Groaning and moaning underwater, humpback whales talk much like humans, Israelis find
Peer-reviewed research by Hebrew University and Edinburgh University experts suggests such patterns might also shape sounds made by other animals, including songbirds and bats
Sue Surkes is The Times of Israel's environment reporter
On the face of it, human language has nothing in common with the lyrical grunts, cries, and moans of the humpback whale.
However, a new study co-led by a Hebrew University researcher of language learning has now found that the two share similar patterns.
The research, published on Thursday in Science, found that human language and whale song both conform to the so-called Zipf’s law.
Named after American linguist George Kingsley Zipf, the law deals with the frequency of use of words in a language. It states that the most common word will occur about twice as often as the second most common word, three times as often as the third, and so on. In English, the most common word is “the,” followed by “of,” and then “and.” Zipf also postulated another law saying more frequently used words will be shorter so as to minimize the user’s effort to produce them.
Now, it transpires that songs sung by male humpback whales conform to both statistical patterns.
Prof. Inbal Arnon, a cognitive scientist and developmental psychologist at Jerusalem’s Hebrew University, researches how language is acquired and how the way we learn affects the structure of languages.
She and Prof. Simon Kirby, an expert in the evolution of language at Scotland’s Edinburgh University, developed an algorithm based on the statistical indications that enable young children to break lengthy blurbs of sound into individual words — to grasp through the frequency of syllables which syllable combinations make up specific words.
This algorithm was applied to more than 30 hours of humpback whale song recorded over eight years by Dr. Ellen Garland near New Caledonia, a group of islands east of Australia. Garland, an expert on whale song at Scotland’s St. Andrew’s University, focuses her research on cetaceans, particularly the cultural transmission, vocal learning, and function of humpback whale song.
The scientists used the same statistical cues babies use to break sound into units to find short sequences in whale songs (listen below), such as a brief rising whistle followed by a squeak. They then assessed how frequently these sequences occurred and how long the most frequent sequences were, discovering that both matched the Zipf laws applied to human language.
In a recording from 2010, for example, the most common whale phrase, groan-groan-moan, was used twice as often as the next most common one, a moan followed by three ascending cries. As in human language, the phrases used most often were relatively short.
“This work shows how learning and cultural transmission can shape the structure of communication systems,” Arnon said, adding, “We may find similar statistical structure wherever complex sequential behavior is transmitted culturally.”
She said the next step would be to probe whether the same principles apply to other animals, such as songbirds, bats, and elephants, whose communication systems are also learned instead of innate.
“These findings challenge long-held assumptions about the uniqueness of human language, uncovering deep commonalities between evolutionarily distant species,” Kirby said.
The paper does not explicitly address whether whale song can be considered language.
The three research leaders, Arnon, Kirby, and Garland, collaborated with Dr. Claire Garrigue (IRD New Caledonia), Dr. Jenny Allen (Griffith University), and Dr. Emma Carroll (University of Auckland).
An unrelated study published last week, also in Science, found that another linguistic law, the Menzerath–Altmann law, applied not only to humans but also to 11 species of dolphins and whales (including humpbacks).
This law dictates that the longer a sentence, the shorter the clauses (by number of words) within it, and the longer the word, the shorter the syllables or morphs (a section of a word such as a prefix) in it.
The author, Mason Youngblood, a postdoctoral fellow at the Institute for Advanced Computational Science at Stony Brook University in New York, wrote that Menzerath’s law and Zipf’s law of abbreviation have been observed in an increasing number of species, including gibbons, African penguins, and house finches.
The reasons humpback whales sing remain a mystery. Two years ago, a research team led by Eduardo Mercado of the University at Buffalo found that while songbirds repeated the same sounds in the same way as part of courtship, humpback whales can improvise.
In other research, scientists have proposed that Zipf’s law can be applied to chords in music but not notes.
