National Geographic : 2018 Jan
134 national geographic • January 2018 Marsh couldn’t get the engine to start and was too afraid to get out, with cars and trucks rushing past the vehicle. A man pulled over, ran across the highway, and helped start the car. “He took an enormous risk running across the freeway. There’s no possible explanation for it other than he just wanted to help,” Marsh says. “How can anybody be moved to do something like that?” Marsh kept turning that question over in her head. Not long after she began working at Georgetown, she wondered if the altruism shown by the driver on the bridge wasn’t in some ways the polar opposite of psychopathy. She be- gan looking for a group of exceptionally kind individuals to study and decided that altruistic kidney donors would make ideal subjects. These are people who’ve chosen to donate a kidney to a stranger, sometimes even incurring financial costs, yet receive no compensation in return. Marsh and her colleagues brought 19 donors in from around the country for the study. The re- searchers showed each one a series of black-and- white photographs of facial expressions, some fearful, some angry, and others neutral, while their brains were scanned using an MRI machine to map both activity and structure. When looking at fearful faces, donors showed a greater response in their right amygdala than a control group. Separately, the researchers found that their right amygdalas were, on average, 8 percent larger than those of the control group. Similar studies done previously on psychopathic subjects had found the opposite: The amygdalas in psychopathic brains are smaller and activat- ed less than those in controls while reacting to frightened faces. “Fearful expressions elicit concern and caring. If you’re not responsive to that expression, you’re unlikely to experience concern for other people,” Marsh explains. “And altruistic kidney donors just seem to be very sensitive to other people’s distress, with fear being the most acute kind of distress—maybe in part because their amygdalas are larger than average.” the MaJority of people in the world are neither extreme altruists nor psychopaths, and most individuals in any society do not ordinari- ly commit violent acts against one another. And yet, there are genocides—organized mass kill- ings that require the complicity and passivity of large numbers of people. Time and again, social groups organized along ethnic, national, racial, and religious lines have savaged other groups. Nazi Germany’s gas chambers extinguished millions of Jews, the Communist Khmer Rouge slaughtered fellow Cambodians in the killing fields, Hutu extremists in Rwanda wielding ma- chetes slaughtered several hundred thousand Tutsis and moderate Hutus, and Islamic State terrorists massacred Iraq’s Yazidis—virtually every part of the world appears to have suffered through a genocide. Events such as these provide ghastly evidence that evil can hold entire com- munities in its grip. How the voice of conscience is rendered in- consequential to foot soldiers of a genocide can be partly understood through the prism of the well-known experiments conducted in the 1960s by the psychologist Stanley Milgram at Yale Uni- versity. In those studies, subjects were asked to deliver electric shocks to a person in another room for failing to answer questions correctly, in- creasing the voltage with every wrong answer. At the prodding of a person in a lab coat who played the role of an experimenter, the subjects often di- aled up the shocks to dangerously high voltage levels. The shocks weren’t real and the cries of pain heard by the subjects were prerecorded, but the subjects only found that out afterward. The studies demonstrated what Milgram described as “the extreme willingness of adults to go to almost any lengths on the command of an authority.” Our social brain is plastic, even in adulthood, and we can be trained to be more kind and generous.