Why Zebras Don’t Get Ulcers

ISBN: 0805073698
ISBN 13: 9780805073690
By: Robert M. Sapolsky

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About this book

Renowned primatologist Robert Sapolsky offers a completely revised and updated edition of his most popular work, with nearly 90,000 copies in print Now in a third edition, Robert M. Sapolsky's acclaimed and successful Why Zebras Don't Get Ulcers features new chapters on how stress affects sleep and addiction, as well as new insights into anxiety and personality disorder and the impact of spirituality on managing stress. As Sapolsky explains, most of us do not lie awake at night worrying about whether we have leprosy or malaria. Instead, the diseases we fear-and the ones that plague us now-are illnesses brought on by the slow accumulation of damage, such as heart disease and cancer. When we worry or experience stress, our body turns on the same physiological responses that an animal's does, but we do not resolve conflict in the same way-through fighting or fleeing. Over time, this activation of a stress response makes us literally sick. Combining cutting-edge research with a healthy dose of good humor and practical advice, Why Zebras Don't Get Ulcers explains how prolonged stress causes or intensifies a range of physical and mental afflictions, including depression, ulcers, colitis, heart disease, and more. It also provides essential guidance to controlling our stress responses. This new edition promises to be the most comprehensive and engaging one yet. Renowned primatologist Robert Sapolsky offers a completely revised and updated edition of his most popular work, with nearly 90,000 copies in print Now in a third edition, Robert M. Sapolsky's acclaimed and successful Why Zebras Don't Get Ulcers features new chapters on how stress affects sleep and addiction, as well as new insights into anxiety and personality disorder and the impact of spirituality on managing stress.

Reader's Thoughts


Robert Sapolsky is one of my favorite science writers. I generally find his work engaging, informative, and conversational, and “Why Zebras Don't Get Ulcers” is no exception. This book is dense! It is jam packed with information on how your body reacts to and copes with stress. By the end of it, I found my self wondering if there was anything that glucocorticoids couldn't screw up. Though parts of it did drag a bit (for me), on the whole I found the chapters in this book to be interesting and full of useful information. I was a bit disappointed with the last chapter, however. I was hoping for more concrete suggestions on how to deal with and lessen stress. But perhaps that was an impractical expectation on my part. I would recommend this book to anyone who worries about what effect their stressful life might be having on their mind and body. This book will clearly lay out those effects in detail, and knowing what's going on (why you aren't sleeping, why you are gaining weight, for example) is the first step to stopping it.

Chris Herdt

This book is a good introduction to stress and its effects on physiology and psychology (Nicola's area of expertise). Although it is written for a lay audience, I often got the feeling it was written for a lay audience of primarily MDs.By the end of the book, you will feel like you and epinephrine, norepinephrine, and glucocorticoids are all old friends--but in spite of the terminology, it is really an easy read and full of good humor and interesting anecdotes (e.g. hyenas are very peculiar).Here is a quote, taken out of context, that I enjoyed:"Every child cannot grow up to be president; it turned out that merely by holding hands and singing folk songs we couldn't end all war, and hunger does not disappear just by visualizing a world without it....Would that it were so. And shame on those who would sell this view."You may not like all of his opinions. Sapolsky is an unapologetic atheist, but appears to have a high opinion of many religious people. He also speaks frankly about sex. He also believes in animal testing, although he thinks that some past tests went too far.

Melissa Hefferlin

I discovered this scientist on a National Geographic film about stress, Silent Killer or something like that. The film I highly recommend. So I sought out the books on the topic. For me, the material is a few clicks higher on the scientifically-detailed chart that I enjoy for recreational reading, but it is an excellent book. I enjoyed it in small chunks. It is highly informative, and displays the author's passion for the research. The effects of stress are truly fascinating, and current knowledge on the subject is presented here with passion and detail.


