By Jacinta Bowler, ABC
Humpback whale songs have been found to have "language-like" structures. Photo: Supplied: Operation Cetaces
Across just a few weeks, complex, never-before-heard melodies sung by humpback whales can spread across thousands of kilometres of oceans.
These whale songs are sung by males as a way to woo a mate, and they can change and morph into a more complicated song each year.
But are these songs simply a collection of sounds, or do they echo some parts of language?
A new study, published in Science today, has found these whale songs share fundamental structural similarities with human language, showing that certain linguistic laws are not unique to humans.
"We did a very meticulous deep dive into humpback whale song," said Jenny Allen, a researcher in whale behaviour at Griffith University in Australia and the University of St Andrews in Scotland.
"We took modelling used in other studies to look at how babies and infants learn [the structure of language], and we ran the whale song through it.
"Essentially, some of the structures were the same."
How are human languages structured?
n the first half of the 20th century, linguist George Zipf found that in any particular language, the most common word (in English that's "the") will occur twice as often as the next most common ("of"), three times as often as the third ("and"), and so on.
Known as Zipf's rank frequency law, it's an interesting quirk of speech that works for almost all human languages.
And the researchers wanted to see if it also worked for whale songs.
The law is relatively easy to see when looking at a human language that we understand. But it's not so easy to apply it to the long, complex and repetitive sounds of whale songs.
To unpick these complex streams of sound, Dr Allen and an international team of researchers worked with a linguist to split up whale songs into their smallest components.
What did they find?
The team used modelling called an 'infant-inspired segmentation method' originally used for understanding how babies learn the smallest elements of language.
Spectrograms can visually show the sounds of whale songs. Photo: Supplied: Griffith University
Language uses sentences, which are made up of a string of words, and those words are made up of a string of sounds.
Applying this principle to eight years of humpback whale recordings from a New Caledonian project called Operation Cétacés, the researchers were able to split the whales songs into smaller and smaller chunks.
When they analysed these 'chunks' in relation to Zipf's rank frequency law, they found it fitted perfectly.
"Whales showed the same structure in terms of their song … they follow a lot of the same rules that language follows," Dr Allen said.
"We were very surprised at the finding."
A second study published in Science Advances backs up the humpback song results.
The researcher in that study took a broader approach, comparing 16 whale species with 51 human languages, and found that many of the whale songs worked for two other linguistic laws.
Stephanie King, a researcher of dolphin behaviour at the University of Bristol, who was not involved in the study, suggests the humpback study shows similarities between the way humans and whales learn.
"The researchers nicely illustrate that whale song shares the same statistical structure as human language," Professor King said.
"[This] likely explains how whales can learn complex new songs - in a similar way to how we learn a new language - using structural patterns to learn associations between sounds."
Are whales talking?
While this research is exciting, Dr Allen notes that whale songs are not a form of communication in the same way that humans communicate.
"The main thing is understanding that 'language-like' and 'language' are two separate things," Dr Allen said.
While the whales might use complex songs as part of their mating ritual, there's no language or information inside the song itself.
"It's learned, but that doesn't mean there's meaning behind it."
Instead, the researchers suggest whale song and human language have the same structural elements because both are learned behaviours.
"We think it's why whales [and human babies] can learn their songs as quickly and efficiently as they do," Dr Allen said.
Humpback whales sing some of the most complex whale songs. Photo: Supplied: Marc Quintin
In a 'perspective' also published in Science, Mason Youngblood from Stony Brook University and Andrew Whiten from the University of St. Andrews suggest that while the new paper is exciting, a "note of caution about the tantalising" results is warranted.
Similar results have also been seen when applying Zipf's rank frequency laws to things such as city sizes and gene expression, and some linguists suggest they may be just statistical artefacts.
However, Youngblood and Whiten also note that humpback whale songs arguably provide "the most compelling case to date" that the structural similarities are due to learned behaviours.
Dr Allen thinks future studies can confirm this theory, by finding that other animals with similar learned behaviours, like birds, might also show the same results.
"What I think will bear out in future studies is that this structure will show up in socially and culturally learned displays," she said.
"It won't show up in species that have vocalisations they're born with, or learn through trial and error."
- ABC
