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High HVR is generally advantageous for those who have acclimatized, as it results in increased oxygen intake, enhanced physical and mental performance at high altitude, and lower susceptibility to illness associated with high altitude.<ref name=":0" /> [[Adaptations]] in populations living at high altitudes range from cultural to genetic, and vary among populations. For example, [[Tibetans]] living at high altitudes have higher HVR than do [[Andean civilizations|Andean peoples]] living at similar altitudes,<ref name=":2" /><ref>Beall, Cynthia M. "Tibetan and Andean patterns of adaptation to high-altitude hypoxia." ''Human Biology'' (2000): 201-228.</ref> even though both populations exhibit greater [[aerobic capacity]] compared to lowlanders.<ref name=":3">Hochachka, Peter W., Hanns Christian Gunga, and Karl Kirsch. [http://www.pnas.org/content/95/4/1915.full "Our ancestral physiological phenotype: An adaptation for hypoxia tolerance and for endurance performance?"] ''Proceedings of the National Academy of Sciences'' 95.4 (1998): 1915-1920.</ref> The cause of this difference is most likely genetic, although developmental factors may also contribute.<ref name=":3" />
High HVR is generally advantageous for those who have acclimatized, as it results in increased oxygen intake, enhanced physical and mental performance at high altitude, and lower susceptibility to illness associated with high altitude.<ref name=":0" /> [[Adaptations]] in populations living at high altitudes range from cultural to genetic, and vary among populations. For example, [[Tibetans]] living at high altitudes have higher HVR than do [[Andean civilizations|Andean peoples]] living at similar altitudes,<ref name=":2" /><ref>Beall, Cynthia M. "Tibetan and Andean patterns of adaptation to high-altitude hypoxia." ''Human Biology'' (2000): 201-228.</ref> even though both populations exhibit greater [[aerobic capacity]] compared to lowlanders.<ref name=":3">Hochachka, Peter W., Hanns Christian Gunga, and Karl Kirsch. [http://www.pnas.org/content/95/4/1915.full "Our ancestral physiological phenotype: An adaptation for hypoxia tolerance and for endurance performance?"] ''Proceedings of the National Academy of Sciences'' 95.4 (1998): 1915-1920.</ref> The cause of this difference is most likely genetic, although developmental factors may also contribute.<ref name=":3" />