This was my text for my Health Psychology class. The only complaint I have about this book is that sometimes it is hard to follow because there are no bolded words or explanations on the side, like ANY other book relating to science would have.But it is very funny, very interesting, very well-researched, and very thought-provoking. Sapolsky has a way of explaining complicated concepts in an approachable way. You will learn how to be aware of, be knowledgable about, and better attack the stress in your life!


Enlightening and full of humor. Complex pathways of stress mechanisms are untangled and presented in a simple yet captivating way.


Should be compulsory reading for every high school biology student. A thorough dismantling of the reductionist cell biology mindset of the 20th century, Sapolsky shows you how very complex and intricate the interaction is between organism and environment, and how 'genes' may be overrated in a lot of ways.

Steven Vandenburg

Why Zebras Don't Get Ulcers explores stress and the physiological, psychological, and societal causes and implications of stress. Sapolsky paints a bleak picture of the impact of stress on the unborn and the young. Sapolsky suggests several methods for minimizing stress including such as: having outlets for frustration, a strong social support system, some degree of predictability, a flexible locus of control, and your perception of your place in your perceived hierarchy. Other factors Sapolsky discusses include sleep and socioeconomic status.One major takeaway I had from this book is the benefit of varied experiences and meeting various types of people to improve tolerance/understanding/empathy. Humans are hard wired (amygdala reacts to the flash of different persons face) to get aggressive/defensive with people whom are different. These reactions are a relic of the past when different looking people were likely to be part of a different group/tribe and thus a higher likelihood of violence or death during your interaction. We need to work to accelerate the reduction of this reaction by promoting travel, education, and experiences with a wide set of people.


some people might not be a fan of all the science of hormones and neurotransmitters, etc. etc.. so if you don't like having to check out the whys and whats of what the body does, this might be a bit irritating to read since there's a lot to slog through in that sense. having said that, i definitely found it to be quite interesting and a fun read. there's a good mix of humor through out the book. overall, i enjoyed it and i feel like i learned a fair bit. it didn't go into as much detail about some things (like depression and dealing with it, how stress reactions predict personalities, etc.) as i would have liked or even as much as i expected. granted, he could probably go on forever about the details of those subjects, so i digress. a fair amount of it could be seen as 'common sense', and i kinda feel like his coping methods are pretty logical and nothing that's revelatory or impressive in the sense of "hey, i should totally try that", but nonetheless, i enjoyed reading it and i do feel more knowledgeable for having done so.


Excellent book about the body's stress response written in a fun and engaging style. This book is so well written that even someone with absolutely no background in medicine or biology could understand this neat little find. I've even used quotes out of this book for my clients--it's really that bite sized and engaging. Must read. Probably the best academic book disguised as popular non-fiction I've ever read.

