Violence Behaves Like an Infectious Disease

“Brain science, social psychology, and epidemiology reveal that violence behaves like an infectious disease”, said Cure Violence founder Gary Slutkin, a physician and professor of epidemiology and international health at the University of Illinois at Chicago School of Public Health, who has worked with WHO on HIV/AIDS, tuberculosis, and cholera in various parts of the world. “It has clustering, it has epidemic-like curves with waves upon waves, and it's transmitted—the likelihood of doing violence is increased by having violence done to you, the same way the likelihood of getting flu is if you're exposed to flu”, he said. . .  

Although the related problems, such as gang activity or drug trafficking, may differ from country to country, the underlying dynamics of firearm violence are similar, said Francisco Pérez, Cure Violence's national director. “Children see, children do”, he said. “It's all about mimicking or modelling behaviour—people do what they see.”

That is from a very interesting article by Barbara Fraser in The Lancet. Barbara writes about the strategies put in place in Colombian cities that led to violence reduction. She cites a study that Julio Cole and I did on homicides around the world (Population and Development Review, 2009):

Latin America's high levels of violence have variously been blamed on poverty, inequality, drug trafficking, and the armed conflicts of the 1980s and 1990s, but Andrés Marroquín says those may not be the most important reasons. An assistant professor of economics at the University of Wisconsin in the USA, Marroquín grew up in Guatemala, where he regularly saw police and ambulances retrieving bodies along public thoroughfares. 

When he and colleague Julio Cole did a statistical analysis of homicide rates around the world, they found that many factors often blamed for rising violence—poverty, increasing urbanisation, income inequality—were not significant. Worldwide, the most violent countries had more ethnic and linguistic diversity, lower educational levels, and weak rule of law—and the highest rates were in Latin America. 

In their 2009 study, “the strongest variable is governance”, particularly the effectiveness of the judicial system, Marroquín said. The implication for policy makers is that scarce resources might best be used to reduce corruption and increase effectiveness in a country's legal system.

At the time of the interview I was teaching in Wisconsin.