1. High levels of Solar Radiation negatively impacts our survival as humans because of the damage to skin cells and DNA within these cells by harmful UV rays. Our bodies benefit from UV radiation by the stimulation it has on the production of Vitamin D. However, overexposure can lead to a plethora of harmful conditions from sunburn to melanoma.
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Short Term Adaptation: As for a short term adaptation to over exposure to solar radiation, there doesn't seem to be any for humans. Lighter skinned people readily sunburn when over exposed to harmful UV rays, while darker skinned people do not. This adaptation can't be seen as short term at all though.
Facultative: A facultative adaption to solar radiation can be seen through tanning of the skin. If we are exposed to the sun for a long period of time, then the melanin granules in our skin increase and become larger, causing skin to appear more tan. Tanning can be much more apparent in lighter skinned people than darker skinned people, while those with extremely light skin haven't adapted the ability to tan and absorb solar radiation, causing sunburning.
Developmental: As I stated above there isn't a short term adaptation to over exposure to solar radiation, there is however a developmental adaptation by those with darker skin. Darker skinned people produce a melanin pigment called eumelanin, while those with lighter skin produce pheomelanin. This adaptation of darker skin is the product of thousands of years of exposure to high solar radiation and extreme heat.
Cultural: A cultural adaptation to solar radiation is apparent in different forms of solar protection, such as clothing, and shelter. The darker skin of African cultures can be attributed partially to a a lack of large shelters and forested areas, which lighter skinned cultures in Europe and elsewhere did possess. Today the use of hats, UV protective clothing, and sunscreen, allow us to protect ourselves from over exposure the its harmful effects.
3. Studying human variation can be helpful because it can help us identify and create solutions for environmental stressors. One such environmental stressor pertaining to solar radiation is the impact of little sunlight on darker skinned people living in northern territories where the sun shines for fewer hours in a day. This circumstance can potentially lead to Rickets disease in areas such as northern Europe. Studying such complications as Rickets can help us to determine what are healthy, sufficient amounts of solar radiation.
4. I would use race as a means to organize geographically groups of people and how they are affected by environmental stressors pertaining to their geographic location. There are dark skinned people in Africa, and there are dark skinned people in Europe. To group dark skinned people as a race and not take into account their geographic location, would be a huge error in understanding and collecting data.
Good post and good work with adaptations.
ReplyDeleteRegarding your final discussion, you say you would use race to organize groups. What would that tell you? At issue, is whether race, which is socially defined, will tell you anything useful regarding biologically based traits as compared with using the alternative adaptive approach?
Otherwise, good job.