Human Variation and Race
The definition of homeostasis is the tendency of the body to see and maintain a condition of balance or equilibrium within its internal environment, even when faced with external changes. The effects of cold weather on the human body can be harmful and even deadly. Peripheral vasoconstriction is a process that occurs when your body is subjected to cold weather, the blood vessels in your outer extremities will constrict, thereby preventing blood from reaching these areas. This is your bodies attempt to concentrate your blood in the core of your body to keep your internal core temperature from plummeting. This causes your blood pressure to raise and your heart to work harder, which can be dangerous for someone with a heart condition. The lack of blood flow throughout your body also reduces its ability to fight of colds and other infections as its resources are being used elsewhere in your body. A persons appetite will also not only increase when subjected to cold weather however it can also change. Your body uses food as a fuel source, and in colder climates it requires greater quantities of food to maintain it's internal core temperature. Heartier foods are also required, your body is able to extract more heat with less energy when it is provided more proteins and carbs rather than with fruits and vegetables. All of these conditions negatively impacts the survival rate of humans as it takes more food and energy to survive. In modern day societies this is not as much of a concern as it was even just a few hundred years ago. The ability for a species to hunt and gather food and construct fires to stay warm is crucial to their survival in harsh climates.
Short-term adaptation: A short term adaptation is peripheral vasoconstriction. This is an almost immediate response by your body when subjected to cold climates. Your body quickly begins to restrict the blood flow to your outer extremities in order to keep your core body temperature from falling. The image below uses and infrared camera to show the temperature differences in a human hand when subjected to a colder temperature, notice how the fingers have a significantly lower temperature than the hand itself.
Facultative adaptation: A facultative adaptation to cold weather could be the change in your appetite. When your body is subjected to colder weather it requires more fuel, or food, to keep warm. Eating things such as fruits and vegetables are not going to be a good source of fuel for your body in a cold climate. Your body will begin to quickly adapt and can change the type of food you are craving to things with higher fat content which will provide a better fuel source for your body. When you remove yourself from the cold climate your bodies cravings for those fattier foods will reduce.
Developmental adaptation: Long-term exposure to cold climates, for example the results of many generations of people living in a cold climate, can alter the DNA of that population. Long-term exposure to cold climates can change the overall shape and height of a population as having a shorter overall height and bulkier build is better suited for survival in colder climates. The shorter body and limbs of a human provide less surface for heat to escape and a shorter travel distance for blood within the body. This coupled with a bulkier build, having a higher fat content in the body, can increase a populations chances of survival in a colder climate. Eskimo's are generally shorter and have a higher body fat content than a population that lives in a warmer climate.
Cultural adaptation: A cultural adaptation to living in a cold climate is the need for a population to live more closely with one another. Populations living in colder climates tend to have smaller dwellings, as apparent in igloos and teepee's. The smaller quarters allowed for multiple individuals to share a small space and use their collective body temperatures and small heating sources to stay warm.
Studying human variation from the effects of cold weather can be extremely helpful. We are able to examine how different populations have adapted to environments, and from that provide us with a better understanding on the history of environmental changes across the planet over thousands of years. By studying the affects of cold weather on a population and how the human body adapts affords us the ability to survive in cold climates with greater success. We are better able to recognize the signs of frostbite and hypothermia, we have medical treatments and procedures that can reverse some of those effects if caught early enough, and we are able to design better housing and clothing for use in colder climates.
An example of using race to understand variations in the adaptations listed above would be comparing Inuit Eskimos and Yupik Eskimos. These two different groups of Eskimos are from completely different regions however both share somewhat similar environments. As you start to compare them you will start to find many similarities as they both have had to adapt and evolve to living in cold, harsh climates. Studying the environment factors and influences on the adaptations themselves who how different groups of people change when presented with different environments, and you will began to notice more differences in the populations.
I really appreciated how in depth, detailed, and organized your post was. You offered very good insight in a professional way that was enjoyable to read. I never thought about it in a way to consider food as a source of this so it gave me something good to think about. Also very much enjoyed the picture use, seemed relative without being exactly direct.
ReplyDeleteYou provide a lot of information in the first paragraph, but a lot is actually a discussion on how the body responds and tries to adapt to cold stress... in other words, information that belongs in the next section. The key question in this first section is how cold stress negatively impacts homeostasis, not how the body tries to adapt to it. So what happens to the body when the core body temperature drops below the optimum temperature of 98.6 degrees? Why can't it function well below this temperature?
ReplyDeleteVasoconstriction actually takes a little time to occur and involves the turning on or off of genes to impact the constriction of those vessels. That means this is a facultative response, not short term. A short term adaptation to cold stress is shivering.
With regard to your facultative response, I'll accept it but remember that we are talking about automatic physiological response that don't require an action on our part. An example is both vasodilation but also alternating vasodilation-vasoconstriction (also called the "hunting reaction") which traps heat near the body core but occasionally releases blood flow to try to prevent tissue death in the extremities.
Good example for your developmental trait, but how does it help with cold stress? That needed to be explained. How can you use Bergmann & Allen's rules to help with this explanation?
Good cultural discussion.
Very good discussion on some of the concrete benefits of this type of study.
Are you actually using "race" in your final section or are you just using the adaptive approach and layering race over top of it? Can you use race to understand human variation? Understand that it is possible to answer this question with a "no".
To answer this question, you first need to explore what race actually is. Race is not based in biology but is a social construct, based in 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.
Hey,
ReplyDeleteI really enjoyed how descriptive you got with your post and how much time you took to make sure we could really understand the point you were trying to make. Also I like the fact that you used visual aids to look at. By far, you’ve had one one the more developed posts, it was quite interesting to read.