The Fear Factor Read online

  Surely you see where I am going with all of this.

  Allomothering, particularly the forms that involve retrieval and protection, is all but indistinguishable from extraordinary altruism. What my heroic rescuer did for me in 1997, an anonymous neighbor here in Washington, DC, did (in an only slightly less extreme form) for a baby blue jay: he spotted a vulnerable creature in distress, felt an instantaneous urge to help, then risked his own safety by swerving to the roadside and running into traffic to rescue it. An even more comparable animal example can be seen in a recent video I encountered in which a Russian motorist risked his life to rescue a kitten stranded on a busy freeway. The urge to respond with protection and care to the young and the vulnerable, even at significant risk and cost to ourselves, is our birthright as mammals. The urge to respond this way even to youngsters who are not our own is our birthright as group-living social mammals who bear altricial young. But a birthright we share with only a very few other species (domesticated dogs among them) is the urge to respond to creatures of a wide range of ages and species—even if we have never seen them before, even if we might in other circumstances consider them predators or prey or pests—if they manage to trigger our highly sensitive and generous “baby!” alarms. It is this urge that lays the groundwork for the emergence of extraordinary altruism.

  Allomothering is altruism, really. Species that allomother are perennially attuned to vulnerability, distress, and need, and they are primed to respond with nurturing and care when they spot it, even if the object of their care is unfamiliar or unrelated to them. A rat pup rescued by a strange adult female, an oryx calf protected from leopards by a lioness, or a blue jay saved from the street owes its life to the person who rescued it just as surely as I owe my life to my roadside rescuer, or Priscilla Tirado owes her life to Lenny Skutnik, or Zina Williams owes her life to Cory Booker, or thousands of patients in kidney failure have owed their lives to anonymous donors. And it may be exactly the same neural mechanisms that impel all of these behaviors.

  Direct evidence that allomothering provides the basis for altruism came from a recent study of humans and other primates that was conducted by Carel van Schaik at the University of Zurich. He and his colleagues were seeking to identify evolutionary causes of altruism, or what they termed proactive prosociality, in which one individual spontaneously helps another without receiving any gains in return. They tested the tendency of twenty-four distinct species of primates, including lemurs, monkeys, apes, and humans, to engage in such behavior using a simple task in which one individual could work to provide other individuals with food while gaining nothing personally. The researchers then examined what other factors were associated with rates of helping across the various species. They considered factors like brain size (a proxy for intelligence), overall social tolerance, frequency of cooperative hunting, and whether the species tends to form strong pair bonds. They also examined rates of allomothering. They found that across all the primate species, including humans, the single best predictor of altruistic behavior was allomothering. Among macaques and chimpanzees, who allomother very little, altruism among adults was almost nonexistent. Among tamarins and humans, who have very little in common except extensive allomothering, altruism was frequent. Most of the other variables the researchers considered ceased to be related to altruism at all once allomothering was entered into their statistical model. The moral: species who care for one another’s babies are also far more likely to help each other out—to be altruistic—even when they don’t stand to gain anything from it. The researchers concluded that “the adoption of extensive allomaternal care by our hominin ancestors thus provides the most parsimonious explanation for the origin of human hyper-cooperation”—or, in other words, altruism.

  This explanation makes a lot of sense. The evolution of mothering is widely agreed to be the origin of the capacity to care about the welfare of any being outside the self; the evolution of allomothering represents the origin of the capacity to spread that care far and wide rather than hoarding it greedily for one’s own progeny.

  But can the relationship between allomothering and altruism also help us understand the rarer phenomenon of extraordinary altruism in humans? I believe it can.

  In all the species I’ve described, individual variation in allomothering responsiveness is evident. Both the impulse to care for infants and the threshold for what triggers the urge to care vary considerably, not only across species but within each species as well. Wilsoncroft studied only five mother rats (who were all first-time mothers), but found clear variation in their mothering ability and motivation. Most lions kill any baby antelopes or baboons they encounter, but a few do not, and some, like Kamunyak, even go to great lengths to care for and protect them. And of course, humans also vary considerably in their allomothering interest and ability, as well as in their altruistic tendencies. The key question is this: what, if any, direct evidence is there that variation in allomaternal responsiveness underlies extreme acts of human altruism? I have already described it to you.

  Recall that my own research, and that of others, finds that one of the best predictors of altruism is responsiveness to fearful facial expressions. Individuals at the very low end of the caring continuum—psychopaths—are notably insensitive to these expressions, probably as a result of dysfunction in the amygdala. They fail to recognize fearful expressions and fail to show appropriate emotional or behavioral reactions to them. Whereas fearful expressions seem to inhibit aggression and elicit empathic concern in most viewers, people who are psychopathic are relatively impervious to their effects. Altruists, on the other hand, are unusually sensitive to these expressions. They recognize them better and show enhanced emotional reactivity to them.

