Monday, March 28, 2011
A Changing Life
In the chapter, "The Meaning Of It All," Shubin discusses how humans developed a sedentary lifestyle over time. With the advent of techonology, it appears that the human race may just become even more sedentary as time progresses. Describe certain characterisitcs of humans that evolved due to the hunter-gatherer lifestyle, and discuss how those characterisitcs might evolve in the future if the human lifestyle becomes more sedentary. vickram.pradhan@yahoo.com Vickram Pradhan 1/2a
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ReplyDeleteThousands and thousands of years ago, the human race had a hunter-gatherer lifestyle. This lifestyle is comparatively the exact opposite of the human lifestyle that exists today. Food wasn't offered at convenient local grocery stores, and freezers and refrigerators weren't available to store food for extended periods of time. The people of the hunter-gatherer lifestyle had very little relaxation time, which is a very prominent difference between the modern and ancient lifestyles. The ancient human diet consisted of meats and fruits from various plants, but these foods weren't accessible via car and grocery store. The food had to be directly gathered, as the title would imply, in order to be obtained. Foods from cows and chickens were constantly be on the move, so the ancient human race would have to be on the move as well in order to survive and eventually reproduce. This active lifestyle continued up until hunter-gatherers realized it would be more efficient to simply take a couple of animals into captivity and raise more animals, essentially more food. This change from hunter-gathering to agriculture occurred about 2000 years ago.
ReplyDeleteThe hunter-gatherer lifestyle was influenced by cycles of feast and famine. "To ensure survival during periods of famine, certain genes evolved to regulate efficient intake and utilization of fuel store" (Journal of Applied Physiology). These fat storing genes called "thrifty" genes certainly aren't needed for the modern day human. The abundance of food everywhere no longer poses a purpose for the thrifty genes, "which in turn abrogates the cycling of certain metabolic processes, ultimately resulting in metabolic derangements such as obesity and Type 2 diabetes" (Journal of Applied Physiology). These thrifty genes may be completely inactive in the future of the human race if the human lifestyle becomes even more sedentary.
Mikey Ling (mikeyling@ymail.com)
As Mikey said, there are genes which help with intake and fuel store moderation. To elaborate on the "thrifty gene" idea, our bodies have evolved over time to allow for fat storage, which is then used when other energy supplies, such as glucose, are low. During hunter-gatherer times, when there was often a lack of food during the "bust" period, this was an efficient system, but today, where we constantly have "rich foods available 24/7" (Shubin 187), this ability to store fat has led to problems such as high blood pressure and heart disease. As we learned previously, this high blood pressure is caused by a hardening of the arteries, also known as arteriosclerosis. The hardening is a result of fat deposits that accumulate when the smooth lining of the arteries is damaged, causing leukocytes to take up lipids such as cholesterol (Campbell & Reece 914). Thus, when we eat more cholesterol and fat-heavy foods, as most people do today, we are putting ourselves more at risk for heart attacks and strokes, the effects of these clogged arteries because blood cannot flow properly throughout the body to reach the brain and the heart. As we become more sedentary, this ability to store fat may no longer be beneficial to us. Furthermore, not only are we more inactive, many of us can also be very careless about what we eat—high-cholesterol is a common problem in the U.S., and one that could be prevented if people would eat more foods rich in HDL (high-density lipoprotein) rather than the LDL (low-density lipoprotein). Highly processed foods with trans fats are also consumed in large amounts, contributing to heart disease in many.
ReplyDeleteAnother attribute that developed as an advent of our former hunter-gatherer lifestyle is our way of blood circulation. We have one-way valves that keep our blood moving up, as well as leg muscles that, when contracted, pump blood “up our leg veins” (Shubin 188), which allows blood circulation throughout our body, from our head to our toes. This is beneficial for an active animal, because it is constantly moving, keeping the blood flow constant throughout the body. This may also explain why athletes are typically healthier than the average person—consistent exercise guarantees that blood will reach all of its destinations, and athletes also typically consume a healthier diet, decreasing the risk for heart disease and other health problems. However, for those that aren’t as active, varicose veins may develop, caused by buildup of blood pooling in the veins that disallows the function of the valves. These veins are not only unsightly, but also cause further issues such as “swelling, fever, redness of the leg, or leg ulcers,” and will not go away with time or self-treatment (http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002099/). However, over time we have been able to develop treatments for these veins, such as sclerotherapy, which is the injection of the veins with “sterile chemical sclerant, which irritates the vessel's lining, making it become inflamed” (http://www.veindirectory.org/content/sclerotherapy.asp) and eventually fade away. Technology creates this cycle of creating more health problems, yet still offering solutions to the problems that it causes.
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ReplyDeleteBecause of our change in lifestyle from hunter-gatherer to couch potato, some advents that were once beneficial are now causing health problems. In the future, as a result of natural selection, some of these characteristics of our bodies may change. For example, it may be possible that the structure of the valves that control our bloodstream will change in a way that prevents heavy buildup of blood, or perhaps has more of a resistance to the pooling of blood. However, on the whole, I don’t believe that there will be any major changes in our characteristics, but instead an overhaul of how we think about what we eat, and how we exercise—it’s more up to us, based on how we think and how cautious we are. Perhaps if humans are to regulate their diet more as time goes on, we will develop new methods of fat storage or will be able to utilize fat more readily, rather than storing it for later. We might also be able to alter how leukocytes store fat in the arteries to decrease chances of heart disease. But once again, as Shubin says, we can only “be tweaked […] so far before major problems arise” (Shubin 185). Our evolutionary history has already created a body that has so many beneficial functions that I don’t think that having a more sedentary lifestyle as we do today will really bring on the advent of major changes to our fundamental characteristics.
Sources:
Your Inner Fish
Campbell & Reece
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002099/
http://www.veindirectory.org/content/sclerotherapy.asp
Kathy Li, kathy2132@gmail.com