The biological secrets that make Sherpas superhuman mountaineers

By Meera Senthilingam, for CNN

Updated 1139 GMT (1939 HKT) October 7, 2016

Everest is the tallest mountain in the world, at 8,847 meters above sea level. Low oxygen at that altitude pushes human endurance to its limits. Pictured, Sherpa mountaineer Pemba Dorje Sherpa and others on Everest, 2009.
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Everest is the tallest mountain in the world, at 8,847 meters above sea level. Low oxygen at that altitude pushes human endurance to its limits. Pictured, Sherpa mountaineer Pemba Dorje Sherpa and others on Everest, 2009.
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Having lived in the Himalayas for centuries, Sherpas have adapted to easily breathe the thin air.
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Having lived in the Himalayas for centuries, Sherpas have adapted to easily breathe the thin air.
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In 2013, the Xtreme Everest research team conducted experiments on Sherpas and other volunteers at high altitudes to discover how Sherpas thrive at such heights.
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In 2013, the Xtreme Everest research team conducted experiments on Sherpas and other volunteers at high altitudes to discover how Sherpas thrive at such heights.
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Researchers set up their laboratory at the highest altitude possible -- Mount Everest base camp.
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Researchers set up their laboratory at the highest altitude possible -- Mount Everest base camp.
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The secret behind this ability lies in their cells; Sherpas have differences in their mitochondria, which means they use oxygen very efficiently.
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The secret behind this ability lies in their cells; Sherpas have differences in their mitochondria, which means they use oxygen very efficiently.
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Nepalese climber Apa Sherpa is the joint world record for most successful climbs of Mount Everest with 21 ascents. Another Sherpa, Phurba Tashi, is the other joint record holder.
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Nepalese climber Apa Sherpa is the joint world record for most successful climbs of Mount Everest with 21 ascents. Another Sherpa, Phurba Tashi, is the other joint record holder.
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For the research, 116 healthy volunteers living in lowland locations and 64 Sherpas were tested before, during and after a climb to Everest base camp.
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For the research, 116 healthy volunteers living in lowland locations and 64 Sherpas were tested before, during and after a climb to Everest base camp.
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The goal was to understand more about hypoxia -- when not enough oxygen reaches the body's organs -- a condition that affects many intensive care patients.
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The goal was to understand more about hypoxia -- when not enough oxygen reaches the body's organs -- a condition that affects many intensive care patients.
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Having collected genetic information from the individuals who took part in the study, the next phase of research will look at genetic reasons behind the Sherpas' adaptations to high altitudes.<br />
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Having collected genetic information from the individuals who took part in the study, the next phase of research will look at genetic reasons behind the Sherpas' adaptations to high altitudes.
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Story highlights

  • Researchers explain why Sherpas are so good at dealing with extreme altitude
  • Xtreme Everest expedition tested Sherpa physiology
  • Sherpas are more efficient at using oxygen and have improved blood flow in their organs

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(CNN)Mount Everest is the ultimate test for adventurers trying to test their boundaries, but when it comes to climbing this natural monument, one group of people excel -- Sherpas.

The Sherpa people are an ethnic group from Nepal who have lived in the high altitudes of the Himalayas for generations. They have long served as guides and porters, whose local expertise has been invaluable for foreigners attempting climbs in the area.
    But while they are admired for the ease with which they deal with the physical challenges of scaling some of the world's biggest peaks, the biological reasons for their mountain-climbing prowess have remained unknown -- until now.
      Denny Levett is a founding member of Xtreme Everest and a consultant in clinical care at University Hospital Southampton, England. In 2013 she took part in Xtreme Everest 2 -- a scientific expedition to the top of E