Clans of whales use vocalizations to mark their c

picture: fig. 1. Composite map of sperm whale clan distribution in 23 labeled regions of the Pacific Ocean using seven-clan tree clan designations (Appendix SI, Table S5 for regional record metadata). Each point is a unique directory, colored by clan. The size of the dots indicates the within-clan correlation of that directory, with smaller dots having lower correlations. The scale bar is approximate and most accurate along the equator. The SI appendix, Fig. S3 includes clan-specific maps.
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Credit: Taylor Hersh – Max Planck Institute for Psycholinguistics

For decades, researchers and the public have been captivated by deep-diving sperm whales; very social animals that live in groups of mothers and young. Whales communicate with series of Morse code-like clicks called “codas”, and whales that use similar coda “dialects” belong to the same cultural group or “voice clan”. Sperm whale researchers have long suspected that whales use certain types of coda to distinguish vocal clans. But previous studies of sperm whale clans were largely region-specific.

This work was the culmination of decades of research effort by people working throughout the Pacific Oceansays first author Taylor Hersh. “We decided to share data and work collaboratively, to learn something new about this enigmatic, charismatic and cultural animal..”

Clan identity

The team set out to determine whether certain sperm whale codas are similar to human ethnic markers, such as dialects or clothing styles. They were specifically interested in “identity codas”; types of coda that are particular to a clan, rather than common to all clans.

Could such codas be symbolic markers of the clan identity of sperm whales? If so, they might reflect human patterns, where cultural groups are most prominent or stand out in regions where multiple groups overlap, perhaps to better signal their group identity. Similarly, sperm whales may rely more on identity codas in areas where multiple clans overlap.

Whales of different clans never interact with each other, even when they share the same waterssays Hersh. “This suggests that whales have a way of distinguishing ‘us’ versus ‘them’, and we wanted to know if they do this using identity codas.”.

Sperm whales of the Pacific Ocean

An international team of 27 researchers studying sperm whales in the Pacific Ocean have pooled their acoustic data sets. This way, the team was able to study click patterns in 23 locations, from Canada to New Zealand and from Japan to South America. For some places they still needed to extract codas from the whale recordings. This was done as part of the “Global Coda Dialect Project” led by Shane Gero (Global Project and Atlantic Ocean Lead), Hersh (Pacific Ocean Lead) and Chris Johnson (Indian Ocean Lead) .

The Pacific Ocean team has mined over 23,000 codas. Next, they determined how many of them were used as identity codas by whale clans, with a method previously developed by Hersh and his colleagues.

The team identified seven vocal clans of sperm whales across the Pacific Ocean, each with their own dialect and identity codas. The dialects of the whales followed the pattern predicted by human culture. As the spatial overlap between clans increased, their dialects in terms of identity coda usage became more distinct.

Non-human cultures

Knowing the culture of nonhuman animals is important for conservation efforts. According to Hersh, the results also point to similarities between human and non-human cultures. “Our results show how culture can structure animal populations. The conditions necessary for the evolution of symbolic markers of cultural identity also exist in nonhuman animals.”.

Previous research on vocal clans has shown that they differ not only in the codas they use, but also in how they move, feed, and socialize. This fits with another human ethnic marker prediction: that the distributions of symbolic markers and social norms should match. However, we know very little about the social norms and “lifestyles” of several of the Pacific Ocean sperm whale clans documented here, and hope to study their behavior more in the future. While current work has focused on the Pacific Ocean, we plan to extend our analyzes to sperm whales in the Atlantic and Indian Oceans as well.



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