In November of 1978, an observer in a Boston institution hurriedly scrawled down a short note that, unbeknownst to them, would eventually send waves through the research field of language development.
“He says ‘Hoover’ in plain English,” the page read. “I have witnesses.”
That sentence wouldn’t have been remarkable, save for one detail: The “he” in question—Hoover—was a harbor seal.
Over the next several months, Hoover’s trainers at Boston’s New England Aquarium discovered that their unusual flippered friend could do far more than speak his own name. Rewarded with treats of fish whenever he spoke, the seal quickly began verbally greeting aquarium employees and patrons alike.
On these occasions, Hoover would adopt a straight-backed posture and square his shoulders (or, at least, the seal equivalent of shoulders) before yelping out phrases like “hello there, how are you,” “come over here,” or “get out of here” in a thick, rumbling New England accent, punctuated by raucous barks. He also appeared to be capable of “laughter,” scientists noted in a 1985 study, and once emitted a “blood-curdling scream” so alarming that an observer logged it as a data point in Hoover’s file.
Researchers later realized that Hoover had picked up several of these quirks from the Maine fisherman who had rescued him from the shores of Cundys Harbor when he was a pup. “Hoover sounds much like a male human with a Boston accent,” they wrote. Others, however, seemed to be Hoover-specific idiosyncrasies: “He often sounds somewhat inebriated,” the paper reads, “probably because of his tendency to slur together sounds representing separate human words.”
Unsurprisingly, Hoover’s remarkable ability to mimic human speech made him a hit—and people from all over flocked to Massachusetts to visit and converse with the world’s one and only “talking seal.” Hoover seemed to enjoy the spotlight, even staging the occasional fit, complete with “raspy breathing” and “strange cries,” to garner the attention of exasperated aquarium staff.
Even after Hoover died in 1985, scientists continued to puzzle over his startling verbosity. While Hoover was clearly producing the sounds of human speech, it was unclear how exactly he’d managed the feat—and researchers weren’t sure if this uncanny ability was just a fishy fluke.
Now, decades later, new research might finally help seal the deal. Reporting last week in the journal Current Biology, a team of scientists at the University of St. Andrews in the United Kingdom provides a fresh batch of evidence that seals can indeed learn and imitate many of the complex sounds fundamental to human speech. Not only can pups belt out clear vowels—a skill that many of our closest primate relatives can’t achieve—but they can also recognizably “sing” the first few notes of tunes like the Star Wars theme song and “Twinkle, Twinkle, Little Star.”
“This is the proof we’ve been waiting for,” says Morgan Wirthlin, a computational biologist studying language development at Carnegie Mellon University who was not involved in the study. “It’s long been thought that [seals and their relatives] have this incredible capacity for vocal learning...but this paper is the first to demonstrate it in a really clearly defined way.”
In the study, University of St. Andrews biologists Amanda Stansbury and Vincent Janik trained three young gray seals named Zola, Janice, and Gandalf to copy tones played from a computer by rewarding them with fish. At first, the researchers focused on notes that were within their species’ vocal repertoire, or something a seal might normally hear from a herdmate in the wild.
Once the seals were comfortable with this task, Stansbury upped the ante, and began including sounds at high, unfamiliar frequencies, as well as sequences that incorporated vowels from human speech. Stansbury even remixed some combinations to recall common jingles and songs that no seal would be expected to produce under natural circumstances.
The renditions were imperfect, and they might not sound as wicked smart as a Mainer from the 1970s. But the accuracy the seals achieved with unfamiliar melodies and human vowel sounds was impressive—especially considering that this is something that non-human primates tend to struggle with, says Stansbury, who is now at the El Paso Zoo in Texas. “Seals are the closest non-human analog we’ve found this behavior in,” she says.
“This is really the first example of a non-human animal that seems to be using vocal learning in the same way we are,” adds Laela Sayigh, an animal behaviorist studying dolphin communication at the Woods Hole Oceanographic Institution who was not involved in the study. “The ability to produce these [vowel sounds]...is so central to our own speech as humans. It’s incredibly fascinating to see that seals have this capability, and that it’s so closely aligned with our own.”
On the whole, animals with vocal capabilities flexible enough to expand in this way are rare. Seals, however, have a rare combination of traits that many other creatures lack, including a key anatomical advantage: a larynx, or voice box—much like the one found in humans.
“The top of the larynx is what allows people to change between vowels, which linguists will tell you is the most basic building block of language,” says Samantha Carouso-Peck, a behavioral biologist studying songbirds at Cornell University who was not involved in the study. Songbirds, she adds, can accomplish something similar with an analogous structure called a syrinx. But a true larynx affords an animal more precise control over the production of sound.
Of course, hardware alone doesn’t make an adept vocal learner—the neural software needs to be in place, too, Wirthlin explains. “What’s impressive...isn’t really that they [can make these vowel sounds], but that they’re able to copy the structure of a human vowel that isn’t part of their normal repertoire,” she says. “That’s about having the right kinds of neural connections and being able to control the vocal apparatus in a way that other animals can’t.”
It’s still unclear why seals in particular have this exceptional ability, but Carouso-Peck thinks it’s likely got something to do with their dynamic social structure. “There’s a very interesting lesson here about how being highly social, being intelligent, and being a vocal learner seem to be a package deal,” she says. Combined with a keen ear, a sharp tongue and flexible learning style may help mothers and pups find each other over the cacophony of large pods, or give bachelor(ette) seals an edge during mating season.
Whatever the reason behind the chatter, the new findings reinforce the idea that humans are far from the only ones with the gift of the gab—and, at long last, validate Hoover’s loquacious legacy.
“Before this, Hoover’s story was an anecdote,” Sayigh says. “This study really cements the reality that seals are capable of modifying their own vocal production based on new sounds they’ve heard...and Hoover was definitely doing that.”
It’s only fitting, then, that the star of this story gets the last word. Now get outta here!