In order to maintain homeostasis in response to the heat, evaporative cooling occurs which helps prevent the body from overheating. Evaporative cooling occurs when the sweat glands perspire, then the sweat evaporates from the surface of the skin cooling off the body. This is an example of a short-term adaptation humans have formed to deal with the heat.
A facultative adaptation that humans have formed due to high temperatures is vasodilation. Vasodilation increases the blood flow to the skin in hot weather by widening the capillaries near the skin's surface. This allows the heat that is carried by blood to be released from the skin to the surrounding air. Vasolidation can cause redness and warming of the skin.
Humans that live in warmer climates have adapted to the heat by having larger appendages. These larger appendages promote heat loss making them a developmental adaptation that formed over time. The same happened to humans living in colder climates, except they have smaller appendages that help reduce heat loss. Another possible developmental adaption was the loss of body hair in humans. Because most of the early humans lived in the woodlands and savannas of East Africa, the weather was generally warm or hot. By losing most of their body hair it helped them adapt to the warm weather because hair reduces the cooling effects of sweating.
A way that we have culturally adapted to the heat is by the use of tools, or technology. As we all know, humans invented air conditioning to keep our bodies cool during times of warm weather. Air conditioning can keep a consistent cool temperature in a controlled environment even during the hottest times of the year.
It is beneficial to look at human variation this way because we see that we are all humans yet so different depending on the way we live. Humans that live in colder climates are generally stockier while humans that live in warm climates are more linear with long arms and legs. We can use this information productively by maybe sending shorter and stockier people to study cold climate places as they will be better suited for the environment.
Race does not change the ability to better handle heat as race does not effect the way humans adapt to heat or extreme weather. Adaptation has nothing to do with race so it is not possible to understand human variation by merely looking at different races. Human variation deals more with where a human lives and how the environment effects them as these factors lead to adaptation.
Great explanation for heat stress and its repercussions.
ReplyDeleteVery good description of each of the four types of adaptations. The only minor correction is that the limbs (and body cores) of people living in hotter climates are longer and leaner, not really "larger". The long lean body shape actually creates greater surface area to allow for excess heat to be released through the skin more readily. Shorter, squatter (not really "smaller") body shapes help retain heat because they have less surface area for a given body mass.
I suppose we could be more selective in our choice of people for given responsibilities based upon their body shape, but could we also use this information to create cultural adaptations/tools to help even non-adaptively shaped people adapt more easily? Could this information be used to help create better clothing for hot environments?
"Adaptation has nothing to do with race so it is not possible to understand human variation by merely looking at different races. "
Correct. Race is purely descriptive. It has no explanatory value because it is lacking that causal relationship with human variation.
I like how you explained how humans have adapted to heat over time. Its very interesting to me to see the transformations. You explained everything well.
ReplyDeleteHi Steven,
ReplyDeleteI also wrote my blog post on heat. I thought it was interesting that you used the idea of our hair loss as a way that we adapted to the heat. I didn't even think about that.
I did not personally choose heat for my blog post so it was interesting to read through yours and compare my blog on Cold to your blog on Heat along with the impacts each have through these adaptations.
ReplyDeleteI enjoyed all the specific detail and background you included on the topic. "Humans that live in colder climates are generally stockier while humans that live in warm climates are more linear with long arms and legs" I also like how you compared the two sides yourself in that information.
I thought it was very interesting that humans that live in colder conditions are heavier set than other warmer climates, but ultimately it makes sense considering that people need to somehow keep warm, and use enough glucose to burn for energy.
ReplyDelete