  The reason this is so incredibly interesting is that, of all the expressions that a human being can make, the one that reconfigures the face to most resemble that of a baby is fear.

  Fearful eyes are wide and large, just like a baby’s eyes, the visible portion of which has already attained adult size by three months of age. Fearful brows are high and angled upward, while the mouth is rounded and low and the jaw is small and receding. Together, these features make fearful faces appear vulnerable, submissive, appeasing, and infantile. Without a doubt, if you were trying to maximize an adult human face’s resemblance to a baby, you’d make it look fearful. That fearful expressions do look babyish has been empirically demonstrated. Some time ago, I published a paper with my undergraduate adviser Robert Kleck and my colleague Reginald Adams Jr. that showed that adopting a fearful expression causes a face to appear more babyish in every sense. Viewers described an array of fearful faces we showed them as infantile and dependent and as possessing all the “key stimuli” of actual babies’ faces, including large eyes, high brows, a small jaw, and a rounded appearance. They perceived fearful faces as babyish even when the faces were altered to retain their key appearance features but to be no longer recognizable as expressing fear, demonstrating that it is the physical appearance of the expression that makes the expresser appear babyish. This may explain why, as my student Jennifer Hammer and I recently found, people respond to fearful expressions with the same patterns of approach that they show infants’ faces, and why this urge to approach is also strongest among people who are the most compassionate (and the least psychopathic). The similarity in this study between how people respond to babies’ faces and how they respond to fearful expressions was striking.

  The fearful facial expression, which incorporates enlarged eyes, high oblique brows, and a rounded mouth and jaw, causes an adult’s face to more closely resemble the face of an infant. Abigail Marsh.

  That fearful expressions evolved to look the particular way they do is almost certain. These expressions, like happiness, anger, and other basic facial expressions, are displayed and recognized by members of many cultures around the world. A meta-analysis conducted by my graduate mentor Nalini Ambady and my colleague Hillary Anger Elfenbein made this clear: they found that in hundreds o
f studies conducted across dozens of cultural groups around the world, viewers can reliably interpret the meaning of fearful, angry, happy, and other expressions displayed by members of even distant cultures. Considering that some of our nearest primate relatives also express their fear, anger, and happiness using similar facial behaviors, it is very unlikely that these expressions are a purely culturally learned or socialized behavior. Instead, these expressions may serve vital functions that have caused them to be evolutionarily conserved across the generations.

  The most powerful evolutionary explanations apply across multiple species—much as van Shaik and his colleagues were able to capture the relationship between allomothering and altruism by looking across multiple species of primates. So it is useful to consider the functions that fearful behaviors serve in other highly allomaternal species, like dogs and wolves. Dogs and wolves employ distinctive behaviors when fearful of attack. They crouch down or roll over, fold their legs and tail close to their bodies, and flatten their ears. They may whimper, lick the jaws of the aggressor, or even urinate. Together, as explained earlier, these behaviors usually trigger the observer’s Violence Inhibition Mechanism and save the cringing, crouching wolf from harm. But why do these behaviors inhibit violence? Or, to alter the emphasis slightly, why do these behaviors inhibit violence? Because, together, they cause the fearful wolf or dog to take on the appearance and other key traits of the one creature that social mammals who bear altricial young are very unlikely to attack: a baby. Key stimuli that set wolf pups apart from their parents are their small size, supine posture, and flattened ears. Pups also emit high-pitched cries, lick their parents’ jaws to request food, and sometimes pee on themselves. That is how these cues inhibit violence: in combination, they very effectively trip not just the aggressor’s “baby!” alarm but the even louder and clangier “oh my God, a baby is in trouble!” alarm, which rapidly suppresses the urge to attack and replaces it with care.

  Human fearful expressions, it seems, may do precisely the same thing—as do other fearful cues, like crouching, frightened body postures, or shrill, high-pitched, fearful screams that echo the high-pitched cries of infants. By signaling both distress and infantile vulnerability, these expressions of fear are tailored with extraordinary precision to move those who encounter them to care. The moral philosopher Adam Smith seems to have intuited this when he wrote: “The plaintive voice of misery, when heard at a distance, will not allow us to be indifferent about the person from whom it comes. As soon as it strikes our ear, it interests us in his fortune, and, if continued, forces us almost involuntarily to fly to his assistance.” This description strikes me as uncannily similar to the way in which many altruists I’ve interviewed described their “almost involuntary” urge to help once they had been alerted to another’s misery. Smith’s only mistake, perhaps, was to infer that this is a response that is equally strong in everyone. That is almost certainly not the case. Rather, those individuals among us who are the most sensitive to these powerfully care-evoking cues are also—not remotely by coincidence—the most altruistic.

