How Irene Pepperberg Revolutionized Our Understanding of Bird Intelligence

With help from her African Grey parrot, Pepperberg found that some birds have cognitive abilities on par with primates.

When Irene Pepperberg started working with parrots four decades ago, the term “bird-brained” was shorthand for unintelligent. “Bird cognition was an oxymoron,” she recalls. But Pepperberg was convinced that birds, especially species that live in complex social networks, were intelligent animals.

Thanks largely to her work with an African Grey parrot named Alex, Pepperberg showed that birds can understand complicated concepts once thought to be the province of people alone. Alex could understand analogies, numbers, colors, and shapes. He knew about 150 words, and could place them into categories. He even understood the abstract idea of zero, a concept that does not arise in humans until around age 4. Pepperberg’s research with Alex revolutionized the way scientists think of bird cognition.

“People really had no understanding of what these birds could do,” she says. “Sure, people understood their song-learning capacities. And parrots can talk, everyone knows that. But that [the birds] understood what these vocalizations meant, and whether we could use that as a window into their cognitive abilities—that was unheard of.”

Pepperberg bought Alex from a pet store in 1977, when she was a doctoral student at Harvard. She was captivated by Alex’s ability to learn and started designing her own experiments, but many of her peers were skeptical.

“The first grant proposal I wrote came back asking me what I was smoking. Literally, that was one of the critiques,” she recalls. “It did take me more than the three years I proposed to do that work, but we did do everything that was in that grant proposal. At some point, we were doing things people had not been able to do with apes.”

African Grey parrots live in large groups and communicate through complicated songs and vocalizations. They can travel up to 35 miles a day in search of food, and live up to 80 years in the wild. Pepperberg says these are among several similarities to great apes, which is one reason she leaned on primate research to develop her experiments.

Pepperberg studied primatology and psychology papers by researchers like David Premack, a psychologist who worked with chimpanzees and other primates. Premack showed in the 1970s and early 1980s that chimps could perform analytical reasoning and could understand analogies. Pepperberg modified some of his experiments and performed them with Alex, showing the parrot could do it, too.

Alex was able to learn various labels, and could identify and distinguish objects by color, type, and texture. This is more complicated than simply determining whether two things are alike or different, Pepperberg says; few animals have been shown to possess this ability. 

“Imagine that I give you toy A and toy B. Alex could look at them and say, ‘Oh, they are different color.’ Or maybe they are different in their material, or maybe the same color and same material, but a different shape,” Pepperberg says. 

She presented early findings at a primatology conference in 1987, in which Premack described his chimpanzee work. “I remember a very old primatologist came up to me and said, ‘You mean to tell me these birds are doing the same thing as Premack’s chimps?’ And I wanted to say, ‘Yeah, and backwards and in heels!’” she recalled.

Pepperberg’s ideas are more widely accepted today; many ornithologists now study bird cognition, and she often is invited to give keynote addresses at animal-cognition conferences. And she has continued working with African Grey parrots, including a male named Griffin and a female named Athena, the latter of whom she raised from a chick. Just this month, Pepperberg published work showing Griffin can exhibit inductive reasoning, meaning he could draw conclusions based on repeated experiences, and can understand probabilities.

While Pepperberg and her colleagues have demonstrated various forms of avian intelligence, ornithologists have also learned that bird brains are more complex than originally thought. Birds lack a brain structure similar to the cerebral cortex, but parrots and corvids, including the crows, have a larger forebrain than other avian species. In 2016, researchers showed that parrots and corvids have just as many or more neurons as primates do.  

Such revelations only lead to more questions Pepperberg is anxious to probe. “Birds are separated from humans by about 300 million years of evolution, give or take. Think about that: The last common ancestor was a dinosaur. And yet these birds are doing things that in some cases are equivalent to 5- and 6-year-old children,” she says. “So, why? How? What is it about their brains? And what could that tell us about our brains?”

Understanding how birds developed their cognitive abilities could lead to new insights about not only avian intelligence but also language and communication in the animal kingdom. Pioneering this field of study was hard, Pepperberg admits, but oh so gratifying. “People want to understand how we relate to these other animals,” she says, “and how they relate to us.”