The shocking mass shooting late Sunday by a gunman who killed at least 58 people and injured more than 500 others at a country music concert in Las Vegas was the latest in a series of horrific events that are fueling a national conversation about the roots of evil. The massacre outside the Mandalay Bay Resort and Casino, the deadliest mass shooting in U.S. history, was carried out by a shooter who sprayed the outdoor concert with rapid gunfire while perched in a room on an upper floor of the hotel. The gunman’s motives were unclear in the hours after the shooting. It occurred about 15 months after 49 people were killed in a shooting at an Orlando nightclub, which at the time was the deadliest mass shooting in U.S. history. Hostility and hatred have fueled unspeakable evil. But as we have seen among first responders and when victims help victims before the shooting stops, humankind also is capable of astonishing acts of kindness.
We at National Geographic have been working on a story about what science tells us about good and evil. We published an early version of the story in August, after a young woman protesting a neo-Nazi rally in Charlottesville, Virginia, was killed when she was struck by car that was purposely driven into a crowd. We are republishing the story now, given the tragic events in Las Vegas. A version will also appear in a future issue of the magazine.
From the kitchen window of her trailer in Auburn, Illinois, Ashley Aldridge had a clear view of the railroad crossing a few hundred yards away. When the 19-year-old mother first saw the man in the wheelchair, she had just finished feeding lunch to her two children, ages one and three, and had moved on to washing dishes—one more in an endless string of chores. Looking up, Aldridge noticed that the wheelchair wasn’t moving. It was stuck between the tracks.
The man was frantically waving his arms as a motorcyclist riding past barely slowed down. Aldridge hurried out to ask a neighbor to watch her kids so she could go help. But then she heard the clanging of the crossing gate as it came down, signaling a train was on its way. She ran, barefoot, over the gravel path along the tracks. When she got to the man, the train was less than half a mile away, bearing down at about 80 miles an hour. Failing to dislodge the wheelchair, she wrapped her arms around the man’s chest from behind and tried to lift him, but couldn’t. As the train barreled toward them, she pulled with a mighty heave. She fell backwards, yanking him out of the chair. Within seconds, the train smashed the wheelchair, carrying fragments of steel and plastic half a mile up the track.
The man Aldridge saved that afternoon in September 2015 was a complete stranger. Her unflinching determination to save him despite the threat to her own life sets her apart from many, including, most strikingly perhaps, the motorcyclist who didn’t stop. Aldridge’s heroic rescue is an example of what scientists call extreme altruism—selfless acts to help others at the risk of grave personal harm. Not surprisingly, many of these heroes—like Roi Klein, an Israeli army major who jumped on a live grenade to save his men—work in professions where endangering one’s life to protect others is part of the job. But others are ordinary men and women—like Rick Best, Taliesin Myrddin Namkai Meche, and Micah David-Cole Fletcher, who intervened to defend two young Muslim women, one wearing a hijab, from a man spewing racist abuse at them on a commuter train in Portland, Oregon. All three were stabbed; only Fletcher survived.
Contrast these noble acts with the horrors that humans perpetrate: murder, rape, kidnapping, torture. Consider for a moment—unsavory as it may be—the chilling remorselessness of a psychopathic serial killer like Todd Kohlhepp, a real estate agent in South Carolina, who appears to have left a clue about his murderous habit in an online review for a folding shovel: “Keep in car for when you have to hide the bodies.” Or think of the sustained brutality inflicted by Ariel Castro, who abducted three young women and imprisoned them in his house in Cleveland, subjecting them to sexual slavery for 10 years, until one finally escaped. In spite of how aberrant these cruelties are, they occur often enough to remind us of a dark truth: Humans are capable of unspeakable cruelty.
Extreme altruists like Aldridge and psychopaths like Kohlhepp exemplify our best and worst instincts. On one end of the moral spectrum, sacrifice, generosity, and other ennobling traits that we recognize as good; on the other end, selfishness, violence, and destructive impulses that we see as evil.
At the root of both types of behaviors, researchers say, is our evolutionary past. They hypothesize that humans—and many other species, to a lesser degree—evolved the desire to help one another because cooperation within social groups was essential to survival. But since groups had to compete for resources, the willingness to maim and kill opponents was also crucial.
“We are the most social species on Earth, and we are also the most violent species on Earth,” says Jean Decety, a psychologist at the University of Chicago. “We have two faces because these two faces are important to survival.”
