Ecuador is a country not only known for mega-diversity in terms of the magnificent biological world, but also referred to its ethnic-diversity. For instance, approximately 96.4% of Ecuador’s Indigenous population are Highland Quichuas who live in the valleys of the Sierra region.
Now, if you have ever wondered why Andean Highlanders seem to go for a stroll while you are already fully exhausted hiking up a mountain take a closer look at this:
It is estimated that at 5,000 m.a.s.l. (Cotopaxi – 5,897 m) every lung full of air only contains 50% of the oxygen of what is contained at sea level. As we are naturally adapted to a lowland environment where oxygen is generally abundant, people from the lowlands can easily suffer from mountain sickness (Hypoxia) when reaching altitudes above 2,500 m.a.s.l. as the lower air pressure makes it more difficult for the oxygen to enter our vascular systems.
For climbers and other lowlanders, a prior acclimatization is essential. Our programs are especially designed to educate and instruct people in high altitude mountaineering between 4,000 and 6,000m, making it possible to reach some of the highest summits in South America (Chimborazo – 6310 m.a.s.l.).
However, studies show that as an instance of evolutionary modification people permanently living in the South American Andes or in Tibet (Mount Everest- 8848m) have adapted to the high altitude. This “High-altitude adaptation” researches physiological and genetic changes which protect the inhabitants from hipoxia and allows to cope with chronic limitations of oxygen availability.
An analysis of 53 samples of Tibetan and Andean high-altitude natives (average altitude of 3,900 m) showed an estimated mean hemoglobin concentration of 16.9 g/dl among Tibetan men as compared with 18.1 g/dl among Andean men. In contrast to people living close to sea level, Andean Highlanders have an increased oxygen level in their hemoglobin, resulting in more oxygen per blood volume. The ability to carry more oxygen in each red blood cell makes the transport of oxygen in their body more effective, while their breathing is essentially at the same rate.
Studies also suggest that Tibetan highlanders have a significantly greater number of capillaries per cross-sectional area of muscle compared with lowlanders and their Andean counterparts. This effectively increases their capillary density-to-muscle fiber ratio and could serve to optimize convective and diffusive oxygen flow to the working muscles. Additionally, other studies tested the physical fitness compared to lowlanders which showed that Andean Highlanders are capable of calf muscle work rates equal to those of highly trained power and endurance athletes.
High-altitude natives are both shorter and lighter than those living at low altitude. In childhood, Tibetans compared with Andeans and other high-altitude populations are initially smaller and lighter. Although the physical growth in body size is delayed, it also appears that the Highland Quichuas have developmentally acquired enlarged lung volumes. However, due to an incomplete adaptation such as elevated hemoglobin levels they are still at risk for mountain sickness with an increasing age.
Lastly, the adaptation of the Tibetans also is associated with a high birth weight, increased breathing, and a higher resting metabolism. Matched for age, height, weight, and smoking history, Tibetans demonstrate significantly larger chest circumferences, total lung capacity, vital capacity, residual volumes, and tidal volumes than Han Chinese lowlanders.
Interested in researching this topic in depth? Why don’t you start with a lecture of the famous anthropologist Cynthia Beall.
