Human Variation and Race

1.     a) heat. Heat has the potential to disturb homeostasis by altering an individual’s body temperature to such an extent that their organs begin to fail, possibly fatally (hyperthermia). Excessive heat is responsible for more deaths, globally, than excessive cold (hypothermia). If the body temperature reaches 105-107 degrees and remains that high for a few days, death is usually the result. Theoretically, hyperthermia would be especially difficult for people of a shorter, thicker stature to tolerate because that kind of body shape is ideal for colder climates; the layer of fat that would be useful in a colder climate would be detrimental to the individual’s health if that person was faced with conditions that instigate hyperthermia.

3. 

Short-term adaptation: An example of short-term adaptation would be radiation (loss of heat from the body in heatwaves, to the surrounding atmosphere) in response to excessive heat. Likewise, evaporative cooling is a short-term adaptation which is particularly effective in climates that are not only hot, but also significantly dry. 

Facultative adaptation: If an individual moved to a warmer climate from a colder climate, it is possible that their appetite would be suppressed because of the heat, causing them to lose the layer of fat designed to keep them warm and thus be able to cool off more efficiently. According to Bergmann’s rule slimmer individuals have an easier time cooling off (i.e. they lose heat to the surrounding atmosphere more quickly) because they have a larger surface-area-to-volume ratio. 

Developmental adaptations: Most individuals within the Masai tribe of East Africa have a specific body shape that maximizes their ability to remain cool in their hot native environment. Not only are they slender, but their arms and legs are also quite long. This body shape is highly contrastive of one that would be advantageous in a cool environment, described earlier. These individuals would thus not do very well in a cool environment because their body shape is not conducive to conserving heat.

Cultural adaptations: In the summertime in Los Angeles and the surrounding communities of Southern California, the attire one will see when walking around a populated area is relatively predictable: shorts, short-sleeved shirts, and dresses for women, and shorts and t-shirts for men, (plus sandals for both sexes) will most likely be sighted. There will also probably be a noticeable absence of jackets, particularly on days of temperatures over 100 degrees. This is an example of cultural adaptations: as Southern Californians, we dress in a certain way in the summer to expose the most skin to the surrounding atmosphere and thus cool off more efficiently. Of course, some of this also has to do with fashion, tanning, and showing off, but in general it also helps with cooling off in these hot Southern California temperatures.

3. In many ways I think that observing human variation across environmental clines is a good way to preserve the perspective that while we all vary according to our environment, we ALL vary; the reasons we are different from one another are the same everywhere. Many tribes in Africa have traditional clothing that exposes a lot of their skin, and this could be for the same reasons Southern Californians wear shorts (cultural adaptations). In other words, this kind of study allows us to see the similarities between populations worldwide, which is perspective-changing in and of itself. 

4. I don't think race can be used to explain any of the adaptations I listed in question 2. Race is generally not a fruitful lens through which to study science or the variation of human populations; indeed, using race scientifically led to a staggering amount of historical atrocities. The study of environmental influences on adaptations is much more effective, because it allows us to observe similarities between different populations who perhaps live on parts of the globe with similar environmental conditions (the similar skin pigmentations of South Indians and some populations of Africa, for example).