Suppose that you are walking at night, and you see someone on your side of the street coming toward you, about to pass you. Is his face angry, or is he just thinking seriously about something?

Your answer to that question may well depend on the faces that you are used to seeing. If you tend to encounter a lot of very angry faces, your threshold for considering a face “angry” is probably high, and so you might well think: He’s thinking seriously about something. But if the faces you encounter are rarely angry, and if you see a lot of friendly people, you might think: He looks pretty angry to me.

The phenomenon I am describing has a name: “prevalence-induced concept change.” It has in fact been demonstrated for judgments about whether faces are angry. When people have seen a lot of very angry faces, they are less likely to perceive arguably angry faces as angry. Prevalence-induced concept change has also been found for ethical judgments: When people see a lot of clearly unethical behavior, they are less likely to characterize arguably unethical behavior as unethical. If, for example, you live in a nation in which corruption is open and rampant, you might not be much agitated when you learn that your neighbors cheat on their taxes.

Prevalence-induced concept change should be seen as a demonstration of the immense power of the normal. What people normally see, or see as normal, establishes the baseline against which they make judgments about both facts and values. That principle helps explain challenges to democracy as well. If a nation is experiencing a significant increase in corruption, or a major deterioration in practices of self-government, its citizens might not be much alarmed today about something that would have been horrifying five years previously.

Christine Webb, a primatologist at New York University, is focused on “the human superiority complex,” the idea that human beings are just better and more deserving than are members of other species, and on the extent to which human beings take themselves as the baseline against which all living creatures are measured. As Hamlet exclaimed: “What a piece of work is man! How noble in reason!… The paragon of animals!” In Webb’s view, human exceptionalism is all around us, and it damages science, the natural environment, democratic choices, and ordinary (human) life. People believe in human superiority even though we are hardly the biggest, the fastest, or the strongest. Eagles see a lot better than we do. Sea sponges live much longer. Dolphins are really good at echolocation; people are generally really bad at it. And yet we keep proclaiming how special we are. As Webb puts it, “Hamlet got one thing right: we’re a piece of work.”

Webb does illuminating academic work on chimpanzees, bonobos, capuchin monkeys, and elephants. She studies empathy and consolation in particular. Do chimpanzees, for example, console bereaved mothers? In her new book, The Arrogant Ape, Webb turns to large ethical questions. She gives pride of place to the concept of the “umwelt,” introduced in 1909 by the Estonian-German biologist Jakob von Uexküll, who used the word to capture the world as it is experienced by particular organisms. I have two Labrador Retrievers, Snow and Finley, and on most days, I take them for a walk on a local trail. Every time, it is immediately apparent that they are perceiving and sensing things that are imperceptible to me. They hear things that I don’t; they pause to smell things that I cannot. Their world is not my world. Webb offers a host of more vivid examples, and they seem miraculous, the stuff of science fiction.

For example, hummingbirds can see colors that human beings are not even able to imagine. Elephants have an astonishing sense of smell, which enables them to detect sources of water from miles away. Owls can hear the heartbeat of a mouse from a distance of 25 feet. Because of echolocation, dolphins perceive sound in three dimensions. They know what is on the inside of proximate objects; as they swim toward you, they might be able to sense your internal organs. Pronghorn antelopes can run a marathon in 40 minutes, and their vision is far better than ours. On a clear night, Webb notes, they might be able to see the rings of Saturn. We all know that there are five senses, but it’s more accurate to say that there are five human senses. Sharks can sense electric currents. Sea turtles can perceive the earth’s magnetic field, which helps them to navigate tremendous distances. Some snakes, like pythons, are able to sense thermal radiation. Scientists can give many more examples, and there’s much that they don’t yet know.

