HUMAN VARIATION AND RACE
1) High levels of solar radiation negatively impact our survival and disturb homeostasis because overexposure is so possible and so common. We as humans benefit by sin exposure, but it is easy to get too much sun and do extensive skin damage, in a number of cases irreversible.
2) Short term adaptation: One example would be human beings wearing sunglasses to protect their eyes, or sunscreen to protect their skin, limiting exposure.
Facultative adaptation: An example here would be changes in skin tone as a result of prolonged exposure. I am specifically referring to getting tanned or sunburned as a result of exposure. Developmental Adaptations: In humans, prolonged exposure could result in chromosomal changes. Melanin levels are increased over time as a result. Cultural Adaptation: One example here could be humans choosing to cover their bodies when they are aware that prolonged exposure could be harmful to them.
3) Studying human variation in this way can help with understanding people from different cultures. It is always easier to accept people from different walk of life if we know how it is they came to be the way they are. For instance, if we were to meet someone with skin color different then ours we might assume we know certain things about them. They may appear to be from one culture or race and that may not be the case at all. For example, we may meet someone from Africa who dresses in heavy clothing from head to toe in the hot sun, and think that appears crazy. When in reality they are attempting to protect themselves from harmful exposure. If we did not try to get that information we might assume all sorts of crazy things that have no basis in reality, but are culturally a necessity for that individual.
4) In regard to race as it relates to high levels of solar radiation, according to skincancer.org the annual incidence rate of melanoma is 1 per 100,000 in blacks, 4 per 100,000 in Hispanics, and 25 per 100,000 in non-Hispanic whites. We could take this to mean that African Americans have made an genetic adaptation to all of the exposure, and do not get skin cancer as easily. That is just one interpretation. However, the numbers are not so skewed to suggest this is the case across the board. Environmental impact on cultures is more reliable than race as an explanation for these changes because the environment you live in plays a much bigger part in who you are-even if on the surface racial stereotypes appear to fit. More often than not it is the environment causing the behavior, not because an individual is part of a particular race and therefore programmed a particular way.
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Good post! I like your answer for question number 3 because racism and different colored skin is an ongoing problem within our society today. It often times does lead to assumptions about the person even if they are not true. I really liked your comment "they may appear to be from one culture or race and that may not be the case at all". I see this everyday at work, my co-worker is Puerto Rican and Scottish but when you look at him you would automatically assume he is African American because of his dark skin and Afro. It is something we as a society need to work on.
ReplyDeleteOkay on your opening description but expanding the explanation would have been helpful. What is the connection between solar radiation and skin damage? Draw a more direct line between the stress and the disturbance to homeostasis.
ReplyDeleteMissing some images for your adaptations?
Remember that short term, facultative and developmental traits will also be biological/physiological in nature, not cultural practices.
Sun glasses would be a cultural adaptation. Humans don't actually have a short term adaptation to solar radiation. That is one of the reasons why it is so dangerous.
Tanning is a facultative adaptation to solar radiation. Sun burns are not. Keep in mind that adaptations are beneficial to the body (even if just in the short term). Sun burns have no benefit. They are an indication that radiation damage has occurred and that the body has not adapted fast enough to protect itself. It is a sign of a failure to adapt, not an adaptation itself.
For developmental, I don't think you mean "chromosomal" which would indicate a change in the number or structure of the chromosomes. You mean "genetic" or a change in the genes on those chromosomes. Those populations on the equatorial areas would tend to develop darker skin tones through increased melanin levels from birth to offer protection against constantly higher levels of radiation. But as human populations moved into higher latitudes, why did their skin tones lighten? Why not just keep the darker skin tones as protection, just in case?
Good cultural explanation.
I agree that we would benefit if there was a general understanding of the biological/adaptive nature of our phenotypic differences. More knowledge is a good thing.
"...the environment you live in plays a much bigger part in who you are-even if on the surface racial stereotypes appear to fit."
And I think you have hit on a problem here. Sometimes race seems to match the information we get from the environmental approach, and so the assumption is often made that race itself has a biological origin. But race is just a sociocultural construct with no basis in biology and that construct is subjective, varying from culture to culture. So how can it be used to objectively understand biological variation? It can't.
Good post Sean, I too did my post on human adaptation to solar radiation. One of the items I think the professor touched on is we don't have a short term adaptation to UV radiation and this poses a big problem. In regards to those of Northern Europe and their lighter skin this has been touched on with the vitamin D hypothesis. I like how you pointed out that "the assumption that race itself has a biological origin." I myself negated the socio-cultural definition of race to my detriment.
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