When guests arrive at the Yerkes Regional Primate Research Center in Georgia, where I work, they usually pay a visit to the chimpanzees. And often, when she sees them approaching the compound, an adult female chimpanzee named Georgia will hurry to the spigot to collect a mouthful of water. She’ll then casually mingle with the rest of the colony behind the mesh fence, and not even the sharpest observer will notice anything unusual. If necessary, Georgia will wait minutes, with her lips closed, until the visitors come near. Then there will be shrieks, laughs, jumps-- and sometimes falls--when she suddenly sprays them. I have known quite a few apes that are good at surprising people, naive and otherwise. Heini Hediger, the great Swiss zoo biologist, recounts how he--being prepared to meet the challenge and paying attention to the ape’s every move--got drenched by an experienced chimpanzee. I once found myself in a similar situation with Georgia; she had taken a drink from the spigot and was sneaking up to me. I looked her straight in the eye and pointed my finger at her, warning in Dutch, I have seen you! She immediately stepped back, let some of the water dribble from her mouth, and swallowed the rest. I certainly do not wish to claim that she understands Dutch, but she must have sensed that I knew what she was up to, and that I was not going to be an easy target. Now, no doubt even a casual reader will have noticed that in describing Georgia’s actions, I’ve implied human qualities such as intentions, the ability to interpret my own awareness, and a tendency toward mischief. Yet scientific tradition says I should avoid such language--I am committing the sin of anthropomorphism, of turning nonhumans into humans. The word comes from the Greek, meaning human form, and it was the ancient Greeks who first gave the practice a bad reputation. They did not have chimpanzees in mind: the philosopher Xenophanes objected to Homer’s poetry because it treated Zeus and the other gods as if they were people. How could we be so arrogant, Xenophanes asked, as to think that the gods should look like us? If horses could draw pictures, he suggested mockingly, they would no doubt make their gods look like horses. Nowadays the intellectual descendants of Xenophanes warn against perceiving animals to be like ourselves. There are, for example, the behaviorists, who follow psychologist B. F. Skinner in viewing the actions of animals as responses shaped by rewards and punishments rather than the result of internal decision making, emotions, or intentions. They would say that Georgia was not up to anything when she sprayed water on her victims. Far from planning and executing a naughty plot, Georgia merely fell for the irresistible reward of human surprise and annoyance. Whereas any person acting like her would be scolded, arrested, or held accountable, Georgia is somehow innocent. Behaviorists are not the only scientists who have avoided thinking about the inner life of animals. Some sociobiologists--researchers who look for the roots of behavior in evolution--depict animals as survival machines and pre-programmed robots put on Earth to serve their selfish genes. There is a certain metaphorical value to these concepts, but it has been negated by the misunderstanding they’ve created. Such language can give the impression that only genes are entitled to an inner life. No more delusively anthropomorphizing idea has been put forward since the pet-rock craze of the 1970s. In fact, during evolution, genes--a mere batch of molecules--simply multiply at different rates, depending on the traits they produce in an individual. To say that genes are selfish is like saying a snowball growing in size as it rolls down a hill is greedy for snow. Logically, these agnostic attitudes toward a mental life in animals can be valid only if they’re applied to our own species as well. Yet it’s uncommon to find researchers who try to study human behavior as purely a matter of reward and punishment. Describe a person as having intentions, feelings, and thoughts and you most likely won’t encounter much resistance. Our own familiarity with our inner lives overrules whatever some school of thought might claim about us. Yet despite this double standard toward behavior in humans and animals, modern biology leaves us no choice other than to conclude that we are animals. In terms of anatomy, physiology, and neurology we are really no more exceptional than, say, an elephant or a platypus is in its own way. Even such presumed hallmarks of humanity as warfare, politics, culture, morality, and language may not be completely unprecedented. For example, different groups of wild chimpanzees employ different technologies--some fish for termites with sticks, others crack nuts with stones--that are transmitted from one generation to the next through a process reminiscent of human culture. Given these discoveries, we must be very careful not to exaggerate the uniqueness of our species. The