For centuries the question of how good and evil originate and manifest in us was a matter of philosophical or religious debate. But in recent decades researchers have made significant advances toward understanding the science of what drives good and evil. Both seem to be linked to a key emotional trait: empathy, which is an intrinsic ability of the brain to experience how another person is thinking and feeling. Researchers have found that empathy is the kindling that fires compassion in our hearts, impelling us to help others in distress. Studies have also traced violent, psychopathic, and antisocial behaviors to a lack of empathy, which appears to stem from impaired neural circuits. These new insights are laying the foundation for training regimens and treatment programs that aim to enhance the brain’s empathic response.
Researchers once thought young children had no concern for the well-being of others—a logical conclusion if you’ve experienced a toddler’s tantrums. But recent findings have established that babies feel empathy long before their first birthday. Maayan Davidov, a psychologist at the Hebrew University of Jerusalem, and others have conducted some of these studies, analyzing the behavior of children as they witness somebody in distress—a crying child or their own mother pretending to be hurt.
At just six months, most children respond to such stimuli with facial expressions reflecting concern; some also exhibit caring gestures such as leaning forward and touching the one in distress. By 10 months, many children also show signs of “cognitive empathy,” that is, trying to understand the suffering they’re seeing. Upon seeing a child cry after bumping his knee against a chair, for instance, the kids might shift between looking at the child’s face, the hurt knee, and the chair. Eighteen-month-olds translate their empathy into pro-social behavior like giving a hug or a toy to comfort the hurt child.
That’s not true of all children, however. In a small minority, starting at ages two and three, researchers see what they term an “active disregard” of others. “When someone reported having hurt themselves, these children would kind of laugh at them or even kind of swipe at them and say, ‘You’re not hurt,’ ” says Carolyn Zahn-Waxler, a professor at the University of Wisconsin-Madison who collaborates with Davidov. “Or they would say, ‘You should be more careful’—saying it in a tone that was judgmental.” Following these toddlers into adolescence, the researchers found they had a high likelihood of developing antisocial tendencies and getting into trouble.
Other studies have measured callousness and lack of emotional expression in adolescents using questions like whether the subject feels guilty upon doing something wrong. Those with high scores for “callous-unemotional” traits tend to have frequent and extreme behavioral problems—showing unusual aggression in fights, vandalizing property, torturing animals. Some end up committing major crimes such as murder, rape, and violent robbery. A number are on their way to becoming full-blown psychopaths as adults—men with cold, calculating hearts who wouldn’t flinch while perpetrating the most horrific acts imaginable.
If the empathy deficit at the core of psychopathic behaviors can be traced all the way back to toddlerhood, does evil reside in the genes, coiled up like a serpent in the DNA, waiting to strike?
The answer isn’t a categorical yes or no. As it is with many illnesses, both nature and nurture have a hand in shaping the psychopath. Studies of twins have established that callous--unemotional traits in many young children and adolescents are inherited from parents, confirming a strong genetic component. Yet in a study of nearly 600 children born to parents with a history of antisocial behaviors, researchers found that the kids who were raised by adoptive families that provided a warm and nurturing environment were far less likely to exhibit callous traits than were those brought up by their biological parents.
Children born with a lack of empathy, says Essi Viding, a psychologist at University College London, often are unable to get a break. “You can imagine that if you have a child who doesn’t show affection in the same way as a typically developing child, and doesn’t show empathy, that child will evoke very different reactions in the people around—the parents, the teachers, the peers—than a child who’s more empathetic,” she says. “And many of these children, of course, reside within their biological families, so they often have this double whammy of having parents who are perhaps less well equipped to parent, less good at empathizing maybe, less good at regulating their own emotions.”
The firefighters tried desperately to save the six Philpott children from their burning house in Derbyshire, England, in the early hours of May 11, 2012. But the heat and smoke were so intense that only one of the kids was alive when rescuers finally made their way upstairs where they were sleeping. That boy, too, perished days later in the hospital. The police suspected arson, based on evidence that the fire had been started by pouring petrol through the door’s mail slot. Their investigation would lead them to a psychopath.
Derbyshire residents raised thousands of pounds to help the children’s parents—Mick and Mairead Philpott—arrange a funeral. At a news conference to thank the community, Philpott made a brief statement about how grief-stricken he and his wife were, sobbing and dabbing his eyes with a tissue that remained curiously dry. Leaving the event, Philpott collapsed, but Derbyshire’s assistant chief constable, walking a few steps behind, was struck by the unnaturalness of the behavior. Two weeks later, the police arrested Philpott and his wife. Investigators determined that they had set fire to the house with an accomplice to frame Philpott’s mistress. A court found the Philpotts guilty of the crime.
