High altitude stresses and Genetic Adaptations

In early 1970s the world was hit by breaking news of the emergence of the African athletics. Kipchoge Keino from East Africa had been declared as the world’s fastest marathon runner in the just concluded Athens Olympique games. Since then Africans have taken a centre stage in the World marathon.  Ethiopians, Kenyans and Moroccans have been the best in all the marathons games. Consequently, the long distance running has been held by individuals from the African continent. Of late the challenge to this field for Africans has been coming from other parts of the world. The later challenge has cropped up from the Latin Americans and the Far East long distance.

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[1]It can be said that athletics is the only sports which is so endogenous among individuals of a particular region. Our western world with all resources at stake has not been able to outdo these people. With new rules being harsh on the use of drugs there has not been any activity in long distance from these parts of the world. The only question we can probably ask, how comes this events seem to favor people of a particular regions of the world. (Greska, 1996). As we are going to see, the endemism of such activities can only be explained by the process of natural selection. Even in these countries themselves, the highlanders are the only favored to this high regions alone.

[2]Therefore, the notion of natural selection has taken a centre stage in the explanation of these biological phenomena.  The introduction of this evolutionary language in the late 1850s was fundamental in explanation regionally segregated traits in individuals of biological nature. An illustration that was given was that of Biston betularia of the early days of industrialization in Britain. The butterflies that were known to camouflage against barks of trees developed this strategy with the release of smoke from the industries. However, some strains of this species could not be able to adapt these facial characteristics .

They were therefore targeted as prey to the predator birds. Consequently, the naturally selected butterflies were grey as a result of the smoke from the factories. The smoke had darkened the barks of the trees and favored the color of the insect. In our context here we are faced with the idea that natural selection has not in any way affected the genetic composition of these insects. However, when the control measures against pollution were put in place, it was the turn of the gray butterflies to capture the attention of the birds because they were no longer invisible to the naked eyes of the birds. Consequently, the natural selection aspect has been fronted to mean that it is the change in the phenotype of an organism in the environment as a result of the changes in the conditions of the later. The largely debated notion as to whether these more or less adaptive features of the butterflies translate into genetic hereditary part of the insect has been a heated debate that has not been resolved yet.

More phenomenon of natural selection that have arguably been regarded as having developed into genetic transmittable materials have been postulated by many scientists of [3]the earlier evolutionary theories. Jean Baptiste de Larmark fronted the notable example of our days. In his research Baptiste suggested that the long neck found among the families of the Giraffes was developed as a result of acquired and transmittable traits. In his mind this great scientist was of the opinion that initially the Giraffes had short necks because then the vegetation was very abundant near the ground. But with time the vegetation reduced and the animals had to start stretching their necks to reach to the higher levels.

Accordingly those ones who were not able to reach the vegetation of the higher branches died because of starvation from lack of food. According to de Larmack the stretching of the neck made to become long and with time they could be transmitted from one generation to another. Therefore, de Larmarks theory of natural selection holds that acquired traits can be transmitted from one generation to the next. From the   researches conducted at the time of Larmark opposed this finding by holding that acquired traits like tallness of disability through an accident can be siphoned to the next generation by heredity.

However, recent scientific developments in agriculture have revealed a strange occurrence among the microorganisms and pests. The development of drugs like Penicillin in the late 1920s served for only a short time and by the turn of the 1940s it was discovered that a certain group of bacteria for whom the drug had been made were already resistant of the biocide effect of the drug. A closer investigation of the microorganisms came to reveal that the effect that transpired in the process of resisting the drug were able to be transmitted to the next generation of microorganisms. Therefore, a different drug had to find a different drug for the microorganisms.

The process of natural selection has taken place in natural environments .The humans in respective natural environments have also undergone the same process. The people of the highlands of the East Africa, Ethiopian highlands, the Atlas ranges of Morocco, the Tibet of china and the Andes of South America have all these specific features that have with time adapted to high areas with thin air.

[4]Probably you have ever wondered why most famous athletes have their practices in the highlands and the mountainous regions of the land. Several weeks to the event of athletics, the runners always have an intensive marathon practice in these areas. The most important condition provided by nature in these areas is the thin air .The common biological explanation that is always provided is the idea of thin air. High altitudes contain very scanty oxygen concentration and as one approaches top of the highest mountains oxygen is almost non-existent. For people in these regions, recent research has shown, they have to undergo acclimatization, a process in which extra red blood cells develop in the system with an adaptation mechanism of increasing the amount of oxygen carried in the blood, and this in turn means that individual will be able to carry more of the gas in the system to effect respiration even at low oxygen concentration.

In the following discussion we are going to discuss in addition to the above explanation, the genetic adaptations of the two groups of people who have, probably by the process of natural selection, been able to exclusively to adapt to the high altitude areas characterized by low oxygen concentration (thin air) and yet they have been able to settle in this regions from their historic times to present day.  We are going to highlight the geographical environments of the two regions in accordance with two natural inhabitants of the respective areas, reasons for their adaptations and we will finally give a conclusion.

