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Humpback whales sing songs with melodies so beautiful they lulled a generation of babies to sleep and sparked a global movement to save the whales from extinction. The sounds that sperm whales produce, however, are far less musical. They emit powerful staccato clicks that call to mind a thumbnail dragging over the teeth of a metal comb, or an underwater jackhammer. But what they lack in musicality they make up for in depth. Scientists are increasingly realizing that sperm whales have one of the animal world’s most sophisticated communication systems.
The latest discovery is that elements of their vocals function in a way that’s fascinatingly similar to human vowels, making their communication more elaborate and nuanced than previously realized. And the breakthrough came with help from an unexpected source: elephants.
(What are animals saying? AI may help decode their languages)
The vowels research, published today in a paper in the journal Open Mind, is the work of a team led by Gašper Beguš, a linguist at the University of California, Berkeley and a member of Project CETI, a multidisciplinary endeavor to translate sperm whale communication. For the past five years, Project CETI has documented the lives of hundreds of whales off the coast of Dominica in the Caribbean, leading to astonishing insights about the communication of sperm whales, some of the most mysterious creatures on Earth. The group hopes this work will inspire a new conservation movement to better protect the species.
Beguš says the genesis of the “vowels” discovery came two years ago, when Project CETI hosted a talk by two elephant researchers, Michael Pardo and Joyce Poole, that helped reframe his approach to analyzing sperm whale vocalizations. Pardo mentioned that when elephants hear their name, they sometimes wait several minutes to respond. “They don’t necessarily react on the same kind of immediate time frame that we do,” Pardo told the audience. Beguš, in turn, wondered if a whale might be more like an elephant than a human when it comes to experiencing time. Whales are the world’s largest animals. They gestate for a long time (14 to 16 months), nurse for a long time (two years, but as long as eight), and live for a long time (around 70 years). In the depths of the ocean, their hearts beat just twice a minute. Maybe their communication is equally slow?
To answer this question, Beguš and his team pored over more than a thousand recordings collected by Shane Gero, Project CETI’s whale biologist and a National Geographic Explorer. They enlisted the help of a custom machine-learning model that pointed them at potentially interesting vocalizations, then closely analyzed the sounds. When they sped up the conversations, composed of vocal patterns called “codas,” to more closely match the pace of human speech, Begus’s team heard something new.
At normal speed, the codas sounded like simple sequences of binary clicks. When Beguš sped up the recordings, however, he could hear new sonic qualities in the codas—sounds that resembled vowels in human speech. “On the surface, their clicks sound nothing like our vowels, but that’s because their clicks are slow and our vowels are fast,” Beguš says. “If we remove silences from their clicks and make their clicks faster, patterns start appearing that look similar to our vowels.”
Beguš and his team identified two vowels used by the sperm whales—analogues of a and i—and he thinks that further analysis will likely reveal more. The presence of vowels in sperm whale codas dramatically increases the variability and flexibility of how codas might be used to embed meaning, much as vowels enable humans to make a nearly infinite array of vocal combinations. That’s not the only similarity: Though whales don’t “speak” with their mouths, they produce these vowels with an anatomy surprisingly similar to humans. Within their heads is a set of phonic lips and an air sac that they use to precisely manipulate sound—not unlike how we humans change the shape of our mouths to make an a or i.
The team also found variables in the codas that they call diphthongs, referring to the way the sounds glide from one vowel to another while spoken, as when an English speaker says “boy.” The diphthongs reveal that sperm whale clicks are not merely binary; rather, the clicks are more like a dimmer switch, with a range of attributes, all very much deliberate and—presumably—laden with meaning. “It’s clean, razor-sharp, precise,” Beguš says of the coda system. “I’ve never seen anything so structured and seemingly intentional.”
The vowels paper builds on earlier work done by Project CETI to chart the nuances of sperm whale vocalizations. Last year, MIT researchers with Project CETI published a paper in Nature Communications that described four new properties of sperm whale codas using the language of music—tempo, rhythm, rubato, and ornamentation. Subtle variations in these properties make up a “phonetic alphabet” of different codas. Their analysis of around 9,000 recordings bumped the known repertoire from 21 different codas to more than 156. A larger repertoire of codas means that sperm whales have greater potential for what they can say.
This latest discovery of vowel-like sounds “blows that through the roof,” says National Geographic Explorer David Gruber, the founder and president of Project CETI. “This adds on another level of complexity and nuance within their voices that we hadn’t known about.”
So far, Project CETI has made no attempt to assign meaning to any of the codas. Understanding what the sperm whales are saying to one another remains a distant possibility. Doing so would require not only further data and computing power but also a much greater understanding of the sperm whale behaviors that accompany their communication.
“What the animal is doing in the context of the other animals is really important,” says Irene Pepperberg, a colleague of Begus’s and a professor of comparative cognition at Boston University. “That’s the next step of what we have to look at with any of these communication systems.” Pepperberg, well known for her 30-year study of the cognitive and communication abilities of Alex, an African gray parrot, described the challenges of her early research. “When we first started out, we thought, ‘Oh, we understand birdsong because we can tape this bird and find out what it’s singing.’ That was just the very beginning of learning their communication system, which is so much more complex than we thought.”
The new research from Begus and Project CETI builds on decades’ worth of work to better understand how sperm whales communicate. These highly social mammals are live in tight-knit clans that hunt, sleep, and raise calves together. All sperm whales learn codas from their clan; babies babble for a couple of years before they learn to click meaningfully. Clans in different locales have different dialects, and each clan has a unique coda to self-identify. It’s no surprise that such complex social creatures might have complex communication. But it’s a long way to go before we’ll know what all those clicks are talking about.
