Human Variation vs. "Race"

1. The stress I will discuss is heat stress, given that we all (presumably) live in sunny Southern California. Heat can have a number of negative effects on human homeostasis; some of these are obvious, and others are less so. Physically, heat can affect the body temperature and hydration level of an individual, making that person susceptible to heat-related illness and death.  Heat resulting from higher exposure to the sun (or more direct equatorial sun) can increase the risk of things like skin cancer. And, heat can limit human reproductive success in other ways: if the temperature is too high, it is difficult to be outside socializing and looking for potential mates.

2. Short-term: This might include increased radiation of heat from the surface of the skin when exposed to heat stress, in order for the body to maintain a proper temperature.

Facultative adaptation: The release of certain hormones can alter the body’s metabolism in order to assist the body in maintaining an acceptable internal temperature in heated environments.

Developmental adaptations: One theory explaining the loss of body fur in hominids posits that heat stress from the African environment in which humans developed led to an evolutionary shedding of hair for improved thermoregulation. 

Cultural adaptations: Clothing styles and air conditioning might be two of the most obvious cultural adaptations to heat. In the summer, humans tend to wear less clothing, and crank the AC up in order to make the environment artificially cool.

3. Information about human variation can be very useful. By looking at variation in adaptations across clines, it is possible to see physiologically (and culturally) where, when, and why the divergent adaptations took place. Exploring the different responses to stress across time and location is beneficial for understanding how humans (and other species, for that matter) got where they are now, and perhaps where evolution might be heading in the future.

4. The idea of race implies that there are separate “species”, if you will, of humans., when in reality, there is only one species that has adapted differently to different environmental pressures. The development of humans in various geographic locations is something that can be defined and studied scientifically much more objectively than saying something like “why did different races develop”. Defining a “race” of people precisely enough to study them as a group seems doomed from the start, since there is so much variation even within groups from similar geographic areas.