Why don’t babies in Nepal and La Paz need oxygen? 

Research comparing ethnic groups that have lived at high altitude for centuries, such as native Tibetans, and more recent immigrants such as the Han Chinese in Tibet, showed changes in adaptation. People living in the Andes, Himalayas and mountains of Ethiopia have higher lung volumes, more nitric oxide in the blood, high oxygen-carrying hemoglobin levels and increased respiratory rates which are genetic.

Those of us living in the mountains of Colorado have been here at the most 150 years, not long enough to establish gene-based adaptation. We do acclimatize over weeks and months with changes in hemoglobin levels, respiratory rates and lung volumes but not to the extent of the above populations.

During my travels to La Paz Bolivia and Cuzco, Peru I noticed the people were smaller. At Ebert Family Clinic we analyzed over 10,000 pieces of growth data on children up to four years old from our electronic medical record. A high percent are below the standard growth chart: seven percent compared to three percent. Most catch up by age two years.