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than they are different. Yet these two lineages have not shared a common ancestor for over a third of human historyl At first I thought this meant that the same solution to the problem of high altitude air arose independently in both lineages. I n biology, two such adaptations aris ing in parallel are thought of as convergent and the trend of separate lineages is to diverge. However, a German colleague, Dr Hans Christian Gunga pointed out that the complexi ties of the systems involved were much too great to have evolved independently twice in one species. He suspected that the similarities in the two groups must have arisen from another source . To explain how this could be, he pointed to East Africa, a region known for its endurance athletes. Have you ever wondered why the fastest long-distance runners are from this part of the world? Here is the connection. Mbutl Pygmy ""', .... , ... , ........ , ... , ........... L,r-----.... C Nllotlc � AFRICAN =,111 .1111111 ,1 .... ' .. -'11'1"1 W. African W. African Bantu E. African San (Bushmen) Ethiopian Berber, N. African S.W. Asian Iranian European European Sardinian Indian Indian S.E. lndlan Lapp NORTH EURASIAN Samoyed Sherpa Mongol Tibetan 1.--- Ainu N. Turklc F;';;;'---1 SOUTHEAST ASIAN OCEANIAN 100,000 PACIFIC ISLAND ..---I � Thai � "L_r麠-- Eskimo Chukchi S. Amerlnd Quechua C. Amerlnd Aymara N. Amerlnd N.W. American S. Chinese Chinese Mon Khmer Indonesian Malaysian Philippine Polynesian Micronesian Melanesian r-------- New Guinean Australian Tibetan Korean Japanese Japanese The origin of our species occurred under con ditions in East Africa that were getting colder, drier and higher. Anthropology had recognized the first two conditions (and proved that stren uous activities such as food gathering would favor endurance and lead to incredible endurance in athletes). But they had pretty well overlooked the third factor-low oxygen in the inspired air. My German colleague cornered me at a high altitude conference in Cusco, Peru, and here, on learning that some East African groups are similar to Sherpas and Quechuas in their efficient use of oxygen, we had our final flash of insight: during some million years of evol ution, this physiology was retained in high altitude populations in a low capacity form (using oxygen carefully and efficiently at all levels of performance). If was also retained in lowland populations as a high capacity form for endurance performance (using oxgyen more and more efficiently the closer an athlete comes to peak performance levels). The reason Andeans and Himalayans share so much of their low-oxygen tolerance is because they inherited it-and the inheritance trail goes all the way back to the beginning of our species. This is only one wonderful exam ple within our own species of how a complex physiology evolves. We generally do not know how different systems evolve in our species or, for that matter, in any species. This is an area of research that is only now experiencing growth and expansion. The take-home message: indigenous highlanders operate better at extremely high altitudes than do lowlanders. They can do so in part at least because their hearts and brains use oxygen more efficiently than lowlanders do at all levels of performance. Endurance ath letes rely on the same mechanism, but can only use it at close-to-peak-performance levels. 50,000 Years before present o