African penguins (Spheniscus demersus) bear the unfortunate nickname "jackass penguins" because they communicate through honking, donkey-like brays. Laugh at them if you like, but a new study suggests that their jackass language actually follows the same basic linguistic rules as ours.
In the study, published Wednesday (Feb. 5) in the journal Biology Letters, researchers recorded nearly 600 vocalizations from 28 adult male penguins living in Italian zoos. (Males tend to vocalize a lot during the mating period, which is why the researchers turned to this population). The scientists knew from prior research that African penguins honk using three distinct types of sound, reminiscent of human syllables, when greeting one another, mating, or defending territory. But the researchers wanted to know whether those "syllables" followed two common linguistic rules.
One of those rules, called Zipf's law of brevity, was proposed in 1945 by linguist George Zipf. The law states that the more frequently a word is used in any language, the shorter it tends to be (think of words like "the," "to" and "of" in English). Previous studies have analyzed more than 1,000 world languages for evidence of Zipf’s law, and the rule holds up in all of them.
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The other rule, known as the Menzerath-Altmann law, says that the longer a word or phrase is, the shorter its constituent syllables are, while shorter words are more likely to have longer syllables. (The word "onomatopoeia," for example, is made of six very short syllables, while "couch" is made of one longer one.) Prior studies have shown that nonhuman primates conform to both these rules when they communicate with each other, but what about jackass penguins?
The researchers in the new study found that, yes, the songs of the male jackass penguin conform to both Zipf's and Menzerath-Altmann's laws: The shortest calls tended to be the most common, and the longest phrases were made up of the shortest syllables. This jackass study provided the first nonprimate evidence that these common linguistic patterns extend into the animal kingdom, the authors wrote, and that's nothing to hem and haw at.
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Originally published on Live Science.