A 2006 study published in the journal NeuroImage may have helped provide some answers. Researchers working through the National Institute of Mental Health scanned the brains of 20 healthy volunteers, watching their reactions as they were presented with various legal and illegal scenarios. The brain activity that most closely tracked the hypothetical crimes— rising and falling with the severity of the scenarios— occurred in the amygdala, a deep structure that helps us make the connection between bad acts and punishments. As in the trolley studies, there was also activity in the frontal cortex. The fact that the subjects themselves had no sociopathic tendencies limits the value of the findings. But knowing how the brain functions when things work well is one good way of knowing where to look when things break down.
Fortunately, the overwhelming majority of us never run off the moral rails in remotely as awful a way as serial killers do. but we do come untracked in smaller ways We face our biggest challenges not when we re called on to behave ourselves within our family, community or workplace but when we have to apply the same moral care to people outside our tribe.
The brutal line we may draw between insiders and outsiders is evident everywhere-mobsters, say, who kill promiscuously yet go on rhapsodically about “family.” But it has its most terrible expression in wars, in which the dehumanization of the outsider is essential for wholesale slaughter to occur. Volumes have been written about what goes on in the collective mind of a place like Nazi Germany. While killers like Adolf Hitler can never be put on the couch, it’s possible to understand the xenophobic strings they play in their people.
“Yugoslavia is the great modern example of manipulating tribal sentiments to create mass murder,” says Jonathan Haidt, associate professor of psychology at the University of Virginia. “You saw it in Rwanda and Nazi Germany too. In most cases of genocide, you have a moral entrepreneur who exploits tribalism for evil purposes.” That, of course, does not take the stain of responsibility off the people who follow those leaders – a case that war-crimes prosecutors famously argued at the Nuremberg trials and a point courageous people have made throughout history as they sheltered Jews during World War II or refused to murder their Sunni or Shi’a neighbor.
For grossly imperfect creatures like us, morality may be the steepest of all developmental mountains. Our opposable thumbs and big brains gave us the tools to dominate the planet, but wisdom comes more slowly than physical hardware. We j surely have a lot of killing and savagery ahead of us before we fully civilize ourselves. The hope—a realistic one, perhaps—is that the struggles still to come are fewer than those, left behind.