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Of all the creatures on Earth, only two can produce human language: humans…and birds. Of the few birds that can imitate human speech, including , crows, and ravens, parrots are clearly the best at it—they s, and even . So why can parrots talk when our closer primate relatives cannot?

Parrots are vocal learners, meaning they grasp sounds by hearing and then imitating them. Although several other bird species can discern and repeat sounds, parrots are the pros.

, a Duke University neuroscientist and vocal learning expert, recently published a in Plos One explaining why. Any bird that’s a vocal learner has a part of the brain devoted to this, called the ‘song system.’ But in parrots, the song system has two layers—an inner ‘core,’ common to all avian vocal learners, and an outer ‘shell,’ which is unique to parrots. Jarvis thinks that this recently discovered ‘shell’ is what allows parrots to be such expert mimickers (though he hasn’t figured out exactly how it works yet).

But why do they copy human speech? Peer pressure, it turns out. Parrots naturally try to fit in, be it among other parrots or other people.

In the wild, parrots use their vocal prowess to share important information and fit in with the flock, says , a research associate and part-time lecturer at Harvard. Pepperberg is best known for her work probing the intelligence of an African Grey Parrot called Alex, who lived in Pepperberg’s lab for 30 years, until his death in 2007.  “A single bird in the wild is a dead bird; It can’t look for food and look for predators at the same time,” Pepperberg says—but in a flock they can trade off responsibilities.

Parrots are even capable of learning and using varying dialects. Yellow-naped Amazon Parrots in Costa Rica, for example, have regional dialects, and when they swap regions, the transplants often pick up the local twang, , who studies parrot vocalization at New Mexico State University, found in his research.

So plop a parrot into a human household, and it will “try to integrate itself into the situation as though the people were its flock members,” says Pepperberg.

Pet parrots have all the essential conditions for picking up language—time, inspiration, and mental ability. Wild parrots, on the other hand, lack the needed close proximity to speech. (Though , presumably learned from escaped pet parrots, this behavior is rare.) “In the wild, parrots focus on other parrots for what they want to learn,” Wright says. It’s only in captivity, when humans become their sources of social interaction, that they start paying attention to us.

The question is, do these precocious birds know what they’re saying? For parrots, words may have some associations but not complex meanings, says Wright. “But they are very attuned to the context in which we use [words], and so I think that often fools people a little bit.” When a parrot says “Hello; how are you?” when its owner enters the room, for example, it’s “not necessarily interested in your well being” but is mimicking what it hears the owner saying when he or she comes in. In fact, a parrot’s understanding of “how are you,” is probably “Oh look, someone has come into the room.” Parrots are also drawn to phrases and sounds associated with excitement and commotion, Wright adds, which may be why the birds are .

With training, though, it can be a different story, says Pepperberg. She bought Alex right after she completed her PhD in 1977, and decided to train him rigorously: The bird listened and watched a pair of researchers identify and exchange simple objects (importantly, objects Alex liked). One human acted as a model for the bird, exchanging objects with the other researcher while Alex watched. They sometimes intentionally made mistakes, so the bird could see that “not any random new noise mediates transfer of the object”—just its label. Only when the bird was “practically falling off his perch” lusting after these objects did the researchers loop him into the conversation—and, if he identified an object correctly, let him play with it.

“Parrots who talk know what they’re saying if they are taught appropriately,” Pepperberg says. For example, a bird trained to identify favorite foods knows exactly what they mean when they ask for them. For example, Waldo, a 21-year-old African Grey Parrot who has been part of the band Hatebeak for 12 years (what started as a joke has become a successful venture), likes snacking on bananas and crackers. As , “We got him dehydrated banana chips, and he pieced it together and called them ‘banana crackers’ on his own. It's a little creepy.”

By the end of his life, Pepperberg’s Alex had learned to identify 50 objects, seven colors, six shapes (such as “three-corner” for triangle and “four corner” for square), and quantities up to eight. He could tell you, for instance, how many purple popsicle sticks (“How many purple wood?”) were on a tray of assorted objects. He could also identify things that were the “same” or “different,” as well as “bigger” and “smaller.” What stood out about Alex was not his vocabulary (at around 100 words, it was average for a parrot). Instead, it was his ability to learn and repeat concepts: For example, when researchers fed Alex cake on his birthday one year, he called it “yummy bread.” He also had his own special word for ‘apple’—‘bannery,’ “cause it probably tasted a bit like a banana and looked like a big cherry,” Pepperberg says.

While that might sound pretty ingenious, remember that many other animals—vocal learning or not—have , one of the most important aspects of any animal’s life). We likely just find parrots particularly endearing because we can understand them.