The story is familiar to us today: Somebody, usually a young man, walks into a public place, kills a bunch of people seemingly at random, and (usually) ends the murder spree with a suicide-by-cop.

But this story—at least, in Western culture—is startlingly new, relatively speaking. In fact, Paul Mullen, a forensic psychologist, says we can pin a date and place on the first time it happened. On September 4, 1913, in the German towns of Degerloch and Mühlhausen an der Enz, Ernst August Wagner killed his wife, his children, and at least nine strangers. He shot more than 20 people and set several fires during his killing spree. He ended up spending the rest of his life in an insane asylum.

But when we try to pin killings like these on mental illness, Mullen says, we're not quite hitting the right point. The people who go on killing sprees are mad, sure. But that's not the same thing as diagnosable, objective, physical mental illness. Only about 10% of the people ever arrested for crimes like this had actual mental illnesses. In fact, Mullen thinks these killings have more to do with culture than brain chemistry. His argument is interesting. And it might sound a little similar to the old "angry music made him do it!" trope. But what Mullen is talking about is different than that. Science journalist David Dobbs tries to explain the distinction:

I'm not saying the movies made Holmes crazy or psychopathic or some such. But the movies are a enormous, constant, heavily influential part of an American culture that fetishizes violence and glamorizes, to the point of ten-year wars, a militarized, let-it-rain approach to conflict resolution. And culture shapes the expression of mental dysfunction — just as it does other traits. This is why, say, relatively 'simple' schizophrenia — not the paranoid sort — takes very different forms in Western and some Eastern cultures. On an even simpler level, this is why competitive athleticism is more likely to express itself as football (the real kind) in Britain but as basketball in the U.S. Culture shapes the expression of behavioral traits.

This is an interesting argument and an interesting thing to think about.

Read the rest of David Dobbs' post about the difference between blaming movies for violence and talking about the consequences of violence in culture.

Watch the video of Paul Mullen discussing cultural violence, mental illness, and spree killings

Read a very good post at the Neuroanthropology blog that expands on Paul Mullen's ideas and provides more interesting links