August 11, 2024, 8:36 am | Read time: 4 minutes
Very few people will deny that great apes are intelligent. However, the fact that they can also hold conversations with each other is rather unknown. A study has now shown that chimpanzees have a sign language with at least 8,500 gestures. This means that they are able to communicate just as effectively as humans. Cultural and linguistic scientist Louisa Stoeffler classifies the results for PETBOOK.
Humans communicate with each other efficiently and swiftly through language. In a conversation, a speaker sends a signal that the recipient of the message understands and returns within milliseconds. This structure can be found in all people across all cultures. However, this capability is not exclusive to us; apes exhibit it as well. Researchers have uncovered that chimpanzees have a repertoire of 8,500 gestures. They have developed a sign language so effective that their communication rivals the speed of human speech. This enables them to converse with one another.
How gestures create language
In linguistics, gesture research and the analysis of sign language are still a very new field. Scientists have only been studying how hand movements support what is said or how meanings are communicated through hands for a few years. In many other disciplines, such as psychology and neuroscience, as well as comparative cultural studies and animal communication research, however, this has long been established.
For instance, the signals and vocalizations that animals employ to signal each other have been extensively studied. This was the case when analyzing the language of meerkats. They consistently emit sounds to signal to others whether they are hunting, marking their territory, or alerting to the presence of predators nearby. However, this communication takes place without actually creating a speech scenario in which two people sit opposite each other and exchange information.
For a long time, it was thought that “talking to each other” was only reserved for humans. Nonetheless, a team of researchers headed by Dr. Gal Badihi from St. Andrews University in Scotland is merging animal and linguistic research to produce groundbreaking findings. By studying the incredible diversity of 8,500 sign language symbols in chimpanzees, they were able to show that primates actually speak to each other.
In the journal “Current Biology”, they detail the strategy of turn-taking, or speaker switching, among apes. Instead of exchanging just one or two simple gestures, up to seven different speech acts could be documented in the observed conversations between chimpanzees!
Chimpanzee sign language draws parallels to human communication
“Human conversation follows very strict rules, which involve taking turns. These are the same in all cultures and languages,” Dr. Badihi told the British daily newspaper “The Guardian“. Based on this, the team wondered whether chimpanzee communication follows its own rules. They also wondered if the rules were similar to those of human communication.
With their study of five wild populations in East Africa, they succeeded. The animals possess gestures not only for commands like “stop”, “come with me”, and “clean me”. The time that elapsed between a communicative signal and the response to it was also comparable. It varied between 120 and 200 milliseconds — and was therefore sometimes even faster than in humans.
The researchers further hypothesize that these analogous conversational structures may have evolved through a similar mechanism. According to the study, the chimpanzees’ gestures also include signals for clarification, persuasion, and negotiation between conversation partners.
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Chimpanzees could even show cultural language differences
Another fascinating possibility that emerges from this research is the possibility of cultural differences between the various ape populations. This is because the researchers noticed that there were different times between the animals’ responses.
These differences in speech have already been well studied in human cultures. For example, a 2009 study found that people in Scandinavia speak more slowly than people who communicate mainly in English, Italian, or Spanish. In Finnish and Swedish, it took an average of a few seconds for the second speaker to respond. In English, there were only minimal gaps between responses, while in Spanish or Italian, some respondents did not even wait for the speakers to finish speaking.1
These differences were also evident in the sign language responses of chimpanzees. In some groups, the timing was the same as in English conversations. However, there was also a signal overlap, as is the case with Italian or Spanish speakers. This suggests that chimpanzees are capable of processing the entire signal and formulating a response even before the speaker has concluded.2