The problem with humans is that our bodies’ stress response evolved to help us get out of short-term physical emergencies—if a lion is chasing you, you run. But such reactions compromise long-term physical health. When confronted with purely psychological stressors, modern humans turn on the same stress response, and if you turn it on too long, you get sick. Nevertheless, Sapolsky believes there are small steps we can take in our everyday lives to prevent some of these problems.

Robert Sapolsky is Professor of Biological Sciences, and Professor of Neurology and Neurological Sciences at Stanford University. He has written A Primate's Memoir, which won the 2001 Bay Area Book Reviewers' Award in nonfiction, The  Trouble with Testosterone, Why Zebras Don't Get Ulcers, and Monkeyluv and Other Essays on our Lives as Animals. He was a MacArthur Fellow in 1987 and in 2008 won Rockefeller University's Lewis Thomas Prize for Writing about Science.