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Violence Drives Global Inequalities in the Variability of Age at Death

global map of how violence and lifetime uncertainty interact
Global lifetime uncertainty and level of violence for men and women conditional on surviving to age 10 in 2017. | Aburto et al., Sci. Adv. 9, eadd9038 (2023)

Variability in the age that people die in a country is linked to how much violence they endure, according to a new study using global data on mortality and violence.

Life expectancy — the average age a person in a given population can expect to live — is one of the most frequently used indicators of population health. But life expectancy can mask the complexities of global mortality — such as the variability in age at death within a population, also known as lifetime uncertainty.

A new global analysis published in Science Advances reports strong ties between lifetime uncertainty in a country and the extent of violence that country endures. José Manuel Aburto and colleagues estimate that in 2017, the remaining life expectancy of a 10-year-old child in one of the most violent countries in the world was up to 14 years shorter than that of a child of the same age in one of the most peaceful countries.

The researchers suggest that lifetime uncertainty caused by violence constitutes a major health crisis that is experienced unequally around the globe.

Important Metrics of Population Health

Globally, life expectancy has generally risen in recent years, with the exception of declines after 2019 as a result of the COVID-19 pandemic. This rise is associated with advances in healthcare, sanitation, and food security, to name a few.

Like life expectancy, lifetime uncertainty has improved globally over the years, but it continues to vary substantially among countries. While lifetime uncertainty is often overlooked as a metric of population health, it can uncover patterns that life expectancy might veil. For example, a 2009 study reported that at similar life expectancies, lifetime uncertainty could differ by up to 70% between countries in the most extreme cases — largely due to high numbers of premature deaths.

"It is clear that premature mortality is a determinant of high lifetime uncertainty," said Aburto, lead author of the study and a demographer in the Leverhulme Centre for Demographic Science and the department of sociology at the University of Oxford. "In my previous research … I found that deaths related to violence are a key driver of high premature mortality in many contexts around the world."

Global Perspective Uncovers Pervasive Inequalities

In the new study, Aburto and colleagues explored how violence contributes to global lifetime uncertainty and thus population health. "By zooming out and bringing a macro perspective, we can show how these patterns in violence and lifetime uncertainty hold across all countries in the world, despite country-specific characteristics," said Vanessa di Lego, a co-author of the study from the Vienna Institute of Demography at the Austrian Academy of Sciences.

boy in Yemen looking at rubble from airstrike
Child looks out over rubble from airstrike in Yemen, one of the countries with the largest levels of lifetime uncertainty. | Felton Davis/ Flickr

By evaluating deaths and violence across 162 countries between 2008 and 2017 using data from the Global Burden of Disease Study and the Internal Peace Index, the researchers found a remarkable link between high lifetime uncertainty and the most violent countries in the world. Most of the uncertainty attributed to violence was the result of younger men dying in more vulnerable places, di Lego noted, including conflict-ridden Middle Eastern or North African countries like Yemen and Syria; Latin American countries with some of the highest homicide rates in the world such as Colombia, Venezuela, and Mexico; as well as other countries that have been embroiled in international conflict for decades, including Afghanistan, Russia, and Ukraine.

Canada and many countries in Europe were among the most peaceful regions, the researchers said, with correspondingly low lifetime uncertainties during the study period — though they note that the recent Russian invasion of Ukraine could change this. The United States fared worse, standing out among G7 nations with greater lifetime uncertainty linked to higher rates of gun violence.

While higher lifetime uncertainty due to violence was associated with lower life expectancy in general, lifetime uncertainty highlights the magnitude of the impact of violence. "Even after considering broader indicators of social and economic development, such as the Human Development Index, violence is not only strongly associated with more unpredictability in length of lifetimes, but even more so than life expectancy itself," di Lego said.

Indirect Public Health Impacts of Violence

The researchers point out that high lifetime uncertainty from violence impacts not only those who are dying young, but the surviving populations that must deal with frequent death and the unpredictability of their lifespans. These people must navigate both the material and mental health consequences of chronic loss and uncertainty due to violence — which could include depression, anxiety, post-traumatic stress disorder, alcohol abuse, and suicidal behavior — and can lead to a perpetual cycle of poverty, insecurity, and violence. "The uncertainty in length of lifetime may impact behavior and long-term decision-making, creating a 'why bother?' mindset that is in itself conducive to more violent and higher-risk health behaviors," added di Lego.

The authors emphasize that women and children in high-violence countries are disproportionately burdened by the indirect impacts of violence, exacerbating vulnerabilities and gender inequalities. "The gendered nature of conflict and pre-existing gender relations in fact expose[s] women and adolescent girls to a myriad of indirect health risks — such as heightened vulnerability to sexual violence and domestic abuse, trafficking, displacement and a lack of access to reproductive health services," said study co-author Orsola Torrisi of New York University Abu Dhabi. Torrisi noted that these layered risks could make the lifespans of those not even involved in violence less predictable still.

Prior research has shown that violence is both a driver and a consequence of socioeconomic inequalities. Others have explored how climate change — while creating its own specific health threats — may contribute to regional insecurities that can intensify violence and its health burdens, even in currently peaceful countries and especially for women and gender minorities.

"Particularly in sub-Saharan Africa and Latin America, violence and insecurity have already been exacerbated by the interplay between a changing climate and rising economic inequality," Torrisi said. "We may anticipate the most serious consequences of this interaction for the population segments that are more vulnerable to the indirect health effects of violence, like women and children."