Chimpanzees and Bonobos Have Social Circles Like Humans

Humans often organize their relationships into layers. We spend the most time with a small group of close friends and family members. At the same time, we keep weaker connections with a larger number of acquaintances. This pattern helps us manage our social lives. A new international study suggests that this way of organizing relationships is not unique to people. It is also found in our closest living relatives.

Researchers from Utrecht University and Universidad Carlos III de Madrid found that chimpanzees and bonobos form social networks. These networks resemble human friendship circles. The findings provide new insight into how complex social relationships may have evolved. They show that the rules for building social bonds may be older than we thought.

To investigate how great apes manage their social lives, researchers examined social grooming behavior. They studied 24 groups of chimpanzees and bonobos. Grooming is one of the most important social activities among apes. It helps to strengthen bonds and maintain relationships. Apes spend a lot of time cleaning each other. This activity is not just about hygiene. It is a way to show trust and build connections.

Using a mathematical model, the team analyzed how individuals distributed their limited time and social effort. They looked at how each ape divided its attention among other members of its group. Time and energy are limited resources. An ape cannot be close to every other ape in the group. It must choose who to spend time with.

The results revealed a familiar pattern. Most apes devoted a large share of their grooming time to a small number of preferred partners. At the same time, they maintained less intensive relationships with many others. This layered structure closely resembles the way human social circles are organized. We have an inner circle of close friends and an outer circle of acquaintances. Apes seem to do the same.

The study also found that apes living in larger groups tended to be more selective. They were more careful about where they invested their social attention. This trend has also been observed in human social networks. As groups get bigger, people become more selective. This helps them keep their social relationships manageable and meaningful.