To better understand the mechanisms and dispositions of humans when reacting to altitude it is worthwhile to consider some general principles of human acclimatization and adaptation.
Adaptation refers mainly to changes that occur over generations under constant exposure to a stress.
When individuals habitually live at sea-level, their energy and muscular systems function optimally to accommodate the existing atmospheric conditions. Climate moderates that functioning. The flexibility of responses of the human body to various combinations of altitude and climates has made it possible for humans to populate many parts of the earth. Generally, the body acclimatizes in a variety of ways depending upon the environmental stresses to which it is exposed. Reactions to excessive stresses are modified by the individual attributes of each person.