We've known that whales are intelligent, emotional mammals who often sing songs.
But now, a team of researchers from Project CETI (Cetacean Translation Initiative) and the MIT Computer Science and Artificial Intelligence Lab have identified what they believe to be an actual consistent phonetic alphabet in whalespeak – not unlike human vocalizations.
There have been rumors of this breakthrough coming for a while, but now the researchers have finally published on Tuesday, a paper in the journal of Nature Communications, 15, Article number: 3617 (2024) titled "Contextual and combinational structure in sperm whale vocalisations".
The team analyzed recordings of 8,719 codas – clicking noises sounding a bit like Morse code made by sperm whales (Scientific name: Physeter macrocephalus) – from around 60 whales collected by the Dominica Sperm Whale Project between 2005 and 2018, using a mix of algorithms for pattern recognition and classification. They found that the way the whales communicate was not random or simplistic, but structured depending on the context of their conversations.
The researchers identified distinct vocalizations that hadn't been previously picked up on. In fact, these pelagic mammals' system of communication is more sophisticated, exhibiting a complex internal structure replete with a “phonetic alphabet”. Similarities to aspects of other animal communication systems and even human language are evident.
Like all marine mammals, sperm whales are very social animals, with their calls an integral part of this. The new study has provided a fuller understanding of how these whales communicate.
“The research shows that the expressivity of sperm whale calls is much larger than previously thought”, said Pratyusha Sharma, a Massachusetts Institute of Technology doctoral student in robotics and machine learning and lead author of the study.
“We do not know yet what they are saying. We are studying the calls in their behavioral contexts next to understand what sperm whales might be communicating about”, said Sharma.
Sperm whales, which can reach about 60 feet (18 meters) long, have the largest brain of any animal. They are deep divers, feeding on giant squid and other prey.
“Why are they exchanging these codas? What information might they be sharing?” asked study co-author Shane Gero, Project CETI’s lead biologist and Dominica Sperm Whale Project founder, also affiliated with Carleton University in Canada.
All told, the researchers identified 156 different codas, each with distinct combinations of tempo, rhythm, rubato, and ornamentation. Gero said that this variation is strikingly similar to the way humans combine movements in our lips and tongue to produce a set of phonetic sounds. The whales, among other things, altered the duration of the codas and sometimes added an extra click at the end, like a suffix in human language.
“All of these different codas that we see are actually built by combining a comparatively simple set of smaller pieces”, said study co-author Jacob Andreas, an MIT computer science professor and Project CETI member.
People combine sounds – often corresponding to letters of the alphabet – to produce words that carry meaning, then produce sequences of words to create sentences to convey more complex meanings.
For people, Sharma said, “there are two levels of combination”. The lower level is sounds to words. The higher level is words to sentences.
Sperm whales, Sharma said, also use a two-level combination of features to form codas, and codas are then sequenced together as the whales communicate. The lower level has similarities to letters in an alphabet, Sharma said.
“Every communication system is tailored to the environment and animal society in which it has evolved”, Sharma added.
The communication system used by sperm whales differs, for example, from the “songs” of humpback whales – and, for that matter, from the whistles, chirps, croaks and assorted other vocalizations by various animals.
“Human language is unique in many ways, yes”, Gero explained. “But I suspect we will find many patterns, structures and aspects thought to be unique to humans in other species, including whales, as science progresses – and perhaps also features and aspects of animal communications which humans do not possess”.
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