ABSTRACT
Many people live permanently at high altitudes which have a significant effect on their physiology (see Chapter 3 for numbers and world distribution). Studies of such populations are hampered by the problem of appropriate comparison groups. Often a group of high altitude residents is compared with a group of lowlanders from a different ethnic, socioeconomic and genetic background so that it is difficult to know to what factors any differences may be attributed. Also it is becoming clear that not all high altitude residents are the same. Recent studies have found interesting differences between South American and central Asian high altitude residents.