Michael Connolly

Sapolsky is a physiologist and primatologist. He discusses the role of stress in many of the body's systems, including the cardiovascular system, gastrointestinal, growth, sex, immune, pain, mrmory, sleep, aging and mental health. The effects of stress are mediated by both the autonomic nervous system and hormones. The autonomic nervous system has three parts: the sympathetic, parasympathetic and enteric. The sympathetic nervous system releases epinephrine and norepinephrine into the blood. The parasympathetic nervous system stimulates the production of insulin. Stress promotes insulin resistance, which can lead to Type II diabetis. The enteric nervous system is in the intestine and regulates digestion. Sapolsky concentrates mainly on the hormones. The major stress hormones are: epinephrine, norepinephrine, glucocorticoid and glucagon. The fast acting hormones are epinephrine (adrenaline) and norepinephrine. But Sapolsky concentrates mainly on the long acting hormones, which are called glucocorticoids. The gluco comes from the fact that they help control glucose metabolism. The cortico is from where the body synthesizes them: the cortex of the adrenal glands, which sit on the kidneys. The oid is from steroid. Stress causes the production of glucocorticoids. Glucocorticoids include cortisone and hydrocortisone, the latter also known as cortisol. Artificial glucocorticoids include prednisone and prednisolone, which are used medically to suppress immune response in autoimmune diseases, such as MS, rheumatoid arthritis and lupus. Cushing's Syndrome can be caused by being given too much cortisone, or naturally, by a tumor on the pituitary gland, in which case it is called Cushing's Disease. Addison's Disease is a rare disorder where the adrenal glands do not produce enough glucocorticoids. Sapolsky has a chapter on the relationship between stress and cardiovascular disease. LDL deposits cholesterol onto the arterial plaques. HDL removes cholesterol from plaques and deposits it in the liver. People with chronic fatigue syndrome have low levels of glucocorticoid in the blood stream. The vagus nerve slows down the heartbeat. Damaged heart muscle is more vulnerable to fibrillation. Ventricular fibrillation often causes a heart attack and death. The term Type A was introduced by Meyer Friedman and Ray Rosenman in the 1960s to describe a personality type that was more likely to have heart disease. Their ideas have been refined over the years. Current opinion is tat unexpressed hostility is a risk factor for heart disease in young and middle aged people.There are two kinds of gastrointestinal disorder: organic and functional. Peptic ulcer is organic. IBS is functional. Functional disorders are sensitive to stress. IBS is caused by overly sensitive intestines. People with IBS have gassy and distended bowels. Childhood trauma is a cause of IBS.Australian pathologist Robert Warren discovered the Helicobacter pylori bacteria. Barry Marshall found the link with ulcers. The combination of stress and H. Pylori causes ulcers.Sapolsky talks about stress dwarfism. Growth hormone stimulates bone growth, cell division and the release of energy stored in fat cells. People who have stressful childhoods tend to be shorter than average. The absence of physical affection from mothers is a cause of stress dwarfism. Sapolsky also talks about the importance of making sure that preemies get plenty of physical stimulation. Stress reduces the immune response, which is why we are more likely to get colds when we are stressed. Also, latent viruses can detect the level of glucocorticoid hormones. This has been found in the herpes, Epstein-Barr and varicella-zoster (chicken pox and shingles). The Freudian school saw depression as aggression turned inwards. Aaron Beck believes depression is more a thought disorder than an emotion disorder. Depressed people see the world in a pessimistic way. Martin Seligman introduced the concept of learned helplessness. Martin Seligman saw the depressed person not as generally pessimistic, but pessimistic regarding the effectiveness of his own actions. Three of the symptoms of depression can be correlated with neurotransmitters. Anhedonia (dysphoria) correlates with dopamine. Psychomotor retardation (sluggishness) involves norepinephrin. Suicidal ideation correlates with serotonin. The causes of depression include the stresses of life, a genetic predisposition, and low thyroid hormone. Unipolar depression is much more common in women than men. Currently, there is research to understand the relationship between female sex hormones and postpartum depression. Amygdala handles fear. Anxiety disorders inclued OCD, PTSD and phobias. People suffering from anxiety disorders have exagerated startle responses. They fear menace. The amygdala controls the emotional reaction to pain. When patients are given control over their morphine drip, it reduces the level of stress, even if the amount of medication is the same as the nurse-dispensed morphine. This is because the element of unpredicability is removed. When a patient presses the call button, the patient does not know how long it will take the nurse to show up, or whether the nurse will be willing to give the patient more morphine.


