Nearly four years ago, a visitor to Brookfield Zoo, outside Chicago, captured an extraordinary event on video. A 3-year-old boy fell into a gorilla enclosure and was knocked unconscious. Within moments, Binti Jua, a female gorilla, approached, picked up the unconscious boy, and cradled him in her arms. Then she walked over and gently put the boy down in front of the caretaker's door. The event captured the nation's heart as newspaper headlines blared: "Gorilla Saves Boy."
Most reports suggested that Binti saved the boy because she felt empathy for him. Although there is no ambiguity about what the gorilla did, there are a lot of questions about why. Did she realize the boy was unconscious? Was she concerned about his well-being? Would she have acted in the same way toward a conscious boy, a cat, a teddy bear, or a bag of potato chips?
Despite what the headlines implied about Binti’s moral fiber, the answer is by no means clear. Studies by developmental psychologists Susan Carey and Frank Keil, for example, have shown that children don’t fully grasp the distinction between when a being is dead or alive until they are almost 10 years old. And to date, no study of ape intelligence comes close to showing that orangutans, gorillas, or chimpanzees have the mental sophistication of a 10-year-old human. We can only guess why Binti did what she did. And one incident is not enough to warrant conclusions.
But Binti’s actions do raise the public and scientific interest in the broad question of what mental traits cause us to behave morally and to what extent other animals possess those tools. As a psychologist, I’m interested in the techniques we use to get at these questions: Can other creatures share, cooperate, punish cheaters, show empathy, and act altruistically?
In a 1988 study, University of Zurich ethologist Eduard Stammbach set up an experiment with long-tailed macaque monkeys he hoped might identify their ability to rein in aggressive behavior and act cooperatively. First each monkey was trained to press a lever on a machine to receive a popcorn treat. Once each animal knew what to do and when, subgroups were created, and a low-ranking member in each subgroup was trained to press a set of levers in a specific sequence that caused the machine to deliver enough popcorn for three individuals.
At first, high-ranking individuals threatened low-ranking individuals to keep them away from the dispenser altogether. Then the high-ranking individuals learned that the low-ranking individuals had a unique skill, so they followed them to the machine and waited to grab all the popcorn. Before long the low-ranking specialists stopped operating the machine. But their strike didn’t last long. Some higher-ranking individuals changed. Rather than chase specialists away or eat all their popcorn, they began to inhibit their aggression. They approached peacefully and allowed the lower-ranking specialists to eat a portion of the popcorn. Further, some high-ranking individuals started grooming specialists more often, even during periods when the machine was inoperative. Although this attitude change enabled low-ranking specialists to access food that would normally be unobtainable, it had no impact on their dominance rank within the group. Specialists kept their low rank but were allowed a moment at the high table when their skills were of use to the royalty.
Other experiments have found that monkeys even have a rudimentary sense of ownership and respect for property. Although these might seem to be srictly human concerns, territorial animals such as sunfish, lizards, sparrows, and gibbons are invested in these issues. The space that a territory owner defends is like his property, and an intruder’s respect reveals his acknowledgement of ownership and property rights.
In a 1991 study, for example, University of Zurich ethologists Hans Kummer and Marina Cords tested macaques that had something other macaques wanted--a see-through tube filled with raisins. The tube was either fixed to a wall or freestanding. If it was freestanding, it was attached to a long or a short piece of rope, or no rope at all. A subordinate animal was allowed first crack at the tube in all the various conditions. Then researchers observed how the more dominant individuals reacted. Although dominants often take resources away from subordinates, the experiments revealed rules underlying their responses. Consistently, dominants took ownership of fixed tubes more often than free tubes, and took over free tubes when the subordinates failed to carry them. Staying close to the tube and looking at it were not sufficient cues of ownership from the dominant’s perspective. A dominant macaque would appear to inhibit its impulse to grab the tube if a subordinate held it close to its body. Here, then, is an intriguing example of how inhibition plays a crucial role in maintaining conventions among monkeys.
But in any social situation with conventions, individuals often find that it pays to break the rules. Would such rule-breakers be punished? To explore this possibility, I conducted experiments on the island of Cayo Santiago, a research station near Puerto Rico that is home to some 800 rhesus monkeys. This particular species has an interesting convention: Unlike long-tailed macaques, which don’t share food, rhesus monkeys tend to call out when they find food. In the study, my colleagues and I located lone individuals and presented them with a small stash of food. Their first response was to look around, presumably to decide if there were enemies near. A few individuals waited and waited and then, as if in an infantry combat crouch, moved cautiously toward the food. Only half the discoverers called out. When they were detected by other group members, some were aggressively attacked. Our initial suspicion was that those who were being attacked were lower-ranking than those who were not. This hunch turned out to be false. Surprisingly, both high- and low-ranking individuals were attacked. Whether or not they were attacked seemed to depend on their vocal behavior. Silent discoverers who were caught with food were attacked more often and more severely than those who cried out. It was as if individuals were being punished for being inappropriately silent, for deceptively withholding information about a rich food source.
In a second experiment, we tested peripheral males, outsiders shifting between groups. Of 26 outsider males who were shown food, not one called out. They beelined to the food and either consumed it on the spot or gobbled a few pieces and then moved to a new location with a stash. Even if other monkeys discovered them with the food, the outsiders were never attacked. Thus, it seemed that members of an established rhesus community abide by a rule that says: Attack members that find food and don’t share it. And the corollary seems to be: Why bother risking harm by assaulting onetime transgressors?
