The United States has, over more than four decades now, chosen to let wealth concentrate intensely in the pockets of a few. The United States has become significantly more unequal, a much more economically stratified society. Europe has not followed suit. Until relatively recently, Europe has been able to maintain most of the landmark egalitarian gains of the mid-20th century.

The United States, by contrast, has let those gains lapse. So why should the resulting inequality translate into poorer health outcomes? Epidemiologists — the scientists who study the health of populations — have been discussing and debating that question for the past quarter-century, ever since the mid-1990s when the prestigious British Medical Journal informed readers that “studies have related income inequality to infant mortality, life expectancy, height, and morbidity, with a consistent finding that the less equitable the income distribution in a country, the less favorable the health outcome.” The studies, the journal added, “seem to show that inequality per se is bad for national health, whatever the absolute material standards of living within a country.”

In one recent review of the literature, the British Equality Trust points to “status anxiety” as the “most plausible explanation for income inequality’s apparent effect on health and social problems.”

“In more unequal societies, the data indicate, status anxiety increases not just among the poor, but across all income deciles,” note Richard Wilkinson and Kate Pickett, authors of the widely influential 2009 book, The Spirit Level: Why More Equal Societies Almost Always Do Better. “We all worry more about whether others see us as capable and successful — or as a failure.”

Threats to self-esteem and social status, the pair add, “turn out to be particularly strong sources of stress.” And stress kills.

“For decades, U.S. politicians on the right have resisted calls for income redistribution and universal insurance under the theory that inequality was a fair price to pay for freedom,” writes the Atlantic’s Derek Thompson in a thoughtful reflection on the new international life-expectancy data. “But now we know that the price of inequality is paid in early death — for Americans of all races, ages, and income levels.”

Greater equality may well be the best medicine any doctor can ever prescribe.

Sam Pizzigati co-edits Inequality.org. His latest books include The Case for a Maximum Wage and The Rich Don’t Always Win: The Forgotten Triumph over Plutocracy that Created the American Middle Class, 1900-1970. Follow him at @Too_Much_Online.