Civil servants must face a naked truth: low ranking creates ill feeling

The very essence of human life and death is laid bare by this book, which explores how individuals' levels of participation and autonomy within society affect their health, well-being and lifespan. The author skilfully leads us through medical and statistical evidence for social inequalities in health, along with associated psychological, sociological and anthropological perspectives.

Excursions into economics and politics make this book fundamentally important as well as fascinating. Social integration within populations can be affected by politics, policy and the actions of individuals, and the book not only lays out evidence for social gradients in human self-realisation (and associated good health) but makes recommendations for building fairer societies in the future. It takes a scientist of Michael Marmot's standing to weave the story with such skill and understated confidence; the multifaceted and multicultural approach of this book, and what it means for us all, makes it a truly sensational read.

Strands of irony running through it, as the author points out, include the fact that he received a definite increase in status upon receiving a knighthood for "doing research that highlighted the lot of those with low status". In addition, much of the research on social forces in health was carried out on subjects in the British Civil Service - the organisation at the heart of the policymaking linked to the results.

These "Whitehall studies" provided researchers with an ideal study population - co-operative yet neatly socially stratified - although perhaps if politicians had foreseen the outcome, they would have been more cautious about allowing the research to take place. Indeed, the Thatcher Government buried the findings in the supposedly forward-looking Health of the Nation document, published in 1992, because their significance was so startling.

The results had shown that governments were ethically and morally bound not only to try to change the health behaviour of the nation but also to change policy that sustained wide social stratification and its associated health inequalities. Marmot takes delight in having participated in the more socially responsible Independent Inquiry into Inequalities in Health, chaired by Donald Acheson, which published its recommendations in 1998.

Heart disease, stroke, lung cancer, chronic lung disease, accidents and violence, including suicide, are all stratified according to place within the social hierarchy. While smoking, lack of exercise and poor diet are socially stratified and contribute to inequalities in lifespan, they are not the only causative factors; the evidence shows that the relationship between social status and health is independent of health-related behaviours. The truly remarkable thing is that society is not split into financial and health "haves" and "have-nots". No matter where we fall within the social gradient, those above us do better and those below do worse. In other words, there is a linear association between status and health. Also noteworthy is that absolute wealth is not relevant to health (above the basic level when life essentials, such as clean water, are taken care of); it is relative wealth that matters - where one stands in the social hierarchy in which one lives. As societies become wealthier, these factors play an increasingly prominent role in the health outcomes of their populations. Those that redistribute wealth and target social support where it is most needed can enhance the social integration of the most disadvantaged members of its community (Japan is used as an example here) and, as a result, reduce the gradient of health inequalities.

Using illuminating case studies, the author shows how being low down on the social ladder leads to reduced control over life events. Unpredictable, negative events can have a huge impact on the socially disadvantaged, and there is little they can do to help themselves. They are trapped in a world with little autonomy and reward in terms of money, esteem or career opportunities. Low income can threaten status, hinder social integration and reduce outlets for frustration, other than destructive health behaviours such as smoking and possibly violence, both of which accentuate social inequalities in health and survival. Marmot's work blows away the myth that poor sections of society are living happily within their close-knit local communities. In truth, the quality and size of social support (known to be an effective buffer from stress) becomes better with increased status.

The stress of living in a society in which one perceives oneself to be worse off than others sparks biological stress responses that smoulder and affect health. For example, the stress hormone cortisol can increase risk of heart disease and affect the balance of the immune system, making people more prone to infection. Stress response systems are not unique to humans; indeed, they were adaptive during evolution, providing animals with the resources for "fight or flight". However, even within colonies of rhesus macaque monkeys, those of lower status develop more heart disease than those of higher status, and this is associated with activation of stress pathways. Similarly, it was shown that levels of cortisol are associated with social standing in baboons; results that were in line with the Whitehall II study data. Indeed, the frequency of the so-called metabolic syndrome (an undesirable cocktail of lower high-density lipoprotein cholesterol, higher triglyceride and higher fasting levels of glucose and insulin) increased as the working hierarchy descended, undoubtedly making a substantial contribution to the associated health outcomes.

Marmot's original Whitehall studies were carried out on men and their status at work. His later studies showed that women display the same pattern of social inequalities in health. However, women handle life stress - the balance between demands and control - differently. The characteristic female behavioural response is more along the lines of "tend and befriend" than "fight or flight". Although their biological stress pathways are the same, female coping strategies of tending to the young and co-operating in groups to provide strength in numbers can be efficient buffers to social stress within modern society. Perhaps that is why the notion that males benefit from marriage (health-wise) more then females has become popular.

Marmot explores this literature with tenacity; the complex set of interconnecting and dependant variables, not to mention direction of causalities, makes the whole thing a statistician's nightmare. But the conclusion is that health outcomes are worse for those living alone and that marriage is protective for both sexes.

Throughout this generous book, Marmot's humanity shines through. His conviction that there will always be inequalities in society but that the magnitude of their effects on health is within our control must be taken seriously. His contribution to research has been huge and already recognised by his peers and country. This book is an opportunity for the rest of us to catch up with what will surely be the big issue for generations to come: determinants of human flourishing. It is no longer good enough for us to accept social gradients in health when we know that something can and should be done about it.

Angela Clow is professor of psychophysiology, Westminster University.