Human Variation & Race

Ultraviolet Radiation, an Environmental Stress

High levels of solar radiation is an environmental stress that can be incredibly detrimental to human survival when there is inadequate adaptation. Ultraviolet (UV) radiation can cause burns of the epidermis, which can cause a mutation of DNA resulting in skin cancer (particularly melanoma). Melanoma is deadly, killing approximately 8,000 people per year in the United States alone. In addition to cancer, the penetration of too much UV radiation into the skin can cause anemia by breaking down folate in the body. Folate is important to humans, and particularly important to pregnant mothers. A lack of folate can cause miscarriages and birth defects.

Short-term Adaptation

I don't really think there is a short term adaptation in response to UV radiation. The human body is not able to quickly adapt to the sunlight, it takes time for a skin tan to form. This makes overexposure to sunlight dangerous. What may be something close to short-term adaptation is the skin beginning to feel hot when exposed to too much sunlight. I can always feel when my skin is starting to burn, and common sense kicks in and says, "Get out of the sun!"

Facultative Adaptation

In response to UV rays, humans, over time, have adapted by way of facultative adaptation. Facultative gene action monitors the environment (in this case, levels of UV rays) and adjusts the phenotypes of humans accordingly. When there are high levels of solar radiation present (like during summer) specialized cells called melanocytes produce melanin in response. Melanin acts as a shield against the sun rays, and results in a darker phenotype (suntan). Over thousands of years, humans have adapted to the level of solar radiation in different areas of the world. Those in areas closest to the equator (i.e. Africa and Australia) face particularly high levels of ultraviolet radiation. Because of this, humans with the most effective facultative adaption by way of creating melanin have survived over time and passed those strong genes on. Skin color goes hand in hand with this, as melanin is a pigment in determining skin color. 

A person's production of melanin is a developmental adaptation.

Developmental Adaptation

There are two types of melanin: pheomelanin and eumelanin. Pheomelanin is a lighter form, eumelanin being dark brown-black. Individuals that produce more eumelanin than pheomelanin are better adapted to living in a solar radiation rich environment and will have a much darker complexion than someone who produces primarily pheomelanin. Because of this, initial populations closest to the equator (roughly within 20 degrees) were dark skinned. As populations radiated from the equator, their levels of melanin altered in order to be more suited to the environment. Populations far north of the equator have much fairer skin (high levels of pheomelanin) and are more likely to burn and peel than they are to tan. Because some UV absorption is important to the human body (needed for the production of vitamin D) populations that live in areas with less solar radiation need to produce lower levels of melanin. Vitamin D is vital in the body's ability to process calcium. If a person produces too much melanin in an area with little sunlight, they face the possibility of developing diseases like rickets and osteoporosis. Because of this, humans in these areas have adapted to a lower melanin production. However, since these same individuals can face overexposure to the sun due to lowered levels of melanin, they are more apt to develop skin cancer.

Cultural Adaption

A cultural adaption to the dangers of UV radiation is the development and use of sunscreen, protective clothing, and shades/umbrellas. Because, over time, populations have spread out across the globe, there are now people of all skin-colors scattered in all areas of the world. Initially, our ancestors utilized shelter and clothing to protect their bodies from the harmful (and hot!) sun rays. With technological advances came the production of sunscreen, which is also better suited to an overall "outdoorsy" culture. Overall, humans enjoy outdoor sports, beaches, hiking, etc.. In order to compensate for low production levels of melanin in some of the population, we needed an artificial way to protect skin when populations began migrating and spreading out to all areas of the globe. Sunscreen has allowed people with all levels of pigmentation to travel, mingle, and migrate.

Benefits

I think there are definitely future benefits to studying human variation from this perspective across environmental clines. I also think that the information we gather in this area has helped us in at least one way: sun screen. We understand that skin less able to adapt to high levels of ultraviolet radiation need more protection than their body is capable of producing. Scientists developing alternative methods of artificially shielding skin from harmful rays have helped to save lives by preventing malignant skin cancers. In addition to this, studying human variation from this angle could help us in the future treatment and prevention of diseases like rickets and anemia. For example, in studying a lack of rickets in people with light skin, scientists and doctors might better understand the level of sunlight needed to avoid the development of this disease.

A Better Way to Understand Variation

I think race should be used only to categorize groups of humans with similar adaptations to similar environments. By classifying race in this manner, we can see how humans have adapted over the years and possibly predict future adaptations in response to particular environmental stresses (like sunlight). By studying the influence that environments have on human populations over time, we could start to detect patterns of adaptations. Certain human adaptations (i.e. skin color) can be permanent. Other adaptations are only present while exposed to a particular environmental stress, as evident by humans ability to tan during the summer due to prolonged exposure to the sun. Because the human race's ability to adapt to environmental stresses is present in all humans, it is apparent that we are connected on a more basic (genetic) level than we are by an outward difference in phenotype. Studying the environmental influences and human response to those environments (our adaptations) can provide evidence that groups of people are not entirely different species. While we have a long way to go before we can solve the problem of racism, studying human phenotype differences in this manner (based on adaptation to differing environments) could help to advance us culturally. It could help us to become more accepting of one another rather than passing judgements based on someones skin tone.