Webb marshals these and other findings to show that when we assess other animals, we use human beings as the baseline. Consider the question of self-awareness. Using visual tests, scientists find that human children can recognize themselves in a mirror by the age of three—and that almost no other species can do that. But does that really mean that human beings are uniquely capable of recognizing themselves? It turns out that dogs, who rely more on smell than sight, can indeed recognize themselves, if we test by reference to odor; they can distinguish between their own odor and that of other dogs. (Can you do that?) In this sense, dogs too show self-awareness. Webb argues that the human yardstick is pervasively used to assess the abilities of nonhuman animals. That is biased, she writes, “because each species fulfills a different cognitive niche. There are multiple intelligences!”

Webb contends that many of our tests of the abilities of nonhuman animals are skewed for another reason: We study them under highly artificial conditions, in which they are often miserable, stressed, and suffering. Try caging human beings and seeing how well they perform on cognitive tests. As she puts it, “A laboratory environment can rarely (if ever) adequately simulate the natural circumstances of wild animals in an ecologically meaningful way.” Suppose, for example, that we are investigating “prosociality”—the question of whether nonhuman animals will share food or cooperate with one another. In the laboratory, captive chimpanzees do not appear to do that. But in the wild, chimpanzees behave differently: They share meat and other food (including nuts and honey), and they also share tools. During hunting, chimpanzees are especially willing to cooperate. In natural environments, the differences between human beings and apes are not nearly so stark. Nor is the point limited to apes. Cows, pigs, goats, and even salmon are a lot smarter and happier in the wild than in captive environments.

Webb now limits her own research to sanctuaries and the wild. She is especially focused on animal emotions. As I have noted, one of her central academic interests is whether chimpanzees console one another after the death of a loved one or after conflicts. Consolation is, of course, an indicator of empathy. In one case, Webb found that after an adult chimpanzee gave birth to a stillborn infant, group members followed her closely, groomed her, and hugged her. “They were attempting to reassure her,” Webb writes, “providing the first clear evidence that other animals console bereaved group members.” Return to the idea of the umwelt: Webb believes that we underestimate the emotional and cognitive experience of other species, including those to which we are not closely related, such as birds and crustaceans. Evolution often finds diverse ways to achieve the same ends. Other species might not have exactly the same abilities that we do, but with the abilities they do have, they might be able to do what we do anyway. For example, crustaceans do not have a visual cortex, but they are nonetheless able to see. Why, Webb asks, should we make human beings the measure of all things?

It would be possible to read Webb as demonstrating that nonhuman animals are a lot more like us than we think. But that is not at all her intention. On the contrary, she rejects the argument, identified and also rejected by the philosopher Martha Nussbaum, that the nonhumans animals who are most like us deserve the most protection, what Nussbaum calls the “so like us” approach. (This is also part of the title of an old documentary about Jane Goodall’s work.) Webb sees that argument as a well-meaning but objectionable form of human exceptionalism. Why should it matter that they are like us? Why is that necessary? With Nussbaum, Webb insists that species are “wonderfully different,” and that it is wrong to try to line them up along a unitary scale and to ask how they rank. Use of the human yardstick, embodied in the claim of “so like us,” is a form of blindness that prevents us from seeing the sheer variety of life’s capacities, including cognitive ones. As Nussbaum writes, “Anthropocentrism is a phony sort of arrogance.”

Webb is especially concerned that the commitment to human exceptionalism tends to be invisible; it is an unspoken assumption, a kind of given. Most broadly, she argues for a sense of awe. Awe “seems to keep egotism in check, prompting a reduction in self-focus and making personal concerns and goals appear less significant.” Awe leads in turn to humility, which, she thinks, is an “unsung virtue” that we ought to apply “to how we relate to the rest of the living world.” She thinks that experiencing humility leads to better science and better lives. That is one reason why she likes the idea of “hope,” which she opposes to “optimism.” Optimism is probabilistic; it suggests that with some probability, things will turn out well. Hope, by contrast, “centers on potential and uncertainty,” and it “is more aligned with humility.”

