An international team of scientists has shown that chimpanzees, like humans, use signals to indicate the beginning and end of social interactions. The researchers believe their discovery suggests that this behavior was characteristic of the common ancestor of humans and chimpanzees. The biologists' article was published in the journal iScience.
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The ability to share their intentions allowed people to perform actions together and gradually led to the emergence of joint obligations. Recently, there is evidence that this behavior is also characteristic of higher apes. A team of scientists from the UK, USA, France and Switzerland, led by researchers from the University of Neuchâtel, suggested that joint obligations arise not only from a sense of duty, but also with a mutual agreement to fulfill them. This means that an example of such behavior can be a simple agreement on a dialogue - with visual contact at the beginning and a signal to end the conversation at the end. The researchers decided to find out if this behavior is present in higher apes.
They analyzed 1,242 interactions between chimpanzees and bonobos (pygmy chimpanzees) in four different zoos. It was found that the monkeys did interact with each other at the beginning and end of the communication. Before starting to play, 90 percent of the observed bonobos and 69 percent of the chimpanzees "greeted" each other. 92 percent of bonobos and 86 percent of chimpanzees said goodbye. Signals included touching, shaking hands, and forehead bumping. The closer the bonobos were to each other, the shorter these signals were. In chimpanzees, such a correlation was not noticed, which is supposed to be explained by a more rigid hierarchy in these primates compared to bonobos. According to scientists, the results of their research indicate that the process of the emergence of joint obligations was characteristic even for the common ancestor of humans, bonobos and chimpanzees.