Facing the Barriers, a Language Blog Post

Facing the Barriers

        

         During the Thanksgiving holiday, I engaged my partner (we will call her "A") in an interesting game of language barriers. Through parts 1 and 2 of our game, I saw power shifts and struggles to communicate on both ends. 

Part 1, the Silent Treatment

In the first part of my conversation with A, I restricted my communication to body language, hand gestures, and nodding/shaking my head. I found it very difficult to communicate this way and noticed that A had a lot of trouble interpreting me. Because it was so difficult to interpret what I was attempting to say, A ended up resorting to only speaking in terms of things I could answer in agreement or disagreement (nodding or shaking my head). This portion of our game seemed to drag on and really got us no where.

During the course of our conversation, A initiated at least 98% of the communication and topic changes. The only power I really had to initiate any changes was to use some gesture of affection (i.e. a hug). Because of my lack of ability to adequately communicate with A, and her resorting to yes/no questions, I think I held a good portion of the power in our conversation. My conversation limits really hindered her communication attempts with me and she was forced to accommodate my lowered language abilities. On the same token, I felt very "left behind" in my inability to change topics or initiate any particular conversation. In this aspect, A also held power in her own way and there was definite frustration on her end as well. 

Imagining that A and I represented separate cultures in this exercise, I would say that she definitely held an advantage in communicating any complex ideas. While she would be able to adequately explain herself, and receive equally understood responses from fellow members of her culture, I would find it difficult to relay any type of complicated information. I can only liken my communication abilities in this game to "infant" or "toddler" abilities. In the scenario of cultures, I can imagine that a speaking culture would definitely look on a non-speaking culture as being less-than or infantile. The closest "modern situation" that might mirror this (that comes to mind) is the communication barriers between Deaf and hearing cultures (worldwide). For a long time, members of the Deaf community were considered "less than"** due to their inability to communicate through hearing and speaking. Even today, Deaf people sometimes face discrimination and frustration in their every day lives. 

** I do not personally feel that any member of the Deaf community is less than. The above statement is made based on historical events involving Deaf Culture. 

Part 2, the Monotone Treatment

For the next part of this game, I had to imagine that I was encased, from head to toe, in clear glue. Or that I had fallen victim to a Harry Potter spell and could only move my lips and eye balls. It was, in no lesser word, constricting. In all honesty, A found this rather amusing initially and she did not have any problems understanding me. The only confusion there really was for her was whether or not I was being sincere. 

I think this experiment actually says a lot about how much our language abilities rely on non-manual markers like raised/lowered eyebrows, nodding, even a slight tilt of the head when asking questions. In normal, day-to-day conversations, these gestures and bodily articulations come naturally and they allow the people around us to more accurately interpret what we are saying. Because I was going against instinct and not providing A with any gestures, facial cues, or voice inflection, she was less capable of interpreting me. Body language allows us to read a person's sincerity, interest in the conversation, and emotions. I was not providing A with any of these things. 

I think body language provides a huge advantage to a person's ability to survive, obtain resources, and reproduce successfully. Without the ability to read body language, we wouldn't (sometimes) know when someone poses a threat and therefore know when to fight or flee. Without body language, it would also be difficult for people to form genuine connections to each other and (eventually) to mate and produce offspring. It helps us to identify whether or not someone is actually interested in seeing us as a potential mate. Body language also helps us to obtain resources in that we may be able to recognize when someone can or cannot meet our needs and whether or not we might key in on their body language and use it to manipulate (maliciously or benevolently) them into providing resources. 

There are definitely people that are worse at reading body language than others. These people are sometimes easily identified by their inappropriate responses to others. While I think it is hardly ever beneficial to be unable to read someones body language, I do think a scenario in which it COULD be beneficial is a job interview. If the interviewer is unable to read the body language of a particularly nervous person, the interviewee may stand a better chance in the interview. Because, any nervous gestures do not necessarily mean that the person would be incapable of handling the job at hand. Of course, this could be a double edged sword because body language can sometimes convey lying. I think everybody has a "tell," or a physically noticeable gesture or facial cue when they are lying and this is definitely beneficial. 

        Overall, A and I both prefer being able to communicate on equal, understandable ground. While we found this exercise interesting, we both learned not to take our language abilities for granted. I also learned that it must have taken a long time and a lot of hard work for humans to develop an adequate form of language in any culture.