It has been revealed that bonobos communicate using grammar similar to that of humans. Just as humans create sentences by linking words, bonobos convey meaning by chaining sounds with different meanings. This research is expected to help illuminate how human language abilities have evolved.
A joint research team from the University of Zurich in Austria and Harvard University in the United States noted on 4th that they discovered that bonobos use grammar thought to be exclusive to humans.
Bonobos are primates classified as part of the family of humans, alongside chimpanzees, gorillas, and orangutans. They resemble chimpanzees but belong to a different species. Humans and chimpanzees diverged from a common ancestor about 5 million years ago, while bonobos split from chimpanzees and evolved around 2.5 million years ago. Thus, bonobos are now considered the closest primates to modern humans.
The research team observed 30 adult bonobos in the Kokolopori bonobo reserve in the Democratic Republic of the Congo for five months. They recorded about 1,000 sounds made by bonobos and examined what happened before and after vocalizations. They observed the situations and behaviors when bonobos made sounds, as well as the actions of other bonobos after vocalizations.
To clarify the meanings of the sounds made by bonobos, the researchers applied methods used in linguistics to identify word meanings. They aggregated sounds that occurred in similar situations and were used repetitively, much like deducing the meaning of words. Dr. Mélissa Berthet, a co-author from the University of Zurich's Department of Anthropology, explained, "It's like creating a kind of bonobo language dictionary," stating, "We assigned one meaning to each vocalization."
In particular, the research team confirmed that bonobos do not produce sounds with a single meaning but combine multiple sounds to convey meaning. Just as humans combine multiple words to create new meanings, bonobos also combine different sounds to communicate their circumstances to their peers.
For example, if a high sound signifying "Pay attention to me" is used along with a low sound signifying "I am excited," bonobos were often found to be threatened by other individuals. The research team interpreted the sounds made by bonobos as meaning, "I am being attacked, so please take care of me." Dr. Berthet stated, "This means that bonobos have a highly complex communication system similar to humans."
Bonobos are considered one of the closest primate species to modern humans. Thus, many of bonobos' abilities are actually similar to those of humans. In February, a research team from Johns Hopkins University in the United States announced in the Proceedings of the National Academy of Sciences (PNAS) that bonobos recognize what their peers are ignorant of in situations where cooperation is required and provide them with information. Kanzi, a bonobo who passed away at the age of 45 on 18th of last month, learned pictorial symbols, communicated at a level above that of a two-year-old human, made and used stone tools, and even enjoyed video games.
The research teams from the University of Zurich and Harvard University expect that the language formation abilities identified in bonobos this time will help find the roots of human language abilities. Professor Martin Surbeck of Harvard University's Department of Human Evolutionary Biology, a co-author of the paper, said, "Humans and bonobos share many traits because they had a common ancestor, and language formation ability might be one of those traits."
References
Science (2025), DOI: https://www.science.org/doi/10.1126/science.adv1170
PNAS (2025), DOI: https://doi.org/10.1073/pnas.2412450122