Human Variation and Race Blog.
1.) Heat increases your heart rate, which causes your blood vessels to dilate, which causes blood flow to decrease going to your heart and pulmonary veins, causing your body to shut down and faint from lack of oxygen if not taken care of right away. It can also cause heat rash, heat exhaustion, and excessive amounts of sweating which can also reduce body moisture.
2.) Short term effects of heat-Heat exhaustion ( a heat related illness that happens when one has been in high temperatures for long periods of time and has become dehydrated; two types- water depletion and salt depletion.)
Falculative adaptions of heat- Skin tone- darker skin tone attracts heat easier than a lighter color skin does. This can be seen by monitoring the production of melatonin and the absorption of vitamin D.
Cultural adaptions of heat- Living near large parts of water, so as to stay hydrated easier.
3.) By studying human variation this way, it essentially removes any and all essences of 'race' from the equation. It brings things to a more non-biased and scientific point of view. It allows us to look at the human species as being one, and not separating and segregating the different variations that humans come as.
4.) Using race to study the adaption of heat in humans would explain why humans with darker skin tones live in parts of the world where heat is an immenent factor in their lives (i.e. the peoples in Africa) and why lighter skin tones can survive in colder weathers (i.e. the peoples in upper northern Europe, such as Iceland, Greenland, Norway, Russia, Ireland, and Great Britian.) However, studying human variations as opposed to studying race allows for a more factual, non-biased way to explain how humans have adapted to the environment.
posted by Unknown @ 2:50 PM
3 Comments
3 Comments:
In your opening paragraph, you are actually describing, for the most part, a factulatative adaptation to heat, namely vasodilation. The question was, how can heat negatively impact the body. If the body can't keep its core temperature at the correct level, increasing body temperatures can lean to heat stroke, organ failure and brain damage.
Some clarification on how the body responds to heat: When the body is exposed to high heat, the body temperature starts to rise. To rid the body of excess heat, the circulatory system kicks in much as you have described it: The heart rate increases and capillaries near the skin's surface dilates (opens), so that blood carrying that excess heat is taken to the surface and dissipates from the body. But this doesn't reduce the amount of blood getting to the heart, though it isn't good for the heart to have to work so hard for an extended period of time.
Heat exhaustion is not an adaptation. Remember that an adaptation is beneficial overall to the body. Heat exhaustion is a symptom of heat stress, not an adaptation to it. The most common short term adaptation to heat stress evaporative cooling (sweating).
Skin tone is an adaptation primarily to solar radiation. A facultative adaptation would be vasodilation (described above).
Yes, it has been suggested that bipedalism was an adaptation to heat stress. Another adaptation is body shape, as described by Bergmann & Allen's rules.
Good cultural adaptation.
Good explanation for the benefits of the adaptive approach.
"Using race to study the adaption of heat in humans would explain why humans with darker skin tones live in parts of the world where heat is an immenent factor in their lives"
Actually, it doesn't explain anything. Race is just a system of categorization of humans, and it is a subjective system, meaning it varies from culture to culture. Race only organizes people into varying groups... it doesn't help explain why variation exists, it only describes the variation. You were on the right track in your final sentence, when you talk about how race is a biased view of human variation. Science must be objective in order to be accurate, so it cannot be based upon a biased, subjective foundation.
Hey Savannah great post! This was the same topic I discussed but your information was very thorough! I liked the fact that you included about darker skin attracting heat more than light skin. This is something that I hadn't known before so thanks for including that! Nice job!
Hi Savannah! I think that in addition to the short-term effect of heat exhaustion, it's important to note how we adapt to avoid heat exhaustion in the way of sweating. It's short-term in the sense that as soon as the environmental stress of heat is removed, we immediately stop sweating. It's also extremely effective at removing heat by bringing it away from the body's core to the periphery so that it can evaporate.
Additionally, from what I read in the anthro.palomar.edu pages, a developmental adaptation that's equally important in hot climates and it is in the cold climates I studied is the development of body shape in terms of mass and surface area. Bodies with more surface area tend to lose heat faster, which is why for instance a giraffe will lose heat faster than a polar bear, or why the polar bear has more mass in a centralized location than the giraffe. The same goes for humans: people living in the heat of the deserts in Africa tend to have more elongated limbs than people living in the arctic tundras, whose bodies are more compact to conserve heat rather than allow its release. Just another interesting point to add!
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