Sherpas' Superhuman Ability That Makes Them So Good At Climbing Mountains

Scaling Mount Everest is the ultimate achievement in the eyes of adventurers the world over, but for some, it's just another day's work. Behind nearly every successful climb, there is a Sherpa, acting as both a guide to the mountain's perilous slope, and a porter, hauling heavy loads of supplies on their backs. Sherpas also set up climbing ropes and ladders along the route, and are responsible for making the camps that shelter mountaineers on their journey. But Sherpa is not just a job title.

Sherpas are an ethnic group within Nepal. They are one amongst a larger collective of ethnic groups called the Bhotia, which have roots in Tibet. The name Sherpa comes from the geographic roots of the group, being drawn from the Tibetan words "shar pa," meaning "easterner". The total population of Sherpas is estimated to be around 150,000, most of whom are based in the Himalayan region.

Sherpas are the world's greatest mountain climbers. The first people confirmed to reach the summit of Everest were Tenzing Norgay Sherpa and mountaineer Edmund Hillary, and as of the writing of this article, the world record for the most summits belongs to Kami Rita Sherpa, who has climbed the peak a stunning 31 times. It's a record that could only be claimed by a Sherpa, because it turns out they have some unique biological traits that make them better suited than anyone else to handle one of Earth's most hostile environments.

The main obstacle to summiting Everest is oxygen access. The mountain's summit is in the uppermost reaches of the troposphere, where oxygen pressure is just one-third of what it is at sea level. For the vast majority of people, this oxygen scarcity prompts the body to start working overtime to make up for it, producing more red blood cells in order to carry more oxygen. However, this has the negative effect of thickening the blood, which puts more stress on the heart. This can cause a wide range of dangerous symptoms including swelling of the brain and fluid buildup in the lungs, potentially fatal conditions that contribute to Everest's death toll. To avoid this fate, climbers need to use supplemental oxygen ... unless they are a Sherpa.

A 2017 study published in the journal Proceedings of the National Academy of Sciences analyzed blood samples and muscle biopsies from Sherpas and discovered something special about their mitochondria, which are structures within cells that utilize oxygen to convert glucose from food into adenosine triphosphate (ATP), the body's main type of fuel. It turns out that Sherpas' mitochondria use oxygen much more efficiently than those of lowlanders. Not all of the oxygen we breathe actually gets put towards ATP production, but Sherpas waste less of it than other people. They also have a higher capacity for anaerobic metabolism, which is ATP production without the use of oxygen at all. This allows Sherpas to survive on less oxygen than a person would typically need.

Sherpas' ultra-efficient bodies are a valuable lesson in the evolutionary process. We tend to frame the course of human evolution as a singular process, but in reality, different groups of people evolve in different ways than others as a product of their respective environments. Sherpas have been living in the high Tibetan Plateau for 6,000 years or more. In that environment, natural selection favors those with mutations that maximize oxygen efficiency.

More efficient mitochondria aren't the only thing working in favor of Sherpas. At high altitudes, their bodies don't go into red blood cell–producing hyperdrive like those of lowlanders. Sherpas' blood flows easily in low-oxygen environments because they produce especially high levels of nitric oxide, which opens up blood vessels. Sherpas also produce higher levels of phosphocreatine at high altitudes, a compound that serves as a backup energy source if ATP runs out. For lowlanders, it's the exact opposite, with phosphocreatine levels plummeting as they climb higher.

Studying the bodies of Sherpas is of particular interest in the medical field. Low oxygen levels lead to a condition called hypoxia, which is closely associated with diseases such as anemia, cancer, and cardiopulmonary issues. At the moment, doctors typically treat hypoxia by trying to give the patient more oxygen, but it's not a very effective approach. Learning how to make the body use low oxygen levels more efficiently, like Sherpas do, would be a major medical breakthrough.