Human Variation & 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.

-          The environmental stress of High levels of solar radiation has a negative Impact on humans by the way it disrupts and affects homeostasis. The UVA or in other words the Ultraviolet Radiation that is sent from high levels of solar radiation, in other words the sun, does this. The affects begin as the UVA penetrates the human’s epidermis and works its way into the dermis. These are also known as the outer layer of skin to the inner layer of skin. The high levels of solar radiation also affects humans through a UVB, which is the same as the UVA but only penetrates the outer layer of skin. Over a long term or period of time of exposure to UV radiation, the radiation is known to cause forms of skin cancer. Short terms and exposures however usually only result in sunburns, this spectrum is most common, ultimately disrupting homeostasis. However, there are some positive effects found as UV waves do give humans vitamin D.

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: Humans have not adapted to high levels of solar radiation. The only form of the body telling itself that it is time to cool down is through sweating to regulate body temperatures.

 Facultative: When exposed to high levels of solar radiation, the phenotype in humans change causing the outer layer of the skin to become darker due to an increased produce of melanin at the top layer of the skin. This process of darkening skin is called tanning and often does not last long term but instead the skin goes back to normal. It naturally occurs when exposed to the sun outside however, can be controlled artificially in a tanning bed.

Developmental: Developmental changes can be shown through the different colors of skin on humans that corresponds to their environment. Genetic change of the DNA in humans through evolution have shown that those who live in warmer areas with a frequently exposed sun are born with a dark skin color. These developed traits are unchangeable over your life span.

Cultural: The most well known cultural ways of dealing with high levels of solar radiation would be the creation of sunblock. Sunblock helps not only protect the skin, but also minimizes the amount of UV waves that penetrate the epidermis and dermis. In addition to son block, there are also clothing made specifically for blocking the sun such as umbrellas, hats, and other shelters which gives humans the ability to be in the sun longer while minimizing the amount of UV waves hitting our skin.

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 important benefits that accompany studying human variation, these include giving us a better understanding of how humans have adapted to the changing environment to protect themselves, in this case from high levels of solar radiation. In perspective of across environments clines, we can study the different migration patterns and the DNA, and traits developed to take on these high levels of radiation. This could be a good indication of how our ancestors may have looked or how we have evolved from our ancestors. Also, studying ourselves and the effects of high levels of solar can provide us with good and accurate indications towards how much UV waves the skin can endure before getting cancer or receiving enough vitamin D without harming your skin.

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. (10 pts)

-Since race is something that we created to categorize the appearance of a human being based on more than just the traits they carry and the region they live in, we cannot use race as a very good indicator to understand the variation of adaptions I listed in number two. For instance, skin color is not always based on your exposure to the sun at times of birth. This is seen in dark colored skin children born in the winter or in a cold place around the world. The study of environmental influences would be a better way to understand human variation since it can be scientifically proven to have causation. This means that humans adapt to environmental changes no matter what race or traits they possess, whether short term or long term, the body evolves to help itself survive against natural stresses. Studying the environment around the human is a better indicator of predicting what variations take effect in order to protect the body, as well as giving us an understanding of the survival of our ancestors.