15 October 2009

Adaptation to High Altitude Conditions

Over generations, humans have adjusted to survive in high altitude environments with many physical stresses imposed upon them. Even today, we are evolving, though the modern world views human race as being the perfect end product with no need for improvement. The truth is, the humans, like the homo ergaster or the homo neanderthalensis will evolve, or stop existing. Humans must change and evolve with their environment. Tibetans are subtly evolving to be fit in their high altitude surroundings. Those who have yet to adapt will suffer.


If an individual who normally lives at sea level, travels to a higher altitude environment, they may experience “symptomatic discomfort, reduced work capacity, accelerated breathing, higher hemoglobin levels, and higher arterial pressure.”(Moran 2008) New comers to the environment may also experience such conditions as hypoxia (low oxygen pressure) or even pulmonary disease due to the lack of oxygen in the air. Other harsh conditions in high altitudes consist of: “cold stress, aridity, shallow soils, steep slopes, and low biological productivity” (Moran 2008). The Tibetan and the Andean populations live in these conditions. Daily, they face environmental challenges that are key in their adaptability to their environment.


Tibetans and other natives have adapted to hypoxia over generations. Their bodies have “increased the availability of oxygen, and the pressure of oxygen at the tissue level”(Moran 2008) Tibetans of both sexes, have much larger chest cavities than populations that live at a lower altitude.


Cynthia M. Beall, is a physical anthropologist who has done studies comparing, the interaction of evolution and adaptation between the Tibetan and Andean peoples at high altitudes. Certain patterns between these two populations has indirectly suggested that there are population-level differences. There is a detected gene for oxygen saturation among the Tibetans(Moran 2008). The oxygen saturation gene evolved due to the environmental pressures that challenges the Tibetans daily. Individuals with the dominant allele for higher oxygen saturation have a selective advantage at high altitude environments. This gene is what makes the Tibetan population more adapted than the Andean population to their environment. Tibetan “women estimated with high probability to have high oxygen saturation genotypes have more surviving children than women estimated with high probability to have the low oxygen saturation genotype.”(Beall 2009) This gene, although it seems insignificant, is proof that humans are still evolving, and in this case, to become more fit in their daily environment.


Although humans are viewed as the end product of evolution, we are still subtly adapting to our environmental pressures, and evolving to match our environment. Each generation plays a part in the evolution of what conditions humans will or will not adapt to.


Sources

1.)Moran, Emilio F. Human Adaptability An Introduction to Ecological Anthropology. New York: Westview, 2008. Print.


2.)"Andean, Tibetan, and Ethiopian patterns of adaptation to high-altitude hypoxia -- Beall 46 (1): 18 -- Integrative and Comparative Biology." Oxford Journals | Life Sciences | Integrative and Comparative Biology. Web. 15 Oct. 2009.

1 comment:

  1. It is interesting to read about the adaptions of women possessing a certain genotype as having more surviving children to further the reproductive adaptive cycle. So if people in certain places are developing a dominant allele for higher oxygen saturation, then why aren't all higher altitude cultures developing this allele? In addition to this they are also developing larger chest cavities to help aid them in dealing with hypoxia. That seems like a great adaptive advantage that all high altitude cultures would hope to reach. It still fascinates me that humans can adapt further, and will have to adapt for their whole existence, or we will die out just like any other species.

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