In chapter 11, Shubin connects our past to the active lifestyle of fish and includes many examples of disease that show how humans are products of a lengthy and convoluted evolutionary history. How do our ancestral traits relate to diseases such as heart disease, hemorrhoids, obesity, and hiccups? Please cite specific examples from the book and relate to our AP biology themes.
Adnan Jahan
(adnanjahan@gmail.com)
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ReplyDeleteSince we have evolved from ancestors such as fish, we have some traits that would have been advantageous for them to have, but that present problems for us. Obesity is a huge problem for humans (especially in the past 50 years) because our bodies have evolved from animals that didn't always have food available to them. Therefore, storing excess food as fat to use at a later time would be an advantageous trait for most of our ancestors to have. This is because until recently, finding food for survival was not always easy. There were often cycles of abundant food and having no food available. In addition, some of our ancestors, such as bears, have bodies that were able to eat in excess amounts, store fat, and then not eat for several months. Since food was often scarce, animals that were capable of storing more fat had an evolutionary advantage (Kolbert, E). Therefore, evolution favored animals that could store a lot of fat, which, over time, has created a population capable of storing large amounts of fat. This adaption is still somewhat present in humans because when we eat a lot of fat, it gets stored for use when we need it. However, with new technology and food production methods, it is rare that humans can not find food if they are hungry (Kolbert, E). This causes the fat storages to keep building up. One way of getting rid of these fat storages is to exercise. Our ancestors had to work for their food by being predators or being active to find plants to eat (Beck, M). Today, if we want to eat, we can drive thru McDonalds or Dunkin Donuts to get our food. We also have very sedentary lifestyles. Another interesting fact is that we have a natural propensity for fatty foods. This is a trait that we inherited from our ancestors-only it was advantageous for them because obesity was not a problem and fatty foods provided more energy. The active lifestyle that our ancestors had to look for food and their ability to store food are still with us today, but now present us with the problem of obesity.
In addition to obesity, hemorrhoids is another problem that we have due to the inherited traits for our ancestors. Hemorrhoids is caused by many of the same factors that cause obesity. For example, consuming highly processed foods (instead of organic) can cause problems in the digestive system that lead to hemorrhoids (Roberts, D). Also, being in a sedentary posture for extended amounts of time and not getting enough exercise can cause hemorrhoids. Hemorrhoids were not a problem for our ancestors because of their active lifestyle and diet without processed and modified foods (Roberts, D). However, since we have evolved from animals like this, we have inherited the traits that, combined with our lifestyles, cause hemorrhoids.
Heart disease is another problem that humans today face because of inherited traits from our ancestors. The basic causes of heart disease are lack of exercise and a high fat diet. Because our ancestors had active lifestyles and a propensity for a higher fat diet (due to lower amount of food available) we have inherited these traits, which present us with the problem of heart disease due to our sedentary lifestyles (Beck, M).
Hiccups also illustrate traits that we have inherited from our ancestors. Hiccups are caused by quick inhalation and closing of the glottis. Hiccups originate in fish; they produced rhythmic breathing and muscle activation, which help with breathing. However, humans have other mechanisms for breathing, such as the diaphragm.
(CONTINUED) Therefore, hiccups are not necessary for us and only present us with a problem. Hiccups, obesity, heart disease, and hemorrhoids in humans illustrate many traits that show that humans have evolved from animals such as fish. It is clear that evolution has allowed us to do many incredible things that our ancestors were not capable of doing, but with these consequences.
ReplyDeleteSources:
http://www.articleconnect.info/health-fitness/three-main-leads-to-of-hemorrhoids/
http://online.wsj.com/article/SB10001424052748704454304575081613327728110.html
http://www.newyorker.com/arts/critics/books/2009/07/20/090720crbo_books_kolbert
Marissa Lobl marissa.lobl@gmail.com