ancients apparently never gave much thought to this practice, the opposite of anthropomorphism, and so we lack a word for it. I will call it anthropodenial: a blindness to the humanlike characteristics of other animals, or the animal-like characteristics of ourselves. Those who are in anthropodenial try to build a brick wall to separate humans from the rest of the animal kingdom. They carry on the tradition of René Descartes, who declared that while humans possessed souls, animals were mere automatons. This produced a serious dilemma when Charles Darwin came along: If we descended from such automatons, were we not automatons ourselves? If not, how did we get to be so different? Each time we must ask such a question, another brick is pulled out of the dividing wall, and to me this wall is beginning to look like a slice of Swiss cheese. I work on a daily basis with animals from which it is about as hard to distance yourself as from Lucy, the famed 3.2- million-year-old fossil australopithecine. If we owe Lucy the respect of an ancestor, does this not force a different look at the apes? After all, as far as we can tell, the most significant difference between Lucy and modern chimpanzees is found in their hips, not their craniums. As soon as we admit that animals are far more like our relatives than like machines, then anthropodenial becomes impossible and anthropomorphism becomes inevitable--and scientifically acceptable. But not all forms of anthropomorphism, of course. Popular culture bombards us with examples of animals being humanized for all sorts of purposes, ranging from education to entertainment to satire to propaganda. Walt Disney, for example, made us forget that Mickey is a mouse, and Donald a duck. George Orwell laid a cover of human societal ills over a population of livestock. I was once struck by an advertisement for an oil company that claimed its propane saved the environment, in which a grizzly bear enjoying a pristine landscape had his arm around his mate’s shoulders. In fact, bears are nearsighted and do not form pair-bonds, so the image says more about our own behavior than theirs. Perhaps that was the intent. The problem is, we do not always remember that, when used in this way, anthropomorphism can provide insight only into human affairs and not into the affairs of animals. When my book Chimpanzee Politics came out in France, in 1987, my publisher decided (unbeknownst to me) to put François Mitterrand and Jacques Chirac on the cover with a chimpanzee between them. I can only assume he wanted to imply that these politicians acted like mere apes. Yet by doing so he went completely against the whole point of my book, which was not to ridicule people but to show that chimpanzees live in complex societies full of alliances and power plays that in some ways mirror our own. You can often hear similar attempts at anthropomorphic humor in the crowds that form around the monkey exhibit at a typical zoo. Isn’t it interesting that antelopes, lions, and giraffes rarely elicit hilarity? But people who watch primates end up hooting and yelling, scratching themselves in exaggeration, and pointing at the animals while shouting, I had to look twice, Larry. I thought it was you! In my mind, the laughter reflects anthropodenial: it is a nervous reaction caused by an uncomfortable resemblance. That very resemblance, however, can allow us to make better use of anthropomorphism, but for this we must view it as a means rather than an end. It should not be our goal to find some quality in an animal that is precisely equivalent to an aspect of our own inner lives. Rather, we should use the fact that we are similar to animals to develop ideas we can test. For example, after observing a group of chimpanzees at length, we begin to suspect that some individuals are attempting to deceive others--by giving false alarms to distract unwanted attention from the theft of food or from forbidden sexual activity. Once we frame the observation in such terms, we can devise testable predictions. We can figure out just what it would take to demonstrate deception on the part of chimpanzees. In this way, a speculation is turned into a challenge. Naturally, we must always be on guard. To avoid making silly interpretations based on anthropomorphism, one must always interpret animal behavior in the wider context of a species’ habits and natural history. Without experience with primates, one could imagine that a grinning rhesus monkey must be delighted, or that a chimpanzee running toward another with loud grunts must be in an aggressive mood. But primatologists know from many hours of observation that rhesus monkeys bare their teeth when intimidated, and that chimpanzees often grunt when they meet and embrace. In other words, a grinning rhesus monkey signals submission, and a chimpanzee’s grunting often serves as a greeting. A careful observer may thus arrive at an informed anthropomorphism that is at odds with extrapolations from human behavior. One