Let's start with the title. Why don't zebras get ulcers? The answer is that zebras don't sweat the small stuff. When a lion comes to attack a zebra, its body stresses out to the max...salivary glands stop working (you don't need them), food processing and waste control shuts down (again, not required) and all bodily functions are maxed out to assist in one thing: Run like the wind. We humans possess the same capacity. Should you ever find yourself hunted by a lion, your body will probably react like a zebra's right up until your body is lion-feed. But here's the rub: We humans spend a lot of time being worried about less pressing things than outrunning lions (bills to pay, need to clean the house, have to get the kids to school on time, guests coming to dinner), but our bodies react in the only way they know how. And that reaction is a lower level form of the zebra's fight/flight physical response. That's not good. The fight/flight physiological experience is meant to last a few minutes, and come every once in a while, not run ad infinitum. So...zebras don't get ulcers because ulcers are born of the body's reaction to never-ending low level stress that zebras don't experience. Sapolsky examines more than ulcers and it's a fun read. His final chapter on how to help our bodies deal with the modern world contains most of the things you would guess (exercise is critical as is being a part of a community) but that doesn't diminish the chapters leading up to it. If you like this book, Sapolsky also has a class for free in the iTunes University store. I ran a string of two books in a row here on how human bodies are not well-adapted to modern times. Of the two, I would give this book the nod over Lieberman's The Story of the Human Body.


I encountered a link to a speech by Sapolsky on Pharyngula, I think, and was immediately engaged by his speaking style. His books, or this one at least, is similarly easy to get into, and manages to discuss topics of fair complexity in an incredibly approachable way. He's clearly aware that his book might be read by a wide range of audiences, and strives to provide something for everyone. I'll definitely be working my way through the rest of his catalog.The book is fascinating, too, although as he notes many times, thinking about and addressing stress is difficult, because trying to act to reduce stress can itself be stressful. As he elucidates what's currently known about the links between stress and disease, a lot of interesting things emerge, some of which are essentially throwaway trivia, like the idea that anti-depressant medication takes a while to work on people that are clinically depressed because of the physiological nature of depression; he doesn't really spell it out, but the obvious corollary is that is someone takes AD medication and instantly feels better, they're probably not actually depressed. This insight was immensely powerful to me in this over-prescribed age of ours.


This is hands down the best medical book I have ever read. In a series of memorable and highly amusing stories and anecdotes Sapolsky explains the complex biology behind why well known principles of psychology, religion, new age philosophy and even voodoo curses work. The central story of the book is how the fight or flight response – the most powerful force that has shaped vertebrate evolution for hundreds of millions of years - is now being turned against modern humans through chronic stress and anxiety. He outlines how modern stress triggers that have nothing to do with immediate survival - whether brought on from traffic, bad bosses, bad relationships - can be linked to exacerbating the development of almost every modern epidemic from cancer to colitis, depression to dwarfism, diabetes to diarrhea, heart disease to infertility to immune disorders. The book concludes with some stories about coping with stress, and the unique psychological profiles of the people who avoid the development of stress-related diseases and experience health improvements with aging in a process he calls “successful aging.”

Bob Klein

Sapolsky is an amazing writer and Primate's Memoir ranks as one of my favorite books. That said, the title, cover, and prior experience with Primate's Memoir led me to have unrealistic expectations of this book. It is thorough and well-written, but approaches the topic of stress from a phsyiological perspective that doesn't spare any of the details. As such, it often calmed my stress by putting me to sleep. The subtitle's promise of a section on "coping" with stress didn't pan out, and amounted to a few pages of an attempt at the end of the book. If you're looking for a tutorial on the physiology of stress and its relationship to a wide variety of human ailments and conditions (sickness, age, gender, etc.) then you might like this more than I did.


Sapolsky's primer on neuroendocrinology benefits greatly from a new edition in that the metaphors are more topical and a great deal of old theory has been validated by modern research, showing that psychological stress does indeed ultimately have a physiological component (organ stress due to wildly fluctuating hormone levels). The upshot is that we all need to find our own unique ways of coping with stress based on our personality types and numerous other factors in order to live long and healthy lives (the only seeming universal being that exercise not in excess seems to benefit everyone). Prior to the concluding chapters on these personal habits, Saplosky also notes the inequality in wealth as a tremendous factor in disease related to stress, asserting that humans have created their own stresses through religion and agriculture (a view I've also held all along), and ultimately advocating for social justice based on eradicating these inequalities.

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