Chimpanzees and bonobos form human-like social circles, study finds
The Story
Researchers from Utrecht University and Universidad Carlos III de Madrid examined social grooming behavior in 24 groups of chimpanzees and bonobos. Using a mathematical model, they found that both species organize relationships into layered networks similar to human friendship circles. Most apes devoted the majority of their grooming time to a small number of preferred partners while maintaining weaker ties with many others. Chimpanzees concentrated more effort on a smaller circle of favored companions, while bonobos distributed their grooming time more evenly. The study also found that chimpanzees become more selective about social partners as they age, a pattern not observed in bonobos. Lead author Edwin van Leeuwen stated that the findings reveal deep evolutionary continuity in how complex societies are organized. The results were published in the journal iScience on May 31, 2026.
Key Facts
- The study was conducted by researchers at Utrecht University and Universidad Carlos III de Madrid.
- Researchers analyzed grooming behavior in 24 groups of chimpanzees and bonobos.
- Both species displayed layered social networks: a small inner circle of close partners and a wider network of weaker connections.
- Chimpanzees focused more on a few favored companions, while bonobos maintained more egalitarian social structures.
- Chimpanzees became more selective with age, investing in fewer partners; bonobos did not show this narrowing.
- The findings were published in iScience on May 31, 2026.
Conflicting Reports
No conflicting reports identified in the source article.
Still Unclear
No open questions identified in the source article.
Misconceptions
No widespread misconceptions addressed in the source article.
Key Figures
- Edwin van Leeuwen – lead author, Utrecht University
- Research team included Diego Escribano, Zanna Clay, Marcel Eens, Jean-Pascal Guéry, Daniel B.M. Haun, Stephanie Kordon, Suska Nolte, Nicky Staes, Jeroen M.G. Stevens, Jonas Torfs, José A. Cuesta, and Angel Sánchez.
Sources: ScienceDaily
