Mount Everest. It is the tallest mountain in the world, standing at 8848 meters tall on the border between China, Tibet, and Nepal. Over the last couple of years it has become popular to try and climb it. Starting from base camp, all climbers are instantly faced with the blistering cold. During the summer the average temperature is around -20C and in the winter it can get as cold as -40C. When combined with winds of over 160 km/h, there’s a real chance that parts of your body will freeze and die off: frostbite. If climbers aren’t careful, the weather can literally cause them to freeze to death. The mountain is littered with dead bodies, some of which are used as landmarks.
A bit higher up the mountain and the altitude really starts to kick in. Climbers become unable to eat and sleep properly, and their mental acuity begins to decline. Many of them get a pounding headache, nausea, and dizziness; acute mountain sickness. In some cases, the body misinterprets the hypoxia (lack of oxygen) and counter-productively expels fluid into the lungs or brain. If the climber does not retreat to a lower altitude and get treatment, death is often inevitable.
Assuming the initial altitude sickness has been overcome, the danger increases exponentially as ascending continues. Above 8000 meters, climbers enter the Death Zone. Oxygen levels are so low that the body begins to shut down as there is simply not enough oxygen to fuel it. Judgement becomes impaired, and the risks for severe high-altitude sickness, heart-attacks, and strokes reach unmatched levels.
Yet there is one community that thrives in these extreme circumstances: the Sherpa’s. They are an indigenous ethnic group to the Himalaya area and have lived there for at least 6000 years. They are much less likely to get altitude sickness, produce up to 30% more power at altitude, have more blood-vessels in their muscles, and have larger chests and lungs. Their bodies use oxygen much more efficiently, despite surprisingly having less haemoglobin and mitochondria in their blood. The amount of creatine phosphates in their body, molecules which can be used as an additional energy source, increases with altitude. In non-Sherpa’s these levels decrease at altitude. And these superpowers are not just due to acclimatisation: if a Sherpa was raised in the Netherlands, he or she would still have these characteristics. Interestingly, other high altitude populations in the world do not share the same superhero genetics.
To understand these Sherpa superpowers, we need to delve deep into history. When our ancestors migrated from Africa some 60,000 years ago, they were not the only ones. The Neanderthals made this journey too, and so did the lesser known Denisovans. The Denisovans are one of our most mysterious hominid cousins, discovered only in 2008. We have only found a very small amount of their fossils: one finger bone, two teeth, a toe bone, and part of a jaw bone. In-depth analysis suggests that Denisovans had sloped foreheads, wide hips, and a much longer jaw (the distance from their front teeth to their molars). They migrated to a large area spreading from Siberia to Southeast Asia. It is thought that they lived predominantly at high altitudes, and through ancient interbreeding with our modern ancestors the high-altitude genes have been passed on to the Sherpa community and some communities in Tibet. Our DNA still contains some genetics traces of unknown species of human, ones we have never found archaeological evidence of. It is incredible how we know there were multiple human species just by looking at our own DNA, and it is fair to say that there could be many findings like the Sherpa genetics to come in the future.
Due to their aptitude for climbing, many people of the Sherpa community have become mountain climbing guides. Commercial expedition groups hire them in order to increase the chance of reaching the summit. They end up having to do all of the dangerous work, like laying out the safest routes before the climbing season starts and hauling all of the clients’ luggage up the mountain. The Sherpa’s have to make up for what the clients lack, which from a genetic point of view alone is significant. Most people are simply not made for living – let alone climbing – at such extreme altitudes. Many Sherpa’s lose their life as climbing guides trying to make a living for their poor families. People should only climb mountains such as Everest if they have the skills and experience to do so, instead of relying on the superheroes that are Sherpa’s.