S. Idell Pyle Professor of Anthropology, Professor of Anatomy and Global Health
Case Western Reserve University, Cleveland, OH

Presentation Title: Human Evolution and Adaptation to High-altitude

Description During the past 100,000 – 200,000 years, humans have moved out of Africa to an enormous range of environments including the world's high plateaus in the Andes, Tibet, and East Africa. The environmental stress at high altitude is clear: lower barometric pressure results in fewer than normal oxygen molecules in every breath, and therefore in circulation. Lowlanders traveling to high altitudes respond to acute hypoxia - or oxygen deficiency - with homeostatic responses of the lung, heart, blood vessels, and blood.  However, native residents of the world’s three high plateaus deliver oxygen more effectively, which is hypothesized to be the result of evolution by natural selection over thousands of years of high-altitude residence. Furthermore, the physiology in these populations differs, which suggests that three replications of the same natural experiment of moving from low to high altitude had different outcomes. There is also evidence of ongoing natural selection – differential survival of genotypes – in the Tibetan population.  Strikingly, the degree of physiological hypoxia of healthy high-altitude natives on these plateaus is in the range considered pathological at low altitudes where it is routinely treated with oxygen therapy. Study of adaptations in healthy hypoxic people may suggest new therapies and interventions for patients with hypoxia at all altitudes.

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Research Interests

Dr. Beall is a physical anthropologist whose research focuses on human adaptation to high-altitude hypoxia, particularly the different patterns of adaptation exhibited by Andean, Tibetan and East African highlanders. Her current research deals with the genetics of adaptive traits and evidence for natural selection, with the role of nitric oxide in oxygen delivery at high altitude and with the human ecology of high-altitude Tibetan nomads. Professor Beall is a member of the U.S. National Academy of Sciences and the American Philosophical Society.

Recent Publications

Beall, C.M 2009. Andean, Tibetan, and Ethiopian patterns of adaptation to high-altitude hypoxia.  Integrative and Comparative Biology 46(1):18-24. doi:10.1093/icb/icj004

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Beall, C.M., Song, K., Elston, R.C., Goldstein, M.C. 2004. Higher offspring survival among Tibetan women with high oxygen saturation genotypes residing at 4,000 m. PNAS 101(39):14300-14304. doi: 10.1073/pnas.0405949101

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Beall, C.M., Decker, M.J., Brittenham, G.M., Kushner, I., Gebremedhin, A., Strohl, K.P. 2002. An Ethiopian pattern of human adaptation to high-altitude hypoxia.  PNAS. 99(26):17215-17218. doi: 10.1073/pnas.252649199

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The Center for Research on Tibet

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Includes papers by Dr. Beall on Tibetan adaptations to high altitude, as well as information about Tibetan culture.

Resources for Teaching

Altitude.org: A High Altitude Resource

This site contains general information about high altitude as well as tutorials and calculators to explore the impact of pressure and oxygen on the human body.

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Hypoxia and adaptation to altitude: Reading between the Genes

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This podcast covers the human temporary acclimatization and evolutionary adaptation to high altitudes. Cynthia Beall is featured.  Also available in Spanish.

Rupert, J.L., Hockachka, P.W. 2001. Genetic approaches to understanding human adaptation to altitude in the Andes.  Journal of Experimental Biology 204:31512-3160

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This accessible review focuses on the research approaches to understanding evolution of high altitude adaptation including heritability studies, migration, co-segregation of polygenic traits, association analysis