Scientists document remarkable ‘phonetic alphabet’ of sperm whales

By Will Dunham

(Reuters) – The different species of whales that inhabit Earth’s oceans use different types of vocalizations to communicate. Sperm whales, the largest of the toothed whales, communicate using bursts of clicking sounds – called codas – that sound a bit like Morse code.

A new analysis of years of vocalizations by sperm whales in the eastern Caribbean has found that their communication system is more advanced than previously known, exhibiting a complex internal structure replete with a ‘phonetic alphabet’. The researchers identified similarities with aspects of other animal communication systems – and even with human language.

Like all marine mammals, sperm whales are highly social animals, of which their calls are an integral part. The new study has provided a better understanding of how these whales communicate.

“The research shows that the expressiveness of sperm whale calls is much greater than previously thought,” said Pratyusha Sharma, a doctoral student at the Massachusetts Institute of Technology in robotics and machine learning and lead author of the study published Tuesday in the journal Nature Communications has been published.

“We don’t know yet what they say. We study the calls in their behavioral context to understand what sperm whales may be communicating about,” says Sharma.

Sperm whales, which can grow up to 60 feet long, have the largest brains of any animal. They are deep divers and feed on giant squid and other prey.

The researchers are part of the Machine Learning Team of Project CETI (Cetacean Translation Initiative). Using traditional statistical analysis and artificial intelligence, they examined the calls of about sixty whales recorded by the Dominica Sperm Whale Project, a research program that has collected a large data set on the species.

‘Why are they exchanging these codas? What information are they potentially sharing?” asked co-author Shane Gero, Project CETI’s lead biologist and founder of the Dominica Sperm Whale Project, also at Carleton University in Canada.

“I think it’s likely that they use codas to coordinate as a family, babysitting, foraging and organizing defense,” Gero said.

Variations in the number, rhythm and pace of the clicks produced different types of codas, the researchers found. Among other things, the whales changed 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 relatively simple series of smaller pieces,” says co-author Jacob Andreas, a professor of computer science at MIT and a member of Project CETI.

People combine sounds – which often correspond to letters of the alphabet – to produce words that have meaning, and then produce strings of words to create sentences that convey more complex meanings.

For humans, Sharma said, “There are two levels of combination.” The lower level is sounds in words. The higher level is words to sentences.

Sperm whales, Sharma said, also use a combination of features at two levels to form codas, and codas are then linked together as the whales communicate. The lower level has similarities to letters in an alphabet, Sharma said.

“Each communication system is tailored to the environment and animal society in which it evolved,” Sharma added.

For example, the communication system used by sperm whales is different from the ‘songs’ of humpback whales – and, for that matter, from the whistles, chirps, croaks and various other sounds of various animals.

“Human language is unique in many ways, yes,” Gero said. “But I suspect that as science progresses, we will find many patterns, structures and aspects that are thought to be unique to humans in other species, including whales, and perhaps also features and aspects of animal communication that humans do not possess. “

If scientists can decipher the meaning of what the sperm whales ‘say’, should humans try to communicate with them?

“I think we need to do a lot more research before we know if it’s a good idea to communicate with them, or even get an idea of ​​whether that will be possible,” Andreas said.

“At the same time, I’m optimistic that we will be able to learn much more about what information is actually encoded in the vocalizations we listen to, what kind of information is in these clicks and these codas, as we begin to understand the behavioral context in which this happens,” Andreas added.

(Reporting by Will Dunham in Washington; additional reporting by Matthew Stock in London; Editing by Rosalba O’Brien)