The Sherpa population in Tibet is world-renowned for their extraordinary high-altitude fitness, as most famously demonstrated by Tenzing Norgay's ability to conquer Mount Everest alongside Sir Edmund Hillary. The genetic adaptation behind this fitness has been a topic of hot debate in human evolution, with recent full genome sequencing efforts completed to look for candidate genes necessary for low oxygen adaptation. However, few have looked at the Sherpa population by sequencing their mitochondrial genomes -- the powerhouse of every cell that helps determine the degree of respiratory fitness by providing 90 percent of the human body's energy demand, as well as controlling the metabolic rate and use of oxygen.

Source: Examining the source behind Sherpa mountain fitness