Human Variation
Heat
High temperatures negatively effect the body’s homeostasis. The body’s response to hyperthermia, when the core body temperature is between 105 and 107 degrees, is to sweat in order to cool down. When this is not effective, depending on the climate or surroundings, there is a disruption of the body’s core temperature ultimately disturbing homeostasis. Our bodies have a few ways of adapting to this stress called heat.
Short term Adaptation: Sweating
Evaporative cooling, as it is also called, cools the body down in dry climates, but also causes major water loss which can be dangerous.
Facultative: Increased Blood Flow; Vaslolidation
The body will increase its blood flow when it begins to overheat. This allows the heat to disperse around the body in attempt to cool it down. Heat is dispersed and exits through the skin’s surface often causes redness of the face or other parts of the body.
Developmental: Linear Body Types
The more surface area, the more heat is dispersed. Length allows for more perspiration to cool the body quicker.
Cultural:
A cultural response to heat can be wearing minimal clothing or using an air conditioning unit. We allow our bodies to “breathe” by wearing less clothing, and we avoid the heat as a whole when we escape to the AC.
There are many benefits to studying human variation. Knowledge allows for preparedness when we face climates we have not previously been accustomed to. Knowing is the first step in preparing to explore a new place as you know the dangers and the safety precautions to take in facing extreme heat, extreme cold, etc. In the case of high altitudes, this information would be helpful because in order to withstand high altitudes if one wanted to climb Mt. Whitney, they would need an oxygen tank, as well as knowing what to do when the body reacts to high altitude.
Race is not a factor because all of these adaptations hold true to the human race. Race is not based in biology, rather culture. It would be more accurate to describe these stresses as in different ways humans adapt.
In your opening section, you get a little side-tracked explaining one way the body tries to adapt to heat stress, namely sweating. What you needed to explain was what you started to cover after that, namely what happens when adaptations fail... but you don't finish the story! What happens to the body when the core body temperature rises above the optimum 98.6 degrees and homeostasis fails? Heat exhaustion, heat stress, organ failure and eventually death.
ReplyDeleteYes, evaporative cooling is a short term adaptation, but how does it cool the body?
Correct, vasodilation is a facultative response to heat stress.
A little more explanation is needed on the developmental adaptation. Linear body shapes are best for hot climates because they possess more surface area *per unit of mass* then do rounder body shapes. It is this relationship between mass and surface area that creates the adaptation.
Good cultural discussion.
I agree that knowledge is always useful, but can you identify a way this knowledge can be useful in a concrete way? Can knowledge on adaptations to hot climates have medical implications? Help us develop clothing that disburses heat more efficiently? Can we develop new means of home/building construction that might help reduce heat retention? How can we actually use this information in an applied fashion?
I agree with your final conclusion and you are on the right track with the logic behind your argument. For clarification: As you say, race is not based in biology but a social construct, subject to beliefs and preconceptions, and used only to categorize humans into groups based upon external physical features, much like organizing a box of crayons by color. Race does not *cause* adaptations like environmental stress do, and without that causal relationship, you can't use race to explain adaptations. Race has no explanatory value over human variation.
You did through job in explaining about heat, I agree with you in the cultural adaptive especially living here in Cailfornia where is pretty much hot all year round and wearing less clothing like shorts and tank tops.I found that interesting that our body over heat that explains a lot because during the summer even if I apply tons of sunscreen my legs get red all over and its just my legs.
ReplyDeleteVery good explanation on how these adaptions are useful for humans, I did the Cold, which involved vasoconstriction as a form of adaptation. I was unaware that vasodilation played just as much a role in response to the heat. Great read.
ReplyDeleteGreat Post! It was very informative. My environmental condition was also heat also. Hyperthermia is when your body temperature rises over 105 to 107 degrees higher than this can lead to failure of organs or worse death. Among warm-blooded animals, individuals in populations of the same species living in warm climates near the equator tend to have longer limbs than do populations living further away from the equator in colder environments. The human body is an amazing integral system of self sustaining work.
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