1.
Although I have lived in southern California my
entire life and have experienced summers where temperatures can be in excess of
100F, I feel like I will never be used to the heat; However, earliest hominins
evolved in the type of weather I have always lived in- mostly warm to hot
woodlands and savannas of East Africa. Over time, hominins have evolved and
adapted to heat to keep our bodies at optimal temperatures as to not do damage
to our internal organs and our brains. The dangers of heat are very real. Just
think about how many people suffer from heat stroke and severe dehydration
during the summer or during sporting events. Heat can even cause death.
2.
One short term adaptation that humans have to
negate the effects of heat on the body is perspiration or sweating. Humans have
the ability to lose heat through the body’s surface through evaporative cooling
– as humans sweat; the salt and water is evaporated from the surface of your
skin draws heat away from the body. This is the most important way humans can
cool down but sweating can also come at a cost. Sweating for prolonged amounts
of time can greatly affect the composition of the body. During perspiration,
humans lose both water and salt – both vital to life. Sweating can only be used
efficiently for heat dissipation for a relatively short time before it actually
becomes dangerous. For example, if a person is doing hard manual labor or
intense exercise in extreme heat, it is possible to lose up to 1.5L of water
and salt per hour through perspiration. For an average person, this is about
1.5% of total body weight and if a person loses 10% of body weight due to
perspiration, the situation can become life threatening.
A facultative adaptation that humans have
to heat is vasodilation. Vasodilation is occurs when capillaries near the
skin’s surface dilate to increase blood flow to the skin (This might cause a
flushing effect when it occurs so skin looks red). Vasodilation essentially
pulls heat from the center to the body to the skin so that it can radiate into
the surrounding air, cooling the internal temperature of the person.
A developmental adaptation to heat is human
body shape. People who live in warmer areas tend to be slimmer, and have
elongated arms and legs so that the surface area of their skin is greater and
can promote heat loss. The larger surface area of your skin, the more effective
things like vasodilation will be in promoting heat loss.
A cultural adaptation to heat is air
conditioning! Most people who live in warmer areas and extremely humid areas
(in many first world countries) use air conditioning to control the climate
within their homes and offices. When temperatures reach over 110 F in the
summer, being able to escape the heat by going into an air conditioned building
is a welcome rest for your body.
3.
The benefit of studying human variation from
this perspective is that it really exemplifies how environment affects natural
selection. Different races might have different skin colors or body shapes specifically
as a result of adapting to their environment. This information would be helpful
to us by showing us what climate we are adapted to and any precautions we might
need to take to protect ourselves from the environment. For example, I am
extremely pale and freckly with light eyes yet I live in an environment that is
very ho and sunny. I need to wear sunscreen everyday to protect myself from
skin damage and potentially cancer, whereas someone with darker skin might not
need to worry about sunscreen or sun damage as much.
4.
I would use race strictly to outline a region
where a group of people came from because their environment affected the
adaptations that were needed for survival. I think in the current cultural and
political climate, the best benefit to studying human variation from this
perspective is that people might have a more enlightened view of other “races
or ethnicities.” That “race” is not simply the color of someone’s skin, but
that it has to do with variations and adaptations needed for survival and in
that way, we are all the same. I think that some people perceive different
races to be different “species.” People sometimes look at different races like
they are comparing birds and fish. I think it would also be good starting point
for understanding different cultures as well because adaptations does influence
culture whether it has to do with food, dress, housing, lifestyle etc. It is
all necessary for survival.