Philpott’s faking of grief and his lack of remorse are among the characteristics that define psychopaths, a category of individuals who have come to embody evil in the popular imagination. Psychopaths have utter disregard for the feelings of others, although they learn to mimic emotions. “They really just have a complete inability to appreciate anything like empathy or guilt or remorse,” says Kent Kiehl, a neuroscientist at the University of New Mexico who was drawn to studying psychopathy in part because he grew up in a neighborhood that was once home to the serial killer Ted Bundy. “These are people who are just extremely different than the rest of us.”
Kiehl has spent the past two decades exploring this difference by scanning the brains of prison inmates. (Nearly one in every five adult males in prison in the U.S. scores high on psychopathy, measured using a checklist of 20 criteria such as impulsivity and lack of remorse, compared with one out of every 150 in the general population.) Since 2007, using an MRI scanner installed inside a tractor trailer, he and his colleagues have imaged more than 4,000 prison inmates as they perform certain tasks, measuring the activity in their brains as well as the size of different brain regions.
Psychopathic criminals show reduced activity in their brain’s amygdala—the primary center of emotional processing—compared with non-psychopathic inmates when recalling emotionally charged words they were shown moments earlier, such as “misery” and “frown.” In a task designed to test moral decision-making, researchers ask inmates to rate the offensiveness of pictures flashed on a screen—a cross burning by the Ku Klux Klan, a face bloodied by a beating. Although the ratings by psychopathic offenders are not that different from those by non-psychopaths, psychopaths tend to show weaker activation in brain regions instrumental to moral reasoning.
Based on these and other, similar findings, Kiehl is convinced that psychopaths have impairments in a system of interconnected brain structures—including the amygdala and the orbital frontal cortex—that help process emotions, make decisions, control impulses, and set goals. “There is basically about 5 to 7 percent less gray matter in those structures in individuals with high psychopathic traits compared to other inmates,” Kiehl says. The psychopath compensates for this deficiency by using other parts of the brain to cognitively simulate what really belongs in the realm of emotion. “That is, the psychopath must think about right and wrong while the rest of us feel it,” Kiehl wrote in a paper he co-authored in 2011.
When Abigail Marsh, a psychologist at Georgetown University, was 19, her car skidded on a bridge after she braked suddenly to avoid hitting a dog. The vehicle spun out of control and finally came to a stop at an angle to the traffic. Marsh couldn’t get the engine to start and was too afraid to get out, with cars and trucks swerving past the vehicle. A man driving by 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 began 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 nothing in return.
Marsh and her colleagues contacted donors through the Washington Regional Transplant Community and brought 19 in from around the country for the study. The researchers 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 MRI to map both activity and structure.
Donors showed a greater response in the amygdala than a control group when looking at fearful faces. Separately, the researchers found that the donors had amygdalas that were, on average, 8 percent larger than those of the controls. Similar studies done previously on psychopathic subjects had found the opposite: The amygdalas in psychopathic brains are activated 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 ordinarily commit violent acts against one another. And yet, there are genocides—organized mass killings that require the complicity and passivity of large numbers of people. Time and again, social groups organized along ethnic, cultural, and religious lines have savaged other groups. Nazi Germany’s gas chambers extinguished millions of Jews, the Khmer Rouge slaughtered Cambodians in the killing fields, Rwandan Hutus wielding machetes slaughtered several hundred thousand Tutsis, and Islamic State terrorists massacred Iraq’s Yazidis—virtually every part of the world appears to have witnessed a genocide. Events like these provide ghastly evidence that evil can hold entire communities in its grip.
How the voice of conscience is rendered inconsequential 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 University. In those studies, subjects were asked to deliver electric shocks to a person for failing to answer questions correctly, increasing the voltage with every wrong answer. At the prodding of an experimenter, who was actually an actor in a lab coat, the subjects dialed 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.”
Scholars studying genocides have identified the stages that can cause otherwise decent people to commit murder. It starts when demagogic leaders define a target group as “the other” and claim it is a threat to the interests of supporters. Soon the leaders characterize their targets as subhuman, eroding the in-group’s empathy for “the other.”
Next, society becomes polarized. The target group is discriminated against. “Those planning the genocide say, ‘You are either with us or against us,’ ” says Gregory Stanton, a former U.S. State Department official and founder of Genocide Watch, a nonprofit that works to prevent mass murder. Members of the out-group are sometimes forced to move into designated areas or ghettos that can be easily targeted. This is followed by a phase of preparation, with the architects of the genocide drawing up death lists, stocking weapons, and planning how the rank and file are to execute the killings. Then the massacres begin.
