Contents

07 October 2016
Vol 354, Issue 6308

About The Cover

Cover image expansion

COVER A Sherpa porter at the base of the Khumbu Ice Fall, Mount Everest. Some human populations exhibit greater tolerance for high elevation, due to genetic variants that likely mitigate the deleterious effects of low oxygen concentrations at altitude. Genetic and epigenetic changes shape our response to the environment and may play a role in disease. For more on the interactions between genes and the environment, see page 52
Photo: Max Lowe/National Geographic Creative