Eric Michael Johnson in The Primate Diaries blog at Scientific American:
While everyone agrees the blame should ultimately be placed on the perpetrator of this violence, the fact remains that the United States has one of the highest murder rates in the industrialized world. Of the 34 countries in the Organisation for Economic Co-operation and Development (OECD), the U.S. ranks fifth in homicides just behind Brazil (highest), Mexico, Russia, and Estonia. Our nation also holds the dubious honor of being responsible for half of the worst mass shootings in the last 30 years. How can we explain why the United States has nearly three times more murders per capita than neighboring Canada and ten times more than Japan? What makes the land of the free such a dangerous place to live?
There have been hundreds of thoughtful explorations of this problem in the last week, though three in particular have encapsulated the major issues. Could it be, as science writer David Dobbs argues at Wired, that “an American culture that fetishizes violence,” such as the Batman franchise itself, has contributed to our fall? “Culture shapes the expression of mental dysfunction,” Dobbs writes, “just as it does other traits.”
Perhaps the push arrived with the collision of other factors, as veteran journalist Bill Moyers maintains, when the dark side of human nature encountered political allies who nurture our destructive impulses? “Violence is our alter ego, wired into our Stone Age brains,” he says. “The NRA is the best friend a killer’s instinct ever had.”