It's complicated: New research reveals more about the social networks of baboons and African monkeys

Sadie Harley

scientific editor

Meet our editorial team
Behind our editorial process

Robert Egan

associate editor

Meet our editorial team
Behind our editorial process
Editors' notes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

peer-reviewed publication

trusted source

proofread

The GIST
Add as preferred source

Like people, nonhuman primates live in groups that vary in size and shape depending on the species. Some primate groups are small and simple; others are large and more layered. Over the decades, primatologists have observed that baboons and other closely related monkeys, the African papionins, typically live in two types of social groups: single-level and multi-level societies.

However, a new study led by Arizona State University reveals it's more complex than a simple divide—and offers fresh insight into how subgroups form. The article, "Disparate social structures are underpinned by distinct social rules across a primate radiation," is published in the Proceedings of the National Academy of Sciences.

"Single-level societies are kind of like soccer leagues," explained Arizona State University primatologist Jacob Feder. "Everyone is an exclusive member of their unambiguous team, competing against other teams to 'win' (access to good food, defend their territory). In general, people have positive feelings and relationships with those who are a part of their team, and are averse to those who aren't."

"Multi-level societies are more like schools," Feder explained. "Everyone's divided up into their respective classrooms, but they regularly pass by each other in the hallways, cross paths during lunch breaks and mingle during recess. While relationships within classes are generally stronger, there's no ill will (and sometimes even friendships) between classes and plenty of social glue keeping everyone together."

So, Feder compiled a new database of 135 years of data from 11 species across 13 field sites to quantitatively show how these groups form and if there is a gray area. Dozens of international scientists contributed to the "Comparative Analysis of Papionin Societies (CAPS)" database.

Why baboons and not chimpanzees, our closest living relative?

"This dataset focused on baboons and papionins because this group of primates has long been used as a sort of model for human evolution. Baboons, geladas and mangabeys were evolving around the same time as our early human ancestors during the Plio-Pleistocene (roughly 5.3 million to 11,700 years ago)," said Feder, a National Science Foundation Postdoctoral Fellow with the Institute of Human Origins and School of Human Evolution and Social Change at Arizona State University.

To map out the societies, Feder used social network analysis and built networks based on grooming behavior. He mapped out how often grooming occurred, how long it lasted and who was grooming whom.

Grooming is unambiguous, and scientists note the behavior the same way. Primates groom to clean each other from lice and bugs, and they groom because it seems to be very relaxing, explained Joan Silk, a research scientist at the Institute of Human Origins and Regents Professor at the School of Human Evolution and Social Change.

What did the new networks show?

"One thing that we discovered in the data, which we had not previously suspected—it turns out that not all of these single-level societies are actually the same," said Silk. "In some ways, they are very similar, strong kin biases, etc. However, some are more cliquish and some are more cohesive."

Another interesting find is that some of these differences in the structure of the networks are driven by females. Female primates might drive these changes by strengthening their relationship with dominant males or their preference for family and other closely ranked individuals.

"Females don't necessarily have more coercive power, but they are creating social structures," said Silk. "The ecological reasons of how and why you have these multi-level societies are still a big question. And now that we've done this work, we can go after that."

This collaborative work between scientists incorporates new statistical methods and insights into how these primates live and their social networks.

Publication details

Jacob A. Feder et al, Disparate social structures are underpinned by distinct social rules across a primate radiation, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2520774123

Journal information: Proceedings of the National Academy of Sciences

Key concepts

Great ApesOld World monkeysCollective behaviorSocial systemsReal world networksNetworks Analysis Tools

Provided by Arizona State University