The New World, on the other hand, had a much better control of their parasites. Though there were still sanitation issues and odd behavioral practices that increase changes of parasitism, such as the intentional ingestion of arthropods that may have carried parasitic disease, Native Americans had far less severe cases of parasitism.
The most recent hypotheses for this stark contrast in New World and Old World parasitism involve the differences in medical technologies of these two groups that are...let's be honest....worlds apart. It seems that religion had a HUGE influence on how people in both regions viewed medical "science". The medical practices that spawned from these beliefs were very, very different.
Let us first look at the New World. Many Native American cultured relied on the use of medicinal plant to cure ailments, including those induced by parasites. Though not all folk medicine has been shown to have true biological capability to cure diseases, many (if not most) of these treatment methods have been scientifically proven to actually work for controlling parasites. There are a variety of plants that have antihelminthic properties, a fact that medicine men where aware of long before the creation of microscopes and ivermectin.
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Now let's shift our focus to the Old World...specifically to Medieval Western Europe. This region of the world at this time was vastly overpopulated. Crowd diseases were ubiquitous...as you might imagine when discussing outbreaks such as boubonic plague. These people had TONS of whipworms and maw worm infections. Not only were these parasites more prevalent than those found in the New World, they were also much more devastating. These sorts of infections can cause much more serious health problems...especially if they are not properly treated.
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By the time of the 12th century Renaissance, medicine had greatly improved as medical texts became available following translation from Greek and Arabic. Prior to these texts, classical medicine was largely influcenced by the works of Hippocrates and Galen. The writings of Galen were based on animal dissections...which gave false assumptions about human anatomy. His work also discouraged physiological research by incorrectly describing the process of circulation.
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Moral of the Story
It is easy to look back now and see the flaws of medical history, but can we apply the lessons learned from those mistakes to our culture today? Is spirituality important? Absolutely! But given a choice between praying for a migrane to go away and taking an asprin...I'd take the asprin (and probably pray too because it couldn't hurt...but I wouldn't rely solely on the prayer...that's just silly!). I doubt God wants any of us to get sick or die, but the world around us is full of infectious agents and eventually we will do both. If you believe that God gave us the free will and the intellegence to develop medical technologies that prolong our life, then you have to agree that using those technologies is not somthing that goes against God's will. Most Christians aren't this stupid (I hope), but there are certainly those who feel that they shouldn't trust medical science and that leaving it all up to chance is a superior option.
That little rant aside, we have archeological evidence to prove that people in the New World had more efficent ways of controling their parasite burdens. Everything from the way these people lived, to the way they treated their sick was superior for keeping parasitic infections at bay. The people of the Old World were much less effective because of overcrowding and flawed medical practices influenced by religion. It is amazing to think of these parasite-ridden Europeans as the very people who would later see the Native Americans as "savages".