Weather is a major environmental stressor specially cold weather. As an example we can look at Alaska, the cold weather here impacts human survival by disturbing homeostasis. The body is under strain to try and keep normal temperatures between 97.6 F and 99.6 F, this causes the body to burn up more energy in order to create this heat making the humans exposed to extream temperatures need more food to fuel their bodies. This becomes extream environmental stressors since in cold place the food is not very abundant. Places such as Alaska get less sunlight than any other place in the world resulting in a lack of ability to produce vitamin D which the body needs to absorb calcium among other things.
If any of us none native to this weather were to take a cruise through Alaska we would experience shivering and or an increase in metabolic rate which temporarily increase body temperature, this are short-term adaptations. If we decided to move to this icy land we would gradually switch between vasoconstrictions which minimize heat loss and vasodilation which provides warmth to the skin, in other words we would be showing facultative adaptation. Once we have fully made home the cultural shock would set in and we would have some cultural adaptation such as the clothing choice and eating foods high in fats and carbohydrates ( mostly frowned upon here in sunny Cali). After generations of our offsprings being born locally and most likely mating with the locals, our family tree would start to show a developmental adaptation, short, stocky and robust bodies with short limbs are a preferable trait in this part of the world as it helps retain heat.
The benefits of studying human variation from the perspective across general environmental clines is that we can learn much about how humans are affected by mutations, natural selection, and other evolutionary effects, and potentially use it to our advantage in the future to find cures for ailments; or at least understand human variation a little better. The fact that we were able to isolate the reason for sickle-cell anemia being popular in areas where malaria was prevalent is a perfect example how we can better understand and learn about human evolution.
It would be unusual and misinforming to use race to understand the variation in adaptations. Eskimo people are accustomed to live in cold temperatures, but you could then look at a similar looking race like the Chinese and assume that they have the same adaptations and be completely wrong just as my homology post on the frog and the lizard being from the same ancestor and having similar properties due to this ancestor it is possible that two different races bare the same looks but they are due to their enviorment . Studying people’s adaptations and the effects of the environments of their home regions is a better way to understand the differences among various groups of people that will give us a much clearer and complete understanding on how and why people have such unique traits across all the regions of the world.
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ReplyDeleteIn your opening section, you are actually explaining one way that the body tries to adapt to the cold, namely that it burns energy to increase body heat, which results in a need for additional food. That need for food is not a direct response to cold. It is a response to the body adapting to cold.
ReplyDeleteSo think about how cold directly impacts homeostasis. You are out on a hike, not prepared for cold weather, and the weather changes suddenly, temperatures plummet and you are stuck without a proper coat. What happens to your body? Well, if the drop in the environmental temperature is significant enough, your body temperature will plummet as well. Our body runs best at an optimal temperature of 98.6 degrees. If the body temperature drops, the blood in our body becomes sluggish and doesn't flow as well, slowing the deliver of oxygen to the body, leading eventually (if you don't get warm) to hypothermia, organ failure, tissue death, and ultimately death itself. Those are the direct impacts of cold stress on the body.
With regard to your adaptations, shivering is indeed a short term adaptation. Raising the metabolic rate actually requires the turning on of genes to produce this response, making it a facultative trait. Correct on vasocontriction/vasodilation as a facultative trait. Correct on the cultural and developmental adaptations.
And let me note that I like the way you explained this as a story. It follows a logical progression that helps your reader understand the adaptive process.
Very good discussion on the benefits of the adaptive approach. Yes, in many cases, this can produce advances in medicine but we can also use them for more mundane things, such as better clothing to help retain body heat and keep out the cold.
You are correct that the use of race results in a lot of unsubstantiated assumptions and leads to incorrect conclusions, whereas the adaptive approach is based upon empirical evidence. Keep in mind as well that race is not a biological construct. It is a sociocultural concept, with no basis in biology, subject to the biases and preconceptions of each culture. Each culture has it's own system of race... so which definition of race should we use? If it has no basis in biology, how can race be used to understand the biology of our human variation?
Good post! Easy to read. I did mine on heat which is the opposite of what you chose and that helps me understand the opposite view and the adaptation that our bodies do in the cold.
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