Heat is one of the environmental stresses that negatively
impacts the survival of humans by disturbing homeostasis because it
causes headaches; fatigue, nausea, vomiting and reduces your energy levels when
exposed to high temperatures. Heat can have negative effects on humans if the environment
is too hot over long periods of time. For example, being exposed to high
temperature can cause dehydration by making you lose fluids by excessive sweating.
Dehydration happens when the amount of fluid coming
out of the body exceeds the amounts of fluids going into the body. In a high
temp environment, this can happen rather quickly so even though dehydration can
occur in any climate, heat is a major factor in someone becoming dehydrated. When
you have too much water coming out of the body, the body can become unbalance
and can even lead to death.
Another way that heat can negativity impact the
survival of humans is by causing someone to have heat strokes. A heat stroke
occurs when the body’s temperature reaches over 104 degrees. Anyone who participates in outdoor activities
are more prone to having a heat strokes as well as heat exhaustion. All because
of being out in the heat for long periods of time or the sun, without drinking
water to hydrate, will cause you to have a heat strokes and have heat
exhaustion. I personally have experienced this while playing softball one day
on a really hot day. It’s dangerous because you slowly start not to feel good
but your unaware of what is happening. You just think that you’re really tired.
This is why it is not a good idea to do out door activates on a really hot day.
This is also why during the summer times we get warnings on when it is too hot
to be outside and when we are to stay in during certain hours of the day when
the sun is at its hottest.
2. Identify
4 ways in which humans have adapted to this stress, choosing one specific
adaptation from each of the different types of adaptations listed above (short
term, facultative, developmental and cultural).
Include images of the adaptations.
(5 pts each/ 20 pts total)
Short term: One way that humans have adapted to heat
is the capacity to dissipate heat by sweating and is seen in all human
populations to an almost equal degree, with the average number of sweat glands
per individual (1.6 million). It is also known as evaporative cooling, a
mechanism that has evolved to the greatest degree in humans. This is how our bodies
are able to maintain homeostasis from heat stress.
Facultative: Another mechanism for radiating body heat
is vasodilation, which occurs when capillaries near the skin’s surface widen to
increase blood flow to the skin. The visible effect of vasodilation is
flushing, or increased redness and warming of the skin, like the face. The
physiological effect is to permit heat, carried by the blood from the interior
of the body, to be emitted from the skin’s surfaces to the surrounding air.
Developmental: Body size and proportions are also important
in regulating body temperatures. A developmental adaption to heat is the
development of long and lean body shapes, both the core and the limbs which
help to provide more surface area for dispersing heat. Two rules that pertain to
the relationship between body size, body proportions, and climate are Bergmann’s
rule and Allen’s rule.
Cultural: Humans have adapted to heat short term by
utilizing the technologies that we have today to stay cool during really hot
days. Staying hydrated is an important factor in staying cool and nowadays you
have an unlimited supply of drinks you can buy to help aide in the hydration
process. Having access to an air conditioner or swamp cooler are other ways on
staying cool short term during really hot days. With the technologies of today,
we have access to cooler air in our cars, homes and our work spaces. We also
have fans that help circulate the air to cool the room down. There are
umbrellas to use, misters, mister fans etc. Depending where you live, there are
different methods we use but in general, it’s all the same objective, stay cool
and hydrated.
3. What
are the benefits of studying human variation from this perspective across
environmental clines? Can information
from explorations like this be useful to help us in any way? Offer one example of how this information can
be used in a productive way. (5 pts)
The benefits of studying human variation from this
perspective across environmental clines is being able to study the changes of
various sample populations over time. It allows us to really have a chance to
evaluate and see the different environmental stressors that contribute to
affecting any population. Now if you took one a particular population with one group
of traits and put them in another environment that is different from their own,
then those traits in which they were born with, you’ll see an evolutionary
adaption to the new environment.
Humans are coping with infectious disease as
we alter the environment and as global climate change facilitates the spread of
disease vectors. Studying the high rate of sickle cell anemia in black populations,
scientist can identify and come up with treatments for this disease. It helps
scientist find cures in order to help other population dealing with the same
disease. Also studying rickets in fair skinned people can help us understand
why they would need sunlight and how much of it can they have and find the
right balance to avoid this disease in the fair skinned population.
4. How
would you use race to understand the variation of the adaptations you listed in
#2? Explain why the study of
environmental influences on adaptations is a better way to understand human
variation than by the use of race.
I would use race to understand the variation of the
adaptions by classifying race as a geographic groups of people who have the
similar sets of adaptions to the same environments in which they occupy. Because
of the environmental stressors this can help us predict what changes might
occur within the human population. When studying the environmental influences
of a group of people over a long period of time, you can see patterns which
evolved as adaptation to those outside stressors. For example, natural
selection is the process whereby organism better adapted to their environment
to survive and produce more offspring.
The study of environmental influences on adaptations is
a better way to understand human variation by the use of race because this way
we can see how our ancestors developed and changed over millions of years to
better understand our origins. As we grow as a population we are learning and adapting
to our ever changing environment. We get to learn about the past and how we
came to be today. I believe this can also help us put our differences aside
because we judge each other by skin color, eye color and pretty much, physical
traits. This has showed me that we are more similar and closely related than we
think. Hopefully this can help us in dealing with racism because this helps us
see that our differences are just response to our environment, not the product
of anything else. Race is a modern idea that has no genetic basis.
Dehydration is actually a secondary, indirect result of heat stress. It is the direct result of the body attempting to deal with heat stress by sweating, causing water loss from the body. The direct impact of heat stress is the increase of the core body temperature, which you describe in your paragraph on heat stroke. That should be the focus here.
ReplyDeleteVery good discussion and explanation on all four adaptations. Good images to accompany them.
Great discussion on the way we can actually apply the knowledge gain from the adaptive approach. Thoughtful explanation.
"I would use race to understand the variation of the adaptions by classifying race as a geographic groups of people who have the similar sets of adaptions to the same environments in which they occupy. "
Are you actually using race here or you just using the adaptive approach and layering race over top of it? In which case, are you actually using race or just the adaptive approach?
Is it possible at all to use race to explain human variation? First of all, understand that it is acceptable to say "no" and explain why not. Second, to answer this question, you need to actually understand what race 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.
Great discussion and information. I have learned a lot through your resources. I never would have guessed that body size and proportions would contribute to body heat. I definitely agree that you will find an evolutionary adaptation to environment if you put a population in an environment they are not accustomed to. Great post!
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