Chimpanzees and bonobos, the two primate species that most resemble humans, communicate with each other using different gestures. This finding was the first evidence of intentional communication outside of human language. So far, scientists have identified more than 80 gestural signals, which translate as ‘Get on my back’, ‘Follow me’, ‘Stop doing that’, ‘Come closer’, ‘Get away’, ‘Coo me’, etc. But not only researchers are capable of interpreting them, any of us is prepared to do so.
That is the main conclusion of a curious study carried out by Kirsty E. Graham and Catherine Hobaiter, two researchers from the University of St Andrews, in Scotland. As they conclude in the journal ‘PLOS Biology’, humans retain the understanding of the gestures made by other great apes, even though we no longer use them.
The researchers tested people’s understanding of the ten most common gestures used by chimpanzees (Pan troglodytes) and bonobos (panicus) through an online game (now open and without data collection). They asked more than 5,500 participants to watch 20 short videos of ape gestures and select the meaning of the gesture from four possible responses such as ‘Take me away’, ‘Give me that food’, ‘Change position’ or ‘Let’s be friends’. The two species share 90% of the gestures.
They found that the participants performed significantly better than expected by chance, correctly interpreting the meaning of chimpanzee and bonobo gestures more than 50% of the time. Giving participants contextual information about what the apes were doing in the video only marginally increased their success rate in interpreting the meaning of the gesture.
Video playback experiments have traditionally been used to assess language comprehension in non-human primates, but this study reversed the paradigm to assess humans’ abilities to understand the gestures of their closest living relatives for the first time. .
ancient communication
The results suggest that even though we no longer use these gestures, we may have retained an understanding of this ancient communication system. The authors say it’s unclear whether our ability to understand specific great ape gestures is inherited or whether humans and other great apes share the ability to interpret meaningful cues due to their similar general intelligence, physical resemblance, and social goals.
A picture of the experiment
“All great apes use gestures, but humans are so gestural (we use gestures while talking and signing, learning new gestures, miming, etc.) that it’s really hard to identify shared great ape gestures just by observing people.” Graham explains. “By showing participants videos of common great ape gestures, we found that they can be understood by people, suggesting that they may be part of an ancient vocabulary of gestures shared evolutionarily across all great ape species, including us.”
The experiment (testing yourself is a fun time and only lasts a few minutes) suggests that we still have a creature inside us that moves on its knuckles.