Scientists have discovered that communication between African penguins conforms to some of the linguistic rules that also characterise human speech.
Just like humans, penguins use short words rather than long ones - while longer words are made up of a series of shorter syllables.
It is the first time that researchers have noted the two linguistic laws that belong to human speech - known as Zipf's Law of Brevity and the Menzerath–Altmann Law - outside of primates.
It has been observed in so-caled jackass penguins, which got their name because of the similarity between their cries and the sound of a braying donkey.
The team behind the study analysed 590 vocal sequences of 28 adult African penguins during mating, recognition and territorial defence instances, and observed that these birds follow two linguistic laws that belong to human speech: Zipf's Law of Brevity and the Menzerath–Altmann Law.
"We demonstrated that the same rules of human language apply to the communication of these African penguins, whose sounds remind those of donkeys”, said Dr Livio Favaro, one of the authors of the study and researcher at the University of Turin.
"There are universal statistical patterns that explain why, in human languages, words that we tend to use more often are shorter, more compressed. ‘Velociraptor’ is not a small word, while ‘me’ and ‘you’ are,” explained Favaro.
“African penguins have three syllables, and tend to use the shorter ones more frequently," he researcher continued.
Jackass penguins do not speak the same way humans do because they have no syntax or semantics, yet they know how to express themselves when communicating with other individuals.
"We have shown that this selection that prioritizes compression interacts with a specific sequence for which penguins tend to keep a specific syllable, a longer one, to show off their lung capacity, and to give themselves a sense of power [or] to show that they are good parents."
"So, proportionally, they tend to maintain some longer syllables and the compression does not occur on all the vocal repertoire."
Since this characteristic is shared between species, scientists believe that these kind of patterns are universal.
They are not found only in a complex communication system like the human language, but they exist also in simpler forms since the necessity of conveying information in the most efficient way runs across all animal species.