Inside Animal Minds: The New Science of Animal Intelligence (2 page)

Alex had lived his entire life in captivity, but he knew that beyond the lab’s door, there was a hallway and a tall window framing a leafy elm tree. He liked to see the tree, so Pepperberg put her hand out for him to climb aboard. She walked him down the hall into the tree’s green light.

“Good boy! Good birdie,” Alex said, bobbing on her hand.

“Yes, you’re a good boy. You’re a good birdie.” And she kissed his feathered head.

He was a good birdie until the end, and Pepperberg was happy to
report that he had finally mastered the word
seven
before he died.

Many of Alex’s cognitive skills, such as his ability to understand the concepts of same and different, are generally ascribed only to higher mammals, particularly primates. But parrots, like great apes (and humans), live a long time in complex societies. And like primates, these birds must keep track of the dynamics of changing relationships and environments.

“They need to be able to distinguish colors to know when a fruit is ripe or unripe,” Pepperberg noted. “They need to categorize things—what’s edible, what isn’t—and to know the shapes of predators. And it helps to have a concept of numbers if you need to keep track of your flock, and to know who’s single and who’s paired up. For a long-lived bird, you can’t do all of this with instinct; cognition must be involved.”

Being able mentally to divide the world into simple abstract categories would seem a valuable skill for many organisms. Is that ability, then, part of the evolutionary drive that led to human intelligence?

Charles Darwin, who attempted to explain how human intelligence developed, extended his theory of evolution to the human brain: Like the rest of our physiology, intelligence must have evolved from simpler organisms, because all animals face the same general challenges of life. They need to find mates, food, and a path through the woods, sea, or sky—tasks that Darwin argued require problem-solving and categorizing abilities. Indeed, Darwin went so far as to suggest that earthworms are cognitive beings because, based on his close observations, they have to make judgments about the kinds of leafy matter they use to block their tunnels. He hadn’t expected to find thinking invertebrates, and remarked that the hint of earthworm intelligence “has surprised me more than anything else in regard to worms.”

To Darwin, the earthworm discovery demonstrated that degrees
of intelligence could be found throughout the animal kingdom. But the Darwinian approach to animal intelligence was cast aside in the early 20th century, when researchers decided that field observations were simply “anecdotes” usually tainted by anthropomorphism. In an effort to be more rigorous, many embraced behaviorism, which regarded animals as little more than machines, and focused their studies on the laboratory white rat—because one “machine” would behave like any other.

But if animals are simply machines, how can the appearance of human intelligence be explained? Without Darwin’s evolutionary perspective, the greater cognitive skills of people did not make sense biologically. Slowly, the pendulum has swung away from the animal-as-machine model and back toward Darwin. A whole range of animal studies now suggests that the roots of cognition are deep, widespread, and highly malleable.

Just how easily new mental skills can evolve is perhaps best illustrated by dogs. Most owners talk to their dogs and expect them to understand. But this canine talent wasn’t fully appreciated until a border collie named Rico appeared on a German TV game show in 2001. Rico knew the names of some 200 toys, and acquired the names of new ones with ease.

Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig heard about Rico and arranged a meeting with him and his owners. That led to a scientific report revealing Rico’s uncanny language ability: He could learn and remember words as quickly as a toddler. Other scientists had shown that two-year-old children—who acquire around ten new words a day—have an innate set of principles that guides this task. The ability is seen as one of the key building blocks in language acquisition. The Max Planck scientists suspect that the same principles guided Rico’s word learning, and that the technique he used for learning words was identical to that of humans.

To find more examples, the scientists read all the letters from hundreds of people claiming that their dogs had Rico’s talent. In fact, only two—both border collies—had comparable skills. One of them—the researchers call her Betsy—has a vocabulary of more than 300 words.

“Even our closest relatives, the great apes, can’t do what Betsy can do—hear a word only once or twice and know that the acoustic pattern stands for something,” said Juliane Kaminski, a cognitive psychologist who worked with Rico and is now studying Betsy. She and her colleague Sebastian Tempelmann had come to Betsy’s home in Vienna to give her a fresh battery of tests. Kaminski petted Betsy, while Tempelmann set up a video camera.

