Researchers say that young adults were up to 183 per cent more likely to carry out some acts of violence if one of their friends had also committed the same act, proving that violence spreads like a contagious disease.
According to the study, violence doesn’t just stop at friends, but it extends by up to four degrees of separation -- from one person to a friend, to the friend’s friend and two more friends beyond.
Though the influence declines with each degree of separation, it is still noticeable, the researchers said.
“This study shows just how contagious violence can be. Acts of violence can ricochet through a community, travelling through networks of friends,” said lead author Robert Bond, Assistant Professor at the Ohio State University in the US.
For the study, the team examined responses from 5,913 students in grades 7 to 12 from 142 schools across US.
The results showed that participants in the study were 48 per cent more likely to have been in a serious fight, 183 per cent more likely to have hurt someone badly and 140 per cent more likely to have pulled a weapon on someone if a friend had engaged in the same behaviour.
Violence spreads within social networks just as characteristics and behaviours from happiness to obesity to smoking spreads, the study revealed.
Much of that association is related to what scientists call a “clustering effect” -- people with similar interests, including the use of violence, tend to cluster together as friends.
“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,” Bond said.
The results appear online in the American Journal of Public Health.