Erythroid adaptation to altitude.

In May 1978, Messner and Habeler were the first to reach the summit of Mt. Everest without the use of supplemental oxygen. This feat illuminated the remarkable capacity of blood to adjust to the environment and support transport of oxygen from the lungs to the tissues despite an ambient oxygen pressure lower than that of normal mixed venous blood. It also met the exacting requirements for a true ascent of Mt. Everest set in 1935 by Frank Smythe in his book "The Spirit of the Hills". Although the conquest may seem more related to the breaking of the four minute mile than to any spirit of the hills, mountaineering has always combined emotional fulfillment with keen competition and scientific curiosity. The early mountain climbers from Petrach to Whymper were reaching for a personal spiritual experience but also were strongly influenced by priorities and first ascents. After the scaling in 1865 of Matterhorn, the last conquered peak in the Alps, a period followed during which physiologists from Bert to Hurtado provided insight into the importance of blood and lungs for oxygen transport and survival at high altitudes. The results of these studies combined with technical skill and competitive grit have permitted the current breed of mountaineers to scale successfully the most vertical mountain faces and the most lofty Himalayan peaks. These field trials of physiologic principles have also been of immense importance for our understanding of the pathophysiology of anemias and polycythemias. For whatever successes we have had in our management of patients with such disorders, we must in no small part give credit to man's eternal fascination with the top of the hills.