COMMENTARY:

How Inequality Kills

Most of this comes from epidemiologists and public health researchers. The articles, dry and overlooked, are gray with columns of statistics. The earliest ones, buried in the stacks at the university, show these scientists hardly believing their own findings. It was only because George Kaplan (1) and John Lynch (2) and their associates at the University of Michigan, for example, and Richard Wilkinson (3) at the University of Sussex all made discoveries pointing in the same odd direction that this topic wasn’t dismissed as a quirk.

We’ve always known poverty is correlated with poor health. But separately, if you measure the inequality of any society—its shape, hierarchical or egalitarian—and if you correlate that with infant mortality, or death from violence, or life expectancy, the correlation number jumps off the page.

Now a whole book of collected reports has been published, showing the same patterns (4). Whether researchers compare different countries, different cities or different states, steeply unequal societies show more breakdown. Violence is up, health is down, infant mortality is up, life expectancy is shorter—and this affects all levels of society. Egalitarian societies are simply healthier.

This is a raw point at the joint between science and politics. It is going ignored. Of course this is not the first time the media have ignored inconvenient facts from health statisticians. The discovery of real hunger in America, quietly admitted by the U.S. Department of Agriculture last year (5), should have lit up the political skies, but was skipped by the press. A very readable article by Robert Sapolsky in the glossy pages of the Scientific American last year (6) should likewise have liberal politicians climbing on the tables, because his article shows that social inequality kills. It is being virtually ignored.

We dismiss this research at our peril.

Look at any community, and its rich and its poor. If you figure how much money you’d have to take from the rich to give to the poor, and keep doing that until everybody was equal, that would be the community’s score on the Robin Hood Index (7, 8), an economic measure of social inequality. Bruce Kennedy and his colleagues (9) did that for each of the 50 states in America. (Turns out the states vary considerably, with Louisiana the most unequal, New Hampshire the most equal.) Next they compared the index with mortality rates. A clear correlation jumped out. By knowing the state’s degree of social inequality, you could accurately guess its mortality rate.

Inequality kills.

And it’s powerful. Digging through piles of data, John Lynch and his co-workers analyzed 282 US cities. They found if you add the ravages of poverty to the life-shortening effect of social inequality, the combination is “comparable to the combined loss of life from lung cancer, diabetes, motor vehicle crashes, HIV infections, suicides and homicides” (10). Is this a fact because sick people fall to the bottom of society, causing deeper inequality? No; analysis shows the reverse. The path is from inequality to bad health.

Those are the health effects, but the impact of inequality ripples through behavioral and criminology data too. It seems nobody tried these correlations before.

In a third study, George Kaplan and his associates went through the archives and found income inequality correlated with all of the following: low birth weight, homicide, violent crime, work disability, expenditures for medical care and police protection, rates of smoking, unemployment rates, food stamps, and imprisonment (11). When Ching-Chi Hsieh and M.D. Pugh, both sociologists, sifted through 34 published research studies and conducted a meta-analysis, they found 97% of the correlations reported between social inequality and violent crime were positive (12).

Exactly why is inequality toxic? They’re still working on this one, but it looks like friendships and social networks are critical in getting through stressful times. Chronic stress can damage the circulation system, cause hormone imbalances, damage the immune system and affect the brain in ways that precipitate depression—this is true for both animals and humans. Some stresses are psychological, some interpersonal. In humans, hierarchy makes friendships difficult. We can think of friendship and hierarchy as inversely related. Egalitarian networks promote camaraderie and trust, but if it is constantly pushed in our faces that we are unequals, we feel more untrusting, alone, and vulnerable.

Among some animals, it appears the accumulating stresses of the pecking order are toxic. Researchers are saying the effects are akin to rapid ageing (13).

One more new point. For humans, it’s not your actual dollar income, but the experience of feeling low on the community ladder that is tied to poor health. Regardless of the nation we live in, we compare ourselves to others around us. If we feel lower, inferior, it’s stressful. So for example, people living in Greece today earn about half what Americans earn, but their life expectancy is longer. America has very steep inequalities but Greece is a more egalitarian society (14).

All this points to one conclusion. Raising a nation’s total wealth is not going to improve average health unless inequality is also reduced (15).

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