Embarking on a hike up the great mountains of the South America you would be wise to pack a flask of coca tea in your rucksack — a traditional remedy for altitude sickness. But if you happen upon some locals when you stop to picnic, you’ll find that they have little need of it. Why so? A case of adaptation.
At 3,637m above sea level, the Bolivian capital of La Paz often afflicts its visitors with altitude sickness. Each breath contains only 60 per cent of the oxygen found at sea level, causing nausea, headaches and dizziness. Yet the native Aymara and Quechua people are adept at pulling oxygen out of thin air.
Known for their bright skirts, colourful shawls and bowler hats — introduced by visiting Victorian railway builders — they have adapted brilliantly to the high life. French doctor Denis Jourdanet was one of the first to note that the typical native had a “vast chest that makes him comfortable”. This is now known to house a greatly increased lung capacity, improving the transfer of oxygen to the blood. And it’s not just a roomy rib cage that helps. Blood samples taken from indigenous populations show a much higher percentage of red blood cells, helping to move oxygen around the body.
But whether these benefits are passed down through generations or are physical adaptations acquired in childhood has had experts arguing until they are blue in the face. Recent research leans towards natural selection — but don’t hold your breath.