== High Altitude Adaptation ==
[[File:World Map of HVR adaptation in high altitude populations.jpg|thumb|This image depicts the three high altitude areas where studied populations have adapted to their environment: (From left to right) Andean Altiplano, Simian Plateau, and Tibetan Plateau.<ref>{{Cite journal|last=Bigham|first=Abigail|last2=Bauchet|first2=Marc|last3=Pinto|first3=Dalila|last4=Mao|first4=Xianyun|last5=Akey|first5=Joshua M.|last6=Mei|first6=Rui|last7=Scherer|first7=Stephen W.|last8=Julian|first8=Colleen G.|last9=Wilson|first9=Megan J.|date=2010-09-09|title=Identifying Signatures of Natural Selection in Tibetan and Andean Populations Using Dense Genome Scan Data|url=http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1001116|journal=PLOS Genet|volume=6|issue=9|pages=e1001116|doi=10.1371/journal.pgen.1001116|issn=1553-7404|pmc=2936536|pmid=20838600}}</ref>]]
Populations residing in altitudes above 2,500 meters have adapted to their hypoxic environments.<ref name=":5">{{Cite book|url=http://link.springer.com/chapter/10.1007/0-306-46825-5_7|title=Oxygen Sensing|last=Beall|first=Cynthia M.|date=2002-01-01|publisher=Springer US|isbn=9780306463679|editor-last=Lahiri|editor-first=Sukhamay|series=Advances in Experimental Medicine and Biology|pages=63–74|language=en|doi=10.1007/0-306-46825-5_7|editor-last2=Prabhakar|editor-first2=Naduri R.|editor-last3=II|editor-first3=Robert E. Forster}}</ref>Chronic HVR is set of adaptations found among most human populations historically native to high-altitude regions, including the [[Tibetan Plateau]], the [[Andes|Andean Altiplano]], and the [[Semien Mountains|Simian Plateau]].<ref>{{Cite journal|last=Bigham|first=Abigail|last2=Bauchet|first2=Marc|last3=Pinto|first3=Dalila|last4=Mao|first4=Xianyun|last5=Akey|first5=Joshua M.|last6=Mei|first6=Rui|last7=Scherer|first7=Stephen W.|last8=Julian|first8=Colleen G.|last9=Wilson|first9=Megan J.|date=2010-09-09|title=Identifying Signatures of Natural Selection in Tibetan and Andean Populations Using Dense Genome Scan Data|url=http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1001116|journal=PLOS Genet|volume=6|issue=9|pages=e1001116|doi=10.1371/journal.pgen.1001116|issn=1553-7404|pmc=2936536|pmid=20838600}}</ref>Up to 140 million people in total reside in such areas, although not all possess these adaptations.<ref>{{Cite journal|last=Moore|first=L G|last2=Regensteiner|first2=J G|date=2003-11-28|title=Adaptation to High Altitude|url=http://anthro.annualreviews.org/doi/abs/10.1146/annurev.an.12.100183.001441?requestedContent=related&|journal=Annual Review of Anthropology|language=en|volume=12|issue=1|pages=285–304|doi=10.1146/annurev.an.12.100183.001441}}</ref>Populations that have permanently settled in high altitude locations show virtually no reaction to acute [[Hypoxia (environmental)|hypoxia]]. Natives of the Andes and the Himalayas have been shown to develop adaptation to [[Hypoxia (environmental)|hypoxia]] from birth to neonatal years in the form of larger lungs and greater gas exchange surface area.<ref name=":6">{{Cite journal|last=Lahiri|first=S.|last2=Delaney|first2=R. G.|last3=Brody|first3=J. S.|last4=Simpser|first4=M.|last5=Velasquez|first5=T.|last6=Motoyama|first6=E. K.|last7=Polgar|first7=C.|date=1976-05-13|title=Relative role of environmental and genetic factors in respiratory adaptation to high altitude|url=http://www.nature.com/nature/journal/v261/n5556/abs/261133a0.html|journal=Nature|language=en|volume=261|issue=5556|pages=133–135|doi=10.1038/261133a0}}</ref>This response can be attributed to genetic factors, but the development of the resistance to acute [[Hypoxia (environmental)|hypoxia]] is highly affected by when the individual is exposed to high altitude<ref name=":6" />; while [[Genetics|genetic]] factors play an indefinite role in a person’s HVR, because long term migrants do not show reduction in their reactions of high altitude even after living in high altitudes in long term, the discrepancy suggests that reaction to HVR is the combination of environmental exposure and genetic factors.<ref name=":5" />


== Anthropology ==
== Anthropology ==

Revision as of 08:08, 13 November 2016

Hypoxic ventilatory response (HVR) is the increase in ventilation induced by hypoxia that allows the body to intake and process oxygen at higher rates. It is initially elevated in lowland people who travel to high altitude, but reduces significantly over time as people acclimatize.[1][2] In biological anthropology, HVR also refers to human adaptation to environmental stresses resulting from high altitude.[3]

In mammals, HVR is a direct result of the decrease in partial pressure of oxygen in arterial blood. Mammals under acute hypoxia experience decreases in aerobic metabolism and oxygen demand, as well as increased ATP production. The initial increase in ventilation from HVR is initiated by the carotid bodies, whose oxygen-sensitive cells become more active in response to hypoxia. Other mechanisms include hypoxia-inducible factors, particularly HIF1.[2] Hormonal changes have also been associated with HVR, particularly those that affect the functioning of the carotid bodies.[4]

As HVR is a response to decreased oxygen availability,[1] it shares the same environmental triggers as hypoxia. Such precursors include travelling to high altitude locations[5] and living in an environment with high levels of carbon monoxide.[6] Combined with climate, HVR can affect fitness and hydration.[2] Especially for lowlanders who traverse past 6000 meters in altitude, the limit of prolonged human exposure to hypoxia, HVR may result in hyperventilation and ultimately the deterioration of the body. Oxygen consumption is reduced to a maximum of 1 liter per minute.[7]

