New study suggests it’s something to do with their kidneys.
The ability of sure-footed Sherpas to scale the oxygen-rare slopes of the Himalayas without losing puff has enthralled the world since Tenzing Norgay summited Everest with Edmund Hillary in 1953.
Now research led by Mike Stembridge, an exercise physiologist at Cardiff Metropolitan University in the UK, has upended the traditional wisdom on how these high-altitude dwellers pull off their remarkable feat.
As you go higher oxygen levels plummet, which means there is a clear cut-off for human habitation. It sits just above 5000 metres, the altitude of the world’s highest permanent settlement, the gold mining town La Rinconada in the Andes of southern Peru.
Humans adapt at these dizzying heights by making more red blood cells, which contain oxygen-carrying haemoglobin. It’s an adaptation that comes, however, with a cost.
More red blood cells means thicker, stickier blood that clots more easily causing strokes and heart attacks.
In a twist, the Sherpas of the Tibetan plateau were thought to have bucked that blood-making trend. They have lower haemoglobin levels compared to folk from the Andes and, consistent with the survival advantage that should offer, better reproductive stats.
They would need to compensate, of course, by extracting more oxygen via the lungs and offloading it better when red cells arrive at muscles and organs.
It’s a theory that fits very nicely with findings that Tibetans are endowed with genes, including one called EPAS1, that lower haemoglobin and bump up the efficiency of oxygen use.
But for Stembridge and colleagues that theory faced a stumbling block.
Read the full article at Cosmos magazine here