Carleton marine biologist helps decode the secrets of sperm whale language

Article content

Scientists studying sperm whales in the Caribbean Sea have made a tantalizing discovery that might one day lead to understanding how the whales communicate with each other.

Researchers used machine learning to analyze and detect patterns in the whales’ distinctive clicking noises, dubbed codas by scientists with Project CETI, the Cetacean Translation Initiative. The findings show the sound patterns, which sound like Morse code, are more intricate than previously thought, revealing a kind of “alphabet” that adds complexity to the whales’ communication, said Shane Gero, a scientist in residence at Carleton University and CETI’s lead biologist. Gero is a co-author of the paper, which was published this month in the journal Nature Communications.

Article content

Article content

Some day scientists may find the key — a kind of cetacean Rosetta Stone — that will help them unlock the meaning behind the clicks.

“This paper doesn’t ascribe any meanings to the coda,” Gero said. “What it shows is that these patterns are much more complicated than we thought and they mirror things that we would expect structurally in very complicated communication systems like human language.”

Gero, an Ottawa native, has spent nearly two decades studying a clan of about 40 sperm whales near the island of Dominica in the eastern Caribbean. He used underwater microphones and cellphone-sized transmitters suction-cupped to the whales to record the whales’ codas. Sperm whales not only have the largest brains of any animal on Earth, they are also the loudest. At 230 decibels, the clicks are loud enough to rupture a human eardrum and can be heard by sperm whales thousands of kilometres away.

Gero shared some of the recordings he’s made with Pratyusha Sharma, a PhD student at the Massachusetts Institute of Technology, who is one of the more than 50 scientists from around the world working with Project CETI. Using her knowledge of computers and machine learning, Sharma plotted the coda on a graph, noticing subtle embellishments and different tempos — labelled rubata by the scientists — that differentiated the codas.

Article content

“She said, ‘if I was going to look at this, I would plot it this way.’ It was just bringing computer scientists to the table and looking at it in a different way that enabled us to find these patterns,” Gero said.

The whales combine the codas and rubata in different ways — A with B, B with C, C with A — potentially indicating different meanings, Gero said. The next mystery is to try to relate those different structures to different situations.

“The first step in determining what these animals might want to communicate is to first identify the different ways these things might vary, then start connecting those to behaviour,” he said. “Are they doing it when they’re diving? When they’re socializing? When they’re feeding? And who are they with?  Is it a grandmother talking to their granddaughter? Is it a mother handing her calf over to a babysitter? Then you can start asking the interesting questions: Why are they making these sounds to each other? What information are they sharing?

“Undoubtedly there’s part of the world about living in the deep ocean when you’re the size of a school bus that we, as terrestrial primates, won’t really get. But things like calf care, and social identity and group movement decision — those are places where we think we stand a really good chance of finding that Rosetta Stone piece.”

Article content

Sperm whales have existed for 50 million years and once numbered about two million, but years of whaling have reduced their numbers to about 800,000 worldwide. An adult male can grow up to 24 metres long and weigh 50 tonnes. Sperm whales can hold their breath for two hours and regularly dive 1,000 metres down, twice as deep as the CN Tower is high.

They spend as much as 85 per cent of their lives in the pitch blackness of the deep ocean, using echolocation to keep in touch with each other and to hunt their main food source, the giant squid.

In 2021, Gero’s work with the Dominica whales and the astonishing photos and video by film producer Brian Skerry, provided many of the most spectacular moments of National Geographic’s Emmy Award-winning four-part documentary Secrets of Whales.

In November, the government of Dominica announced the creation of the world’s first sperm whale reserve, to protect the whales and to manage the research and tourism the whales bring to the tiny country.

Gero dreamed of being a marine biologist since he was a boy and says one of the rewards of CETI has been to draw scientists from other fields into his research with sperm whales.

Article content

“It’s been fun to bring people like computer scientists who thought their career was going to be in neural network processing or robotics onto a boat and see their world pivot when they hear sperm whales for the first time,” he said. “It’s been amazing to see someone like Pratyusha, who listened to the sperm whales and visualized their audio and did all the analysis, come out on the boat for the first time and actually see them. To say, ‘Oh, this is (the whale named) Pinchy’ or ‘This one is Tag 143A that has all the ornamentation in its coda.’ You get to see her world explode.

“These aren’t all naturalists who’ve wanted to be biologists since they were eight. It’s brought all these amazing minds to questions that we’ve been thinking about.”

Gero is confident that one day scientists will find that Rosetta Stone and begin to understand what the whales are saying. But that’s not what drives him.

“It’s trying to understand what’s so important with the whales that they want to talk about it with other whales,” he said. “The narrative of having a two-way conversation with a sperm whale isn’t what the momentum is for me. It’s about learning what’s important for someone who lives right next to us, and then trying to determine what that means for my behaviour.”

Article content