The Tibetans of the Himalayan Mountain Ranges:

[5]The Himalayan mountain ranges are found in the Asian continent. The mountain ranges, which are probably the mountain ranges in the world, are occurring between the larger Indian subcontinent and the famous Tibetan plateau. Scientifically the Himalayans have been regarded as having the highest peaks in the world. It forms the famous Himalayan system comprising of six countries. These are the Nepal, Pakistan, and Kashmir, china, Nepal and the republic of Bhutan.

These countries are the homelands of the famous Tibetan tribes of the Himalayan ranges. The tribes in the six countries include the Bhutiyas of Bhutan and Mongolia (Brown, 2003), Nepalis of Nepal, Rais, Limbus, Khasas, Doms, Brahmins, and Ladakhis. The natural environment of these people is this mountain range stretching from the Pakistan on the western side with Burma forming the Eastern end. Northern India, Nepal and Bhutan border this mountain ridge. Actually to the Tibetans this ranges forms a unique environment with specified geographical conditions and it is because of this that scientists have attributed some genetic adaptation to this environment by this group of people.

Regionally it has been confirmed that actually the Tibetan tribes are related to other Asian people like the Chinese, the Koreans and the Japanese. It has been found out that the people of the mountain have a high frequency of the allele Y as compared to their counterparts in the lowland Asia. It seems that the later effect weighs more heavily on Nepal, which because of its proximity to India and her between India and the rest of the Tibetan tribes has produced more genetic diversity in her people than it has happened in either of the two.

In addition to the above hypothesis it ca only be said that a lot of genetic evolution that has in this people is only because of the unique geographical environment they have been exposed to hence the diversity. Just like any mountain environment the Himalayas provides unique climatic affiliation on both of its sides. On the north east (the Tibetan side) it is dry and very cold compared to the Nepal country where it is dry with occasional winds. This environmental condition only supports the studies that the Himalayas have actually acted as a barrier in preventing the normal dispersal movements of the natives of this area. . This confinement as some studies (van Ndrem, 2004) reveal has been on the forefront to preventing the gene flow to the neighboring plains.

[6]Stressing on the fact that the mountain ranges have acted as barrier flow to the genes can only be explained from the historical point of view. According to these records several attempts to cross these mountain ranges have been made by ancient tribe of these ranges. Accordingly, the settlement of people to these areas has occurred because have at one time crossed the barrier and settled in the area. (Su, 2001). With migration it has been extensively possible for the sharing of gene materials to take place. For example, the sharing that has been extensively recorded in the Y alleles and the O haplogroups.

The gradual settlement of the area has been documented to occur periodically and therefore as a result according to the findings the opposite migration has been very limited. Additionally, there has been preferential gene flow southwards and this has accounted for the harsh climatic conditions being experienced on one side of the mountain (the Tibetan side) have discouraged the flow of population towards it.

[7]The genetic adaptation with time to this mountain has enabled the Tibetans to emerge as the true natural inhabitants of the region. Despite this we have just pointed out the Tibetans have come to coexist with the stresses on the mountain range. The harsh climatic conditions of the area to the Tibetan side and the more obvious adaptation to the thin air have been the stresses that these natives have had to coexist with. Therefore it is worth noting that these genetic adaptations have only helped the Tibetans to develop physiological characteristics necessary for the resistance of these stresses. I t has been noted that compared with the rest of the population in the neighboring regions these tribes have recorded a relatively higher red blood cells count. This adaptation mechanism has enabled them to carry more oxygen per cubic centimeter and this has guaranteed a normal respiratory process even with thin oxygen. (Townsend, 2004).

Apart from the above adaptation, the Tibetans, according to Poirier (2000) have been observe to possess a barrel like chest which is more suited for a wider expansion of the lungs and for the more intake of the oxygen gas. Comparatively, the lungs are of large size and are encircled in dense bed of capillaries. The diaphragm, which forms part of the respiratory system, is enlarged and said to be powerful. Consequently, the respiratory system is well placed to maximize oxygen intake even with little oxygen.

THE QUECHUA OF SOUTH AMERICA:

[8]The Andes of the South America is another highland region occupied by certain tribes of people of which the Quechua of Peru, Bolivia, Argentina and Chile are inclusive. From time in history when it was not possible to settle on highlands, with time humans have been able to comfortably live on the Islands. Geographically the Andes have an altitude of about 3500m above sea level.

We are going to mention that there are two tribes of people in this region: the Aymara and the Quechua. The tribes who have been together for along time can be said to have coevolved together and their genetic adaptation to this high altitudes are the same. However, it is important to note that the communities have lived on the mountain for along time (Lynch, 1970) and it is possible that the process of evolution has taken place in the population. A long period is important in the sense that it provides reasonable natural selection to take place and by this helps to alter gene frequency in the population.