“Dogs’ understanding of human forms of communication is something new that has evolved,” Kaminski said, “something that’s developed in them because of their long association with humans.” Although Kaminski has not yet tested wolves, she doubts they have this language skill. “Maybe these collies are especially good at it because they’re working dogs and highly motivated, and in their traditional herding jobs, they must listen very closely to their owners.”

Scientists think that dogs were domesticated about 15,000 years ago, a relatively short time in which to evolve language skills. But how similar are these skills to those of humans? For abstract thinking, we employ symbols, letting one thing stand for another. Kaminski and Tempelmann were testing whether dogs can do this too.

Betsy’s owner—whose pseudonym is Schaefer—summoned Betsy, who obediently stretched out at Schaefer’s feet, eyes fixed on her face. Whenever Schaefer spoke, Betsy attentively cocked her head from side to side.

Kaminski handed Schaefer a stack of color photographs and asked her to choose one. Each image depicted a dog’s toy against a
white background—toys Betsy had never seen before. They weren’t actual toys; they were only images of toys. Could Betsy connect a two-dimensional picture to a three-dimensional object?

Schaefer held up a picture of a fuzzy, rainbow-colored Frisbee and urged Betsy to find it. Betsy studied the photograph and Schaefer’s face, then ran into the kitchen, where the Frisbee was placed among three other toys and photographs of each toy. Betsy brought either the Frisbee or the photograph of the Frisbee to Schaefer every time.

“It wouldn’t have been wrong if she’d just brought the photograph,” Kaminski said. “But I think Betsy can use a picture, without a name, to find an object. Still, it will take many more tests to prove this.”

Even then, Kaminski was unsure that other scientists would ever accept her discovery because Betsy’s abstract skill, as minor as it may seem to us, may tread all too closely to human thinking.

Still, we remain the inventive species. No other animal has built skyscrapers, written sonnets, or made a computer. Yet animal researchers say that creativity, like other forms of intelligence, did not simply spring from nothingness. It, too, has evolved.

“People were surprised to discover that chimpanzees make tools,” said Alex Kacelnik, a behavioral ecologist at Oxford University, referring to the straws and sticks chimpanzees shape to pull termites from their nests. “But people also thought, ‘Well, they share our ancestry—of course they’re smart.’ Now we’re finding these kinds of exceptional behaviors in some species of birds. But we don’t have a recently shared ancestry with birds. Their evolutionary history is very different; our last common ancestor with all birds was a reptile that lived over 300 million years ago.

“This is not trivial,” Kacelnik continued. “It means that evolution can invent similar forms of advanced intelligence more than once—that it’s not something reserved only for primates or mammals.”

Kacelnik and his colleagues are studying one of these smart species, the New Caledonian crow, which lives in the forests of that Pacific island. New Caledonian crows are among the most skilled of tool-making and tool-using birds, forming probes and hooks from sticks and leaf stems to poke into the crowns of the palm trees, where fat grubs hide. Because these birds, like chimpanzees, make and use tools, researchers can look for similarities in the evolutionary processes that shaped their brains. Something about the environments of both species favored the evolution of tool-making neural powers.

But is their use of tools rigid and limited, or can they be inventive? Do they have what researchers call mental flexibility? Chimpanzees certainly do. In the wild, a chimpanzee may use four sticks of different sizes to extract honey from a bee’s nest. And in captivity, they can figure out how to position several boxes so they can retrieve a banana hanging from a rope.

Answering that question for New Caledonian crows—extremely shy birds—wasn’t easy. Even after years of observing them in the wild, researchers couldn’t determine if the birds’ ability was innate, or if they learned to make and use their tools by watching one another. If it was a genetically inherited skill, could they, like the chimps, use their talent in different, creative ways?

