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What are sperm whales saying? Researchers find a complex 'alphabet'

Sperm whales have lengthy exchanges, made up of clicks, which scientists have found is more complex than previously thought.
Alexis Rosenfeld
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Sperm whales have lengthy exchanges, made up of clicks, which scientists have found is more complex than previously thought.

Sperm whales have a lot to say. The animals spend much of their lives in darkness, searching the ocean's depths for giant squid. So sound rules their world, especially in their tight-knit family groups where they can be downright chatty.

Sperm whales don't sing in the melodious way humpback whales are known for. Instead, they make clicks in long exchanges that sound like a blend of Morse code and popcorn popping. For decades, scientists have recorded their conversations in the hope of teasing out their patterns.

Now, a new study finds that sperm whales have far more nuanced communication than previously thought. Using machine learning, researchers at Massachusetts Institute of Technology and a collaborative called Project CETI identified a bigger lexicon of sound patterns, like an "alphabet," one they say could possibly be combined in ways that convey meaning, as a language does.

"Our results show there is much more complexity than previously believed and this is challenging the current state of the art or state of beliefs about the animal world," says Daniela Rus, director of the MIT Computer Science and Artificial Intelligence Laboratory.

Scientists have long debated whether animals have language, with some insisting that humans are the only species capable of its complexity. The question is whether new technologies like artificial intelligence could decode the mysteries of animal communication that humans have so far missed.

"Some of what they're doing might be totally different from our way of communicating and we're probably never going to be able to fully grasp those differences," says Taylor Hersh, postdoctoral researcher at the Marine Mammal Institute at Oregon State University.

Sperm whale family talks

From grandmothers to granddaughters, sperm whale family groups often dive together, hunt together and even babysit each other's young. Having spent years with these whales as part of the Dominica Sperm Whale Project, biologist Shane Gero says these exchanges sometimes seem very familiar.

"It's hard not to see cousins playing while chatting," Gero says, who also works on Project CETI. "To not see moms hand over to a babysitter and exchange a few words before walking out the door, so to speak, to go eat in the deep ocean."

Their vocal exchanges can last an hour, with different whales clicking and repeating after each other. "It's not rude in sperm whale society to talk at the same time and overlap one another," Gero says.

Their communications can be broken down into repetitive patterns, called codas. A common one for Caribbean sperm whales is the "1+1+3", where the first two clicks are followed by three faster ones. Family groups can have dozens of codas, all with different clicks and pacing.

Even a few minutes of sperm whale recordings could take researchers hours to catalog. So Gero teamed up with artificial intelligence researchers to create Project CETI in the hope of decoding what sperm whales are saying. They analyzed more than 9,000 recordings of Caribbean sperm whales using advanced computer algorithms.

"In using machine learning to detect the clicks, we found that there were so many more clicks than people could manually segment from the data set," says Rus, who worked on the project.

The team found sperm whales have a large repertoire of clicks, which they've catalogued in a sperm whale "phonetic alphabet." Sometimes they slightly vary the tempo of the clicks in a coda. Sometimes the length of the coda is subtly longer or shorter. Sometimes the whales throw in an extra click. These variations can be matched closely by different whales communicating. The patterns also appear to be based on the context of the conservation.

"They can be predicted by machine learning in the same way you might predict the sequence of syllables or the sequence of words in a sentence," Rus says. "It really turned out that sperm whale communication was indeed not random or simplistic, but rather structured."

The researchers say this shows sperm whales potentially have the tools to make different combinations of codas, something that's considered an ingredient of language. Humans can recombine many meaningless pieces of language - like sounds and syllables - and turn them into something meaningful.

So what are sperm whales saying?

Determining what sperm whales mean with different codas or combinations of codas is a much tougher task. Project CETI is gathering more recordings of whales and trying to link them to behaviors and actions as part of the research. But it's challenging to know what contexts are important and what matters to the whales.

"If we only ever studied North American English-speaking society in the dentist office, we'd walk away with the fact that the key part of their communication system is the word 'root canal," Gero says. "We'd just be wrong because we didn't have a comprehensive picture."

Many of the linguistic ways humans define language may also not be applicable for sperm whales, which have been communicating in the oceans far longer than humans have been speaking.

"I think there is value in seeing if patterns in animal communication mirror patterns in human language," says Hersh. "But I think it's important to remember, just because we don't find evidence of something, it doesn't mean that system isn't complex in ways we don't understand."

Sperm whales are still recovering after being decimated by commercial whaling and are facing newer threats, like ship strikes and plastic pollution. Gero says looking for similarities to humans is useful because humans have so much influence over the whales' environment.

"Finding the fundamental underlying similarities is important," Gero says. "When we can talk about whales and how important their grandmothers are, or how important being a good neighbor is, or the importance of cultural diversity in society, that really resonates with people and can drive change in human behavior in order to protect the whales."

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Lauren Sommer covers climate change for NPR's Science Desk, from the scientists on the front lines of documenting the warming climate to the way those changes are reshaping communities and ecosystems around the world.