Himalayan Powerhouses: How Sherpas Have Evolved Superhuman Energy Efficiency
Sherpas have evolved to become superhuman mountain climbers, extremely efficient at producing the energy to power their bodies even when oxygen is scarce, suggests new research published today in the Proceedings of the National Academy of Sciences (PNAS).
The findings could help scientists develop new ways of treating hypoxia – lack of oxygen – in patients. A significant proportion of patients in intensive care units (ICUs) experience potentially life-threatening hypoxia, a complication associated with conditions from haemorrhage to sepsis.
When oxygen is scarce, the body is forced to work harder to ensure that the brain and muscles receive enough of this essential nutrient. One of the most commonly observed ways the body has of compensating for a lack of oxygen is to produce more red blood cells, which are responsible for carrying blood around the body to our organs. This makes the blood thicker, however, so it flows more slowly and is more likely to clog up blood vessels.
Mountain climbers are often exposed to low levels of oxygen, particularly at high altitudes. This is why they often have to take time during long ascents to acclimatise to their surroundings, giving the body enough time to adapt itself and prevent altitude sickness. In addition, they may take oxygen supplies to supplement the thin air.
Scientists have known for some time that people have different responses to high altitudes. While most climbers require additional oxygen to scale Mount Everest, whose peak is 8,848m above sea level, a handful of climbers have managed to do so without. Most notably, Sherpas, an ethnic group from the mountain regions of Nepal, are able to live at high altitude with no apparent consequences to their health – as a result, many act as guides to support expeditions in the Himalayas, and two Sherpas are known to have reached the summit of Everest an incredible 21 times.
Previous studies have suggested differences between Sherpas and people living in non-high altitude areas, known collectively as ‘lowlanders’, including fewer red blood cells in Sherpas at altitude, but higher levels of nitric oxide, a chemical that opens up blood vessels and keeps blood flowing.