Why Zebras Don’t Get Ulcers
Author: Robert Sapolsky

Overview

The subject of this remarkable book, teeming with critical neurochemicals and essential hormones, is the pervasive and destructive phenomenon of stress. In its enlightening review of the biological foundations of stress, the book discusses the regulation of every bodily metabolic function, and it exhaustively explores the complicated physiology and damaging pathology of stress. The book also paints a graphic picture of the catastrophic clinical consequences of stress, especially noting the extensive range of modern day stressors which it pointed out are ‘a far cry from the physical world of hunger, injury, blood loss, or temperature extremes’ which plagued our ancestors. And beyond its academic themes, the book’s content is enhanced by a fascinating history of the giants and godfathers of stress physiology‘ – scientists such as Hans Selye, Walter Cannon, and Bruce McEwan, and by a repository of enlightening anecdotes – from the social dominance of female hyenas to the breastfeeding methods of Kalahari bushmen (pages 7-9, 127-129 and 132-134).

 

Synopsis

At the centre of the book’s narrative is the acute stress response – the body’s attempt to restore balance after this has been disrupted by stressors. The book details the varied biological hallmarks of this response which include a ‘rapid mobilization of energy from storage sites and the inhibition of further storage‘, and a halt to ‘long-term, expensive building projects’ such as digestion, growth, reproduction, and immunity. With helpful diagrams and cartoons, the author also described how stress causes an acute elevation in the levels of epinephrine and norepinephrine, initial responders which act ‘within seconds‘, and a subsequent rise, ‘over the course of minutes or hours’, in the level of glucocorticoids – the secondary responders. Although these are the ‘workhouses of the stress-response’, the author nevertheless emphasised that they are supported by other hormones such as glucagon, prolactin, endorphins, anti-diuretic hormone, insulin, growth hormone, and testosterone, all acting to ‘shunt energy from fat and non-exercising muscles to the exercising ones’ (pages 10-11, 30-38, 50-55, 59, 73, 80-81, 109-112, 120-123, 132, 141 and 211-212).

The physical manifestations of the acute stress response are quite striking in their constellation of such symptoms as a sharpening of the senses, a heightening of memory, a dimunition of appetite, a reduction in urine formation, and a tendency to empty the bladder and bowel. Whilst this picture is often characterised as the fight or flight response, the author pointed out that in females, because of their need for ‘social affiliation‘, it is more likely to manifest as a ‘tend and befriend‘ response. The book also depicted the crucial consequences of the acute stress response, from the risk of miscarriage and preterm birth, to the danger of sudden cardiac death from ventricular arrhythmias – a factor which it said explains the ‘psychological death‘ that is associated with voodoo. The book also explores chronic stress in a narrative that demonstrated the perils of persisting stress which include peptic ulcer, diabetes, hypertension, atherosclerosis, dwarfism, and osteoporosis. The author further vividly illustrated the effects of chronic stress with such anecdotes as that of the institutionalised Romanian orphans who became chronically stressed from ‘massive sensory, intellectual, and emotional deprivation‘ (pages 12-13, 41-43, 66-68, 87, 95, 101, 106, 116, 131 and 213-222).

Perhaps the most enlightening themes of the book relate to the direct and indirect effects of stress on the nervous system. For example, the book pointed out that stress inhibits the autonomic nervous system and thereby suppresses the immune system‘s ability to produce lymphocytes and antibodies. Another intriguing association of stress and the nervous system the author discussed is the link between stress and depression, what he referred to as ‘the bread and butter of human misery‘. In this discourse, he argued that people with major depression ‘often experience elevated levels of glucocorticoids‘, and that ‘people who are prone to depression tend to experience stressors at a higher than expected rate’. Chronic stress also impairs the nervous system by compromising cognitive function, the author noting that stress makes ‘the formation and retrieval of memories go awry’ partly due to glucocorticoid neurotoxicity killing off brain cells. Other worrying associations of stress which the book covered included its links with accelerated aging and reduced longevity, but, surprisingly, not the risk of cancer (pages 144, 151, 174, 213-222, 247-251, 271, 276 and 291).

 

One of the most compelling of the book’s interesting anecdotes relates the rivalry that sullied the relationship between Roger Guillemin and Andrew Schally – the two researchers who pioneered the scientific endeavour to understand stress physiology. The author described how the two, who started off as collaborators in their efforts to isolate the brain hormones that regulate stress, fell into ‘notorious acrimony’ and became antagonists in a rivalry that he said was ‘enshrined in the annals of science’. Also portraying it as ‘the great slaughterhouse war‘, the author described how the contention between Guillemin and Schally played out in their attempts to isolate the ‘miniscule‘ amounts of the hormones that are found in the brains of animals, an endeavour that required them to acquire ‘truckloads of pig or sheep brains‘. He however said that, against the scepticism of the scientific community, the two invented ‘new types of chemistry’ and ‘novel ways of testing the effects on the living body of the hormones that might or might not actually exist‘. By isolating the relevant hypothalamic releasing hormones, the author said the two rivals proved that the brain was ‘the master gland‘ – a feat that earned both Nobel Prizes in 1976 (pages 27-29).

 

Alongside the academic themes and illustrative anecdotes, the book also offered practical recommendations on preventing and managing stress. For example, the author advocated the use of such activities as exercise and distracting habits as outlets for frustration, and he encouraged the use of support networks to avoid social isolation. Intriguingly, the author also suggested engaging in non-boring occupations, and holding on to a belief structure because this helps to rationalise negative life events. The book also advised people not to try to ‘control things that have already come to pass’, explaining that ‘those who cope with stress successfully tend to seek control in the face of present stressors. Other recommendations the book made were the use of meditation, and interventions such as psychotherapy (pages 255-257, 261-265, 391-395, 401-402 and 416).

Opinion

With a light-hearted style that belies the intricately academic topics the book reviews, the author of this book not only highlights one of the body’s most important regulatory systems, but he also gives helpful recommendations on maintaining it. The conversational writing style helped to lighten the otherwise academic tone of such themes as metabolic pathways and regulatory feedback mechanisms. The book is perhaps excessively detailed on the minutiae of biological processes, many chapters being sufficient lectures on biology and physiology. On the other hand, the author went to great lengths, at the risk of being verbose, to explain the complex themes with striking metaphors and anecdotes.

Overall assessment

By describing the basis of stress and its diverse manifestations, this book performs a vital public health service. Its elucidation of the triggers and manifestations of stress are as vivid and detailed as its portrayal of the preventative and therapeutic approaches to its management. More practically, the book serves as a do-it-yourself stress management guide that is relevant to all of healthcare. The book also brilliantly correlates basic science with clinical themes crossing most medical specialties, an approach that greatly enhanced its modern healthcare relevance, and I recommend it to all doctors.

Book details

Publisher, Place, Year:  St. Martin’s Press, New York, 1994
Number of chapters: 18
Number of pages: 539
ISBN: 978-0-8050-7369-0
Star rating: 4
Price: £10.99