TURIN — Very different species are sometimes united by the use of common linguistic patterns. The Cape penguins are known as "jackass penguins" because their particular call is so similar to the donkey's bray. But their language, notably their use of the syllables at their disposition to speak in the most "economical" way, is strikingly similar to humans.
The discovery, published in the prestigious Biology Letters scientific journal, is the work of two Italian scholars. University of Turin researcher Livio Favaro and Professor Marco Gamba, from the Department of Life Sciences and Systems Biology, have shown that the tendency to compress language — when writing text messages, for example — belongs not only to humans, but also to this particular penguin species' way of communication.
"Recent studies have shown that animals genetically very close to humans, such as primates, reflect this law in their organization. This is found, for example, in gibbons and macaques," explain the two scholars.
The discovery marks the first time this language rule is observed in a species other than primates.
During their breeding period, male Cape penguins — the only penguin species living on the African continent — produce vocalizations consisting of different types of syllables associated with particular movements. They consist of vocalizations with two types of functions. The first is territorial defense, while the second is to attract females and convince them to form a stable couple.
"Previous research had already shown that the spectro-temporal characteristics of these syllables encode information about the speaker," the two researchers write.
African penguins in Boulders Beach, South Africa — Photo: Kallerna
By analyzing vocalizations of a group of penguins in captivity, Favaro and his group discovered that adult penguins have a particular type of call to express "detachment" or "sense of isolation" from the group. They called them "contact calls." These calls are different from those that penguins use during fights for territorial defense, and from those expressed during mating time or nesting.
Interestingly, in their vocal sequences, penguins always keep several long syllabic elements useful to underline their body size. This aspect plays a fundamental role during breeding periods.
Words we use most in our language tend to be short.
Some of these syllables contain information correlated to the penguin's physical size "and tell us how big the male is and how capable he is of being a good partner: strong, a brave hunter, and able to protect the nest."
Precisely by continuing to study hundreds of vocalizations, researchers realized that they mirrored human linguistic principles.
"These laws tell us that in communication systems and the acoustic elements that are most frequently used, there is a tendency to compress information and to minimize," they write.
This fact explains why the words we use most in our language tend to be short. "I, You, We, You" or all conjunctions are the most effective examples. Conversely, long words are less frequently used.
"The most important thing to keep in mind is that, when we refer to animal vocal sequences, we do not refer to complex lexical structures. We must always be very careful to highlight the fact that these vocal sequences, unlike human language, do not have precise semantics or syntax," write Favaro and Gamba.
That's why "parallelism with humans has to be sought in terms of the duration of acoustic elements and the proportion of their use. What emerges from our research is that we have a pattern of the production of these vocal signals which follows a linguistic vision similar to that of human language. Above all, they follow a common principle: when the elements conveyed become numerous, shorter sequences are used. This rule occurs in all languages; the mechanism of communication is always the same."
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