An environmental stress that negatively impacts the survival of humans would be high altitude. Many things occur when someone travels to high altitudes. The climate itself often has hot days and freezing nights with strong winds, low humidity and most importantly low air pressure. All of these factors negatively impact human survival. For example, strong winds and low humidity often cause dehydration. Moreover, when the air pressure lowers it makes it more difficult for oxygen to enter our systems which can result in Hypoxia, oxygen deprivation. This in turn causes many obstacles for humans to continue with symptoms such as: fatigue, distorted vision, difficulty in thinking clearly, pneumonia, fluid around the brain, and death if normal air pressure does not resume. There could also be heart failure because of the extra work that the lungs, heart and arteries are doing at such high altitudes.
There are many ways that humans have adapted to this stress placed on the body. A short term adaptation would be the normal physiological adaptation to the changing pressure by the breathing and heart rate increasing.
The body also then naturally acclimates itself and more red blood cells and capillaries are produced to carry more oxygen. This is a facultative adaptation because it remains as long as the stress exists.
In addition, a developmental adaptation would be that humans who live in high altitudes have developed a higher fitness level because of the greater lung expansion and increase in red blood cells.
Finally, cultural adaptations vary in how people have adapted to high altitudes. Indians from Peru have attempted to increased their lung expansion capability where others like the Tibetans began breathing faster to take in more oxygen.
Benefits of studying human variation by looking for patterns that explain how the trait is expressed in various environments helps to get a more conclusive reason for the trait itself. This information is useful to possibly show how certain traits have developed over time. If people have responded to environmental stresses that caused genetic change overtime, that explanation seems more feasible than merely it being race related.
With that, I don’t think I could use race to understand the variation of adaptations listed above for high altitude. I think that the idea of race is so blurred that one cannot define something purely based on race for the simple fact that there is so much variation within “racial” groups to begin with. Environmental influences on adaptations just seems to be a more logical way to understand human variation because it deals with a multitude of similar factors affecting a multitude of different groups in possibly different areas.
3 comments:
Great job outlining your adaptations and I love the use of your choice of images.
I like your comment about being able to find patterns by using clines to analyze human variation. This is the advantage of clinal analysis over the use of race. Studying variation based upon race offers no biological patterns, which means the results have no predictive value, which is the benefit of any scientific study.
I didn't think that cultural adaptations would include an interesting acquired trait such as increased lung expansion. Its interesting how people living in different areas can adapt to a wide variety of conditions.
Javon,
Football players playing at Mile-high stadium try to show up a few extra days before playing the Denver Broncos so that they can jump start their acclimatization process, giving them a fighting chance of breathing through the game. Definitely a learned, cultural behavior... but I do see your point.
Any other cultural adaptations to high altitude?
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