Newman says that “according to most people, race is a category of individuals labeled and treated as similar because of common inborn biological traits such as skin color, color and texture of hair, and shape of eyes, nose or head (p. 338). Newman goes on to explain, however, that to sociologists, race is more meaningful as a social category than as a biological one. Newman cites some evidence from biology that runs contrary to the idea that race is a valid way to categorize people from a biological perspective, including the facts that there is no gene that is found entirely in one form in one race and entirely in a different form in another race, and that no disease is found exclusively in one racial group (p. 339). Instead of a biological classification system, Newman contends that race is a social construct composed of the characteristics a society chooses to use to differentiate one ethno-racial group from another. These social ideas about race and ethnicity shape social rankings and determine access to resources (Newman, p. 339).
My human evolution class also considered the question of whether race is a biologically valid means of classifying humans. The evidence as considered by the physical anthropologists, says that it is not. Here are some of the findings from physical anthropology on this issue that go beyond those included in the Newman text:
According to Larsen, race is a social construct and not a biologically valid means of classifying humans (Larsen, p. 125). Larsen put it best this way: “Race is neither a useful nor an appropriate biological concept” (Larsen, p. 153). The reasons why physical anthropologists do not view race as a biologically valid means of classifying humans are as follows:
· Traits such as human head shape are not static, but instead change over time, as shown by Franz Boas’ study of cephalic index in European immigrant parents and their American-born children (Larsen, p. 123). Due probably to improved nutrition available to the immigrant children compared to the nutrition their parents received when they were young, the children’s head sizes were larger than their parents. The differences had nothing to do with race. Boas’ study showed that it’s just not valid to classify human variation typologically, and his findings led scientists to focus on biological processes (such as nutrition) instead of typologies to explain human variation (Larsen, p. 123).
· Racial traits are not concordant, meaning that traits that have been used to classify humans on the basis of race don’t correlate with their distribution (Larsen, p. 124). If race were a valid biological construct, then genetic diversity would be accounted for by them. In the 1970’s, R.C. Lewontin proved this wrong by studying global genetic variation in blood groups, serum proteins and red blood cell enzyme variations, and finding that only about 5-10% of the variations were accounted for by “races” (Larsen, p. 123). Most of the variation occurred across human populations without regard to any kind of racial classification (Larsen, p. 123-24). According to Larsen, other scientific studies on a wide range of characteristics such as genetic traits and cranial morphology have also demonstrated that multiple traits don’t lead to clear racial classifications because they cut across human populations in different ways (Larsen, p. 124). In fact, most of the genetic variation is found within groups, not between/among them (Larsen, p. 124). What this means is that humans who are thought to be in the same “race” may actually differ more genetically from each other than they do from humans who are thought to be in a different “race”. That shows that the concept of race as a means of explaining human variation is biologically invalid.
· Human variation is clinal, not racial. That means that human diversity tends to follow a geographic continuum (a “cline”) rather than a racial classification. There is considerable evidence that so-called “racial traits” do not adequately divide people into groups. Evidence for this is that frequencies in blood type B change gradually across the geography from East Asia to far Western Europe (Larsen, p. 124). In addition, the frequency of hemoglobin S increases in areas where malaria is endemic but decreases in areas where it is not (Larsen, p. 124). These traits are thus distributed by geography, not by racial typography. Skin color is also a trait that is distributed continuously by the geographic continuum of latitude, and not by racial groups. As C. Loring Brace explains, what this means is that if you walked from the top of the world to the equator, for example, you would not notice any visible boundaries between one “people” and another because the changes from place to place are very small and very gradual: While the people you saw at the top (Scandinavia, for instance) would look very different from the people you would see living at the equator, the people anywhere you stop along the journey would look more like each other than they would look like anyone else (Brace). That is because in general, boys marry the girl next door, but next door goes on without regard to any kind of boundary across the world (Brace). Clinal variation shows that while a trait can be more frequent in one geographic population over another one, it does not mean that trait can only be found in that population. Clines are entirely independent from one another (Brace).
· It makes much more sense to explain human variation in terms of life history and the biology of growth and development than in terms of racial categories (Larsen, p. 125). For example, human skin color variation is best explained as an environmental adaptation. Although there is a certain level of skin pigmentation that is inherited, exposure to solar radiation can change skin color considerably (Larsen, p. 141). When mapped, skin color varies from its darkest at the equator to its lightest at the poles to illustrate the point that the darkest skin is associated with the highest UV radiation while the lowest UV radiation is associated with the lightest skin (Larsen, p. 141). Living at the equator exposes skin to the most direct and prolonged UV light year around, which causes the skin to produce more melanin, a brown pigment whose concentration level determines the darkness or lightness of the skin (Larsen, p. 141). Melanin can be either an advantage or disadvantage: Too much melanin can interfere with vitamin D synthesis necessary to prevent rickets, but too little won’t protect skin from UV radiation (Larsen, p. 142) . William Loomis’ theory is that as human ancestors moved out of Africa and to higher latitudes, natural selection favored alleles for light skin to bring about the proper balance between UV radiation protection (needed less at higher latitudes) and vitamin D synthesis necessary to prevent rickets (needed more at higher latitudes) (Larsen, p. 142). This shows how skin color is an environmental adaptation and how the influence of nutrition and climate are important influences on the human phenotype. Nutrition plays a role too, as vitamin D deficiency from not enough UV radiation can be made up for, as least partially by eating fatty fish such as salmon (Larsen, p. 142). Another example showing the influence of climate on human phenotype is new research showing that folate acid deficiencies are linked with health issues resulting from DNA-related problems affecting cell division and homeostasis (Larsen, p. 42). Since skin color and the production of melanin help to protect the body from losing too much folate acid, natural selection would have favored the dark skin allele where UV radiation is highest (Larsen, p. 142).
Based on all of this evidence, physical anthropologists agree with the conclusion of sociologists that race is a social construct and not a valid biological means of classifying humans. The physical anthropologists would conclude, as Newman does, that human variation is better explained in terms of life history and the biology of growth and development than in terms of racial categories (Newman, p. 339).
Works Cited
Larsen, C.S. (2011). Our Origins: Discovery of Physical Anthropology. 2nd. ed. W.W. Norton & Co.: New York, N.Y. Brace, C. L. (2000). Does Race Exist? An Antagonist’s Perspective. Nova Beta Evolution. PBS website. < http://www.pbs.org/wgbh/nova/evolution/does-race-exist.html> Accessed November 19, 2011.
Newman, D. M. (2010). Sociology: Exploring the Architecture of Everyday Life. 8th ed. Pine Forge Press, Thousand Oaks, CA.
No comments:
Post a Comment