Humans have spread across the planet, settling in deserts and marshes and deep forests. They’ve adapted to their new homes, not just culturally but genetically, as natural selection has favored certain genes over others. But nowhere has this adaptation been more intense than at high altitudes–in places like Tibet, the Andes, and the Ethiopian highlands. For my Matter column in the New York Times this week, I look at the latest research on mountain life, and at the lessons it can teach us about evolution in general.

Originally published May 30, 2013. Copyright 2013 Carl Zimmer.