High HVR is generally advantageous for those who have acclimatized, as it results in increased oxygen intake, enhanced physical and mental performance at high altitude, and lower susceptibility to illness associated with high altitude.[1] Adaptations in populations living at high altitudes range from cultural to genetic, and vary among populations. For example, Tibetans living at high altitudes have higher HVR than do Andean peoples living at similar altitudes,[4][8] even though both populations exhibit greater aerobic capacity compared to lowlanders.[9] The cause of this difference is most likely genetic, although developmental factors may also contribute.[9]

High Altitude Adaptation

This image depicts the three high altitude areas where studied populations have adapted to their environment: (From left to right) Andean Altiplano, Simian Plateau, and Tibetan Plateau.[10]

Populations residing in altitudes above 2,500 meters have adapted to their hypoxic environments.[11]Chronic HVR is set of adaptations found among most human populations historically native to high-altitude regions, including the Tibetan Plateau, the Andean Altiplano, and the Simian Plateau.[12]Up to 140 million people in total reside in such areas, although not all possess these adaptations.[13]Populations that have permanently settled in high altitude locations show virtually no reaction to acute hypoxia. Natives of the Andes and the Himalayas have been shown to develop adaptation to hypoxia from birth to neonatal years in the form of larger lungs and greater gas exchange surface area.[14]This response can be attributed to genetic factors, but the development of the resistance to acute hypoxia is highly affected by when the individual is exposed to high altitude[14]; while genetic factors play an indefinite role in a person’s HVR, because long term migrants do not show reduction in their reactions of high altitude even after living in high altitudes in long term, the discrepancy suggests that reaction to HVR is the combination of environmental exposure and genetic factors.[11]

Anthropology

Populations

Andeans

Cusco, Peru, which has an altitude of 11,000 ft

The Andean peoples are one of three central populations of study that have an increased HVR. These populations notably inhabit areas in and around the Andes mountain range, which has an average altitude of 13,000 ft.[15] HVR has been studied in inhabitants of Cusco, Peru, which lies at 11,000 ft.[15] Living in such high altitudes has led to cultural adaptations, including the consumption of coca tea.

Tibetans

Mount Everest, the highest peak of the Himalayas.

The Tibetan people are an ethnic group native to Tibet that live throughout the Tibetan Plateau. They live at altitudes up to 15,000 ft,[16] and are thus of extreme interest to researchers investigating HVR in high altitude populations. One of these populations are the Sherpa people, a group of Tibetans who are sought after for their knowledge of and skill with navigating through the Himalayas. Historically, Sherpas have been contracted to guide expeditions up Mount Everest, but the practice has since declined in light of exploitation of the Sherpa guides. The energy and ease at which the Sherpa ascend and descend mountains is due to their ability to use oxygen more efficiently.[17] This ability to excel at mountaineering has shifted their culture around it. Tourism has become a driving force for the financial income of the Sherpa people. The Sherpa are able to make much more money[18] acting as travel guides due to their local knowledge, and climbing ability.

Amhara

Simien Mountains 14,900 ft

The Amhara people are the occupants of the central and northern Highlands of Ethiopia in the Amhara Region, where the elevation ranges consistently between 1500 m (4,921 ft) to 4550 m (14,928 ft). Researchers of HVR are especially interested in the populations that live in the Simien Mountains above 3,000 m (9,842 ft).[19] Historically the Amhara people have ruled in this region for close to 750 years,[20] and have lived there for approximately 2,000 years.[21]

