Human Variation and Race

1. High Altitude is an environmental stress that negatively impacts the survival of humans by disturbing homeostasis. When breathing, in high altitudes, the low air pressure makes it difficult for oxygen to enter the human vascular system, causing oxygen deprivation, also known as hypoxia: hypo, meaning low or little and oxia referring to oxygen. Hypoxia starts with the failure to take on normal physical tasks without exhaustion. This “high altitude sickness” also includes symptoms such as: lack of appetite, vomiting, headaches, distorted vision, fatigue, and difficulty thinking clearly. In some cases, the lungs and brain begin hemorrhaging and causes death within days. Also, due to high altitudes, added stress is placed on lungs, arteries and heart, which increases the risk of heart failure.

2. However, humans have adapted to high altitude stress through short term, facultative, developmental and cultural adaptations:

· Short Term: Our bodies begin adapting to the high altitude by increasing its breathing and heart rates to almost double the norm, even during resting. As the heart pumps harder to increase oxygen to cells, our pulse rates and blood pressure peak. These series of heart modifications are very stressful on the body especially for those with weak hearts.

 

· Facultative: In high altitudes our bodies produce more red blood cells and capillaries in order to efficiently carry more oxygen throughout the body. Our lungs, in turn, increase in size to process that oxygen and carbon dioxide. To enhance transfers of gas, our bodies also increase the vascular network of muscles. This results in successful acclimatization to low oxygen pressure.

· Developmental: Populations are most successful when their ancestors have lived at high altitudes for thousands of years. Natural selection plays a significant role in developmental adaptation for populations to live in high altitudes. Primary solutions for those who live in high mountain areas include: increased production of hemoglobin and increased lung expansions to increase oxygen in blood. Some populations adapt to breathing faster in order to intake more oxygen resulting in broad arteries and capillaries allowing for higher rates of blood flow and greater amounts of oxygen to muscles. A study proved that villagers, who reside at 15,000 feet, have 10 oxygen-processing genes that are not usually found in lowland populations.

· Cultural: There are many cultural adaptations to higher altitudes. Mountain climbers usually use oxygen tanks to aid in breathing in order to achieve peaks that are over 5 miles high. Many athletes, for greater lung expansion and capacity, train in higher altitudes. This physiological change, results in increased fitness levels when competing in lower altitudes.

3. There are many benefits of studying human variation from this perspective across environment clines. For example, if we are headed to Big Bear or Mammoth for a winter trip to the snow, it would be very useful to know that our bodies will be lacking oxygen and might go through hypoxia. This will probably change the way we hike up the hills or maybe change the agenda to allow for more resting time.

4. I don’t think that we would be able to use race to understand the variation of high altitude adaptations because race has no impact on how our bodies adjust to different levels of oxygen. The study of environmental influences on adaptations is a better way to understand human variation than by use of race because humans are unique in their given uses of environmental stresses. It allows for a better comprehension of physical adaptations under certain altitudes, whereas race only pertains to phenotypic characteristics and geographical ancestry.