Week 8: Human variation and Race blog
1.I chose high solar radiation for the environmental stress. Our bodies create a pigment called melanin that is essential to our ability to shield ourselves from the solar radiation, which is produced in the epidermis. But melanin doesn’t block out all radiation, some short wave radiation is vital to because it helps the body produce vitamin D. Too much solar radiation may cause the breakdown of folate in the body, which can cause anemia. Folate is from folic acid within our food. This can affect pregnant women because the lack of folate can increase their risk of miscarriages and babies with neural tube defects. Folate is needed for DNA replication in dividing cells and its absence can have a negative impact on many body processes, for instance, the production of sperm cells. It can also cause mutations in our DNA and can increase chances of cancer.
2. A) There isn't any short term adaptation to high levels of solar radiation.
B) A facultative adaptation to high levels of solar radiation is our ability to tan. This adaptation occurs when we have prolonged exposure to the sun. This is most apparent during the summer seasons because the sun's rays hit the earth at a steeper angle, which increases the amount of energy being absorbed by the earth. The prolonged exposure will gradually turn an individual into a tanner skin tone due to the increased production of melanin, which will help protect the individual from overexposure to solar radiation. This adaptation is not permanent because for instance during the winter an individual will have a lighter skin tone because of the decreased exposure to solar radiation.
C)The long-term adaptation is the actual change of DNA of a population of individuals in response to the long-term stress to produce a phenotypic change through evolutionary forces. An example of a long-term adaptation is the skin color of people from African, they have evolved to have darker skin color due to the increased production of melanin and more exposure to solar radiation than people who are from Europe. The darker skin color is more helpful because it protects us from the suns radiation. Places in Europe where there is less solar radiation, caused the population to have a lighter skin color because they weren't exposed to as much solar radiation as people in Africa which results in a decreased production of melanin.
D)The cultural adaptation to high levels of solar radiation is wearing clothing that covers up the skin, using sunscreen, and looking for places that have shade like an umbrella or a canopy.
3. The benefits of studying human variations are essential to our understanding of how populations change due to environmental stresses. Solar radiation, for example, is something that affects everyone, but it is more apparent in people who live in the southern hemisphere. Knowing this we can deduce why some people have darker skin color and why others have fairly light skin colors. I think that it can be useful to us because through this we can further our research into cancers that involve exposure to solar radiation and how we can possibly find a cure for it.
4. I don’t really think race has anything to do with the variation of high solar radiation because it affects us all. Darker skin colors are directly the result of long exposure to solar radiation, which can happen to any individual no matter the race. Using environmental influences on adaptation is a better way to understand human variation rather than race because we are genetically similar, the changes in populations arise from different environmental stresses that we have encountered or will encounter in the future.
For your opening discussion, no need to talk about melanin just yet as this is part of the process of adaptations, which comes in the next section. Otherwise, good discussion of the problems related to solar radiation, particularly with a good coverage on the issue of folate and how this negatively impacts reproduction. Usually students focus on skin cancer dangers, so it was refreshing to see an alternative focus. Do we get anything beneficial from the sun that might produce a conflict in our adaptive process? What about Vitamin D, the "sunshine vitamin"?
ReplyDeleteCorrect, there is no short term adaptation to solar radiation, which is why it is such a dangerous stress.
Good discussion of the facultative trait.
Okay on your developmental discussion, but can you explain why those in the northern latitudes have less melanin production? You suggest it is just because of less exposure to solar radiation, but remember that humans originated in Africa and would have had the high levels of melanin to begin with. Why did they lose that melanin level? And how does Vitamin D absorption help to explain this?
Good cultural discussion.
A note on images: I see images for the cultural section but missing images for the other three adaptive sections.
Yes, better understanding how skin cancer develops certainly can help us better treat it, but can we also learn how to prevent it? Can we use this information to better develop clothing that blocks UV radiation? And perhaps that clothing can also still allow for Vitamin D absorption?
While I understand the point you are trying to make in the last section, and I agree with your ultimate conclusion, this doesn't really explain why race doesn't help us understand 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.
Hello Brian,
ReplyDeleteI enjoyed reading your post, especially the last two discussions you left. I think it's really important for us to understand how our body adapts to certain environments it can help us learn what to do during certain situations and what to invent in the future. Aside from that race really doesn't have much to do with solar radiation besides skin color. It can explain why some races are darker than others.