Income Inequality: A Matter of Life and Death

There is strong new evidence that inequality can be deadly. Linda Zhao, Philipp Hessel, Juli Simon Thomas, and Jason Beckfield's research establishes that income inequality within U.S. localities contributes directly to death rates in those same areas. That means that people living in neighborhoods with significant disparity in family income are more likely to die than people in neighborhoods where family income is more similar.

It is easier for us to grasp intuitively that poverty kills. Poverty interferes with obtaining basic inputs to life like food, shelter, and health care, but are there ways that inequality kills other than by increasing the share of people exposed to poverty? Yes.

Zhao and her colleagues distinguish direct and indirect effects of inequality on mortality risk. When inequality increases poverty, which then leads to higher mortality, the effect of inequality on death is indirect—operating via individual poverty. Similarly, when inequality increases mortality by creating ghettos where the health risks go beyond those of individual poverty (e.g., exposure to violence), its effect is still indirect, this time via neighborhood poverty.

Direct effects are different, and the new research provides evidence that income inequality contributes directly to mortality risk. How? At the individual level, inequality can evoke stressful social comparison. We already knew that social comparison influences behavior—lower income men are less likely to marry in unequal areas where social comparison leaves them feeling financially unfit for marriage than in more equal areas where their low earnings are more typical. But evidence that stressful social comparison increased local death rates has previously been lacking.¹ Believing that relative deprivation can have health consequences in the absence of absolute deprivation does not require much imagination. Research has already established that even perceived relative deprivation increases stress levels, anxiety, and reduces self-reported happiness. These issues "get under the skin" in a measurable way—they increase allostatic load, which makes individuals more vulnerable to death from a wide range of causes.

Also consider how inequality can change neighborhoods. When the haves and have nots live close together, there is less social cohesion than with shared poverty or shared wealth. In fact, inequality may be socially corrosive, such as where there are fewer expectations of what neighborliness means among people who do not have common reference groups. There may also not be shared norms about how common resources like parks or police should be used, and this can make collective resources less valuable. The authors write:

Weaker community life, less trust, and less civic engagement reduce the ability of local areas to provide public goods and resources that are protective to health. This in turn shapes mortality risk; for instance, local areas can differ in their provision of cardiopulmonary resuscitation in out-of-hospital cardiac arrests or in engagement with public infrastructure in reporting hazardous or unsafe environments. Neighborhood corrosion can not only reduce social engagement, increase the risk of accidental death, and weaken community life, it can also trigger hostility and violence, which are especially relevant in local areas, between individuals who are in close proximity. Overall, these ideas suggest that: living in U.S. census tracts with greater income inequality increases mortality directly.

Their analysis does not reveal how much the importance of relative deprivation matters for mortality compared to the importance of social corrosiveness, but they nonetheless contribute by showing that income inequality has a direct effect on mortality above and beyond indirect effects through individual socioeconomic status and the poverty of neighborhoods. In addition, they confirm previous findings that inequality in large geographic areas like states contributes to mortality, and further demonstrate that local inequality (within census tracts) is consequential as well. The picture we had before of how inequality contributes to death was incomplete. Their careful treatment of other measurement issues (that might seem esoteric to many) also increases my confidence in the robustness of their central finding that local income inequality directly produces higher mortality rates.

I remember the first time I ever thought seriously about the question of whether relative poverty mattered. It was 1989, and the economist Morris D. Morris asked my college senior seminar in “Development Studies” whether the lowest castes in India, the Untouchables, really cared whether they stayed at the bottom of the social ladder if life was improving. His example was of Untouchables gaining wealth through the leather craft: the Hindu belief that touching leather polluted people did not deter castes that were already considered unclean from developing small-scale leather businesses, so many Untouchables grew both richer and economically independent.

At the time, I was impressed by the Dalit leather example. I imagined that if I had come to a place where I could reliably feed my children, it wouldn't necessarily bother me that higher income folks were now driving cars. My moral sensibility that a caste system was fundamentally unjust nonetheless had to concede that life trumped equality. At some level, it had to be true that absolute poverty eradication was more important than reducing income inequality. Zhao and her colleagues have now made me equally as certain that relative poverty is also a matter of life and death. 

Laurie DeRose is a senior fellow at the Institute for Family Studies, Assistant Professor of Sociology at the Catholic University of America, and Director of Research for the World Family Map Project. Anna Barren is a graduate of the Philosophy program at Christendom College and is the administrator of the Sociology department at the Catholic University of America.

1. Zhao and her colleagues explained that although the positive inequality/mortality relationship was somewhat contested, previous work cast more doubt on the link between local inequality and mortality than the link between state or national inequality and mortality.