Plagues and Peoples was written by William H. McNeill. The basis of this book all falls on epidemiology, also known as the study of patterns, causes, and effects that disease and health conditions have on certain populations. McNeill’s writing shows how the relationship that mankind, referred to a macroparasites, and parasites, referred to as microparasites, have made an impact on the world through history. The relationship at first during existence was said to be “balanced”, but when mankind in Africa started to leave trees and become hunters, spread into new lands, and eventually become smarter and more advanced, the relationship started to become more and more unbalanced. Thus, creating many of the deadly diseases that have emerged throughout history. In Plagues and Peoples McNeil covers many areas of the world, but the most important happen to be Africa, China, India, Europe, the Mongol empire, and the New World, he claims that, “This book is to bring the history of infectious disease into the realm of historical explanation by showing how varying patterns of disease circulation have affected human affairs in ancient times as well as modern times.” To support his claim he uses migration, immunity, the Columbian Exchange, the Mongols, the Black Death, religion, cleanliness, and the very beginning of mankind and parasites to show its effects on humans throughout time. Before explaining how his supporting evidence helps his thesis, we must look at how parasites and a plague can affect a population and civilization. When parasites begin to become prominent and flourish, it will infect a host, usually a human or through an animal that humans have much contact with. If the population is small, the parasite will not spread, but over time if and when the population reaches its threshold the parasite will start to attach itself to new hosts. If those hosts are not immune to the new parasite, they will have the disease that the parasite has and thus a plague will form. During the plague mass depopulation occurs because almost everyone infected will result in death. Overtime however, the people in the region will start to develop an immunity to the disease the parasite originally carried and the parasite will eventually die out. This sequence starts a new cycle whenever a new parasite is carried into a civilization. McNeil first starts his book in Africa. Africa was warm and moist, with a tropical climate, which was the perfect breeding ground to parasites. Soon parasites began to rise and accumulate. Early mankind started to be affected by the parasite early on which was why they weren’t large in numbers. Overtime early mankind’s brain began to develop and they started moving around. Firsts they moved from trees to land, and then they moved around even more when they started to hunt. Since animals started to die out, they began to migrate north. This changed a lot. As they moved north, many of the parasites could not survive the new northern climates it was exposed to. As the human body developed, parasites could not keep up. The ones that could survive could not reach the point of a plague because the population was too low for it to have any affects. Northern climates did eventually develop its own parasites, but they aren’t as numerous and disastrous as the ones in Africa. At about 10,000 BC, what we know at the Neolithic Revolution occurred. During this time humans began to domesticate animals and plants, which led the way for civilizations and mass populations. Ultimately this led to the opportunity for parasites to flourish. Many of the people in India and China worked in irrigation systems and water, where parasites could attack easily, leading to many parasitic infections. Animals were now in even more contact with humans, so more parasitic infections could happen.
Overtime civilizations were spread across Africa to China. Just as the cycle keeps gyrating, new parasites that belonged to each region began to infect...
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