must also always be aware that some animals are more like ourselves than others. The problem of sharing the experiences of organisms that rely on different senses is a profound one. It was expressed most famously by the philosopher Thomas Nagel when he asked, What is it like to be a bat? A bat perceives its world in pulses of reflected sound, something we creatures of vision would have a hard time imagining. Perhaps even more alien would be the experience of an animal such as the star-nosed mole. With 22 pink, writhing tentacles around its nostrils, it is able to feel microscopic textures on small objects in the mud with the keenest sense of touch of any animal on Earth. Humans can barely imagine a star-nosed mole’s Umwelt--a German term for the environment as perceived by the animal. Obviously, the closer a species is to us, the easier it is to enter its Umwelt. This is why anthropomorphism is not only tempting in the case of apes but also hard to reject on the grounds that we cannot know how they perceive the world. Their sensory systems are essentially the same as ours. Last summer, an ape saved a three-year-old boy. The child, who had fallen 20 feet into the primate exhibit at Chicago’s Brookfield Zoo, was scooped up and carried to safety by Binti Jua, an eight-year-old western lowland female gorilla. The gorilla sat down on a log in a stream, cradling the boy in her lap and patting his back, and then carried him to one of the exhibit doorways before laying him down and continuing on her way. Binti became a celebrity overnight, figuring in the speeches of leading politicians who held her up as an example of much-needed compassion. Some scientists were less lyrical, however. They cautioned that Binti’s motives might have been less noble than they appeared, pointing out that this gorilla had been raised by people and had been taught parental skills with a stuffed animal. The whole affair might have been one of a confused maternal instinct, they claimed. The intriguing thing about this flurry of alternative explanations was that nobody would think of raising similar doubts when a person saves a dog hit by a car. The rescuer might have grown up around a kennel, have been praised for being kind to animals, have a nurturing personality, yet we would still see his behavior as an act of caring. Why then, in Binti’s case, was her background held against her? I am not saying that I know what went through Binti’s head, but I do know that no one had prepared her for this kind of emergency and that it is unlikely that, with her own 17-month-old infant on her back, she was maternally confused. How in the world could such a highly intelligent animal mistake a blond boy in sneakers and a red T-shirt for a juvenile gorilla? Actually, the biggest surprise was how surprised most people were. Students of ape behavior did not feel that Binti had done anything unusual. Jörg Hess, a Swiss gorilla expert, put it most bluntly, The incident can be sensational only for people who don’t know a thing about gorillas. Binti’s action made a deep impression mainly because it benefited a member of our own species, but in my work on the evolution of morality and empathy, I have encountered numerous instances of animals caring for one another. For example, a chimpanzee consoles a victim after a violent attack, placing an arm around him and patting his back. And bonobos (or pygmy chimpanzees) have been known to assist companions new to their quarters in zoos, taking them by the hand to guide them through the maze of corridors connecting parts of their building. These kinds of cases don’t reach the newspapers but are consistent with Binti’s assistance to the unfortunate boy and the idea that apes have a capacity for sympathy. The traditional bulwark against this sort of cognitive interpretation is the principle of parsimony--that we must make as few assumptions as possible when trying to construct a scientific explanation, and that assuming an ape is capable of something like sympathy is too great a leap. But doesn’t that same principle of parsimony argue against assuming a huge cognitive gap when the evolutionary distance between humans and apes is so small? If two closely related species act in the same manner, their underlying mental processes are probably the same, too. The incident at the Brookfield Zoo shows how hard it is to avoid anthropodenial and anthropomorphism at the same time: in trying to avoid thinking of Binti as a human being, we run straight into the realization that Binti’s actions make little sense if we refuse to assume intentions and feelings. In the end we must ask: What kind of risk we are willing to take- -the risk of underestimating animal mental life or the risk of overestimating it? There is no simple answer. But from an evolutionary perspective, Binti’s kindness, like Georgia’s mischief, is most parsimoniously explained in the same way we explain our own behavior--as the result of a complex, and familiar, inner life.