When whales sing, what do they sing about? Researchers haven’t yet cracked that code, but they say a statistical analysis shows that those songs reflect a structure that’s similar to human languages.
Two studies, published in the journal Science and in a sister publication called Science Advances, lay out evidence that the songs of humpback whales follow long-accepted rules of efficient communication at least as well as our own spoken languages do.
Listen to whale songs recorded by Operation Cétacés:
“As humpback whale song becomes more complex, elaborate, and takes more time to sing, it’s more costly to produce,” said Mason Youngblood, a postdoctoral researcher at Stony Brook University and the author of the Science Advances study. “You have to cut corners in other areas to keep the overall cost so that as low as you can.”
Linguists use two rules, known as Menzerath’s law and Zipf’s law of abbreviation, to measure how efficiently those corners are cut.
Menzerath’s law predicts that longer sequences of communication will be composed of shorter elements. Zipf’s law predicts that more frequently used elements will be shorter in duration. For example, the most common words in the English language are “the” and “be.”
Youngblood’s study looked at the statistical profiles of the songs sung by baleen and toothed whale species (including orcas and dolphins), and compared them to the profiles of 51 human languages (including Arapaho and Lower Sorbian). Eleven of 16 whale species exhibited Menzerath’s law, sometimes to a greater extent than human speech.
There was enough data available to rate the utterances of five whale species on the scale for Zipf’s law. Two of those species — humpbacks and blue whales — met that standard, and the structure of humpback songs followed the law to the extent seen in human speech.
The second study, published by Science, looked at humpback whales and how closely the structure of their communication conformed to Zipfian standards. The research team also analyzed at how infants structured their speech as they learned their language, and compared that to how whales structured their songs.
The research team, led by Inbal Arnon of the Hebrew University in Jerusalem, reported that the whale songs had “the same statistical structure that is a hallmark of human language.”
“This commonality, in two evolutionarily distant species, points to the role of learning and cultural transmission in the emergence of properties thought to be unique to human language,” the team said.
Does that mean whale songs qualify as language? Not necessarily.
“We have little understanding of the ‘meaning’ of the songs, let alone the different units, for humpback whales,” Arnon and her colleagues wrote. “Furthermore, having similar statistical structure does not entail a similar expressive function. In fact, similar statistical structure is also found in music — a culturally transmitted behavior where individual units do not have explicit expressive meaning but nevertheless show a good fit to a Zipfian distribution.”
Previous research has suggested that the songs, which are sung exclusively by male humpback whales, may serve to attract mates, fend off challengers and mark territory. If that’s the case, the meaning of whale songs could be similar to that of birdsongs.
Youngblood, who got into studying whale songs as part of his wider interest in non-human communication, said birdsongs also score highly on language-like standards when it comes to efficiency and structure.
“There are a lot of whales that probably learn their vocalizations and exhibit a lot of complexity in their vocalizations, but there are thousands of bird species that learn vocalizations, and they exhibit huge variety in how complex those vocalizations get,” he said. “It’s a very human desire to to want to create a ranking, but I do think that there are a lot of bird species that would give humpback whales a run for their money. Of course, I’m very biased in that opinion, since I’m primarily a birdsong researcher.”
So, does that mean whales are incapable of language? Not necessarily.
Youngblood said he’s intrigued by the clicky communication system that’s used by sperm whales.
“There’s a lot of really incredible work being done in sperm whales that indicates that they are actually conveying a lot more information than we previously thought, and that they may be the cetacean species whose communication is closest to something like a language,” he explained. “Although that work is still very preliminary, it’s very promising and interesting — and so I think that’s the species I’ve been most interested in after this.”
Previously: Scientists dig jazz from bowhead whales
In addition to Arnon, the authors of the Science study, “Whale Song Shows Language-like Statistical Structure,” include Simon Kirby, Jenny A. Allen, Claire Garrique, Emma L. Carroll and Ellen C. Garland.
Youngblood is the sole author of the Science Advances study, “Language-like Efficiency in Whale Communication.” Andrew Whiten and Youngblood are the co-authors of a commentary in Science titled “Convergent Evolution in Whale and Human Vocal Cultures.”
