![]() The hypothesis of a possible evolutionary genetic adaptation makes sense. Scientists started to notice the extraordinary physical performance of Tibetans since the beginning of Himalayan climbing era in the early 20th century. Physiological basis Tibetans A Sherpa family One of these students, anthropologist Cynthia Beall of Case Western Reserve University, began to conduct research on high altitude adaptation among the Tibetans in the early 1980s, still doing so to this day. Baker, Penn State University, (in the Department of Anthropology) also conducted a considerable amount of research into human adaptation to high altitudes, and mentored students who continued this research. Roberto Frisancho of the University of Michigan in the late 1960s among the Quechua people of Peru. The first scientific investigations of high-altitude adaptation was done by A. This is particularly true among Tibetan babies, whose average birth weight is 294–650 (~470) g heavier than the surrounding Chinese population and their blood-oxygen level is considerably higher. ![]() These women are known to give birth to heavier-weight infants than women of lowland inhabitants. It has been known that women of the long-resident, high-altitude population are not affected. One of the best documented effects of high altitude is a progressive reduction in birth weight. Highlanders are thus constantly exposed to a low oxygen environment, yet they live without any debilitating problems. It is estimated that at 4,000 meters (13,000 ft), every lungful of air only has 60% of the oxygen molecules that humans at sea level have. Certain natives of Tibet, Ethiopia, and the Andes have been living at these high altitudes for generations and are protected from hypoxia as a consequence of genetic adaptation. Īn estimated 81.6 million humans live at an elevation higher than 2,500 meters (8,200 ft) above sea level, of which 21.7 million reside in Ethiopia, 12.5 million in China, 11.7 million in Colombia, 7.8 million in Peru, and 6.2 million in Bolivia. In women, pregnancy can be severely affected, such as development of high blood pressure, called preeclampsia, which causes premature labor, low birth weight of babies, and often complicated with profuse bleeding, seizures, or death of the mother. Hypoxia is one of the principal causes of death among mountaineers. For several days, the affected will breathe excessively and burn extra energy, even when the body is relaxed. ![]() The sickness is compounded by related symptoms such as cerebral oedema (swelling of brain) and pulmonary oedema (fluid accumulation in lungs). Symptoms include fatigue, dizziness, breathlessness, headaches, insomnia, malaise, nausea, vomiting, body pain, loss of appetite, ear-ringing, blistering and purpling of the hands and feet, and dilated blood vessels. Some humans get the illness even at above 1,500 meters (5,000 ft). When humans from the general lowlands go to altitudes above 2,500 meters (8,200 ft) they experience altitude sickness, which is a type of hypoxia, a clinical syndrome of severe lack of oxygen. Humans are naturally adapted to lowland environments where oxygen is abundant. Origin and basis Himalayas, on the southern rim of the Tibetan Plateau The adaptation of the Tibetans is the fastest known example of human evolution, as it is estimated to have occurred any time around 1,000 BCE. This special adaptation is now recognised as an example of natural selection in action. However, the high-altitude populations in South America, East Africa, and South Asia have done so for millennia without apparent complications. Īround 81.6 million humans (approximately 1.1% of the world's human population) live permanently at altitudes above 2,500 meters (8,200 sf), putting these populations at risk for chronic mountain sickness (CMS). These humans have undergone extensive physiological and genetic changes, particularly in the regulatory systems of oxygen respiration and blood circulation, when compared to the general lowland population. While the rest of the human population would suffer serious health consequences, the indigenous inhabitants of these regions thrive well in the highest parts of the world. This adaptation means irreversible, long-term physiological responses to high-altitude environments, associated with heritable behavioural and genetic changes. High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at altitudes above 2,500 meters (8,200 ft). ( January 2023) ( Learn how and when to remove this template message) This article may require copy editing for grammar, style, cohesion, tone, or spelling.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |