Human Variation and Race

Environmental Stress: Cold

Homeostasis is typically disturbed by the cold when the body is exposed to extremely cold temperatures.  When this happens, the body’s temperature lowers below the normal healthy temperature of 98.6 degrees Fahrenheit and risks hypothermia.  Hypothermia is a medical emergency where the body is unable to produce heat at the same speed that the body is losing heat and therefore the overall body temperature lowers and the body’s energy decreases.  A low body temperature is dangerous as it can slow heart rate, brain activity and breathing.  Therefore, the cold negatively affects homeostasis as it can cause hypothermia, which can be a danger to survival if treatment is not urgent and persistent.

Short-Term Adaptation

In response to cold stress, a short-term adaptation is shivering.  Shivering is a temporary involuntary mechanism triggered to maintain homeostasis.  The body uses small, generalized and uncoordinated muscle contractions to create heat. The increased muscle activity produces some heat. 

Facultative Adaptation 

A facultative adaptation in response to cold stress is vasoconstriction.  Vasoconstriction is a normal physiological response of narrowing the blood vessels near skin surface (Dennis O’Neill, http://anthro.palomar.edu/adapt/adapt_2.htm).  Many times, heat is lost when warm blood travels close to the skin surface.  This contraction of blood vessels near the skin reduces the amount of warm blood that flows close to the skin surface and therefore reduces amount of heat lost.  

Developmental Adaptation

Another way the body protects itself from cold stress is through the developmental adaptation of having a thick fat layer around the body and vital organs that provides insulation and the retention of heat.  People who live in colder climates are typically larger than others.  Their bodies have developed a thicker fat layer in order to adapt to the colder climate and essentially survive.

 Cultural Adaptation

Many humans dating back hundreds of thousands of years ago started wearing clothing in order to keep warm.  Many Neanderthals and hominids much more recent than them used animal skin and fur for another layer of insulation and protection.  The use of clothing as a mechanism against the cold is considered a cultural adaptation to the cold stress.  

The benefits of studying human variation and race from this perspective across environmental clines is how we can develop our ways in which we stay warm in order to survive through analyzing how others have approached this task.  Everyone thinks differently and has different experiences; therefore it is best to learn from each other in order to find the most effective way to cope with the cold weather.  Hypothetically for example, while people living in the Middle East may only be using thick wool clothing for insulation when outdoors, countries like the United States are selling small packets that generate heat.  You can hold them in your hand or stuff them in your shoes and use the heat to stay warm.  People in the Middle East could benefit from studying ways in which we stay warm and they could start using these heat packets.  

I would not use race to understand the variation of the adaptations for cold stress as race does not matter.  Different races do not have advantages or disadvantages in dealing with cold stress compared to others.  The study of environmental influences on adaptations is a better way to understand human variation rather than race because since there is no connection with race, the humans must have adapted to the different environments over time and in variation as humans developed in many different parts of the world individually.