Zebras and Stress

In Why Don’t Zebras Get Ulcers, Stanford Biologist Robert Sapolsky examines how human patterns of disease have evolved over time through the lens of stress. Earlier generations preoccupied themselves with infectious diseases such as malaria and bubonic plague, as well as diseases stemming from poor nutrition and hygiene. In contrast, we are now plagued by diseases that are “ones of slow accumulation of damage - heart disease, cancer, cerebrovascular disorders”. Modern medicine has come to recognize that extreme emotional disturbances can adversely affect both physical and mental health, and many of these slow accumulation diseases have been linked to stress. What this book does well is to serve primer on stress, its biological components and how our body reacts to and deals with stress.

The biggest thing I took away from Sapolsky’s book is really just how complicated of a system the human body is. Indeed, many of the stress-related diseases that Sapolsky dissects come not directly as a result of external stressors to the human body, but rather are caused by the body recovering from the counter-measures it put into place to deal with stress. For decades, scientists and doctors believed the ulcers were directly caused by the bacterium helicobacter pylori, but more recent research reveals that stress is one of the key factors in the formation of ulcers. One theory, called acid-rebound, posits that your stomach cuts back on acid secretion during long stressful periods - because digestion is being inhibited. Because less acid is being secreted overall, your stomach decides to save energy by cutting back on the systems that are in place to keep the stomach from digesting itself. But once the stressful period is over, your stomach gets flooded with acid and does not have as strong as defenses to protect itself. After several cycles of this rebounding, ulcers form in the stomach.

It seems as though in order for the human body to adequately deal with stress, the brain needs to carefully regulate how it is releasing hormones and glucocorticoids. It needs to keep everything in a delicate balance, this is the essence of the idea of allostasis that Sapolsky refers to throughout the book. I believe that this book functions very well as a primer on stress and stress-related diseases. It breaks down the biological, physiological, and psychological components of stress in a easy-to-understand yet well thought-out manner. The constant reference back to scenario of a zebra running away from a lion on the Savannah works well as a metaphor, as it demonstrates that, while the body’s stress-responses work incredibly well out in the wild, they have much less desirable effects if they continue to act over long periods of time.

-Jon Wei