The events surrounding the police's part in a British man's death catalyzed riots that quickly spread in England this week. Although race tensions seem to influence the rioting, unemployment, cuts to public programs and a stale economy have factored in, too.
But how do riots' destructive and violent grasps on an area spread?
Kristian Skrede Gleditsch, a professor of government at the University of Essex in the United Kingdom, told Discovery News that the geography of riots and how they spread seem to show certain patterns -- patterns similar to those followed by wildfires.
"There's some evidence suggesting that ... the severity of riots is inversely proportional to their frequency," he said. "It's kind of like a forest fire. Most fires go out very quickly, but a few become catastrophic. Once they reach a certain magnitude, they can become self-sustaining and very hard to contain."
In the case of the England riots, Gleditsch said the situation has moved past the point where police can contain violence from spreading to new locations. He said it will be interesting to study what allows urban riots to grow to this magnitude, whether they're shaped by police strategies or other factors.
Jack Levin, a professor of sociology and criminology at Northeastern University, said most rioting consists of two phases in which people's motivation to behave violently or destructively may change. Dropping one's personal identity and responsibility and adopting those of a group's (a behavior known as deindividuation) often happens in the first phase of rioting, he said. Usually, people are pushed to their personal limits before expressing their grievances this way.
Following the initial catalyst, and with rioting spreading, people's rationales for participating change, too.
"It has to be recognized that economic times are pretty harsh, not only in the United States but in England. There are desperate individuals who will unfortunately go outside of the law simply because they've lost confidence in mainstream politics, see the police as the enemy of occupation, and don't see the light at the end of the economic tunnel," Levin said. "They may take advantage of a dire situation in order to accumulate certain items -- such as flat screen TVs -- that they otherwise might not."
These free-for-all bouts of looting, Levin said, transition into a second phase of rioting and often happen when newcomers join with individuals they already know. For example, friends showing up at a riot are probably pressured by one another to act destructively rather than acting to support the original grievance.
Though outsiders should try to understand the rationale of riot participants, Levin said riots can range from the "sublime to the ridiculous," adding that it's become trendy to riot over less serious events such as the victory or loss of a sports team.
Another researcher points out the difference between violent and destructive behaviors, adding that riots are more likely to lower people's standards for themselves, regardless if they have a criminal history. Overall, vandalism and looting -- which are technically property crimes -- are easier for people to justify than behaving violently.
"I think the threshold to engage in their choice of [destructive] behaviors is lower," said Sherry Hamby, a research associate professor of psychology at Sewanee, University of the South. "The main thing to understand about this group psychology is that individual psychology probably explains a small percentage of these behaviors."
Though police reports and media sources might focus on the extremes of a riot and accuse all participants of having a criminal history, the truth is existing criminals are unlikely behind this riot's genesis and progression, she said.
"The criminal element doesn't really change from week to week or month to month -- they're always out there," Hamby said. "You can't usually pinpoint something like that. It's not the criminals that are getting the riots really going; they're more political events than they are criminal events."