Human Variation and Race

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.

Although solar radiation is a great source of Vitamin D, too much solar radiation can cause harmful damages to our skin. First, you can get sun burn which is red, painful skin that feels hot when you touch the affected area, normally it happens when you are exposed to too much solar radiation for a short period of time. A more harmful and much more serious that can arise from solar radiation is skin cancer. According to skincancer.org, “Skin cancer is the uncontrolled growth of abnormal skincells. It occurs when unrepaired DNA damage to skin cells (most often caused by ultraviolet radiation from sunshine or tanning beds) triggers mutations, or genetic defects, that lead the skin cells to multiply rapidly and form malignant tumors.”

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.

Short term Adaptation for solar radiation is basically the same as heat, normally the body like to keep body heat, however when it comes to solar radiation, it body doesn’t hold body heat but tries to get rid of it. Sweating mechanisms make it easy for heat loss to evaporate.

 

A perfect example of Facultative Adaptation is the change of skin color, in more simpler terms, tanning.  Skin color is primarily the cause of melanin, which is a dark to black pigment occurring in the hair, skin, and iris of the eye in people and animals. It is responsible for tanning of skin exposed to sunlight. Melanin is located in the outer skin layer. Melanin is caused by cells called melanocytes, these cells have receptors that detect ultraviolet radiation from the sun and other sources. After a few hours of exposure to solar radiation you get melanin and your skin starts to get darker.

An example of Developmental Adaptations is the Skin pigmentation we have. Human skin pigmentation is the result of two clines produced by natural selection to adjust levels of constitutive pigmentation to levels of UV radiation. One cline was the result of high UV radiation near the equator and the other was by the requirement for UVB photons to maintain the cutaneous photosynthesis of vitamin D.

 

The most famous Cultural Adaptations we have created the use and invention of the Sun Screen or Sun block. It typically comes in spray or lotion and it is applied when the skin is in direct contact with solar radiation. Depending on the brand, it helps with the UVA rays. When applied it helps decrease the chances of skin cancer, and getting sun burned.

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.

There are many benefits to studying human variation. Especially now, that times are changes and the earth is getting warmer, we are need to study past human behavior to help us adapt to future climatical changes. As society and our surrounding change, we need to change with it if we want the human race to survive.

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 a better way is to understand human variation than by the use of race.

When it comes to solar radiation, you cannot use race to understand the difference in human adaptations. Mainly because race has no play in it, just because one person have a different skin color than another person doesn’t justify that the lighter person receives less solar radiation than the other. Earth is a sphere and being that it is a sphere different region of the world receive less solar radiation than the others, and that’s what we need to focus on. On how the amount of solar radiation in a region differs from a region that receives more solar radiation. Race us a unimportant variable being that many people from different races live amongst each other in same region.