  I am willing to bet that by now you can easily guess what part of the brain is considered the entry point into the parental care system. Yup, it’s the amygdala. Of course, the amygdala isn’t solely responsible for parental care any more than it is solely responsible for any other cognitive or behavioral outcome. But it is essential for getting parental care going.

  Incoming sensory information of any motivational significance gets channeled inexorably toward the amygdala. When key baby stimuli are detected—like the large head and eyes and small lower face that create babies’ classically cute appearance—off to the amygdala this information goes. Leslie Zebrowitz and others have found that any face that carries these appearance cues reliably engages the amygdala, regardless of whether the cues belong to an actual baby or an adult who just looks like a baby. Babies’ cries are directed to the amygdala as well, and listening to them results in more activation there than do non-cry sounds of even very similar pitch and loudness. This fits in with the amygdala’s perennial alertness to signs of distress, like the bright pop of a wide, frightened eye or the ragged sound of a scream. The reason for the amygdala’s strong response to fearful cues, then, is likely twofold: fearful expressions and screams not only signal distress but carry infantile features that are important to the amygdala in their own right. The really interesting question is, what happens next? What happens when stimuli like fearful expressions or screams that signal both babyishness and distress arrive in the amygdala together? How does the signal processing in the amygdala lead to the urge to care?

  We already know a little bit of the answer, of course. Seeing or hearing distress cues leads to an internal simulation of the distressed state. Externally, this registers as a slight uptick in heart rate, blood pressure, and sweat on the palms. This is an empathic response, in the sense that it helps the person experiencing these changes recognize and understand the other person’s distress. But another change that occurs when people see someone in distress is a little counterintuitive. Usually, events that cause mild fear reactions in people, like the sight of a snake or a gun, also trigger the urge to flee, to escape. But we know that, in the average person, this is precisely what people do not desire to do in response to others’ distress. The lever tasks I’ve run show that most people respond to others’ fear with approach, not escape.

  This suggests that something approaching alchemy happens within the amygdala in response to others’ distress. Although it enables a viewer to conjure up a little internal simulation of another person’s frightened state—to empathize—this simulated fear results in the urge to approach, which is a behavior totally incompatible with escape but quite compatible with providing care and protection. And this response kicks in very rapidly—in roughly a second. The instant urge to approach someone who is frightened and vulnerable almost certainly results from that person’s similarity to an eminently approachable infant. In our lever studies, people responded the most quickly to both babies and fearful expressions when they categorized the two kinds of faces together instead of separately, suggesting an implicit association between them. What seems to be happening, then, is that after the sight of a fearful face results in a simulated fear response, somewhere within the brain—likely the amygdala, which regulates approach and avoidance behaviors—the rumbling train of behavior that follows switches tracks in the busy railyard of neurons within it. Because a fearful face carries key infantile stimuli, the train is redirected down an entirely separate track toward caring, protective behaviors. Empathy has been transformed into caring.

  But who, or what, is doing this switching? In all likelihood, the switchman responsible for turning social lead into gold is not any single brain structure but rather a brain chemical that changes the activity of multiple brain structures—the amygdala included—simultaneously. This chemical is a neurotransmitter composed of nine linked amino acids produced in only one place on earth, which is the hypothalamus of all living mammals. This molecular alchemist is called oxytocin.

  It is difficult to specify exactly when or how the first molecule of oxytocin came into being, but it almost certainly was in the brain of a cynodont, as all the cynodonts’ descendants—and only their descendants—produce it. Oxytocin—and its sister hormone vasopressin—probably originally cleaved from an older hormone called vasotocin that fish, reptiles (including sea turtles), amphibians, and birds still produce today, and which differs from oxytocin by only one amino acid.

  But what a difference an amino acid makes!

  Oxytocin is responsible for two key physiological functions that mammals require to reproduce. The first is stimulating contractions in the smooth muscles of the uterus to get babies out of it. If you or someone you know has had labor induced by a drug called Pitocin, you know how effectively oxytocin brings the walls of the uterus crashing inward. Pitocin is just a Frankenstein form of oxytocin created in a laboratory. One of my two labors was induced
with Pitocin, and after the nurse inserted the IV and sent it flowing through my veins, I went from no contractions to wall-clawing labor within two hours. I imagine I would have found it fascinating from a scientific perspective had I not been preoccupied by the sensation that I might be about to explode.