Seven ancient sperm whale “clans” live in the vast Pacific Ocean, proclaiming their cultural identity through distinctive click patterns in their songs, according to a new study.
This is the first time that cultural markers have been observed in whales, and they mimic markers of cultural identity among human groups, such as distinctive dialects or tattoos.
The discovery is also a step towards a scientific understanding of what whales say to each other in their underwater songs – something that remains a mystery despite years of research.
Bioacoustician Taylor Hersh, a postdoctoral researcher at the Max Planck Institute for 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 sperm whales exchange often strong click streams between them. others when resting near the surface between dives in deeper water—sometimes more than a mile deep—for prey like squid and fish.
The streams of clicks are divided into so-called ‘codas’ and the calls are known as sperm whale ‘songs’ – although they are not very musical and may sound like hammer blows and squeaks (Naval sonar operators called sperm whales “carpenter fish” for this reason).
No one knows what all sperm whale codas mean, but they can have distinct rhythms and tempos, called “dialects,” Hersh said. And the new study shows they include specific patterns – bursts of clicks lasting just a few seconds, like fragments of Morse code – that whales use as “identity codas” to proclaim their membership of a particular clan. .
“Identity codas are really unique to different cultural groups of whales,” she said.
The study also shows that sperm whales emphasize their dialects when rival clans are nearby – a telling behavior also seen in humans – with the result that whales from different clans generally do not interact with each other. others when occupying the same waters, she said.
The study analyzed more than 40 years of records of underwater sperm whale calls made at 23 locations in the Pacific Ocean, from Canada to New Zealand, from Japan to South America. From these, the researchers extracted more than 23,000 click patterns, then used an artificial intelligence system to determine which of them were distinctive identity codas.
They have now determined that there are at least seven distinct “voice clans” of sperm whales in the Pacific Ocean, each with their own identity codas, Hersh said.
Each clan could be made up of thousands of individual sperm whales, and calls from members of the same clan have been recorded at the ends of the Pacific Ocean, sometimes over 9,000 miles away. It is unknown how many sperm whales exist in the world’s oceans, but it is estimated that there could be as few as 360,000; about half of them could live in the Pacific.
And sperm whale clans can be thousands of years old. Hersh said the mother and daughter sperm whales still share the same vocal clan. Males, however, often travel between groups and can be more fluid in their clan affiliation.
Since sperm whales live for around 70 to 90 years, the age of a grandmother and granddaughter can span around 150 years. “So the clans definitely seem to be hundreds of years old, and possibly much longer,” she said.
Sperm whales spend most of their lives away from humans and in a very different environment – diving into the depths of the ocean – so little is known about their behavior. Although researchers can’t yet say how 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 their prey, Hersh said.
Gašper Beguš, an assistant professor of linguistics at the University of California, Berkeley who was not involved in the study, compares sperm whale vocal clans to dialect clusters among humans.
A well-known linguistic study decades ago found that Martha’s Vineyard Islanders were more likely to emphasize their distinctive Island dialect when speaking with non-Islanders, a- he declared.
Similarly, researchers in the latest study found that sperm whales were more likely to emphasize their clan dialects of clicks in regions where they were more likely to encounter members of other clans, a he declared.
Beguš is part of the CETI project – the Cetacean Translation Initiative – which was created last year to decipher the sounds of sperm whales. The project will combine linguistic studies and machine learning to understand what sperm whales are saying to each other, and perhaps enable interspecies communication with them.
“We are starting to collect data with microphones on the whales and in the water,” he said. “We follow their behavior and we learn a lot about their environment and their social structure.”
Although sperm whales have previously been known to exchange information in codas, this is the first time that the identity codas of whale clans have been determined – a discovery that will be crucial in deciphering their entire songs, did he declare.
Janet Mann, a dolphin and whale expert, professor of biology and psychology at Georgetown University, who was also not involved in the latest study, agreed that the research could help better understand the speech of sperm whales .
“As the authors note, we still have little understanding of 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 also the forces that shape cultural evolution in animals.”