Social forces that motivate emigration and immigration can vary from persecution to religion to wealth. The desire to escape from adverse conditions or to find better opportunities in other parts of the world usually drives the movement of people across the globe. Migration in the past and in the present has a dramatic influence on humans and their societies. Certain macroevolutionary factors, particularly the phenomenon of the spread of disease, led European travel to be much more than just migration. European travel helps to explain why the world’s demographic looks as it does today.
It is often noted that “religion supplie[d] the pretext and gold the motivation” for European expeditions to the New World beginning in the fifteenth century (Cippola 1996, p. 133). Religion emboldened soldiers in battle to pursue new territories and fostered Christian missions to convert non-Christian societies. The hierarchical structure of European society also perpetuated travel in search of wealth. Only the oldest son inherited land, so younger children were left with no choice but to find wealth elsewhere if they intended on moving up the social ladder. They often attempted to search for wealth by traveling to lands that they believed held more opportunity. Additionally, peasants were unable to break the caste system without attaining wealth somehow, and since performing duties outside of their profession was not rewarded, they had only travel to give them hope of advancing in society (Cippola 1996).
While motivations for European expansion were mostly due to the search for gold and the desire to fulfill religious ideals, as a society looking to prosper, Europe was interested in exploration and trade. Again, technology was a factor, because Europe had the mindset that their technology set them apart from other parts of the world. Thus, they were more eager to use it for navigation purposes and the like (Adas 1989). European countries had the strongest naval fleets, and essentially had control of the seas because of their innovative uses of technology, such as the idea to use cannons on ships (Cippola 1996, p. 137). Unlike China, which was relatively self-sufficient and insulated from other parts of the world, Europe consisted of many nations in competition with one another. In order to attain wealth, European nations created colonies abroad. These colonies were established so that nations could extract necessary resources and trade with their colonies. Traveling was risky, especially overseas, but for various reasons explained earlier, people did it despite the risks it involved. Travel was so dangerous, in fact, that only half as many Europeans that traveled made it to their destination (Cippola 1996, p. 134).
Hundreds of years ago, Europeans traveled the most of any other peoples, and left the most impact on the environment, which influenced present day societies. The biggest impact was arguably the spread of disease. Inherent trade, exploration, and migration came the spread of germs across societies, dramatically influencing population demographics. Microbes and humans are surprisingly similar when it comes to survival. Just like humans, microbes’ reproduction enhances survival of the species. Humans and animals are hosts to germs, and while it may seem that germs kill themselves when they kill their host, they find many creative ways to reproduce. For instance, sneezing, coughing, insect bites, and sores are symptoms for humans, but tricky ways of reproduction for germs that easily spread disease. Another example is cholera, which causes diarrhea in its victims, resulting in infected water supplies that can get others sick. Rabies runs through the saliva and causes animals to bite other animals or humans, thereby further passing on infection (Diamond 1997, p.199). While their host develops immunity to a particular microbe over generations, the microbe also adapts to form various strains that humans have not yet learned how to fight.
In Europe, people often lived in close quarters and eventually developed immunity to certain deadly diseases. This happened in other societies in the world, but more so in those where people lived close to one another or had domesticated animals (Ponting 1995). Jared Diamond explains that many diseases that afflict humans originally evolved from domesticated animals (Diamond 1997, p. 197). In Europe, people tended to live in close proximity with their farm animals. “Crowd diseases”, as Diamond refers to them, develop in densely populated areas. While population density is not high in rural areas, urbanization became more common because cities offered promising opportunities for struggling farmers. In reality, poverty is often widespread in cities, catalyzing the migration of germs (Ponting 1995).
In the Americas, only five animals were commonly domesticated, and they did not share the same disease-inducing characteristics as those in Eurasia. Llamas, for instance, were kept in smaller herds, so disease did not spread as widely or as quickly. Humans also did not drink their milk, which might have the capacity to pass on harmful bacteria. Additionally, Native Americans did not keep their animals inside with them (Diamond 1997, p. 213).
When the Europeans – often from densely populated areas exposed to various microbes - arrived in the Americas, they brought with them not only advanced war technology, but crippling epidemics that the Native Americans were not immune to. In the New World, the microbes may have spread even faster than the Europeans did themselves. Since Native Americans did not live in close proximity to one another or to their animals, and were often mobile hunter-gatherers, they were susceptible to many of the diseases that the Europeans unknowingly brought with them, such as smallpox and measles (Ponting 1995, p 230). They were so susceptible that the Spanish conquest of the sixteenth century is likely to have caused a drop in the Aztec population from twenty-five million to one million people (Ponting 1995, p. 230).
This is probably why there are so many people of European descent in the Americas, and why Native Americans are now found only in small, isolated reservations dispersed throughout the country. The phenomenon of how germs spread is also why Europeans could not colonize Africa until long after they landed in the New World. In the case of Africa, disease was a disadvantage for Europeans. Malaria, cholera, and yellow fever were tropical diseases that prevented Europeans from settling in areas such as Africa, tropical Asia, and Indonesia (Diamond 1997, p. 214). We see far less people of European descent in Africa and other tropical areas than we do in North America, likely because the diseases local to the region were too much for the European immune system to handle.
The motivations for travel and its problems have not disappeared. Many countries have very large income gaps between the rich and the poor, with no effective public policies in place to help the poor move above the poverty line or into the middle or upper-income classes. Though it may be futile, immigration may happen largely because people believe that they have more opportunity to succeed in a country with higher standards of living. Ironically enough, they may be more susceptible to certain diseases when they move, or they may carry bacteria that they are immune to with them. Furthermore, it is now commonplace to travel the country or the globe for pleasure or business. Technology makes travel much easier than before, because cars, ships, and planes move people from place to place in a matter of hours or days, rather than in a matter of weeks or months. While humans have evolved to be immune to certain microbes, there is an endless possibility of evolving bacteria that can cause new diseases. The swine flu virus (H1N1), for instance, adapted from a disease that affected pigs to one that affects humans, and it spread throughout the world very quickly because traveling was so easy and fast. If a microbe evolves faster than humans or modern medicine can, we may see another instance in which the population demographic changes. However, hopefully modern medicine and better sanitation will separate the diseases of this century from the epidemics of the last few hundred years.
Adas, Michael. “Machines as the Measure of Men”. 1989. Cornell University Press.
Cippola, Carlo. Guns, Sails, and Empires: Technological Innovation and the Early Phases of European Expansion, 1400-1700. Sunflower Univ. Press, 1996.
Diamond, Jared. “Chapter 11: Lethal gift of livestock.” Guns, Germs, and Steel. W.W. Norton & Co, 1997.
Ponting, Clive. “Chapter 11: The Changing Face of Death.” Green History of the World. St. Martins Press, NYC, 1995.
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