Human Variation and Race Blog
1. Select only ONE of the following environmental stresses: (a) heat, (b) high levels of solar radiation, (c) cold, or (d) high altitude. Discuss specifically how this environmental stress negatively impacts the survival of humans by disturbing homeostasis.
- The environmental stress I chose to analyze was the cold. This stress negatively impacts our homeostasis with how it forces our bodies to adapt to the temperature change. If cold enough, our bodies will start to adapt by implementing a number of short-term adaptations. The most common illness that can come from too cold of conditions is hypothermia and this is when the body is dissipating more heat than it is absorbing.
2. Identify 4 ways in which humans have adapted to this stress, choosing one specific adaptation from each of the different types of adaptations listed above (short term, facultative, developmental and cultural). Include images of the adaptations.
- In order to adapt to this stress, the bodies will automatically begin shifting over to short-term adaptations because of the temperature.
2a. The blood vessels of the individual will change during dilation and constriction in such a way so that warm blood can stay closer to the internal organs. This process will begin to occur faster when the body learns to adapt, causing the body to become more efficient at transferring the blood back and forth throughout.
2b. Another common short-term adaptation that is made when a cold stress is apparent is the act of shivering. When someone is shivering, this is the body relaxing and contracting muscles as a way to generate heat. Once an individual becomes more acclimated to a cold environment, the shivering one will experience will get less violent over time.
2c. One adaptation I did not know until this assignment was that the body increases it's resting metabolism. In order to conserve energy and stave off hunger, the body will lessen the amount of calories that gets burned while the body is stagnant.
2d. The last common short-term adaptation the body makes when there is a stress of cold is the amount of brown fat that is stored. Automatically, the body increases the amount of brown fat it stores because brown fat is metabolically active. Unlike white fat, it generates heat while burning calories.
3. What are the benefits of studying human variation from this perspective across environmental clines? Can information from explorations like this be useful to help us in any way? Offer one example of how this information can be used in a productive way.
- By studying human variation in this fashion, we are given more information about how the structure of the individuals were developed rather than just examining their skin color. Gathering information using these methods can benefit us in a multitude of ways. One of them being that we learn the scientific reasoning behind why everyone looks the way they do and in the future, we can make artificial adjustments to environments so that they better suit the needs of those in them.
4. How would you use race to understand the variation of the adaptations you listed in #2? Explain why the study of environmental influences on adaptations is a better way to understand human variation than by the use of race.
- By using race, we can decipher only some of the adaptations there bodies made to the environmental stresses. If two men were to stand side-by-side, both of different color with one white and the other African American, we would initially understand some of the differences just from the colors. The African American's body produces plentiful amounts of melanin which would mean that his body would need more protection against radiation and the white man's body has adapted to absorbing more UV rays. Using the study of environmental influences gives better information with how it explains the reasons why the body had adapted the way it did rather than just by examining looks.
The focus of the opening section was to identify how cold stress negatively impacts homeostasis and survival. You briefly mention hypothermia, but that's about as deep as you go. What happens to the body when the core body temperature drops below the optimum temperature of 98.6 degrees? What, specifically, happens to the internal organs, particularly the brain, and the circulatory system? Why can't it function well below this temperature?
ReplyDeleteThe guidelines asked you to identify four different adaptations, one each of the four identified categories: Short term, facultative, developmental and cultural. You specify two examples as "short-term" and don't identify what the other two are. I'll review them one by one.
Vasoconstriction: This is actually a facultative adaptation, because it requires the turning on and off of genes that produce this result. Your description of the adaptation is fine, but you needed to demonstrate that you understood what type of adaptation it was.
Shivering: Yes, this is classified as a short term adaptation.
Slowing metabolism: This is another example of a facultative adaptation. It requires the "tweaking" of the metabolism through genetic adjustments and when external temperatures warm, the metabolism can return to the former level.
Brown fat storage: This is another facultative adaptation.
So you are missing the developmental and cultural adaptations. A developmental adaptation for cold stress would be body shape, as explained by Bergmann and Allen's rules. Take some time to review those concepts. Cultural adaptations would of course include warm clothing, heated homes, and even the control of fire.
" we can make artificial adjustments to environments so that they better suit the needs of those in them."
How could we change our environment with this knowledge? How can we change our environment when it gets too cold. We can't control the outside environment. We can change the inside environment, but lighting a fire in the fire place or raising the temperature on our furnace... but don't we already do that without this knowledge? We get uncomfortable in the cold and that doesn't require understanding of our body's reaction. If you meant something else, then a clearer explanation was needed.
an you identify a way this knowledge can be useful in a concrete way? Can knowledge on adaptations to cold climates have medical implications? Help us develop clothing that retains heat more efficiently? Can we develop new means of home/building construction that might help increase heat retention? How can we actually use this information in an applied fashion?
"it explains the reasons why the body had adapted the way it did rather than just by examining looks. "
You are onto a good point there, but needed to take this out a bit more. Yes, race focuses on external phenotypes, but that by itself doesn't explain why it is not useful in understanding human variation. To answer this question, you first need to explore what race actually is. Race is not based in biology but is a social construct, based in beliefs and preconceptions, and used only to categorize humans into groups based upon external physical features, much like organizing a box of crayons by color. Race does not *cause* adaptations like environmental stress do, and without that causal relationship, you can't use race to explain adaptations. Race has no explanatory value over human variation.
Hey Justin, very insightful post I couldn't help but notice the you put shivering as a way to generate heat to the body. Since I choose heat as my environmental stress the body has a totally different react to the heat when trying to cool off. When the body is hot it sweats as way to cool off so I thought it was kinda cool how you motioned the exact opposite when the body is cold. I didn't know about the brown fat and white fat thank you for sharing that I guess we do learn something new every day.
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