Hand chimps and bonobos a smartphone, and they will immediately get hooked on a group chat.
Humans are known to keep some close friends and form a “friend circle,” and to maintain weaker social connections scattered at work, schools, etc. However, maintaining a hierarchy from close confidants to the casuals is not a pattern unique to humans. A new international study by researchers from Utrecht University and Universidad Carlos III de Madrid found that chimpanzees and bonobos also form social networks that resemble friend circles.
Great Apes Make Their Social Efforts Worth
Chimpanzees and bonobos spend time in social grooming to manage their social lives. Grooming is an important social behavior in great ape groups, helping them strengthen bonds and maintain relationships. Using a mathematical model to analyze 24 groups of chimpanzees and bonobos, the team examined how individuals allocate their limited time and social effort among other members of their groups.
The results revealed that most apes devoted a large share of their grooming time to a small number of preferred partners, and didn’t give the same effort in being close with many others. The pattern is quite familiar to how human social circles are built and organized. The study also found that apes living in larger groups are pickier about where they invest their social attention, much like humans.
Bonobos Like to Groom Equally
Although both chimpanzees and bonobos showed human-like social structures, chimpanzees deviated from the bonobos’ egalitarian approach to maintaining relationships. While bonobos distributed their grooming more evenly among group members, chimpanzees focused their grooming on a smaller number of favored individuals.
The difference lies in the brain structure of bonobos and chimpanzees. Bonobos have a more developed amygdala than chimpanzees, which makes bonobos calmer. Bonobos are also better at handling stress and anxiety than chimpanzees. While bonobos keep an inclusive circle, chimpanzees are far more suspicious of strangers.
Bonobos are also better at de-escalating disputes, which are resolved through kissing, hugging, and other affectionate activities. To the contrary, chimpanzees start to show aggression and dominance, establishing a clear, strict social structure.
Chimpanzees Shrink their Friend Circle with Age
People become more selective of their relationships with age, and chimpanzees do the same, focusing on a smaller inner circle of close friends. Bonobos, on the other hand, do not shrink their social circles over time.
“Possibly, this is due to their more egalitarian social systems. Bonobos appear to live together in more fluid relationships, with social bonds that transcend group boundaries, something we rarely see in chimpanzees,” explains lead author Edwin van Leeuwen.
Ape Friendships can Give Insights to our Own
Complex societies are organized around fundamental roles that guide how individuals allocate social effort, and these rules apply across multiple species. The differences in how chimpanzees and bonobos build their social circles also suggest that there are multiple evolutionary strategies for managing social connections. Seeking insights from primates will help us better understand cooperation, social learning, and emotional well-being in humans.
Almost 35 years ago, Robin Dunbar, Professor of Evolutionary Psychology at the Department of Experimental Psychology, University of Oxford, studied the correlation between group size and brain size in primates. Using those observations and applying them to humans, Dunbar gave us “Dunbar Number”— the number of people humans can maintain stable and meaningful relationships with at once, which, according to him, was 150.
For people in their teens or young adulthood, navigating how to prioritize relationships can be difficult. Maybe further research into how our primal cousins figure out a way out in social settings can offer a clue to making socializing easier.
If you liked reading this story, click here to check out the story of Kanzi, a bonobo that could understand human language and play Minecraft.
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