Human language is one of a kind in the animal kingdom. This is not only great vocabulary, but also our ability to pronounce different letters and sounds. What makes our languages ​​special is the intricate combination of words for words and words for sentences, thereby creating innumerable different sequences, each of which has its own meaning. Combinations are not random, of course – they are determined by the syntax of each language. With their help we can tell about past events, plan for the future, or discover things that never happened.

No animal has symbolic language For human beings, each expresses an object or idea using a large vocabulary. Studies have shown that some animals can learn a lot of words and understand at least part of their meaning. A shepherd bitch named ChaserFor example, she remembers the names of thousands of dolls and toys, and she knows how to associate each doll with an appropriate name. And were present Monkeys who have learned hundreds of words, Can communicate using sign language or by pointing to a particular symbol. But these were all specially trained animals from humans. In nature, animals do not communicate in symbolic language.

Instead, animals have a limited list of sounds that they can create, and they usually do not connect them to each other in a significant way. Exceptions are songbirds and whales that compose songs that repeat in different combinations and contain an array of different characters. But these poems do not seem to have a symbolic meaning: different letters do not refer to different ideas or objects, and their composition in a new way does not provide new information. Some other animals have been reported Combine several sounds together to create sequences, Seemingly meaningful – but even these only utter a few “sentences” that are far removed from the complexity and diversity of our language. Even the closest thing to us animals and monkeys is a limited sound communication system – so at least we thought so.

In a new study, Researchers from Germany challenge this assumption. The researchers examined the sounds made by chimpanzees in more depth than ever before and found about 390 combinations, each containing at least two types of sounds. The combinations showed the order of the votes selected and the hierarchical combinations – that is, the “sentence” of two votes in the longest combination of three or four votes. Although they still do not know the meaning of any such sentence, many combinations show that the vocal communication of our chimpanzee relatives is much richer and more flexible than we thought.

Flexibility and order
The researchers collected 900 hours of recordings, including the sounds of 46 chimpanzees from three different groups living in Ivory Coast, West Africa. They analyzed more than 4,800 readings and recorded 12 different types of sounds that chimpanzees can produce. They include “ho ho ho”, which is probably the most recognizable of chimpanzees, as well as moans, “barks”, screams, and cries.

In most cases, the collected readings contain only one type of sound – a unit, researchers call it, or repeat the same “unit” over and over again. But in one-third of cases, chimpanzees have composed two or more sounds to form “sentences”. Up to ten of the three or more votes cast in the 15 per cent reading. The researchers recorded 390 combinations, but they estimate that chimpanzees have other combinations that do not appear in the recording. The reason is that they found new combinations even near the end of 900 hours of recording.

The researchers focused on three features of sound combinations that are characteristic of human language. The first is flexibility: some basic units, in this case 12 sounds produced by chimpanzees, appear in a longer combination. The researchers found the best flexibility in chimpanzees: 11 of the 12 sounds appeared in “sentences” of two or more units.

The second feature is order – in human language, not all words appear equally everywhere in a sentence, but there are words that usually appear before or after other words. The researchers found such an order in some two-unit terminology of chimpanzees, i.e., if we mark one sound as A and the second sound as B, the chimpanzees pronounce only A, followed by B and not A. Half of the recorded two-unit expressions had no such preferences, so A and B appeared equally in one or two positions.

The third and final feature is related to the use of short and two-unit expressions in longer sentences. The researchers examined three unit sentences and found that they were not randomly arranged and that they were in order. Sentences with a particular phonetic order were more common than others, and the preferred order of two-unit expressions continued even within longer sentences. Together, they “show that the vocal communication of chimpanzees is far more complex and structured than we previously thought.” Tatiana Bortulato said (Bortolato), one of the researchers who signed the article.

In one-third of cases, chimpanzees composed two or more sounds for sentences, suggesting complex vocal communication (Photo: Liran Samuni, TAÏ Chimpanzee Project)

Evolution of language
“Observing animals in their natural environment and in their natural social groups reveals a hitherto unknown complexity in the way they communicate,” added Cedric Girard-Buttos, who led the study. This is very likely, the researchers say, as other species also present complex interactions, which we have not yet discovered.

This study not only reveals many details about the communication of animals closest to us – the researchers hope that it will also shed light on the evolution of our language. “Syntax is the hallmark of human language,” said Emiliano Zacarella, who co – led the study with Girard-Botos.

“This is the first study of a major project,” added Catherine Crockford, a senior researcher who signed the paper. “By studying the complex and rich vocal combinations of chimpanzees, a social species like humans, we hope to gain new insights that will help us answer questions such as where we came from and how our unique language evolved.”

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