To find out, Kacelnik and his students brought 23 crows of varying ages (all but one caught in the wild) to the aviary in his Oxford lab and let them mate. Four hatchlings were raised in captivity, and all were carefully kept away from the adults, so they had no opportunity to be taught about tools. Yet, soon after they fledged, all picked up sticks to probe busily into cracks and shaped different materials into tools. “So we know that at least the bases of tool use are inherited,” Kacelnik said. “And now the question is, what else can they do with tools?”

Plenty. In his office, Kacelnik played a video of a test he’d done
with one of the wild-caught crows, Betty, who had died recently from an infection. In the film, Betty flies into a room. She’s a glossy-black bird with a crow’s bright, inquisitive eyes, and she immediately spies the test before her: a glass tube with a tiny basket lodged in its center. The basket holds a bit of meat. The scientists had placed two pieces of wire in the room. One was bent into a hook, the other was straight. They figured Betty would choose the hook to lift the basket by its handle.

But experiments don’t always go according to plan. Another crow had stolen the hook before Betty could find it. Betty is undeterred. She looks at the meat in the basket, and then spots the straight piece of wire. She picks it up with her beak, pushes one end into a crack in the floor, and uses her beak to bend the other end into a hook. Thus armed, she lifts the basket out of the tube.

“This was the first time Betty had ever seen a piece of wire like this,” Kacelnik said. “But she knew she could use it to make a hook and exactly where she needed to bend it to make the size she needed.”

They gave Betty other tests, each requiring a slightly different solution, such as making a hook out of a flat piece of aluminum rather than a wire. Each time, Betty invented a new tool and solved the problem. “It means she had a mental representation of what it was she wanted to make. Now that,” Kacelnik said, “is a major kind of cognitive sophistication.”

This is the larger lesson of animal cognition research: It humbles us. We are not alone in our ability to invent or plan or to contemplate ourselves—or even to plot and lie.

Deceptive acts require a complicated form of thinking, because you must be able to attribute intentions to the other person and predict that person’s behavior. One school of thought argues that human intelligence evolved partly because of the pressure of living in a complex society of calculating beings. Chimpanzees,
orangutans, gorillas, and bonobos share this capacity with us. In the wild, primatologists have seen apes hide food from the alpha male or have sex behind his back.

Birds, too, can cheat. Laboratory studies show that western scrub jays can know another bird’s intentions and act on that knowledge. A jay that has stolen food itself, for example, knows that if another jay watches it hide a nut, there’s a chance the nut will be stolen. So the first jay will return to move the nut when the other jay is gone.

“It’s some of the best evidence so far of experience projection in another species,” said Nicky Clayton in her aviary lab at Cambridge University. “I would describe it as, ‘I know that you know where I have hidden my stash of food, and if I were in your shoes I’d steal it, so I’m going to move my stash to a place you don’t know about.’ ”

This study, by Clayton and her colleague Nathan Emery, is the first to show the kind of ecological pressures, such as the need to hide food for winter use, that would lead to the evolution of such mental abilities. Most provocatively, her research demonstrates that some birds possess what is often considered another uniquely human skill: the ability to recall a specific past event. Scrub jays, for example, seem to know how long ago they cached a particular kind of food, and they manage to retrieve it before it spoils.

Human cognitive psychologists call this kind of memory “episodic memory,” and argue that it can exist only in a species that can mentally travel back in time. Despite Clayton’s studies, some refuse to concede this ability to the jays. “Animals are stuck in time,” explained Sara Shettleworth, a comparative psychologist at the University of Toronto in Canada, meaning that they don’t distinguish among past, present, and future the way humans do. Because animals lack language, she said, they probably also lack “the extra layer of imagination and explanation” that provides the running mental narrative accompanying our actions.

Such skepticism is a challenge for Clayton. “We have good
evidence that the jays remember the what, where, and when of specific caching events, which is the original definition of episodic memory. But now the goalposts have moved.” It’s a common complaint among animal researchers. Whenever they find a mental skill in another species that is reminiscent of a special human ability, the human cognition scientists change the definition. But the animal researchers may underestimate their power—their discoveries compel the human side to shore up the divide.