Many of the perpetrators remain untouched by remorse, not because they are incapable of feeling it—as is the case with psychopathic killers—but because they find ways to rationalize the killings. James Waller, a genocide scholar at Keene State College in New Hampshire, says he got a glimpse of this “incredible capacity of the human mind to make sense of and to justify the worst of actions” when he interviewed dozens of Hutu men convicted of slaughtering Tutsis. Some of them had axed children to death. Their rationale, according to Waller, was: “If I didn’t do this, those children would have grown up to come back to kill me. This was something that was a necessity for my people to be safe, for my people to survive.”
Our capacity to feel empathy and channel that into compassion may be innate but it is not immutable. Neither is the tendency to develop psychopathic and antisocial personalities so fixed in childhood as to be unchangeable. In recent years researchers have shown the feasibility of nipping evil in the bud as well as enhancing our pro-social instincts.
The possibility of preventing violent young boys from hardening into lifelong criminals has been put to the test at the Mendota Juvenile Treatment Center in Wisconsin, a facility that houses serious offenders but is run more as a psychiatric unit than as a prison. The adolescents referred to the center come in with already long criminal histories—teenagers who are a threat to themselves and to others. “These are folks who essentially have dropped out of the human race—they don’t have any connection to anyone, and they are in a real antagonistic posture with everybody,” says Michael Caldwell, a senior staff psychologist.
The center attempts, first and foremost, to build a connection with the kids despite their aggressive and offensive behaviors. Even when an inmate hurls feces or sprays urine at staff members—a common occurrence at many correctional institutions—the staff members keep treating the offender with kindness. Based on their conduct, the kids are scored on an anger scale every day. If they do well, they earn certain privileges the following day, such as a chance to play video games. If they score badly, say, by getting into a fight, they don’t get penalized. That’s different from most correctional institutions where bad behavior invites punishment.
Over time the kids start to behave better, says Greg Van Rybroek, the center’s director. Their callous-unemotional traits diminish. Their improved ability to manage their emotions and control their violent impulses seems to endure beyond the walls of Mendota. Adolescents treated in the program committed far fewer offenses over a five-year period after release than those treated elsewhere, a study found. “We don’t have any magic,” Van Rybroek says, “but we’ve actually created a system that considers the world from the youth’s point of view and tries to break it down in a fair and consistent manner.”
Over the past decade, researchers have discovered that our social brain is plastic even in adulthood and that we can be trained to be more kind and generous. A pioneer of studies that have demonstrated this potential is Tania Singer, a social neuroscientist at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany.
Several years ago, Singer and her colleagues found that the brain’s empathic response to watching another person suffer doesn’t automatically lead to a desire to help. It can result in what’s known as empathic distress—a negative emotion that makes the onlooker want to turn away from the sufferer to preserve his or her own sense of well-being.
Singer and others have tested the effects of various training exercises to enhance compassion. A prominent exercise, derived from Buddhist traditions, involves having subjects meditate on a loved one—a parent or a child, for example—directing warmth and kindness toward that individual, and gradually extending those same feelings towards acquaintances, strangers, and even enemies, in an ever widening circle of love. Singer’s group has shown that subjects trained in this form of loving-kindness meditation had a more compassionate response—as measured by the activation of certain brain circuits—than untrained subjects, when watching short film clips of people in pain. In another study, Singer and her colleagues tested the effects of compassion training on helpfulness using a computer game in which subjects guide a smiley emoticon on a computer screen to a treasure chest, opening gates along the way. They can also choose to open gates for other smileys wandering about, looking for treasure. The researchers found that subjects who underwent compassion training were more helpful than those in a control group toward the other smileys—the equivalent of strangers.
That we might be able to mold our brains to be more altruistic is an ennobling prospect for society. One way to bring that future closer, Singer believes, would be to introduce compassion training in schools. “Having empathy, becoming more cooperative, more altruistic, more caring about others, learning to accept your difficult emotions—to equip children with these fundamental capacities will help make them into more responsible citizens,” she says. The result could be a more benevolent world, populated by people like Ashley Aldridge, such that reflexive kindness loses its extraordinariness and becomes a defining trait of humanity.
Yudhijit Bhattacharjee is a contributing writer for National Geographic. Lynn Johnson has photographed many features for the magazine.