“It’s not just living in big groups, it’s the complexity of social life,” Clayton says. This social hypothesis gives the animals a reason for evolving intelligence, which their physical environment alone might not demand. Clayton suggests that a cognitive arms race among their own kind drove corvids to evolve, as the spy-versus-spy game of caching, stealing, hiding, and deceiving escalated the need for an ever-sharper mind.
Once the ability to think flexibly emerges in an evolutionary line, descendants can apply it to face varying challenges.For example, ravens and killer whales, both highly social, also both alter the ways they gather food and use their habitat so they can live near the equator as well as in the high Arctic.
Last year Emery investigated the latent intelligence of corvids by testing rooks, which do not use tools in the wild, with complex tasks requiring tools. With each step in his laboratory experiments, the challenges got harder and more complicated, but because of the rooks’ understanding of cause and effect, they produced solutions without resorting to trial and error. They chose rocks and sticks to drop down a tube in order to open a door to get food. In an experiment inspired by Aesop’s fables, Emery presented the rooks with a worm floating out of reach in a tube of water. The birds put rocks in the tube to raise the water level to capture the worm. They even manufactured tools, bending a wire to make a hook to pull a bucket holding food out of a tube. The tool worked only with a bend of a precise curvature, around 100 degrees. “We wouldn’t have expected that at all,” Emery says. “That’s why we said in the paper that it is an example of insight. It’s coming up with a novel solution, to innovate.”
Birds and mammals are distant on the tree of life. Their last common ancestor lived 280 million years ago and their brains are quite different in size and structure; birds notably lack the mammalian six-layer cortex. So Clayton and Emery argue that intelligence had to evolve separately in corvids and primates, starting at distant points but converging to solve the same problems of managing social interaction.
Intelligence might turn up anywhere it aids survival—in the use of protective coloring or the ability to molt, for instance. It may be rare only because it is not needed very often. “We think intelligence is this great thing because it’s the thing that has made us special,” Clayton says. “Yet when you compare us with insects, such as species of mosquitoes, there are a number of measures where we are not the best.”
We cannot say for certain how important thinking is for action, whether in animals or in human beings. Shettleworth concedes that Clayton’s scrub-jays met the behavioral criteria for future planning when they cached their breakfast in the right cage before bedtime. “Does that mean they are thinking about breakfast when doing it?” she asks. “We don’t know.”
Shettleworth notes that the unconscious connections of associative learning can, even among people, produce complex behaviors, such as unconsciously eating a bowl of cereal. “Conscious cognition may be very much overrated in our conduct of daily life,” she says.
In the end, we cannot be sure of another person’s conscious thinking, much less the thinking of another species. A computer can be programmed to seem conscious. Scrub-jays might be built to seem conscious too. Presumably even a person could be conditioned to claim consciousness falsely. As Emery says: “I could be lying to you. I could be completely unconscious but telling you I am conscious.”
NICKY CLAYTON’S BIRD’S-EYE VIEW
Nicky Clayton’s fascination with birds does not end when she leaves her Cambridge University office. Over the years, the avian world has infiltrated her personal life as well, informing her off-hours interests in dance and social connection. And conversely, she has developed ideas related to her research by looking at bird behavior through the prism of her own experience.
With a slight frame and sharp mind, Clayton likes being compared to a bird. As busy as the corvids she studies, she dances six days a week, even during university terms. And to push her metaphor further, you might say that she pays close attention to her plumage: Her dresses come from Milan, and she perches on stiletto heels day and night, whether relaxing at home, practicing salsa, or striding across the medieval flagstones of Cambridge at a breakneck speed.
Last year Clayton had a rare opportunity to bring her two sides together when Mark Baldwin, the artistic director of the London-based Rambert Dance Company, asked her to help create a contemporary dance commemorating the 150th anniversary of Charles Darwin’s On the Origin of Species. She agreed and then spent weeks sorting out how to express evolution in dance. “I was thinking I could just give them a straight science talk, but that’s a bit boring,” she says. “Given that I love to dance, it made sense for me to merge the two.”
Clayton borrowed elements from tango and then added some moves based on avian sexual selection; as reference, she showed the Rambert dancers video of the mating ritual of birds of paradise. “I referred to it as bird ballet,” she says of the ritual. “The maestro comes on the scene—I call him the principal dancer—and he’s seen to do this amazing series of jetés across his little stage. And you see all these females gathering and critically looking, and then you see him benefit from his successful performance by mating with them all.”
In the resulting work, titled “The Comedy of Change,” Baldwin included a solo that evoked the bird of paradise video. Reviewers found the piece beautiful but, as with the behavior of the birds Clayton studies, a bit mysterious. One writer who attended a performance in Northampton that was primarily for schoolchildren appreciated it more—thanks no doubt to a talk Clayton gave in advance.
Clayton still glows about this experience. As a young girl she loved birds, dance, and clothes. Now she has all three, adding dance company science adviser to her list of titles and honors. All of that curiosity and optimism spills right back into her academic work, as she attempts to decode the minds of her scrub-jays. “I just like watching them behave,” she says, “and using that to generate ideas.”