According to research, chimpanzee audio communication is more complex than expected: our animal relatives also combine voices according to certain rules into a large number of special sound sequences. Further research should now clarify to what extent chimpanzees use these sequences to convey complex information.
We are very similar in many ways – but one important aspect sets humans apart from their closest relatives in the animal kingdom: monkeys communicate, we use language. Although animals also make significant sounds at times, the human system is capable of conveying very complex information. Our concept is based on a special combination of sounds into words and words into hierarchically structured sentences. How this special ability emerged throughout the history of evolution is an intriguing question of anthropology. So, for clues, it’s worth taking a look at the communication skills of primates, which are our closest relatives: chimpanzees.
Basically, it becomes clear that the complexity of human language is not solely based on the enormously large variety of possible individual sounds that we combine to speak. Because chimpanzees can make many different sounds as well. What is special is the way in which we orderly combine sounds into words and combine them hierarchically into sentences to convey complex information. It was already known that chimps also combine different calls. However, a Franco-German research team is now working systematically with the structure and diversity of chimpanzee sound sequences.
I listened carefully to the chimpanzees
Scientists examined recordings of thousands of sounds made by members of three groups of wild chimpanzees in Taï National Park in Côte d’Ivoire. “This is the first study in a larger project. By studying the complexity of the sound sequences of chimpanzees in the wild, a species with a complex human-like social life, we hope to learn more about how our unique language has evolved, ”says co-author Catherine Crockford of the CNRS Institute for Cognitive Sciences in Bron, Lyon.
According to the researchers, they discovered the distinctive features during the structural analysis of chimpanzee tone sequences. They have identified 390 unique sound sequences that consist of combinations of up to ten different types of calls from the entire chimpanzee repertoire. The order of the invitations follows the rules – they have been linked in a structured way, the researchers found. It turned out that calls – in combination with certain other calls – always occur at certain positions in the sequence.
Surprisingly complex and orderly
‘Essentially, this ability of chimpanzees to organize discrete units into structured sequences provides a versatile system potentially suitable for expansive meaning generation,’ the researchers write. Co-author Tatiana Bortolato of the CNRS Institute of Cognitive Sciences says: “Our results show that the chimpanzee voice communication system is much more complex and structured than previously thought.”
The researchers emphasized that the research laid the foundations for further research that could shed light on chimpanzees’ communication skills and the origins of human language. “Putting words or groups of words into sentences – syntax – is a feature of human language. To study their origins, we first need to understand exactly how great apes ‘vocalizations are constructed,’ says co-author Emiliano Zaccarella of the W.A. Max Planck and Human Cognition and Brain Sciences in Leipzig.
Through further research, the team now wants to elucidate in more detail how far the similarities in chimpanzee communication characteristics and human language actually reach. They also plan to explore an exciting question that almost raises the question: to what extent do our animal relatives use sound sequences to convey a wider range of information to other animals?
Source: Max Planck Institute for Evolutionary Anthropology, Article: Communications Biology, doi: 10.1038 / s42003-022-03350-8