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Sperm whale ‘clans’ in the Pacific mark out their culture with songs

Sperm whale ‘clans’ in the Pacific mark out their culture with songs

Seven ancient “clans” of sperm whales live in the vast Pacific Ocean, proclaiming their cultural identity by distinctive patterns of clicks within their songs, according to a new study.

It’s the first time cultural markers have been observed among whales, and they mimic markers of cultural identity among human groups, like distinctive dialects or tattoos.

The discovery is also a step toward a scientific understanding of what whales say to one another in their underwater songs — something that’s still a mystery despite years of research.

Bioacoustician Taylor Hersh, a postdoctoral researcher at the Max Planck Institute of Psycholinguistics in Nijmegen in the Netherlands and lead author of the study published this month in the Proceedings of the National Academy of Sciences, said that sperm whales often exchange streams of loud clicks with each other when they’re resting near the surface between dives into deeper waters — sometimes more than a mile down — for prey like squid and fish.

The streams of clicks are divided into what are called “codas” and the calls are known as sperm whale “songs” — although they’re not very musical and can sound a bit like hammering and squeaking (Navy sonar operators used to call sperm whales “carpenter fish” for this reason). 

No one knows what all the sperm whale codas mean, but they can have distinctive rhythms and tempos, known as “dialects,” Hersh said. And the new study shows they include specific patterns — bursts of clicks that last only a few seconds, like fragments of Morse code — that the whales use as “identity codas” to proclaim their membership of a particular clan.

“Identity codas are really unique to the different cultural groups of whales,” she said.  

The study also shows that sperm whales emphasize their dialects when rival clans are nearby — a tell-tale behavior also seen among humans — with the result that whales from different clans usually don’t interact with one another when they occupy the same waters, she said.

The study analyzed more than 40 years of recordings of underwater sperm whale calls made at 23 locations across the Pacific Ocean, from Canada to New Zealand to Japan to South America. From these, the researchers extracted more than 23,000 click patterns, and then used an artificial intelligence system to determine which of them were distinctive identity codas.

They’ve now determined that there are at least seven distinct sperm whale “vocal clans” across the Pacific Ocean, each with their own identity codas, Hersh said. 

Each clan could consist of thousands of individual sperm whales, and calls by members of the same clan have been recorded at the extremes of the Pacific Ocean, sometimes more than 9,000 miles apart. It’s not known how many sperm whales exist in the world’s oceans, but it’s estimated there might be as few as 360,000; roughly half of them could live in the Pacific.

And the sperm whale clans may be thousands of years old. Hersh said that mother and daughter sperm whales always share the same vocal clan. Males, however, often travel among groups and may be more fluid in their clan membership. 

Since sperm whales live for about 70 to 90 years, the ages of a grandmother and her granddaughter could span about 150 years. “So clans definitely seem to be hundreds of years old, and maybe far longer,” she said. 

Sperm whales spend most of their lives far from humans and in a very different environment — diving in the deep ocean — so little is known about their behavior. Although researchers can’t yet tell how the identity codas in sperm whale songs reflect other distinctive aspects of their clan culture, there is evidence that different clans use different techniques to hunt for prey, Hersh said.

Gašper Beguš, an assistant professor of linguistics at the University of California Berkeley who wasn’t involved in the study, likens the vocal clans of sperm whales to dialect groups among humans.

A well-known linguistic study several decades ago found that islanders on Martha’s Vineyard were more likely to emphasize their distinctive island dialect when speaking among people who were not from the island, he said.

In the same way, the researchers in the latest study found that sperm whales were more likely to emphasize their clan dialects of clicks in regions where it was more likely they would encounter members of other clans, he said.

Beguš is part of Project CETI — the Cetacean Translation Initiative — which was established last year to decipher the sounds of sperm whales. The project will combine linguistic studies and machine learning to figure out what sperm whales are saying to each other, and perhaps to enable interspecies communication with them.

“We are starting to collect data with microphones on whales and in the water,” he said. “We are following their behavior, and we are learning a lot about their environment and their social structure.”

Although it was known before that sperm whales exchange information in codas, this is the first time the identity codas of whale clans have been determined — a finding that will be crucial for deciphering their entire songs, he said.

Dolphin and whale scientist Janet Mann, a professor of biology and psychology at Georgetown University who also wasn’t involved in the latest study, agreed that the research could help better understand sperm whale speech. 

“As the authors note, we still understand little about the function of sperm whale codas,” she said in an email. “This is an important step in determining not only the function and meaning of codas, but the forces shaping cultural evolution in animals.”

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