Human Variation and Race
1. Heat negatively impacts the survival of humans by disturbing homeostasis when the body either gets too hot or looses to much heat. When our bodies get hot our body's way of regulating itself is by sweating. Sweat helps the body cool down, but while we sweat our bodies are not only getting rid of water they are also getting rid of important things like electrolytes, like sodium and chloride. If our bodies lose enough water and electrolytes and we do not replenish them, this can cause serious harm to our bodies. We can become dehydrated which can make us tired, get headaches, and become confused. Becoming too hot also poses health risks, if our body temperature reaches 104 degrees Fahrenheit, we can get what is known as a heat stroke, this can bring on symptoms of confusion, fainting, vomiting, seizures, coma, and even death. Heatstroke is a real medical emergency.
2. Four ways in which humans have adapted to this stress are:
Short term adaptation would be sweating, sweating happens when the body gets hot, so as soon as the stressor is removed the body returns back to normal and stops sweating.
Facultative adaptation would vasodilation which is the expansion of blood vessels permitting increased blood flow to the face. This flushing allows for the heat from the inside of the body to be emitted to the outside.
Developmental adaptation would be the loss of body hair. While the human species evolved it began losing body hair and this helped the body be able to adapt to heat.
Cultural adaptations would be to dress in light clothing and keep to stay hydrated to avoid becoming ill.
3. The benefits of studying human variation from this perspective across environmental clines are useful in the sense that it gives us an idea of how it is that we all come from the same species, yet we all look different. It is interesting to learn that these differences have a lot to do with where our ancestors came from and that their characteristics or features come from the type of environment that they lived in. Their bodies adapted to whatever environment they were in order to survive, and then those traits were passed to us.
4. The way that I would use race to understand the variation of the adaptations is by saying that people that live in hotter climates are more adapted to the heat than people that are not. Although we all have the same sweat glands it all depends on the type of heat that a person is in that will determine how much someone sweats. Humid heat makes the evaporation of sweat harder, so humans can adapt better to dry heat. The study of environmental influences on adaptations is a better way to understand human variation than by the use of race because we have to remember we are all humans, being one race or another doesnt make us superior or inferior, we are all made up of the same thing so studying this helps us better understand how it is that we all got our different traits.
For your opening section, the first and last parts are what are pertinent here, focusing on heat stress itself and how that negative impacts the body.
ReplyDeleteDehydration is not directly tied to heat stress. Dehydration occurs when we try to adapt to heat stress by sweating and we don't resupply the lost fluids (i.e., it is *indirectly related). Sweating is an adaptation to heat stress and shouldn't have been discussed until the next section.
Good discussion on your short term and facultative adaptation.
Hair loss *might* be an adaptation to heat stress, but it is very questionable. After all, millions of other animals lived in the same early environment as humans and didn't lose their hair as an adaptation to heat stress. It may be more accurate to say that hair loss was the result of sexual selection rather than natural selection. A more reliable example here would be a long, lean body shape, as explained by Bergmann & Allen's rules.
Good cultural adaptation.
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 releases 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?
Are you actually using race to understand human variation in the last section? Or are you using the adaptive approach and layering race over top of it? Is it really possible to use race to understand human variation? Understand that it is entirely acceptable to answer this question with "no".
To answer this question, you first need to explore what race actually is. Race is not based in biology but 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.