The evidence is incontrovertible: inequality damages human health. The poor suffer more from illness and disease; their height is reduced; and they die earlier. The traumas they suffer are even passed on to future generations. The time may come when policies promoting inequality, as under austerity, are prosecutable as crimes.

      Societies have always tended to regard the poverty around and within them as if it were an unsightly growth that it ought to be possible to remove somehow, leaving the rest of society pristine and unaltered. But it now seems that the real specter at the feast is not poverty per se, but the inequality of the society as a whole.

      Inequality is injurious in itself. It impedes and distorts technological progress. It also impairs people, makes them ill, causes them to die sooner – in very specific and increasingly predictable ways. The new evidence on this derives from breakthroughs in computing and statistical science that were achieved in the Second World War and its egalitarian aftermath. Computers made it possible to analyze health data for whole populations, and to discern patterns that had lain invisible before. In this way, the computer, and the skills that grew up with it, have served a similar revolutionary function to that of the microscope a hundred years earlier.

      In the mid-1970s Richard Wilkinson, then a postgraduate researcher in community health, applied the new statistical and computer techniques to Britain’s public health data and found that, while health overall had improved, unexpected, large, and growing differences in illnesses and life expectancy had appeared between the wealthiest and poorest fifths of the British population. The gap was two or three times as large in the 1970s as it had been in the 1930s.

      When all other factors, such as local and cultural variations in diet and climate, had been eliminated, inequality stood out as the sole, constant predictor of increased child mortality, cardiovascular disease, stroke, various cancers… a list that would subsequently grow to include diabetes, obesity, mental illness, and a constellation of societal disorders, including youth suicide, alcoholism, drug use and violent crime. It wasn’t just that illness was retreating more slowly among the poorest; new major illnesses, like diabetes, were emerging and claiming lives across the board, but especially among the poorest.

      In December 1976, Wilkinson summarized his findings in an open letter to the British Labour government’s health minister published in the magazine New Society. The health minister promptly commissioned a fuller study by an expert panel headed by the government’s chief scientist, Douglas Black. Three years later, the Black Committee’s report confirmed the trends Wilkinson had identified, and concluded that they were not just related to inequality – they were caused by inequality. The implications of this finding triggered other studies, and initiated a ferment of research and further revelations.

      This turn of events might easily not have happened. The Black Committee delivered its report just weeks after Britain had elected one of the most aggressively anti-egalitarian governments ever chosen by a democracy – that of Margaret Thatcher – which tried to bury the report, failed, but turned Britain anyway into a nation-sized inequality lab.

      Wilkinson retained his focus on the original anomaly: the failure of increased wealth to produce commensurate health benefits. His own work has continued to concentrate on rich countries.¹ By the 1990s, he was able to show that the trends he’d identified in the 1970s held true not only within other countries but also between them, and moreover that the trends waxed and waned in step with changes in economic policies – with a clear correlation between global pandemics, for example of depression and obesity, and the growth of economic inequality.

      The findings imply that the health impacts of inequality can no longer be dismissed as just misfortunes. They arise not by accident but because of specific decisions and actions taken by specific individuals, who cannot escape responsibility for what happens.

INEQUALITY REDUCES LIFE EXPECTANCY

      People of all social classes in highly unequal societies do not live as long as people in more egalitarian ones. In Britain (one of the world’s most unequal rich countries), in the years immediately before the latest global economic crisis, being among the poorest 20 per cent shortened women’s lives by 7 years and men’s lives by 7.3 years.² In the world’s most unequal large economy, the US, the penalty for being in that lower fifth was about 14 years.³

      The financial crash wiped trillions off the world’s economy, but it was those who were already suffering most who bore the brunt. Income and wealth inequality continued their upward trends and so did the death toll. By 2015 the British press was reporting official figures showing that ‘People born in parts of the UK have lower life expectancy than those in war-torn Lebanon’.⁴ Not only were people in the poorer areas dying younger; a much bigger chunk of those shortened lives was taken over by illness and disability. Also in 2015, researchers from the King’s Fund reported a 17-year difference in ‘healthy life expectancy’ between the poorest and wealthiest health-service districts and ‘if you happen to be female and live within the borders of NHS Guildford and Waverley in Surrey you will – on average – have 20 more years of healthy life than if you happen to be male and live within the borders of NHS Bradford’.⁵

      Other harms that go with inequality – including depression, suicide and substance abuse – all follow the same pattern. So do the factors that might drive someone into despair: incidents of inter-personal violence, such as rape, are more common; so is vandalism. You are more likely to be imprisoned in a less equal society than in a more equal one: rates of incarceration reflect a society’s position in the ‘inequality league table’. Thus, the US prison population quadrupled between 1978 and 2005 – the main period during which inequality soared. At approximately the same time, Britain’s prison population doubled, whereas it rose only modestly if at all elsewhere – and actually fell in Finland during the 1990s. Wherever the increases occurred, it was overwhelmingly the poorest and blackest who were imprisoned, which fits with another finding: that racist attacks are more common in more unequal societies.⁶

      Those who defend inequality sometimes say it’s needed because it rewards ambition; social mobility and equality of opportunity are what matter most, they say. Yet social mobility is lower in more unequal societies than in less unequal ones. Even the politically conservative journal The Economist has repeatedly focused on this phenomenon over the years⁷ – and it is especially true in the ‘land of opportunity’ itself, the US.

      Extending back in time, the statistics reveal that the trend toward greater inequality, and the harms that flow from it, began in earnest in the 1970s – in other words, Wilkinson ‘hadn’t seen nothing yet’ when he wrote his article, and nor had Douglas Black’s committee. This reversed a trend towards greater equality that had started just after the Great Depression (which started in the US in 1929, with the Wall Street crash, but slightly earlier in the UK, with reversion to the gold standard). In Britain, inequality had fallen most rapidly during the Second World War – and public health improved faster than at any other time in the country’s history.⁸ The gains were generally attributed to egalitarian measures, such as rationing, which ensured that many people had enough to eat for the first time, and everybody had a reasonably balanced diet, even if it was an extremely meager one by today’s standards. There was a general turn away from ostentation. Large cars were taxed more