Human
Variation and Race Blog Post:
High Levels of Solar Radiation:
1) Those that are exposed to high levels of solar
radiation can be harmful to the balance of human physiology in many ways
including uncomfortable burning of the skin, destruction of folic acid, and the
increase risk of skin cancer. People who
are at higher risk of these problems are people who have lighter skin coloring.
This is because it can produce a defective form of skin protein called
melancortin- 1 receptor. This defective gene causes their pigmentation to be
lighter allowing for less protection from ultra violet rays. While this is
beneficial for the absorption of the necessary amounts of vitamin D, lighter
pigmented people do not benefit from the same protections against the harmful
aspects of high levels of solar radiation. The destruction of folate can cause
anemia which can cause bleeding problems, bruising and fatigue. The destruction
of folic acid can cause birth deficiencies in pregnant women because folic acid
is essential to the reproduction of DNA. With less protection from the ability
to produce melanin people with lighter pigmentation are at greater risk of skin
cancer like melanoma. Burning of the skin, increased risk of birth deficiencies
and diseases such as cancer and anemia all can result in upsetting the balance
of human physiology making it hard for certain types of skin pigmented people
to survive in environments that they were not evolutionarily adapted to. On the
other hand, people who have darker skin color can adapt more easily to living
in places with high levels of solar radiation because they have developed the
ability to produce melanin which helps protect their skin from the sun’s ultra
violet rays. As darker pigmented people thrive in areas with a lot of UVB,
these people suffer from the inability to produce vitamin D in areas that do
not receive the high levels of solar radiation. This too can affect the balance
of the human physiology in that these people may develop weak bones due to the
lack of vitamin D produced in their bodies.
2) A) Humans have adapted to dealing with high
levels of solar radiation through four different methods: short-term,
facultative, developmental, and cultural. Short-term adaptations for higher
levels of solar radiation in the body’s physiology are hard to pin-point. Maybe
there really is not any short-term way to defend the skin from high levels of
solar radiation unless that population’s skin coloring already has large
amounts of melanin. Other strategies for short-term adaptation may be something
like seeking shelter or shade or simply covering the skin in an effort to
protect it from solar radiation.
B)
Facultative adaptation in light pigmented
people would be the increased amount of melanin in that population’s skin. The
increase of melanin is considered a seasonal adjustment in that melanin is
increased in the summer and decreased in the winter. Melanin is the body’s
natural defense against radiation from the sun. It gathers under the skins
surfaces to act as a natural sunscreen against the harmful rays of ultra violet
light. Special cells called melanocytes
produce the melanin in response to radiation which can cause a change in the
skins pigment generally a few hours (however sometimes in can just take minutes
in very warm weather and especially if you’re not wearing sunscreen) after
exposure. The increase in melanin is seen by a change in the skins coloring,
tanning. Tanning is a facultative adaptive trait to help the body’s physiology
to remain in a balanced state.
C) Developmental adaptations
is another example of a way to protect you from the harmful UVB rays. This
adaptation to high levels of solar radiation is what produces the difference in
skin coloring (pigmentation) which establishes the idea of race. The
developmental trait of skin pigmentation to allow a certain degree of UVB to
either penetrate or not penetrate a person’s skin is a metamorphic trait that
has been developed over a long period of time through natural selection to
allow those people with lighter skin optimal survival capacity in the environment
where they live. These traits are inherited through birth and are developed
over generations. There is evidence to this in respect to where people live in
the world and their environments. The
populations who live closer to the equator experience a higher level of solar
radiation. In response to this higher level of solar radiation, these
populations developed darker pigmented skin through the level of melanin in their
skin. This acts as a natural sunscreen protecting these people from skin cancer
and the destruction of folate and folic acid in their bodies. Populations that
live closer to the poles and experience less solar radiation over time have developed lighter skin pigmentation in order
for their bodies to receive more of the solar radiation in an effort to produce
vitamin D. Since these populations live in an area that receives less radiation
from the sun it is essential to optimize the absorption of the suns radiation
in order to maintain a balance of vitamin D in their systems, however they are
more at risk for sunburns and skin cancer.
D) Cultural adaptations
have been made to accommodate the contrasting needs of different pigmented
people. Darker skinned people have since moved away from the equator and lighter
skinned people have since moved closer to the equator which creates a perception
of how to culturally adapt to the new environments in which their skin
pigmentation is not acclimated for. Dark pigmented people adapt culturally to
areas with less solar radiation in order to find other ways to receive the
necessary amounts of vitamin D. Since people who live closer to the tundra are
relatively dark pigmented for living in a place with low solar radiation they
had to find a way to ensure they were receiving the amount of vitamin D they
needed. These people have adapted to their vitamin deficiency by eating a diet
that consist of fish and large mammal blubber. Another cultural adaptation to
the lack in vitamin D could be the production of manufactured vitamin D that
people can take in a supplemental form. Light pigmented people who have moved
to areas with higher levels of solar radiation have adapted culturally through
the use of sunscreen and protective clothing in order to shield their skin from
harmful radiation. Clothing such as breathable material that have a special protect
ant layer to shield skin under the clothes from the sun, sunscreen, bathing
suits, and large hats can all be seen as a cultural response to shield
radiation.
3)
Studying human variation has benefits in order
to assess their ability to tolerate solar radiation across the environmental
clines mainly because the better understanding we have of our genetic make-up
in response to environmental stressor the better we are to ensure maximum
survival. The research of skin pigmentation in relation to solar radiation is very
important to understand. As a light skin colored person I found it interesting
to see how my genealogy evolved to allow the absorption of UV rays in order for
my ancestors to maintain the necessary levels of vitamin D needed to
function. The ability for my skin to tan
( I actually don’t tan anymore after years of tanning and abusing my skin as a
teen I now burn, peel and turn white again) is a fascinating way to see that my
pigmentation can adapt facultative to help shield the destructive properties of
solar radiation. Personally for me and maybe other light skinned individuals it
is important to understand the damaging effects of the sun and know how to
protect your skin from it. It is also important for those people with darker
skin to understand that they still need vitamin D. Most people are aware of the
damaging effect of too much solar radiation, but many are unaware of the
damaging effect of too little solar radiation in darker pigmented people. This
is an important aspect of the studying of human variation and environmental
clines to ensure that light and dark pigmented people are aware of how to
maximize their health in an environment they may have not been adapted to
through evolution.
4) People usually don’t understand the reason
behind skin color that it has to do with pigmentation and environment and not
because of race. Why should the color of a person’s skin determine that
person’s worth? What does skin color have
to do with politics, intelligence, ability to perform different jobs, social
status, or wealth, when really skin pigmentation is an evolutionary result of a
population’s ability to survive in the environment. The study of evolution to
environmental stresses is a better way to study human variation rather than
race because it allows us to see why persons from Africa have darker
pigmentation. It allows people to understand that people with darker
pigmentation developed that trait in order to withstand the environmental
stressors in their area. The reason why lighter skinned persons developed
lighter pigmentation is so they could establish that they were able to produce
vitamin D from the lower amounts of solar radiation in their environment. When
human variation is studied through evolution, it is fascinating to see how
evolution works through natural selection in order to increase a higher rate of
survival. When looking at human variation through evolution, race is no longer
relevant. Without race, racial discrimination would no longer be relevant. If
more people had to really look into why skin is the color it is maybe there
wouldn’t be “racism”? However I still feel people would always be in
competition with each other it just wouldn’t be over the color of a person’s
skin.
