Chicago's Record Shootings Reflect a Social Contagion of Violence

New research sheds light on how epidemic gun violence spreads through communities via social networks.

Chicago saw 762 homicides in 2016 and 3,550 shootings - a nearly 50 percent increase over last year and a record number of shootings since police began tracking them in 2011. The number of gunshot victims totaled 4,331, according to the Chicago Police Department.

On Monday, President-Elect Donald Trump suggested Chicago Mayor Rahm Emanuel should seek federal help in curbing violent crime in the city.

A new study, published in the Journal of the American Medical Association, may shed some light on how gun violence spreads through communities, and offers potential solutions.

The study, conducted by researchers at Harvard and Yale, found that people who associate with victims of gun violence are more likely to be shot themselves.

"A great deal of research in recent years has shown that many behaviors such as obesity, smoking and political opinions spread through networks due to social influence," Ben Green, Harvard graduate student and one of the study co-authors, told Seeker. "Since crime and violence are known to be social behaviors, they are likely candidates to also be intimately connected with social networks and contagious processes."

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Based on arrest records from 2006-2014, Green and his colleagues examined every gunshot injury that occurred in Chicago. They created social networks by identifying relationships between pairs of those who were arrested together for the same offense.

For every gunshot victim who was influenced by social contagion, researchers identified which person in their network was primarily responsible for him or her becoming a victim of gun violence.

"All of the individuals in our network are individuals who were arrested during the study period, although not necessarily for anything related to gun violence," Green said. "While such individuals are typically considered 'offenders' and therefore addressed with increased policing, our [findings] highlight how we should also recognize them as likely victims. Our study aims to shift the narrative toward saving lives and reducing trauma, regardless of other societal labels," Green said.

Previous studies of gunshot violence have primarily focused on demographic factors such as race, gender and socioeconomic status, but Green and his team are some of the first to trace gun violence through social networks and track the spread.

Over the Christmas weekend, police investigated 27 shooting incidents in Chicago, 12 of which resulted in fatalities. There were also six people slain and 49 people injured in various shooting incidents in the city over New Year's weekend.

From Jan. 1-Dec. 25, 2016 there were 753 homicides in Chicago, but there were 3,495 shooting incidents. Gun violence is most often reported by the media only when it involves a fatality, but the number of incidents involving gun violence in Chicago is much greater than the number of fatal gun incidents alone.

According to Green's study, Chicago's rate of gun violence is more than three times the national average, but from 2006-2014 more than 70 percent of all subjects of gun violence were located in networks containing less than 5 percent of Chicago's population.

This indicates that not only is gun violence concentrated within certain communities, but it spreads specifically via social interaction. It may also explain why some individuals become subjects of gun violence, while others who encounter the same high-risk environments do not.

"We observed that gunshot victims are highly clustered in particular pockets of the social network, and meanwhile there were other large segments of the network with few or no victims," Green said. "One potential explanation for this clustering is that victims influence those around them to also become victims, thus generating concentrated victims in the social network."

Green's study is consistent with findings from another recent study out of Ohio State University, which also observed that violence spreads in disease-like epidemics, particularly among adolescents. Results showed that adolescents were up to 183 percent more likely to commit some act of violence if one of their friends had also committed the same act.

Insights like these are particularly valuable in understanding how to create effective anti-violence initiatives.

"If we can stop violence in one person, that spreads to their social network. We're actually preventing violence not only in that person, but potentially for all the people they come in contact with," Robert Bond, lead author of the Ohio State study told the University's news publication.

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Based on their findings, Green and his team discovered a need for violence prevention to be a matter of public health, rather than exclusively a matter of law enforcement.

"Our results suggest that approaches developed to curb other epidemics may be valuable for limiting gun violence," Green said. "Violence prevention efforts should focus on identifying and blocking the pathways of transmission."

The study explains that offender-based intervention programs used in the past have often relied on law enforcement, but the subjects observed in the study are not often in direct contact with the criminal justice system.

They are, however, very much embedded with housing, education, and other government programs, indicating that prevention efforts should target these systems more often. "The ability to identify individuals at high risk to be shot means that it is possible to target social services to individuals in new ways," Green explained.

According to Green and his co-authors, an effective public health approach to gun violence reduction should focus on the specific networks that create these situations in the first place.

"Previous approaches to predicting gun violence that focused on hotspot locations where violence was likely to erupt typically led to an increase in policing efforts in predominantly urban minority neighborhoods," he said, adding, "Our study allows for a more targeted approach that could provide coordinated services such as mental health and housing to potential victims at the exact times they face the highest risk."

Photo: Wooden crosses with names of Chicago's murder victims in 2016 are marched down Michigan Ave. Credit: Getty Images WATCH VIDEO: Why the Government Stops Gun Violence Research