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Human language seems very complex compared to other forms of communication observed in the animal world. Scientists are still trying to understand the mechanisms that led to such a difference during evolution. To this end, researchers from the Max Planck Institutes for Evolutionary Anthropology, Cognition and Brain Sciences in Leipzig, and the CNRS Institute of Cognitive Sciences in Lyon, have recorded and analyzed hundreds of hours of wild chimpanzee vocalizations. It appears from their study that these primates use well-organized vocal sequences to communicate with each other.
We are the only species known to communicate through language. So used to talking like this every day, we tend to forget how extraordinary (and unique) this ability is in the animal world. But the complexity of our language is not due to the number of sounds we produce – fewer than fifty in most languages. What sets us apart from other types is how we combine these different sounds to make words, and then how we combine the words to form an infinite number of sentences with many different meanings.
Where does this ability come from? To trace the evolutionary origins of our language, a group of researchers have taken an interest in the vocal production of other animals, especially primates. The latter uses nearly forty different screams to communicate with each other, and shouts that they don’t unite with each other (or very rarely). At least, that’s what the experts thought so far. This new study shows that chimpanzees are indeed able to form meaningful vocal sequences from different types of screams.
Communication is based on a very precise syntax
The team analyzed thousands of sounds (4,826 recordings in total, or 900 hours) produced by 46 wild adult chimpanzees from Tay National Park, located in Côte d’Ivoire. The researchers identified 12 different types of screams that the animals used to form vocal sequences, revealing a “hitto unknown complexity in their methods of communication,” asserts Cedric Gerard Bottos, a protozoologist attached to the Max Planck Institute. The study’s first author.
Chimpanzees have been known to make several distinct sounds: growls, roars, barks, and squeals. They are generally issued on a one-time, one-time basis; But sometimes chimpanzees also string together a series of sounds into a sniff (the animal inhales between each sound), as shown in this video by famed anthropologist Jane Goodall:
The researchers set out to determine, from their recordings, whether some of these typical shots appeared more often than others. They postulate that the architecture of a communication system capable of coding flexible meaning should require at least, but not exclusively, the following three structural capabilities: flexibility (the combination of single-use screams in phonemic sequences), order (location of sound units in sequence) and recombination ( A combination of independent audio sequences into longer sequences).
They finally highlighted several combinations that repeat themselves regularly: The team identified a total of 390 unique sound sequences, combining two to ten types of calls from their repertoire. ” More than a third of their vocal output consists of at least two units, with 15% of audio sequences containing three to ten units These cries occurred in predictable ways at certain points in the sequence, following what linguists call “rules of communication.” Sometimes two sequences are combined to form longer “sentences.” In other words, chimps will also communicate according to specific structures. Well.
Sounds are emitted differently depending on context
This is the first time such a diversity of vocal production has been shown in non-human primates. ” Our results highlight a more complex and structured vocal communication system in chimpanzees than previously thought. Tatiana Bortolatto, of the Max Planck Institute for Evolutionary Anthropology, and co-author of the study said.
The researchers noted that the sounds were emitted in a subtle manner or in the form of panting depending on the contexts. For example, simple grunts are pronounced primarily for food, while “gasping” grunts are pronounced as a submissive greeting expression. However, it is possible that researchers have missed some of the more subtle building blocks of crying, which can vary depending on the situation. For example, the shriek emitted in response to a predator may have a completely different tone than the shriek emitted during a friendly meeting.
It also remains to understand the meaning of recorded sentences. Researchers on this topic note that the order of the phoneme sequences can be important: in fact, some sounds tend to appear at the beginning of sentences, while others are almost always placed at the end of them. So the team will attempt to clarify this puzzle and determine whether, through their ‘language’, chimps are able to broaden the range of topics on which they can communicate with each other, as we do.
This study of exploring the complexity of the vocal sequences of wild chimpanzees—a socially complex species like humans—could also shed new light on our origins and how our unique language evolved, says Catherine Crockford, co-author and director of the Taï Chimpanzee Project and co-author of the study.