It turns out that apes also signal the start and end of communication with 'hello' and 'goodbye'

by Mark Dumont

When communicating with others, such as conversations, humans first say hello and say goodbye when they say goodbye. This greeting was called 'joint commitment' as 'a signal to cooperate and communicate with others toward a common goal' and was regarded as a human-specific behavior. However, a research team at Durham University in the United Kingdom reports that apes such as bonobos and chimpanzees have also found joint commitments.

Assessing joint commitment as a process in great apes: iScience
https://www.cell.com/iscience/fulltext/S2589-0042 (21) 00840-3

Like humans, apes communicate to start and end social interactions
https://phys.org/news/2021-08-humans-apes-social-interactions.html

For example, in an experiment with human children, if the experimenter suddenly stops playing while playing with the children, the children will be asked to present toys and continue playing, or they will say 'still playing'. The results show that they want to be, and the behavior of these children is considered to be a kind of joint commitment.

Rafaela Heesen, a postdoctoral researcher at Durham University, one day witnessed a situation in which two bonobos were interrupted while they were grooming, but resumed with some gestures, and joined apes. I wondered if there was a commitment. So, as a result of the analysis of 1242 cases of communication by a group of bonobos and chimpanzees in the zoo, Hysén et al. I found out that I was doing it.

For example, bonobos have a 90% chance of sending gestures such as 'touching each other', 'holding hands', and 'hit their heads' before playing with others, and chimpanzees have a 69% chance of exchanging eyes. He said he was doing it. Also, when quitting play, Bonobo has a 92% chance of showing some kind of gesture to the other party, and Chimpanzee has an 86% chance of showing it to the opponent.

You can see how the two chimpanzees actually start communicating with the gesture in the following movie.

Chimps entering a grooming interaction-YouTube


First, two chimpanzees cross their eyes

After that, touch the body of the larger chimpanzee (right image) and the smaller body (left image).

After a few touches, the larger one started to groom the smaller one.

Furthermore, in the case of bonobos, it was found that the closer the psychological distance to each other, the shorter the length of the communication start / end signal. 'Human people don't often say hello when interacting with close friends,' Hysén said. In other words, Bonobo's joint commitment is influenced by individual friendship and the strength of social ties.

On the other hand, in chimpanzees, the length of communication start / end signals did not change regardless of friendship or social ties. The research team found that bonobo societies are generally egalitarian, with an emphasis on friendships, alliances, and parent-child relationships between women, while chimpanzee societies are based on a tyrannical power hierarchy. I speculate that psychological and social distances did not affect the greeting.

'Animal behavior is not fossilized. Excavating bones from the ground does not reveal how the animal's behavior evolved, but the Bonovo, which is closest to us humans, You can study chimpanzees. Whether this kind of joint commitment can be found in other species will be an interesting point in future research. '