Life for mountain people, as a rule, has always been a challenge. For this reason, it might appear that if given a choice, humans would perhaps tap the wealth of the mountains — such as their minerals, forests, their possibilities for tourism, etc. — but not live there permanently.
However, human association with the mountains is almost as old as their relationship with the sea. The terms of life are usually much harder for humans at high altitudes and are controlled by three important factors: the terrain, the climate (including the thin atmosphere), and the isolation from the rest of mankind.
Yet despite all of this, higher elevations in the tropics may be the best habitat for humans in these areas. They are free from malaria, sleeping sickness (African trypanosomiasis), and other diseases of the hot lowlands.
In many highland areas near the equator there is no such thing as changes of seasons, as most of us are used to. In these areas the climate is springtime all year, and fields yield several crops annually. In fact, it is this type of environment in the Bolivian and Peruvian Andes that led to the only great civilization to be found at high altitudes — the Incas.
In the last 4,000 years millions of people have lived in the high valleys of the central Andes, and many of them established some of the highest permanent habitations on Earth. However, most of these are below 13,000 feet (3,962 m.), as even near the equator it just gets too cold and the air too thin above this altitude to be very suitable for most people as a permanent habitation.
Most humans live near the bottom of a 62-mile deep ocean of air that we call the atmosphere (99.999 % of the atmosphere’s gases are found below 62 miles; the small amount of gases above this are detectable out to about 300 miles).
Because of all this weight of air above the Earth, the pressure of it pushing against our bodies at sea level is about 14.7 pounds per square inch (PSI).
This pressure is critical for getting oxygen into the blood stream, as it forces the oxygen through the thin membranes in the lung capillaries of the alveoli (air sacs) and into the blood by a process known as “passive diffusion.”
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