Our body adaptdivity

I was also able to make interesting observations among Indians living in the Andes. The mountain Indians on the Altiplano were born at an altitude of 4,000 to 5,000 meters. They are tough, hardy and able to carry heavy loads while walking with quick short steps over the green plateau. Many work in copper mines where even today the ore is quarried as high up as 5,000 meters. Only Indians who were born there and have known nothing else all their life are capable of working at this elevation. They have chests that are much more expanded than those of people living in lower regions and at the same time they have good lungs. These people are bound to this way of life and work and are satisfied with little. They weave their own woolen clothes, using a poncho for protection against winter weather. They wear only sandals the year round, unless perhaps going barefoot in the warmer season. These mountain Indians cannot simply move and resettle in the lowlands without running the risk of contracting tuberculosis or dying from a decline in strength. In spite of these bad prospects, resettling does occur from time to time. In the mountains they were never exposed to TB bacilli and they therefore have no resistance in the lowlands with its different living conditions and unaccustomed atmospheric pressures. And adults are sometimes unable to adjust to the new demands. For the most part these otherwise tough and strong people decline noticeably when living in the lowlands, in fact, in a relatively short time.