Thus research indicates that animals can inhibit their impulses and punish those who violate community rules. But what about empathy? What about Binti? Unless we can establish that animals understand the thoughts and feelings of others, we cannot assume that their behavior is moral as humans understand the word. Codes of moral behavior are founded on beliefs of right and wrong. How we form those beliefs is based on an idea of justice, a consideration of how particular actions affect others. And to understand how our behavior affects others requires empathy.
Ethologist Frans de Waal has offered several observations of apparent empathy among nonhuman primates in his 1996 book Good Natured: The Origins of Right and Wrong in Humans and Other Animals, but richer insights come from a series of studies published about 40 years ago, when standards for animal welfare were minimal. Today the experiments would be deemed unethical, but they do provide a window on animal emotion that has yet to be opened by more recent observations.
The experiments were designed by psychologist Robert Miller and his colleagues to see if a monkey could interpret another monkey’s facial expression, a presumed indicator of emotion. First, a researcher trained rhesus monkeys to pull a lever to avoid electroshock after hearing a specific sound. Then one of the monkeys, the actor, was put in a room with a lever and a live television image of a second animal, the receiver, which was out of sight and earshot. The receiver was exposed to the sound that indicated a shock was coming but lacked a lever to avoid it.
The assumption underlying this experiment was that the receiver would hear the sound, anticipate the shock, and show fear on its face. If the actor understood the receiver’s facial expressions, then he would use this information to pull his lever. If the actor failed, both animals received a shock. Because shock trials were presented randomly, and neither animal could hear the other, there was no way to predict the timing of a response except by using the receiver’s image in the monitor. As it turned out, the actor pulled the lever significantly more when the receiver heard the sound. Miller concluded that the actor was able to read the receiver’s facial expressions. Moreover, he and his colleagues suggested that the animals behaved cooperatively: to avoid the shock, the receiver gave a signal and the actor read the receiver’s signal.
Did the receiver intend to provide information to the actor? Was this a cooperative effort? The receiver, to be sure, must have felt helpless and afraid. But to establish that he was signaling the actor, one would have to demonstrate that he knew about the actor’s presence. And, given the experimental design, he certainly did not. Rather, the receiver’s response was elicited by the sound, perhaps as reflexively as we kick out our foot in response to the doctor’s tiny mallet. It seems likely that the actor picked up on a change in the receiver’s activity, one that was consistent enough to predict the shock. Using an expression to predict a response is not the same as seeing the expression as an indication of another’s emotions.
This experiment leaves many loose ends. Although it is clear that rhesus monkeys can learn to avoid shock by attending to a facial expression, we don’t know if this response is motivated by empathy, and empathy is necessary for altruism. One has to feel what it would be like to be someone else, to feel fear, pain, or joy. We don’t know whether the actor was even aware of the receiver’s feeling. There is no reason for the actor to care. From the actor’s perspective, all that matters is that the image displayed on the video monitor functions as a reliable predictor of shock. A better experiment would allow the actor to see what was happening to the receiver but would restrict the shock to the receiver.
In a 1964 study, Jules Masserman and his colleagues ran a different experiment, again with rhesus monkeys. An actor was trained to pull one of two chains to receive its food in response to a brief flash of blue or red light. Next, a receiver was put into cage nearby, where the first could see it. The experimenter then changed the consequences of responding to the color of the flash. Pulling in response to one delivered food; pulling in response to the other delivered both food to the actor and a severe shock to the receiver. Most actors tested pulled the chain delivering the shock far less often than the chain delivering food. Two of the 15 actors even stopped pulling both chains for between 5 to 12 days; interestingly, these two had both experienced being shocked. When the actors were paired with new receivers, most continued to refrain from pulling the chain that delivered the shock. There was a tendency for pairs that knew each other well to show more altruistic behavior than pairs that were unfamiliar.
What is most remarkable about this last experiment is the possibility that some monkeys refrained from eating to avoid injuring another. Perhaps the actors empathized, feeling what it would be like to receive the shock. Alternatively, perhaps seeing another monkey grimace in pain is unpleasant or threatening, and rhesus monkeys will do whatever they can to avoid unpleasant conditions. Or perhaps the actor worried that one day it might be the recipient of a shock. Although refraining from eating appears to be a response of empathy or sympathy, it may actually be a selfish response.
As the experiments show, animals are by no means robots driven solely by instinctual responses. They are sensitive to their social and ecological environments, and under certain conditions they can inhibit one response and favor another. Moreover, they can punish others and sometimes alleviate another’s pain. But no experiment to date has provided evidence that animals are aware of others’ beliefs or intentions. And without such awareness, there can be no ethical judgment.
Asking what it means to be moral challenges us to think about how our own capacity for moral agency came about. Monkeys demonstrate rulelike strategies for promoting the welfare of a group, including maintaining peace, observing boundaries, and sharing food. And they can abide by these rules without necessarily understanding them. Humans are a different kind of animal: We can consciously evaluate whether behavior is right or wrong, but we tend to do so depending on the conventions of our society. In that regard, the roots of our moral intuition are entwined with the self-interest shown by other animals. What we don’t know is exactly when the uniquely human capacity for empathy and justice emerged in our ancestors and how cultures build on a universal moral sense. What is certain is that our moral potential is still far from fully realized. As Agesilaus, a Spartan king, said, “If all men were just, there would be no need of valor.”