Whale calls reveal cultural evolution

(CN) — Scientists have caught sperm whale dialects changing over time.

Researchers studying the endangered population found that whales living near Greece have developed a distinct vocal dialect while still occasionally reverting to an older version used elsewhere in the Mediterranean.

The findings, published Tuesday in the Proceedings of the Royal Society B, offer a rare glimpse of cultural evolution unfolding in real time.

Sperm whales communicate using short patterns of clicks known as codas, which help identify membership in larger cultural groups called vocal clans.

By analyzing 20 years of recordings from across the Mediterranean, an international team of researchers found that whales living around the Hellenic Trench off Crete had developed a faster version of a coda long associated with the region’s sperm whales.

What surprised researchers was that some groups occasionally switched back to the older version.

Lead author Taylor Hersh of the University of Bristol said the behavior suggests the eastern whales have not entirely abandoned the dialect used by earlier generations.

“These findings paint a picture of the history of sperm whales living in the Mediterranean, consistent with a progressive occupation from west to east, ending with the development of a distinctive dialect in the animals living in the east, starting in the Hellenic Trench,” Hersh said in a press release. “What’s interesting is that the new dialect is a clearly modified version of the presumably ancestral slow 3+1 and that groups in the east also clearly remember that dialect as they have these ‘throwback’ days.”

Researchers believe sperm whales first entered the Mediterranean around 20,000 years ago and gradually spread eastward from Gibraltar. Today, the population numbers only a few thousand animals and is considered endangered due to threats including ship strikes and entanglement in fishing gear.

For years, scientists believed all Mediterranean sperm whales belonged to a single vocal clan identified by a characteristic pattern known as the “3+1” coda, a sequence of three clicks followed by a pause and a final click.

The new research suggests that while the whales still share a common cultural heritage, regional differences have emerged over time.

It provides one of the clearest examples yet of how sperm whale dialects can change while retaining traces of their origins.

Luke Rendell of the University of St Andrews Sea Mammal Research Unit, who coordinated the study, said the findings offer new insight into how whale culture develops.

“The Mediterranean has been the cradle of significant aspects of human cultural evolution from ancient Greece onwards. Over that entire period, sperm whale culture has also been evolving – we now have a much better idea of just how slow that process is,” he said in the press release. “It also helps us understand the origins of dialect diversity in sperm whales globally. But there are still many unanswered questions, like why that new dialect evolved at all and in that particular location.”

According to researchers, understanding these vocal traditions could also help conservation efforts by providing new information about the social structure of the endangered population.

“This finding reminds us that the cultural history of the Mediterranean does not belong exclusively to humans,” said Txema Brotons of Asociación Tursiops in the press release. “While the civilizations of the Mare Nostrum were developing their own languages, customs and identities, sperm whales were also passing down their vocal traditions from one generation to the next.”