Hundreds of generations of the Sherpa ethnic group living on the plateau have undergone a genetic revolution to adapt to low oxygen conditions.
For at least 6,000 years, the Sherpa people have inhabited the high plateau region of the Himalayas, at an altitude of nearly 4,500 meters above sea level. Today, they are renowned as one of the best mountaineering groups in the world, holding numerous climbing records. The Sherpas also secure safety ropes on climbing routes and guide Westerners who wish to summit Everest.
But that’s the story of the present. Before the 1920s, the Sherpa people made their living through agriculture in the high mountains, herding livestock and spinning wool. The Sherpas passed by the peaks of the Himalayas but did not ascend them, as they believed these mountains were the homes of the gods.
When the British began planning expeditions to climb the Himalayas, they hired Sherpas as porters. Since then, mountaineering has become an essential part of Sherpa culture. Their willingness to guide Western climbers and their ability to reach the highest peaks have significantly contributed to Himalayan exploration efforts.
On the towering peaks of the Himalayas, this Nepalese ethnic group is celebrated for their speed records in climbing, pioneering routes that had never been climbed before, their guiding capabilities, and many other skills.
The Extraordinary Sherpa People
What enables the Sherpa people to excel in climbing at the high altitudes of the world’s tallest mountains?
According to a recent study, they may be better at controlling and utilizing oxygen than others. This finding also suggests potential solutions for normal individuals whose cells suffer from oxygen deprivation due to illness.
“You don’t need to stay long to realize that the people here, specifically the Sherpas, perform exceptionally well at high altitudes, much better than we do,” said Andrew Murray, a physiologist at the University of Cambridge (UK) and one of the study’s authors. “Their abilities are certainly quite extraordinary.”
A Sherpa carries a ladder for climbers attempting to summit Everest. (Photo: Tashi Sherpa/AP).
Additionally, the research provided evidence regarding their gene role.
For at least 6,000 years, Sherpas and other ethnic groups have lived in the Himalayan plateau region, at an altitude of nearly 4,500 meters above sea level. Today, most of us still cannot adapt to life at such heights.
Individuals from lower altitudes moving to higher elevations face many risks. Exposure to limited oxygen at altitudes above 2,500 meters can lead to symptoms such as headaches, loss of appetite, and difficulty sleeping. Severe cases of altitude sickness can result in cerebral edema or pulmonary edema, both of which can cause rapid death.
Pregnant women also face increased rates of miscarriage and other complications due to high blood pressure while moving to high altitudes. This demonstrates the potential for a selective revolution of genes that help mountain dwellers cope with oxygen shortages.
So how do the Sherpas manage this? Murray explains that over thousands of years, the bodies of high-altitude people have evolved to utilize oxygen more effectively.
When we climb mountains, the hormone erythropoietin (EPO) stimulates the production of more red blood cells, which then transport more oxygen to the muscles. However, the additional cells also thicken the blood, increasing the pressure on the heart to pump blood, potentially causing altitude sickness (also known as acute mountain sickness). Sherpas also increase their red blood cell count at high altitudes, but not as much as those from lower regions.
Sherpas are professional porters earning a living on the roof of the world. (Photo: Tashi Sherpa/AP).
To understand this better, Murray and colleagues studied a group of 15 Sherpas and 10 people from lower elevations during a trek to Everest Base Camp in 2013.
Weeks before, they were not allowed to climb high. The journey began with a flight from London (UK) or Kathmandu (Nepal) to Lukla, Nepal, at an altitude of nearly 2,800 meters. All participants were provided with the same food during the 10-day trek to Everest Base Camp, located at 5,300 meters.
Before, during, and after the trek, the research team collected blood samples and small muscle tissue samples from all subjects. The results were published in the Proceedings of the National Academy of Sciences.
The muscle cells of the two study groups exhibited interesting differences. In the muscle tissue of the Sherpas, the mitochondria – the energy-producing organelle – converted more oxygen into energy. Murray stated: “The mitochondria in Sherpas have fewer leaks, making them more efficient than mitochondria in Westerners. They (the Sherpas) are better at utilizing oxygen.”
Sherpas can also produce more energy in the absence of oxygen through a process known as anaerobic respiration.
According to Tatum Simonson, a researcher in genetics and physiology of altitude adaptation at the University of California (San Diego, USA), these findings connect to discoveries from previous studies revealing the DNA mutations of the Sherpas. In 2010, Simonson and colleagues examined the genomes of high-altitude Tibetans and identified several genes with significant mutations that seemed related to oxygen metabolism, adapting to low-oxygen environments.
To further investigate the potential role of one of these genes (which also appears in the ancestors of high-altitude Ethiopians), Murray’s team built on Simonson’s research and made further progress.
According to this study, metabolism in Sherpas and lowland dwellers operates similarly at lower elevations. Thus, the genetic differences between the two groups only appear at high altitudes.
Since the Sherpas have adapted to high altitudes over hundreds of generations, they have opened doors to the potential of our bodies in coping with oxygen deprivation.
A girl suffering from altitude sickness breathes through an oxygen mask to prevent hypoxemia. (Photo: Thinkstock).
Simonson noted that the genetic differences that help the Sherpas thrive in low-oxygen environments occasionally appear in the general population on Earth. This research explains why some individuals can endure better in low blood oxygen conditions, whether due to altitude, heart disease, respiratory conditions, or cancer.
According to Murray, in hospitals, about 25% of people with low blood oxygen levels die. Survivors do not recover as robustly as before. Traditional treatment focuses on increasing oxygen concentration, but this approach is often ineffective and can even be harmful.
We might explore treatments that help patients mimic what the Sherpas are doing – effectively utilizing the limited oxygen available to them.
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