Human language is infinite – although it consists of only a very limited number of sounds. We can form words from them and combine them into new sentences according to fixed rules. Researchers at the Institut des Sciences Cognitives Marc Jeannerod in Lyon and the Max Planck Institute for Evolutionary Anthropology in Leipzig have now demonstrated such grammatical structures in chimpanzees for the first time. They report their results in »Nature Communications Biology«.
The scientists around the anthropologist Cédric Girard-Buttoz examined three properties of language that form the basis for an inexhaustible vocabulary: Sounds must be able to be combined with one another as desired. In addition, these sound sequences must be able to be strung together, just like individual words in a sentence. All this should be done according to certain rules. Such a rule could be, for example, that a certain sound occurs particularly frequently at the beginning of an exclamation. The team analyzed almost 5,000 recordings of 46 wild chimpanzees in Taï National Park in Ivory Coast. For the first time, they have observed all three properties of language in a non-human animal. Some monkeys systematically string together up to ten sounds.
“Our results show that the chimpanzee’s verbal communication system is much more complex and structured than previously thought,” says co-author Tatiana Bortolato. In theory, primates could express hundreds of different meanings by combining twelve sounds. In the current work, the anthropologists were not able to find out whether they actually exploit this potential because they did not take into account the context in which the apes communicated with each other. This is exactly what they want to investigate in the future.