Gun Violence Is Like an STI in the Way It Moves Between People


Criminologists and politicians have taken to referring to gun violence as a “public health issue.” This is a roundly good thing, since studies suggest that when people are primed to thinking of violence as a disease rather than as a “monster,” they’re more likely to recommend trying to improve the economy or provide better health care than build bigger jails or put more cops on the street. But as Yale University sociologist Andrew Papachristos tells Science of Us, gun violence is more of an “epidemic” than you might assume. In fact, the virus of shootings behaves a lot like a sexually transmitted infection (STI).

“Gunfire is much more like HIV or hepatitis C than a flu or a cold,” says Papachristos, whose research has brought network analysis to understanding patterns of gunfire. “If you caught a bullet like a cold, there would be way more innocent bystanders. In fact what you see is the opposite. You see it cluster around individuals who are victims, which suggests that the mode of transmission is not ‘airborne,’ as it were.”

In a study of all arrests in Chicago from 2006 to 2012, Papachristos and his colleagues found that 70 percent of all nonfatal gunshot injuries happened within a network of people accounting for under 6 percent of the city’s population. These people were “co-offenders,” meaning that at the time of arrest, they were arrested with at least one other person. Even more compelling, 89 percent of the gunshot victims belonged, in the researcher’s analysis, to a single social network of 107,740 people. In the city as a whole, the rate of gunshot victimization during this period was 62 per 100,000 people. (While it’s notoriously hard to track down nonfatal gunshot data — or other firearm data — research indicates that the Chicago rate is half that of Detroit and more than double that of New York, depending on the year). Within the Chicago co-offending network, the researchers find that the nonfatal gunshot rate was an astounding 740 per 100,000 people.

The findings, which Papachristos published last year in Social Science & Medicine, make gun violence look at lot like other risky behaviors that move along social networks in what epidemiologists call “social contagion.” In the contagion of a virus, a disease is passed between people because they have close contact. With social contagion, people imitate, communicate, and otherwise pass along behaviors to people they know. It’s not just colds that move between clusters of people, but substance abuse, smoking, and obesity — if a close friend becomes obese, you have a 57 percent chance of becoming obese in that same time period, too. And as all those public health PSAs warned you — when you sleep with someone, you’re sleeping with everyone they’ve ever slept with — STIs spread through networks by contagion, too. In the case of gunfire, violence gets passed on by cultural norms around retaliation and respect in high-crime communities (similar to the violent “honor culture” ascribed to Appalachia). In a 2013 study of gang homicides in Boston and Chicago, Papachristos found that killings were driven by status-seeking, retaliation, and the organizational memory of a gang — all of which are networked, socially symbolic behaviors.

The networked nature of gun violence gives a much more precise understanding of who’s at risk to kill or be killed by gunfire. While it’s tragically true that young black men in Chicago are likely to be involved with gun violence — the nonfatal gunshot rate for black males between the ages of 18 and 34 is 599.65 per 100,000 people, or 1 in 200 in the group are nonfatal shooting victims every year — not everybody who fits that demographic is equally at risk. It’s the people who are most embedded in the relatively small networks of violence that are at risk. Which also helps with the prevention of violence.

“Changing networks means changing communities,” Papachristos says. “You can’t arrest your way out.” As other sociological research has shown, the community you’re embedded in — down to the city block — has tremendous outcomes on educational attainment. To Papachristos, this will need be addressed holistically in the same way obesity is being tackled by everyone from the NFL to Michelle Obama. There will be need to be better ways for young men of color with criminal records to disassociate from these violent networks, and there are questions of how to help school-age children who aren’t in these networks to stay out of them. But there’s lots of evidence to be hopeful for changes: Americans have collectively changed their minds on public health issues before: Everybody agrees seat belts are necessary, even Kanye, and smokers, once the coolest people you knew, are now, in the words of Papachristos, treated kind of “like lepers.” And there are localized solutions, too: “venue-based” interventions work for preventing the spread of HIV in the U.S., so there’s reason to believe that it could be a similar case for gun violence. If you know which networks of people are at risk for things that could kill them — whether it’s getting shot or getting HIV — then it’s way easier to help them.