Legendary for their strength and abilities to operate at high altitudes, climbing sherpas are elite mountaineers who have become ubiquitous on high-altitude expeditions. When climbers succumb to the mountain, it is often the sherpas who mount and execute a rescue.
They are the subjects of the newest documentary set on Everest, called Sherpa, premiering on the Discovery Channel on April 23 at 9 ET/8 Central.
The term sherpa is derived from the name of an ethnic group of Himalayan locals. Sherpas are an ethnic minority in Nepal and it is believed that they migrated from the high grasslands of Kham in Tibet to the high Himalayan Mountains between the 1400s to 1700s. While the terms are often used interchangeably, climbing sherpas are not necessarily a member of the Sherpa ethnic group.
Nearly everyone who spends extended periods at high altitude becomes acclimated to it. Low-altitude dwellers' bodies respond to being in high-altitude environments by making more red blood cells, which contain hemoglobins, the proteins that carry oxygen.
In the sherpa population, scientists have found the presence of higher hemoglobin levels without over-production of red blood cells. On average, sherpas have hemoglobin levels that are 20 percent higher than those of sea level-dwelling humans; this is just the beginning of what makes sherpas better suited to life and work in the Himalayas.
A recent survey of the results from hundreds of scientific papers on sherpas found physiological and genetic adaptations across all major systems in the body. To name a few, sherpas tend to be less sensitive to low-oxygen environments and have higher musculoskeletal strength at altitude. Their hearts have greater capacity; they have larger and more efficient lungs, better blood circulation, more well-regulated metabolisms, higher oxygenation at the cellular level, and protective features for brain function not found in lowlanders.
It's no wonder sherpas are considered super humans.
Within the scientific community, the high-altitude adaptations in sherpas are collectively considered one of the clearest examples of human evolution at work. Scientists often attribute their adaptations to natural selection in response to the stressors they've faced over the 500 generations they've lived in a high-altitude environment.
Those who are better able to handle the stress of high-altitude environments thrive over their less-adapted neighbors, and pass on their genes to more offspring.
To learn more about the various physiological adaptations found in sherpas, see the American Physiological Society Journal article titled: King of the Mountains: Tibetan and Sherpa Physiological Adaptations for Life at High Altitude.To learn more about the genetic variations, see University of Chicago's post on the Genetic Origins of High Altitude Adapations in Tibetans.