When we talk, we usually take turns talking very quickly or even interrupt each other. Behavioral biologists have now discovered that chimpanzees do something similar. They take turns exchanging gestures just as quickly as we humans do exchanging words. And there is another unexpected similarity that chatting chimpanzees have with human conversations.
Human conversations are rarely linear in the sense that person A speaks for two minutes and then person B gives a monologue. Rather, we take turns speaking very quickly, react to what the other person says and sometimes even interrupt each other. Such rapid turns of phrase, with an average pause of just 200 milliseconds in between, can be observed across all human languages.
Chimpanzees change as quickly as we
But just because the wild back and forth in conversations seems typically human, it doesn’t have to be reserved for humans alone. Researchers led by Gal Badihi from the Scottish University of St Andrews have now investigated for the first time whether chimpanzees – our closest relatives – also communicate in similar patterns. To do this, they collected data on the “conversations” of five wild chimpanzee groups from East Africa. Instead of using words, the animals communicate primarily with gestures. In total, the team was able to record over 8,500 different gestures from 252 individuals and then searched for patterns in this treasure trove of data.
The result: In 14 percent of the recorded interactions, the chimpanzees exchanged only gestures. Most of the time, such exchanges consisted of just one gesture per side of the conversation, for example when one group member asked another to do a certain thing and the other then responded to the request. In some cases, however, the gesture exchange consisted of up to seven turns – and these were carried out at a similar speed to humans, with pauses of an average of 120 milliseconds in between. “The similarities to human conversations reinforce the description of these interactions as a genuine gestural exchange in which the gestures produced in response depend on those of the previous round,” explain Badihi and her colleagues.
There are slow and fast speakers
And the talkative chimpanzees have another thing in common with us humans: the different communities of these great apes took different amounts of time to respond to what the other person said. “Among humans, it is the Danes who respond ‘slower’, and among the eastern chimpanzees, it is the Sonso community in Uganda,” reports senior author Catherine Hobaiter from the University of St Andrews. “Fascinatingly, the chimpanzees seem to share both our universal timing and subtle cultural differences.” This in turn suggests that human language may not be as unique as it appears at first glance.
However, it is still unclear whether humans and chimpanzees communicate in a similar way simply because they are so closely related, or whether the rapid-fire nature of conversations is a basic principle of communication. “To get to the bottom of this question, we need to study communication in more distantly related species – so that we can find out whether it is a characteristic of apes or one that we share with other highly social species such as elephants or ravens,” explains Hobaiter.
Source: Gal Badihi (University of St Andrews) et al., Current Biology, doi: 10.1016/j.cub.2024.06.009