disease-free, at least within the European definition of the term. With little domestication of livestock, they were not exposed to diseases like small pox and measles (Ponting, 226). They more than likely experienced some forms of debilitating outbreaks – they did have concentrated populations and advanced agricultural practices – but their immunity to European diseases was non-existent. Therefore, conquistadors were able to, even with only one member of a ship infected, wipe out huge portions of the populations. The first plague to strike reached Hispanola in 1520, brought by Cortez’s troops in their battle against the Aztecs (Ponting, 230). Measles, typhus, and influenza, all diseases that were being limited to childhood within Europe, were the next to strike. Although tough to estimate true death tolls, the most reliable figures suggest that a combination of war and disease shrank the population in the valley of Mexico from 25 million in pre-1500, to 6 million in the mid-16^th century, and down to 1 million in 1600. Through contaminated blankets and clothing, physical contact, and simpler cohabitation, the Europeans were able to eliminate entire cultures almost inactively. And surprisingly, they were able to avoid similar effects on their own populations.

Disease traveling back to Europe from the colonized countries and trade partners was fairly limited. Except for the notable exception of the Black Death, there was no devastating disease to rack Europe that did not originate there, especially not from the New World. Why is it that that they were able to reap the benefits of foreign diseases on the enemies without paying similar costs? For the most part, there are a few obvious answers. There are some experts who argue that Europe did experience a transfer of disease back to the Continent, citing syphilis as the main example (Ponting, 231). However, others have said that it is a mutation of another disease known as yaws, known throughout Europe long before transatlantic exploration. And syphilis provides the strongest case for the reverse travel of disease despite its controversy. Ponting points to other reasons that a transfer of disease back to Europe was not as prevalent. A fairly obvious reason he cites is the temperature difference in Europe and the Americas (Ponting, 231). Europe’s climate was fairly cool in comparison and therefore could not breed the types of illnesses that were native to the Americas. This in and of itself is probably not enough to combat the spread of new disease. After the devastation of the Black Death, the Europeans had learned a few things about the nature of contagions. By limiting travel they were able to limit exposure while still dispensing infested blankets. Cippola notes the tendency of Europeans to be stronger militarily at sea rather than on land. This phenomenon seems to translate to their behaviors on new soil. He notes the powers of Europe at sea – with colonization – and their devastation on land – with the Turks (Cippola, 140). In the New World, the explorers remained close to the coast, limiting their interactions. Their strong-holds were all naval bases, never deep within the conquered lands. The same was true within Asia. “The few Europeans who ventured into the hinterland were rapidly killed or incapacitated by malaria, tropical fevers, disease, and lethal climate (Cippola, 142).” By limiting their travel and therefore their physical interaction, they were able to limit the disease they carried back with them to Europe. This combined with public health measures that limited travel of sailors after trips abroad significantly limited any exposure of new diseases to the large public of Europe. If any new illnesses were brought over, they were contained and quelled before they had a chance to spread.

Disease has plagued the world since the beginning of time. Only recently has modern medicine been able to scratch the surface of what causes death in humans, and even now, we are perplexed by many ailments. In fact, through out time, public health measures have only limited the spread of disease, never fully prevented it. But it is exactly these public health measures, so strongly influenced by the concept of travel, that have prevented many outbreaks. Beginning in the 1300s with the Black Death, decrees prevented travel in hopes of containing the disease. Later, after the age of exploration, quarantine again was implemented to limit the spread of new diseases. And as Cippola notes, it is probably the limited travel restricted to the coastlines that prevented the contraction of many of these New World diseases in the first place. Nonetheless, travel, be it limiting it within countries or encouraging it in new lands, has influenced the spread of cultures and simultaneously the spread of disease