References

  1. ^ a b c Cymerman, A; Rock, PB. "Medical Problems in High Mountain Environments. A Handbook for Medical Officers". USARIEM-TN94-2. US Army Research Inst. of Environmental Medicine Thermal and Mountain Medicine Division Technical Report. Retrieved 2009-03-05.
  2. ^ a b c Teppema, Luc J., and Albert Dahan. "The ventilatory response to hypoxia in mammals: mechanisms, measurement, and analysis." Physiological Reviews 90.2 (2010): 675-754.
  3. ^ Stanford, Craig, John S. Allen, and Susan C. Anton. Biological Anthropology : The Natural History of Humankind. 2nd ed. Upper Saddle River: Prentice Hall Higher Education, 2008. 151-52.
  4. ^ a b Hornbein, Thomas F., and Robert B. Schoene. High Altitude: An Exploration Of Human Adaptation. n.p., New York: Marcel Dekker, c2001., 2001. OskiCat. Web. 8 Nov. 2016.
  5. ^ "Altitude Hypoxia Explained." Altitude Research Center. Altitude Research Center, n.d. Web. 08 Nov. 2016.
  6. ^ Karius, Diane R. "Respiratory Adaptations in Health and Disease: Forms of Hypoxia." Forms of Hypoxia. Kansas City University, n.d. Web. 08 Nov. 2016.
  7. ^ West, John B. "Human responses to extreme altitudes." Integrative and comparative biology 46.1 (2006): 25-34.
  8. ^ Beall, Cynthia M. "Tibetan and Andean patterns of adaptation to high-altitude hypoxia." Human Biology (2000): 201-228.
  9. ^ a b Hochachka, Peter W., Hanns Christian Gunga, and Karl Kirsch. "Our ancestral physiological phenotype: An adaptation for hypoxia tolerance and for endurance performance?" Proceedings of the National Academy of Sciences 95.4 (1998): 1915-1920.
  10. ^ Bigham, Abigail; Bauchet, Marc; Pinto, Dalila; Mao, Xianyun; Akey, Joshua M.; Mei, Rui; Scherer, Stephen W.; Julian, Colleen G.; Wilson, Megan J. (2010-09-09). "Identifying Signatures of Natural Selection in Tibetan and Andean Populations Using Dense Genome Scan Data". PLOS Genet. 6 (9): e1001116. doi:10.1371/journal.pgen.1001116. ISSN 1553-7404. PMC 2936536. PMID 20838600.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  11. ^ a b Beall, Cynthia M. (2002-01-01). Lahiri, Sukhamay; Prabhakar, Naduri R.; II, Robert E. Forster (eds.). Oxygen Sensing. Advances in Experimental Medicine and Biology. Springer US. pp. 63–74. doi:10.1007/0-306-46825-5_7. ISBN 9780306463679.
  12. ^ Bigham, Abigail; Bauchet, Marc; Pinto, Dalila; Mao, Xianyun; Akey, Joshua M.; Mei, Rui; Scherer, Stephen W.; Julian, Colleen G.; Wilson, Megan J. (2010-09-09). "Identifying Signatures of Natural Selection in Tibetan and Andean Populations Using Dense Genome Scan Data". PLOS Genet. 6 (9): e1001116. doi:10.1371/journal.pgen.1001116. ISSN 1553-7404. PMC 2936536. PMID 20838600.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  13. ^ Moore, L G; Regensteiner, J G (2003-11-28). "Adaptation to High Altitude". Annual Review of Anthropology. 12 (1): 285–304. doi:10.1146/annurev.an.12.100183.001441.
  14. ^ a b Lahiri, S.; Delaney, R. G.; Brody, J. S.; Simpser, M.; Velasquez, T.; Motoyama, E. K.; Polgar, C. (1976-05-13). "Relative role of environmental and genetic factors in respiratory adaptation to high altitude". Nature. 261 (5556): 133–135. doi:10.1038/261133a0.
  15. ^ a b "Andes Mountains | mountain system, South America". Encyclopedia Britannica. Retrieved 2016-11-10.
  16. ^ "Plateau of Tibet | plateau, China". Encyclopedia Britannica. Retrieved 2016-11-10.
  17. ^ CNN, Meera Senthilingam, for. "Scientists discover why Sherpas are superhuman climbers - CNN.com". CNN. Retrieved 2016-11-11. {{cite web}}: |last= has generic name (help)CS1 maint: multiple names: authors list (link)
  18. ^ "Guide: What does a Sherpa at Mount Everest do? - CBBC Newsround". 2014-04-23. Retrieved 2016-11-11.
  19. ^ Scheinfeldt, Laura B.; Soi, Sameer; Thompson, Simon; Ranciaro, Alessia; Woldemeskel, Dawit; Beggs, William; Lambert, Charla; Jarvis, Joseph P.; Abate, Dawit (2012-01-01). "Genetic adaptation to high altitude in the Ethiopian highlands". Genome Biology. 13: R1. doi:10.1186/gb-2012-13-1-r1. ISSN 1474-760X. PMC 3334582. PMID 22264333.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  20. ^ "Amhara | people". Encyclopedia Britannica. Retrieved 2016-11-11.
  21. ^ "Amhara facts, information, pictures | Encyclopedia.com articles about Amhara". www.encyclopedia.com. Retrieved 2016-11-11.
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