2. Short term Adaptation: These kinds of adaptation allow organisms to respond quickly to changes in the environment to maintain homeostasis. For example, sweating would be something that would qualify for short term adaptation because humans sweat to cool down their body temperature. By allowing sweat to evaporate, heat transfer to the evaporating sweat and leaves the body. However, sweating for a long time could be dangerous for the body as it can lead to dehydration.
Facultative Adaptation: Facultative traits are genetic traits. Our skin color can be a facultative adaptation to heat stress. Lighter colored skin means that people living in that climate does not require much protection against the UV rays and have opted out to absorb more Vitamin D. Dark colored skin provides better protection against the UV rays but gives up the better ability to absorb Vitamin D.
Developmental Adaptation: These adaptations are traits developed by changing the DNA over a long period of time. Our response to heat includes bipedalism. While standing on two feet, we are exposed to less heat from the sun because we have less surface area that is showing to the sun. In addition, standing allows our skin to have more contact with breezes by exposing a lot of surface area.
Cultural Adaptation: Cultural adaptations vary between cultures, but they can also work together. One very obvious cultural adaptation would be the usage of air conditioners to bring the temperature lower than the outside. We love to cool off next to an air conditioner when the outside temperature is higher than 110 F.3. By studying variation in human adaptation to the heat, we can figure out what to do in certain climates. We know how to deal with the heat; we avoid it, tolerate it, or embrace it. We have invented air conditioners, fans, and made bright clothing, shading structures, and swimming pools to survive the heat. We know that we have to stay hydrated as much as possible and avoid being hurt by the heat.
4. I believe that the variations of adaptations to the heat is due to the difference in race because it is the environment that affects the adaptations. People from a certain race will adapt according to the environment when they are sent to different parts of the world, not according to their race. Environment is the factor that affect adaptations made by humans.
I find it hard to believe that bipedalism is actually a development we've made to adapt to the gradually warming weather.
ReplyDeleteBut just one question: you stated, "People from a certain race will adapt according to the environment when they are sent to different parts of the world, not according to their race." What did you mean by this? I just need a little clarity.
But otherwise, great post! It was really informative, and everything else made perfect sense for me.
First, on the part where you pointed out about the bipedalism, I do not mean that we developed bipedalism JUST to reduce our exposure to heat. However, I do believe that bipedalism IS part of our efforts to survive from the heat.
DeleteI can clarify the second part of your comment right now. What I am saying is that people from same cultural background will not try to survive using their cultural methods when they are moved to a whole different environment. In a new environment setting, they will adapt TO the environment, and their race/cultural background will have little to no effect on the way they survive.
Heat is its very own stress. It can cause dehydration, but this is a secondary stress resulting from the body trying to deal with heat stress. So focus on heat itself. Our bodies must maintain an internal temperature of 98.6 degrees. Why? What happens when that temperature goes up? How does this harm us?
ReplyDeleteGood explanation on evaporative cooling. Yes, it can be dangerous over long periods of time, but that is why it is a short term adaptation. It is temporary, giving the other three adaptations time to kick in and rescue the body more efficiently.
Skin color is an adaptation to solar radiation, not to heat. Yes, you tend to see darker skin in hotter climates, but this is because sun exposure, not heat. An example of a facultative adaptation to heat stress is vasodilation which helps to dissipate excess heat from the body.
One of the arguments for the evolution of bipedalism is that it reduced the amount of skin directly hit by the sun, which reduced the threat of heat stress. This is an interesting idea, but recognize that it is one of several hypotheses. One of the problems with this idea is that the one part of the body that can tolerate heat the least, namely the head, carrying around the brain which just HATES heat, is the part most exposed to the sun in the bipedal position. Yes, we kept our hair on our head, but still, that raises questions about the validity of this argument.
Good discussion on cultural adaptations.
Great explanation on the practical applications of this approach to studying human variation.
"I believe that the variations of adaptations to the heat is due to the difference in race because it is the environment that affects the adaptations."
This is a misconception of race. Race is a subjective social construct, not a biological one, so how could we use it to objectively understand biological traits? Race has no causal relationship with biological traits. The environment does. Without a causal relationship, you can't use race to explain why human traits vary. It can only describe and categorize.