Human Variation & Race

The environmental stress I am going tone discussing today is high levels of solar radiation. This negatively impacts the survival of humans by disrupting homeostasis. One of main effects of this disruption at the hands of high solar radiation levels is skin cancer which can definitely reduce someone's chances of reproduction. Another, is a disruption in vitamin D development. A lack of vitamin D can affect bone growth and fetal development and thus affect someone's ability to reproduce. One way in which humans have attempted to adapt to this radiation, culturally, is through the development of sun screen that acts as another layer of protection against solar radiation. Facultative adaptations to high levels of radiation by humans can be found when humans tan themselves and purposefully expose themselves to UV rays in order to tan the skin. The tanning of the skin is caused by an increase in melanin production and thus people who are most susceptible to UV rays are better prepared to withstand it because of the increase in melanin. A developmental adaptation to this would be the evolution of people with naturally darker skin tones. Darker people are naturally less susceptible to the negative effects of solar radiation. However, darker skinned people do have a greater chance of having a vitamin d defficiency. I think there are many benefits to studying human variation from this persoective because it reinforces the fact that are phenotypic differences are not forms of superiority over one another but displays of adaptations to the various environments across the globe. You could use race to understand the developmental adaptation of darker skinned people as it literally pertains to the color of someone's skin. I also think race can be used to understand the facultative adaptation I mentioned as it is usually lighter folks who go to get tanned as darker people don't necessarily have the need to go and do that.