Week 8

1.         Overexposure of solar radiation can cause the skin to burn and can also cause damage to DNA. High levels of solar radiation can lead to genetic mutations in skin cells which can lead to skin cancer and if left untreated can spread to other organs and cause death.

UV radiation also rapidly depletes serum foliate levels in light skinned individuals. This affects pregnant women and can cause spina bifida of babies. The breakdown in B vitamins can also cause anemia.

2. 

High Levels of Solar radiation: Short Term. We do not have a short term adaptation. When exposed to too much solar radiation, the skin burns.

 High Levels of Solar radiation: Facultative. An example of facultative adaption is tanning.  Tanning is an example of acclimatization because it is a temporary and rapid adjustment.  The tan is temporary and the skin will return back to its original skin tone after sun exposure has been reduced or stopped.

 



High Levels of Solar radiation: Developmental. Long term adaptations in humans include deeply pigmented skin. If individuals are born with dark skin it will not get lighter if they are never exposed to sunlight. Skin color is affected by melanin. Melanin is extremely important as it acts as a built in sunscreen because it absorbs potentially dangerous ultraviolet rays.  Melanin protects us from overexposure to UV radiation. Light skin produces small amounts of melanin.  Deeply pigmented skin produces maximum levels of melanin.  Individuals that have darker skin have higher exposure to solar radiation. They tend to live in warmer climates. Over time, they produce more melanin which protects them. Individuals that live in northern areas are usually colder so these individuals wear more clothing that helps block the UV exposure and protect their fair skin.

High Levels of Solar radiation: Cultural. There are numerous cultural adaptions to solar radiation.  Shelter, shade, clothing, and sunscreen provide protection from solar radiation.  Individuals can wear clothing with UV protection, hats, sunglasses, carry umbrellas and wear sunscreen.  Although sunscreen will not protect the skin for a long period of time or

protect it completely, it will let the individual spend more time outside in the sun to work or enjoy recreational activities without causing damage.

3.         The benefit of studying human variation across environmental clines is to see how humans adapt to environmental influences.  If we studied only one environment we would not be able to see the impacts of solar radiation.  We would only have data from one source instead of multiple clines. As an example, if we studied solar radiation and skin color for individuals living near the equator, we would get different data than if we studied individuals that live in Alaska. Those that live near the equator have darker skin and higher tolerance to solar radiation than those that live north and are light skinned.  Being able to study the variation across environmental clines helps us understand solar radiation affects.  There are positive and negative affects of solar radiation which include skin cancer or on the flip slide, the lack of solar radiation can cause lack of Vitamin D which can cause anemia, rickets disease and even osteoporosis.

4.         We could use race to help understand the variation of adaptions of solar radiation.    Characteristics of skin color, hair color, and eye color could help us understand the over or under exposure of the solar radiation.   It would be helpful to include the environmental influences as well and study how these individuals adapted to their environment.