Sperm whales ‘click’ out cues to their origin: complex social hierarchy and sophisticated language abilities identified

Sperm whales communicate through unique ‘codas’ (morse-code-like-click series) akin to human names revealing their individual identity, family, and cultural clan.

Yes, you heard it right! Sperm whales can say “Hello” to a relative in the vicinity or “Hey, there! Haven’t we met?” to an old pal or a distant cousin.

A decade-long study led by Shane Gero, a research fellow at Aarhus University in Denmark under the Dominica Sperm Whale Project, has shed light on the complex social patterns including distinct families and cultural groups or clans in the Caribbean waters. They also seem to possess advanced communication skills such as a clan-specific vocal dialect or accent.

Despite the difficulties in studying sperm whales, which spend significant time hunting in the depths of the ocean, Gero’s team has recorded nearly 4000 calls between 2005 and 2010 while the whales were both diving and socializing. They also tracked individual whales by tagging their tail fins. These calls or click patterns, termed ‘codas’, are different from the echolocation clicks they emit while hunting.

sperm_whale_mother_with_calf

Sperm whale mother with calf. Credit: Gabriel Barathieu / Réunion Underwater Photography [CC BY-SA 2.0], via Wikimedia Commons

The three levels of identity observed in Caribbean Sperm whales

This new study has added solid evidence to the team’s speculation (from previous studies) that whales may have individuals calls or identities. Of the 20 unique codas among Caribbean sperm whales, only one with 5 rapid clicks (five regular, 5R) was common with sperm whales from all over the world. Individuals produced a signature 5R with slight variations in the click-emitting speed or emphasis in the beginning, middle, or end, that served as their personalised marker or ‘first name’. This system is probably essential for them to recognize or keep track of each other.

It turns out that the whales have far sophisticated language abilities. Gero and his co-authors found that four of the nine family units they followed made their own distinctive four-click coda, a family marker.

Further, individual whales across the Caribbean families produced a particular 1-1-3 coda which was not recorded in the Pacific or elsewhere in the world. The call was indistinguishable across individuals and families in the region even when digitally analyzed.

“Each family teaches new calves the coda, precisely duplicating the pattern used by every family in the clan. This is an indication that that call is really important for all the families,” Gero told Ars. “It’s a marker of their cultural heritage. They’re basically saying, ‘I’m from the eastern Caribbean.'”

Such peculiarity, even among individuals that do not mingle, is a strong indicator that this coda could have been socially learned through generations across a shared culture or a ‘vocal clan’. A clan may comprise of a few related families or even hundreds of individuals that live across geographies.

These three levels of distinct codas are clear-cut indicators of a complex communication system, which is crucial for a complex society.

Possibility of Sperm whale ‘Civilizations’

“It makes sense that sperm whales communicate in this way”, said Gero. “They need to be able to differentiate between their family and clan members even when submerged, and we know that they have long-lasting preferences for the individuals they spend most time with.”

The team believes that such a social structure would likely have evolved in response to environmental challenges and out of necessity for support. Females are often left to care for their young in warm waters closer to the equator, whereas males often travel to the poles.

“Still, they learn to produce codas before leaving. Acquiring a dialect might help prevent male sperm whales from inbreeding”, Gero suggests, “but increasingly, I think they come home and visit. For nomadic sperm whales in the vast nothingness of the ocean, the only constant is their family,” he says. “Marking that [through dialect] is really important.”

The females are also capable of recalling friends and families for a very long time after they met. Such characteristics are vital for survival and typical of advanced civilizations, where developing trust among immediate and extended families to safeguard the young is crucial for coexistence.

“Sperm whales were around before we were walking upright,” Gero adds. “Their traditions have existed a lot longer than we have.”

Whales that belong to different ‘cultural clans’ might be different in food habits or travel different routes. Culture could explain why the sperm whales around Dominica like to stay close to the island, and don’t roam around as much as other whales. Some animals in the Pacific, on the other hand, will range over thousands of kilometers.

Impact on conservation

The team further plans to playback codas that are yet to be comprehended in an attempt to understand what they mean to the animals. Given the high calf mortality rate due to human activities, Gero insists that it is essential to understand the cultural boundaries and lifestyle in order to manage conservation programs effectively.

“Cultural patterns in sperm whales really can be defined as traditions in the true sense of the word. If all the anthropogenic impact is on just one cultural group of whales, what happens when you lose that group?”, he cautions.

The original study publish in Royal Society Open Science can be found here.

Sources: BBC Earth, Ars Technica, Hakai Magazine

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