The cold
can negatively impact the survival of humans and disturbs our bodies’
homeostasis by dropping our core body temperature. A normally person’s body
temperature is 98.6 degrees, with some variations because of body size. When a
person’s core body temperature drops below 94 degrees, hypothermia begins to
occur. Hypothermia is when your body is losing heat faster than it can produce
it. This can result in death if the temperature continues to drop because your
heat, nervous system, and organs cannot function properly.
A developmental
adaptation that occurs is the evolution of more compact and round bodies of
people who live in colder weather. Less surface area is exposed and individuals
are therefore better able to retain heat. People also wear heavier more
insulated clothing which is a cultural adaptation. A short term adaptation is
the narrowing of blood vessels near the skin surface to store more body heat by
limiting blood flow. Lastly, a facultative adaptation is the eating of high
calorie foods. This intake leads to an increased basal metabolic rate, which
creates extra body heat.
The benefit
of studying human variation from this perspective is understanding that many
traits develop as a result of our environment that we live in, not because of
our race. For example, many people would say the Eskimo “race” tends to be
rounder. This is not because of their race, but exists as a result of the
cold climate they live in. Their excess body weight in their torso creates more
heat for them and has developed as a way to better survive and adapt. This information could be used to educate ignorant
people who stereotype races and their traits based off their skin color.
Human variation
is better than using race as a measure of traits because it reveals the true
underlying cause for why a trait may have developed. As previously mentioned,
Eskimos tend to be more overweight as a result of their adaptation to a colder
climate. The wearing of warmer, heavier clothes, for instance, can be attributed
to many “races”, but not because their race genetically predisposes them to
this. They need to wear this clothing in order to survive in their environment.
Great description of cold stress and its impact on homeostasis.
ReplyDeleteGood explanations of your four adaptations. Raising metabolisms is a facultative trait but it takes time and may not help if temperatures plummet and require a faster response. An alternative is alternating vasodilation/vasoconstricition. This pulls blood to the body core to retain heat but occasionally opens the surface capillaries to help slow tissue damage.
I agree with the educational value of the adaptive approach but can you think of any way we use this information in a more applied way? Can this help in the medical field? Can it help us develop better clothing for cold climates?
"Human variation is better than using race as a measure of traits because it reveals the true underlying cause for why a trait may have developed."
In science, we call this looking for an "ultimate" cause, instead of a "proximal" cause, and you are right that this is one of the benefits of the adaptive approach, but your use of the term "better" worries me a little since it suggests that it is still possible to gain some understanding of human variation through race. Is that true?
Race is a social construct, subject to the biases and preconceptions of individual cultures, and it is designed to divide humans into categories, not to explain variation. It is not a biological/genetic construct, so how can it be used to objectively explain biological/genetic variation?
A caution: "As previously mentioned, Eskimos tend to be more overweight as a result of their adaptation to a colder climate."
Inuit ("eskimo is actually a derogatory term) are not "overweight". :-) This is a judgmental, ethnocentric statement which we try to avoid like the plague in anthropology. It tells me more about you than about the Inuit. Instead, we use factual terms the paint a more accurate image of their body, such as that Inuit and other populations that live in colder climates tend to have shorter, rounder body shapes that help them to retain heat in their body cores. Notice the difference in how that describes the Inuit?