Adopting to living at high altitudes – NSP NEWS

People living in high altitudes have the same basal metabolic rate as people living in low altitudes
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The village of Karzok in Ladakh, with a population of 1,300, is the highest settlement in our country — at 4,570 meters above sea level. The villages of Komic and Hanle in Himachal Pradesh are both over 4,500 msl. Globally, it is estimated that 6.4 million people (nearly 0.1% of the world’s population) live at elevations greater than 4,000 msl. Large numbers of these have lived on the high-altitude plains of the Andes (S. America) and Tibet (Asia) for more than 10,000 years. People living at lower altitudes have difficulty adjusting to the cold and to the reduced atmospheric pressure and therefore less oxygen at these altitudes. So how do people living there adopt, and what difficulties do they face?

Economic outlook

But first, a look at economic factors. Lack of opportunities is the main reason why very few people settle down in places such as the Himalayas. Agriculture requires land to be first shaped into terraces along steep mountain slopes. Water for irrigation is a major challenge. Also, as you go higher, there are fewer organisms such as fungi and nematodes to enrich the health of the soil.

Grazing of livestock like yaks in the Himalayas, and the llamas, alapacas and vicunas in the Andes is feasible only for the warmer months of the year. Mining is done where resources are found. The world’s highest settlement, La Riconada in Peru (5,100 msl), has attracted thousands of settlers after gold was discovered there. These days, adventure tourism provides sustenance too – the village of Lobuche (4,950 msl) in Nepal supports climbers trying to scale Mount Everest.

Lung capacities

A low altitude dweller, when taken to high altitudes, shows a 25-30% increase in basal metabolic rate, which is the calories you burn while remaining in bed all day. This means that more oxygen is required by the body, even though the air has less oxygen. It takes a few weeks to acclimatize to low oxygen.

High-altitude-adapted Tibetans and Andeans have the same normal basal metabolic rate at high altitudes as other people on their home grounds. The forced vital capacity (FVC) is the maximum amount of air that you can exhale after filling your lungs. The FVC is 15% higher in men, and 9% higher in women adapted to higher altitudes. FEV1, the amount of air that is exhaled in one second, is also higher.

The Quechua, who are an aboriginal people of South America (the Incas belonged to this group) have deep chests, and the FVC is higher in individuals born and brought up at high altitudes compared to their kith and kin who have grown up nearer to sea level.

The difficult living conditions ensure fitness. Studies in the Kinnaur district of Himachal Pradesh have shown that the average blood pressure in the 70-74 age group remains 120/80.

For all the hardships associated with living at high altitudes, there may be some compensatory benefits too. A recent study (PLOS Biology, May 2023) took a strain of mice with genetically short life span. These mice lived 50% longer when brought up in a low-oxygen atmosphere that simulates the Everest base camp!

(The article was written in collaboration with Sushil Chandani, who works in molecular modelling. sushilchandani@gmail.com)