Humans have inhabited the Andean region as far back as 15,000 BC. The first humans were believed to migrate to these great mountains for the security they offered. However, the new region imposed an entirely new environmental stress: high altitude. In high altitudes, the oxygen level is lower and dispersed, causing lower pressure than the low-lands surrounding it. With less oxygen in the air, humans would inhale less oxygen particles into the lungs, allowing a limited supply to be absorbed by the red blood cells. In result, the red blood cells cannot carry and supply sufficient oxygen to vital organs causing hypoxia.  This greatly impacts the survival of humans in that oxygen is extremely vital to keep our bodies working properly.  

Luckily, humans are extremely adaptive in that we are a diverse species. Humans have adapted to this environmental stress through short term, facultative, developmental, and cultural types of adaptations. Imagine you plan a trip to the Andes to learn about the Quichia, the largest of any indigenous peoples in the Americas.  As you elevate, the atmosphere becomes lighter, your pulse rate and blood pressure go up causing stressful, but effective changes. This particular adaptation is only beneficial if you’re only visiting. 

                                                    

This is where a facultative adaptation would come in. If after your visit to the mountains you decide that you’re better off moving there, your body will turn on and off genes to alter a phenotypic expression in response to the stress without altering your DNA. This means the amount of oxygen your blood cells carry will increase whenever you experience a reduction in atmospheric pressure. 

                                         

After your visit, you fall in love with the people and lifestyle of the culture, so you decide to stay.  You marry a nice Quichian and have a child. These particular peoples have developed an increase in lung capacity and an increased chest size allowing an increase in pulmonary diffusion capacity. This developmental trait is a change in the DNA of the population and is called developmental adaptation. Although you lack this trait, your partner has passed it on to your child, thus giving them the advantage of survival in high altitudes.

Now, you’re learning that not only do you have to cope with the low atmospheric pressure, but you have to deal with extreme weather conditions. To keep warm in the freezing winter, the Quichian give you colorful garments made of Alpaca wool. Potatoes are freeze-dried by a special technique to preserve for the rest of the year and prepared in hot stews.

Studying human variation from this perspective across environmental clines is extremely beneficial in that we can understand how humans adapt to diverse environments.  In better understanding that adaptation to high latitudes is a gradual process, mountain climbing illnesses can be prevented. If one understands that if given the right amount of time, your body will endure a facultative adaptation giving you better oxygen supply and endurance.  Another example would be skin color. In response to high levels of solar radiation, specialized cells called melanocytes will produce a pigment called melanin to reflect the radiation. Humans in regions where there is a high level of solar radiation are darker in skin color, giving them an advantage. If scientists can develop a product that can mimic this process it can protect many people from skin cancer.

If I were to use “race” to help understand the variation of the adaptations I spoke about earlier, I would declare that the skin color, nose, and head size of the people of the Andes are all reasons to adaptation in the region. However, people of another “race” living in similar regions do not have the same skin color, nose, or head size. Therefore it is more beneficial to understand the environmental influences on adaptation to understand human variation rather than “race”.

Sources:
http://jeb.biologists.org/content/204/18/3151.full.pdf

http://www.academia.edu/1242438/Bolivian_Andes_from_climate_change_to_human_displacements_

http://www.peoplesoftheworld.org/text?people=Quichua