Perspectives on functional adaptation of the high altitude native.

The major physiological processes that enable humans to attain a complete acclimatization to high altitude are briefly reviewed. The available data indicate that: (a) complete acclimatization to high altitude is associated with changes of environmentally modifiable functional traits such as lung volume but not associated with the expression of genetically controlled features such as chest size; (b) as judged by measurements of maximal aerobic power, the high altitude native has attained at high altitude an adaptation that is comparable to that attained by the low altitude native at sea level; the available information suggests that such adaptation is acquired through growth and development in an hypoxic environment; at present, however, we do not know the developmental modifications that occur within each component of the oxygen transport system, such as ventilation, pulmonary diffusion, and oxygen transport, that enable a sea level native to attain a complete functional adaptation to high altitude; and (c) at comparable altitudes among high altitude natives, there are some inter-regional differences in hemopoietic response, so that the samples derived from mining regions of the Andes are characterized by higher hemoglobin concentration than those derived from non-mining areas or the Himalayas. The source of these differences remains to be investigated.