Webb’s vivid and moving book can be read in two different ways. You can read it as a linked set of striking and even dazzling scientific findings about the capacities of nonhuman animals—how they think, what (and how much) they feel, and what they are able to do. The findings are inspiring and potentially life-changing. After reading Webb’s book, it is hard to think of nonhuman animals in the same way. You might love dogs (I certainly do), but if you attend to what Webb has to say, you will appreciate them more and differently, and perhaps show them greater respect. And if you are inclined to evaluate nonhuman animals by reference to the capacities of human beings, Webb will get you to rethink. She demonstrates that if science insists on using the human umwelt, it will deprive itself of a world of knowledge—and that if ordinary people do that, they will have a blinkered understanding of other living beings. It’s as if Webb takes a black-and-white world and reveals that it’s full of colors.

Webb’s book is also a distinctive moral argument for protecting the well-being of nonhuman animals, informed by but not reducible to scientific findings. To get hold of the distinctiveness of that argument, consider what is probably the most famous passage ever written on the topic of animal rights, by the philosopher Jeremy Bentham, founder of utilitarianism:

The day may come, when the rest of the animal creation may acquire those rights which never could have been withholden from them but by the hand of tyranny.… [A] full-grown horse or dog is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day, or a week, or even a month, old. But suppose the case were otherwise, what would it avail? the question is not, Can they reason? nor, Can they talk? but, Can they suffer?

Webb’s book makes that passage seem not at all wrong, but inadequate, thin, and a bit obtuse. To be sure, she enthusiastically agrees that suffering matters, and she offers a great deal of evidence that nonhuman animals can indeed suffer. But when Bentham says that suffering is “the question,” what does he mean, exactly? Why is that the question? In his own way, Bentham (and some though not all of his utilitarian followers) can be taken to be using human beings as the yardstick, with the important notation that with respect to the capacity to suffer, human beings are not exceptional at all. On that count, nonhuman animals are indeed so like us. Webb’s response is essentially this: “The question is not, Can they reason? Nor, can they talk? Nor, can they suffer? Nor, are they similar to us? But, what are they capable of?”

That is a more open-ended question. It is humbler. It does not load any dice. It is also a kind of doorway to a host of further questions. If we ask what nonhuman animals are capable of, we should certainly seek to reduce suffering; but we might also want to promote, and certainly not damage or stifle, a range of other capabilities on their part. After all, a good life for people includes much more than an absence of pain. If a powerful species put in control of our planet focused only on reducing our suffering, we would not think that they understood us at all. You can read Webb as endorsing the capabilities approach that Nussbaum elaborated in her Justice for Animals; Webb doesn’t do so explicitly, but her argument is certainly compatible with that approach. What makes Webb’s account novel and fresh is the sheer wealth of detail that she offers about the capabilities of nonhuman animals, and her use of that detail to support her plea for humility and awe.

Webb is a scientist who thinks that human exceptionalism is unscientific, but she is also a reformer who thinks that human exceptionalism is wrong. She claims that it “is at the root of the ecological crisis.” In her account, scientific experimentation on nonhuman animals is often cruel, and because laboratory conditions are so artificial, its findings are often bogus. She does not think that gorillas, chimpanzees, dogs, and rats should be seen as objects for human use. (If you are deciding whether to become a vegetarian, Webb might make that decision seem really easy.) She also urges that human exceptionalism is not good for people; it is “backfiring on us today, spurring forest fires, sea level rise, mass extinctions, and pandemics like the coronavirus.” In her view, human exceptionalism is a literally dangerous way of seeing things, a product of “brainwashing” that can be found wherever you look.

Webb’s claims about the concrete consequences of human exceptionalism may or may not be right; the causal chains are not simple here. Nor is her remarkable book a policy manual; it operates at a higher level of abstraction than that. But her ultimate goal for arrogant apes, including scientists, is resonant. It is nothing less than a re-enchantment of the world.