Beautiful view of the high altitude location of Tibet. |
High Altitude can negatively impact the survival of humans
through Hypoxia, solar radiation, cold temperatures, low humidity, wind,
reduced nutrition base and rough terrain. Hypoxia is when the human body has in
sufficient levels of oxygen in the body tissue, or oxygen deficiency. This is
the most dangerous to humans effecting their lungs, heart, and brain. Hypoxia
leads to increased infant deaths due to the fetus not getting enough oxygen
through the mother. Mothers have a higher chance of preeclampsia due to the
elevation and higher chance of a miscarriage. If a baby survives to birth, they
are more prone to be premature and/or have low birth weights putting them at a
disadvantage to surviving.
Here is a child that has survived birth at a high altitude despite the odds. |
Solar radiation can affect the skin color of a person
through hemoglobin, protein carotene, and melanin, under the outer layer of
skin which helps protect humans from UV radiation. With more solar radiation,
depending on genetic bases for hemoglobin levels, can make a person more prone
to skin cancer. For example, most Europeans have fair skin meaning their
hemoglobin is far more relaxed from those that live closer to the equator. This
makes them burn and peal painfully without developing a nice bronze tan. This
also makes them more susceptible to skin cancer. Skin cancer usually develops
later in life, meaning adults who develop skin cancer already have the ability
to conceive meaning natural selection will not work in this scenario. Also, offspring are affected with solar
radiation with neural tube defects such as spinal bifida. With lack of vitamin
D, which can come from UV, can also prevent bone development, cause rickets, bow
legs, and other skeletal deformities. Natural selection can occur with vitamin D
deficiency because skeletal defects in women can cause a misshapen pelvis which
prevents her from reproducing. Solar radiation can kill any human exposed to
UV, but also prevent humans from reproducing if there is a lack of exposure.
Living in a high altitude means colder temperatures meaning
higher chances of hypothermia and frostbite. Winds will amplify these chances.
Also, these locations mean difficult living conditions for other animals and
plant life making substance difficult to find. With high altitude come low humidity
making rapid dehydration a serious issue. All of these issues have the same
major issue for humans, cold means humans burn more calories trying to stay
warm, meaning they need more nutrition, with lack of game, humans will have to
exert more energy trying to scout out food, exerting more energy, also creating
a situation for dehydration.
Warmer temperatures in high altitudes, however, the land looks barren and the only animals in sight belong to this farmer. |
Even though these stresses seem to make life in high
altitudes impossible, humans have found a way to make it work. The first step
is acclimating to high altitude, which all happens within one’s body and can be
shown physically, except for increase breathing. Acclimating to high altitudes
would make a person’s heart rate increase, metabolic rate will increase, and
productions of red blood cells will also increase. Shortly after leaving the
high altitude, the human body will return to normal. Those that choose to stay
in these conditions find other ways to beat the cold by either increasing basal
metabolic rate or fat insulation of vital organs. The ladder is only in places
that show short temperature drops, not prolonged cold, as this would not be
able to prevent frostbite from taking appendages. In consuming high calorie,
fatty foods one can increase their basal metabolic rate which will create extra
body heat. Due to culture and
technological advances survival is not as heavily based on intake or body
acclimation. Buildings, homes with heating, fire, heavy clothes all keep people
alive in high altitudes. Medicine and science have also created oxygen tanks,
inhalers, and other assisted breathing contraptions. People tend to stay active
while out in the cold and they might sleep in huddles at night to stay warmer.
Due to bottle neck, human variation isn’t very diverse. In
studying extreme environmental differences and comparing the human body’s
ability to adapt we not only see what humans are capable of, but we can see how
our environment causes adaptation, mutation, and evolution forcing diversity in
the human species. Studies of humans living in such conditions for long periods
of time can give insight to secrets that only these people posses. For example,
these studies have shown that people living in higher altitudes tend to live
longer and have a lower risk of coronary artery disease. Exposing oneself to
these harsh living conditions, can eventually show signs of a positive nature. Having a mild form of hypoxia from high altitude will improve the heart function. This
might be particularly beneficial for someone with genetic heart problems. Perhaps
an environmental change will increase life expectancy more than medicines. At
least this is a good alternative for holistic type people.
Race is such a difficult thing to determine or distinguish
between people. Basing characteristics, such as skin color, hair color, hair
type, and other characteristics, is not a valid way to determine a person’s
adaptations to environment. Natives to high altitudes have solar radiation
causing a darker skin tone, much like those that live close to the equator, but
they are not the same people. The only true physical indication of
environmental locations would to use animals such as polar bears. Yes, they
have white (or clear) fur like other arctic animals, however, it is their body
surface compared to their size that make them ideal for the cold weather. Humans
tend to have a similar tendency as this, with taller, skinnier people in more warmer climates, and shorter, compact people in colder climates. I feel that
this comparison, like skin color, is too vague to distinguish a person’s
environmental region. Looking at a human’s ability to overcome environmental
stress gives a more clear distinguishing factors that race cannot do. Most
environmental adaptations are below the surface of the skin, and race is only
skin deep.
Picture taken from the reading this week. I felt like this was a great example of how two different people in high altitudes can be similar, but yet different. |