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Sperm whales are saying more than we thought. Can we understand what they mean?


Sperm whales are saying far more than we thought. But, what exactly are they talking about?

Like seasoned musicians, the whales appear to be spinning 21 basic phrases into hundreds of different variations, a new study found. The research is part of an initiative to communicate with other species.
May 8, 2024

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When two sperm whales from the same family meet in the Caribbean Sea, they emit loud clicks from their heads, like Morse code. One of the most common patterns is a five-click phrase with the rhythm of a ballroom dance: cha…cha…cha-cha-cha.

A whale will repeat this over and over, something you can hear in this audio track. cha…cha…cha-cha-cha, cha…cha…cha-cha-cha, cha…cha…cha-cha-cha.

Getting a little bored? This phrase is one of only 21 click patterns or “codas” that researchers have heard coming from Caribbean sperm whales, a distinctive subset or “dialect” of the roughly 150 codas found around the world. So is that all sperm whales have to say with their massive 18-pound brains?

“We know these animals are living very complicated social lives. And it didn’t make sense that they just had such a finite amount of coda types,” said David Gruber, a City University of New York biologist.

Now, a research initiative founded by Gruber has discovered that these massive animals might have a lot more to say. Like seasoned musicians, the whales appear to be spinning these 21 phrases into hundreds of different variations by playing with subtle changes in tempo or adding occasional extra clicks, like little accents.  

The findings, spelled out this week in Nature Communications, suggest this handful of codas are the foundation of a more rich and sophisticated communication system than previously known. For Gruber, it also marks another step in his ambitious—some would say misguided—effort to harness recent scientific advances to communicate directly with whales.

“One of the risks of this project was that sperm whale communication was very simplistic,” says Gruber. “Now we’re beginning to see that there’s hundreds or possibly, you know, infinite possibilities.”

Project Ceti, the organization he launched, has brought together renowned marine biologists, computer scientists, linguists and others to see if artificial intelligence, paired with new tools for monitoring whales, might finally enable humans to crack the communication code of another large-brained species.

Proponents have suggested such communications could advance marine conservation efforts, much like recordings of humpback whale songs in the 1970s inspired the “Save the Whales” movement. Gruber points to parallels between this effort and what humans might need to do if we ever encounter intelligent life from another planet.

Fueled by $33 million from the philanthropic Audacious Project, the group has focused on several matrilineal clans of Caribbean sperm whales, which have been closely studied for decades. In the new research, a team of computer scientists at the Massachusetts Institute of Technology (MIT), examined audio recordings of 8719 codas from at least 60 whales in the 400-whale Eastern Caribbean 1 clan.

Codas had already been studied for tempo—how long a coda lasted; and rhythm—the length of time between clicks. The researchers saw that all of the Caribbean codas were clustered into 5 tempos and 18 rhythms.

More importantly, they found previously unknown features when they studied the recordings in the context of multiple codas and interactions between whales, rather than just one coda at a time. “These variations only become evident in the wider context of the call,” said Pratyusha Sharma, a PhD student in computer science at MIT who did much of the analysis.

One element was an extra click sometimes added to the end of a coda. The researchers found these codas shared a rhythm with surrounding codas missing that click, rather than with other phrases that usually had the longer number of clicks. This bonus click, which the scientists called “ornamentation,” occurred at specific moments during an encounter between whales: when a whale started clicking along with a whale it was following, when the follower paused, or when it went silent, as well as at the beginning and end of a series of calls.

The analysis also revealed that a whale would subtly slow or speed the tempo of a string of codas, and that a companion whale would mirror that tempo shift even if it was using different codas, like two jazz musicians in a duet.


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All these variables explode the potential combinations from the 21 basic codas to hundreds, creating the possibility of transmitting a broader array of information. Consider the difference between 21 hieroglyphs and a 26-letter alphabet that can be combined in almost infinite ways. The team’s analysis revealed the whales in the recordings used around 300 different variations. The researchers dubbed this the “sperm whale phonetic alphabet.”

“We don’t know what they are talking about,” said Sharma. “But the fact that they have those combinatorial basis … it’s already very interesting.”

But referring to what whales are doing as talking is problematic for some, who worry that using characteristics of human language risks overlooking what’s distinctive about whale communication.

Luke Rendell, a marine mammal researcher at the University of St Andrews in Scotland, helped to identify the ways different groups of whales around the world use different sets of codas. He questions whether behavior such as two whales synchronizing their tempo is transmitting discreet bits of information like a conversation between humans. Instead, it’s possible that this interaction creates a feeling of a close bond between two whales, he said, much the way music can evoke a strong, inarticulable emotional response. “There’s no consideration of other alternatives, like maybe this is more like music,” says Rendell.

Daniela Rus, head of MIT’s Computer Science and Artificial Intelligence Laboratory, and a member of CETI, says the team isn’t claiming to have discovered a whale language with features comparable to human language. But the terminology of linguistics can help describe what the scientists have found. And what they found is unusual. “We do not know of any other study that discovers complexity in other species in the way that we show with codas,” she says.

Perhaps part of the challenge is that humans inevitably rely on human language to describe what another species does to communicate. If sperm whales could characterize the tiny, squeaking sounds that come from us humans, what would they make of them? And is there a way to put it in a coda?

cha…cha…cha-cha-cha, cha…cha…cha-cha-cha(cha)

Sharma, et. al. “Contextual and combinatorial structure in sperm whale vocalisations.” Nature Communications. May 7, 2024.

Photo by willyam/Adobe Stock

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