Race, Environment, and Adaptation

1. Select only ONE of the following environmental stresses: (a) heat, (b) high levels of solar

radiation, (c) cold, or (d) high altitude. Discuss specifically how this environmental stress

negatively impacts the survival of humans by disturbing homeostasis. (5 pts)

I am choosing cold.  While it is completely possible to survive outside in moderate cold temperatures (I say as someone who has lived in a tent for an entire winter when temperatures dipped to single digits), extreme cold is a killer.  Hypothermia can come on suddenly when someone is not prepared for it (so can hyperthermia, which I know as someone born and raised in the desert).  When encountering extreme cold, the human body loses heat rapidly.  The skin will grow cold and white as the capillary constriction begins to conserve heat.  This is followed by shaking to attempt to warm up the body through movement.  When the shaking stops, numbness and frostbite have already begun in the peripheral and appendicular anatomy.  When the shaking stop, it gets really scary.  Numbness, pain, and loss of consciousness will follow (and directly in line behind those is coma and death).  Once when the temperature dropped really rapidly and I was not dressed for it (and miles from home) my entire body just ached and numbness and temporary neuropathy set in.  My hands didn’t feel numb they just stopped working and I’d randomly start dropping things.  My feet hurt.  I eventually took a taxi because I couldn’t actually control my body well enough to walk three blocks to the train station and that was scary.

Cold kills.  The body’s normal temperature of 98.6 (ish) is given away into the environment that is significantly colder.  The body’s systems slow and stop. The muscles contract in an attempt to heat up.

These facts are in some instances used by doctors to slow down medical processes in order to slow down the body processes during things like surgery.

2. Identify 4 ways in which humans have adapted to this stress, choosing one specific adaptation

from each of the different types of adaptations listed above (short term, facultative,

developmental and cultural). Include images of the adaptations. (5 pts each/ 20 pts total)

We adapt by using layers of warm clothing (natural fibers such as wool and fur are among the warmest), including a few layers for air to add insulation helps.  We also adapt by using shelter, such as caves, huts, tents, houses and in these houses use heat sources.  In my tent I used an electric blanket and about 8 blankets to survive single digits during the coldest parts of winter.  Fire, heated stones, bed warmers, and sleeping communally are other less technologically based heating adaptations.  The body also adapts to tolerate a certain range of temperature better than others… I am not sure of the physiological explanation but I know that for both my brother and I who grew up in the desert and then went to college outside of California (he in Colorado and I in Chicago), we both started out having a hard time with the cold (though he worse than me), and then by the end, the cold was no big deal but summers in California were brutal.  I am also really light skinned.  Light skin is an additional adaptation for living in colder climates where there are long periods with little sun.  The lower levels of melanin allow the body to absorb more vitamin D from the sun more quickly (or so they tell me).  It is less adapted for warmer sunny climates (like the bloody desert I live in now) where the skin is prone to burning due to radiation from the sun.

3. What are the benefits of studying human variation from this perspective across environmental

clines? Can information from explorations like this be useful to help us in any way? Offer one

example of how this information can be used in a productive way. (5 pts)

The benefit of studying variation in this way is to see how different environmental factors effect human behavior, development, and physiology.  The more we know the more we can use this knowledge.  One example is the induction of hypothermia to slow down body processes to help the body survive in situations where there are low levels of blood flow such as myocardial infarction or stroke in order to lower blood pressure and heart rate and slow down the clock so that doctors can intervene.

4. How would you use race to understand the variation of the adaptations you listed in #2? Explain

why the study of environmental influences on adaptations is a better way to understand human

variation than by the use of race. (10 pts)

Environmental influences on adaptations make the differences make sense and remove the biological determinism from the equation.  The philosophy of biological determinism has allowed people to have an excuse for blatant bias such as racism (and still happens with bias based on heterosexism as well).  But when one says, well, some humans adapted to living at climates close to the equator by developing dark skin that would protect them from burning in constant exposure to the sun, whereas in colder climates where there as significantly less sun for parts of the year to allow them to absorb more Vitamin D from exposure to the sun (it makes me wonder if there is any greater level of SAD with people with darker skin who live in more wintery climates).  It takes the value based judgments out of the equation when one says that these differences are due to adaptation to the environment instead of the curse of Cain or some other values based statement.