It's not just high altitude. It's genetics + altitude, but genetics may be an even stronger factor. Otherwise we'd have Tibetans, Peruvians, and Mexicans running right alongside the African runners in the Olympics. That's not to say that the former are slow, since the Tibetans, Peruvians, and Mexicans dominate all the regional competitions where there are no East African elite runners. Tibetans (like Duo Bujie) dominate the East Asian championships, and Peruvians (Luis Ostos and others) and Mexicans (Juan Luis Barrios, Arturo Barrios) the Latin American championships. Tibetans and Peruvians are born at even higher altitude than the Kalenjin are.
But how do you explain North African, Somali, Djiboutian, and Sudanese dominance in elite distance running? They're all born at or close to sea level. Genetically and linguistically, these guys are all related to the Ethiopian runners (mostly ethnic Oromo) who live at high altitude, and they are all descended from the same founding father within the past 10,000 years (haplogroup E1b1b).
Here are the ethnic groups in Africa that have produced world's top elite runners:
Afro-Asiatic peoples
- Oromo (high-altitude): Haile Gebreselassie, Bekele brothers, Dibaba sisters, and more
- Tigrinya (high-altitude): Meb and others
- Tigray (high-altitude): Dejen Gebremeskel and others
- Somali (low-altitude): Mo Farah, Mohammed Ahmed, Abdihakem Abdirahman, Hassan Mead, and more
- Berber (low-altitude): Moroccans, Algerians, and Tunisians
Nilo-Saharan peoples
- Kalenjin (high-altitude): Nilotes of western Kenya
- Buya (low-altitude, from South Sudan): Lopez Lomong and his brothers
- Fur (low-altitude, from Darfur): Ismail Ahmed Ismail, Mohamed Babiker Yagoub
How does one possibly explain Somali success in running? Somalia is right at sea level, and it's hot as a frying pan. It's got no running culture either. These guys then move to Western countries that are also at sea level, and then start dominating local races with hardly any experience. Genetics has to be playing a big part here. In the U.S., we simply don't get an equal share of refugees dominating local races. They're usually from Somalia, Eritrea, and even Sudan, but very rarely from Haiti, Vietnam, Afghanistan, Iraq, Myanmar, or whatever other refugee-producing non-East/North African country is out there.
Somalis are very closely related to the Oromos of Ethiopia. The Oromo of Bekoji and Asella in south-central Ethiopia live at high altitude, and that's where Haile Gebreselassie, Bekele brothers, Dibaba sisters, and so many more Ethiopian elite runners came from.
Similarly, many elite North African runners are from towns that are right on the coast.