Our scientific research goals: what can an Ethiopian monkey tell us about human evolution?
Human beings are unique in their ability to carry out acts of extreme violence, but also in their capacity to restore peaceful relationships after conflict. This ability to reconcile and repair broken bonds is a cornerstone of complex societies. To understand its evolutionary roots, the BRIDGES/Geladas for Cooperation project focuses on the gelada monkey (Theropithecus gelada), an Ethiopian primate that lives in highly complex multilevel societies.
Why geladas? Geladas represent one of the most intricate social systems among primates. Their basic unit consists of one adult male, several females, and their offspring. Multiple units aggregate into larger groups, which can then form “bands” and eventually vast social communities numbering hundreds of individuals. In such a dynamic and layered environment, conflicts are unavoidable. Yet, maintaining cohesion is essential for survival. This balance between conflict and cooperation makes geladas a powerful model species for studying natural mechanisms of conflict resolution.
Another reason to focus on geladas is their exceptionally rich communicative repertoire. Compared to closely related baboons, geladas display a wider variety of vocalizations, facial expressions, and body signals. This complexity suggests that communication plays a central role in preventing, managing, and resolving conflicts.
The project investigates how geladas manage conflicts and restore harmony. Specifically, we focus on post-conflict interactions: how aggressors and victims approach each other and repair relationships, multimodal communication: the role of vocal, visual, and tactile signals in reconciliation, contextual variables: how factors such as kinship, friendship, gender, or rank influence reconciliation strategies, vocal exchanges: testing the hypothesis that certain calls allow individuals to “make peace at a distance,” reducing tension without the risks of close contact.
To address these questions, we combine long-term behavioral observations with playback experiments. This integrative approach allows us to explore not only which signals are used, but also their effectiveness in reducing stress and re-establishing social bonds.
Broader implications. By studying geladas, we aim to shed light on the evolutionary roots of empathy and cooperation. Their multilevel social structure resembles human communities in striking ways, raising the question of whether reconciliation and peace-making are uniquely human achievements or whether they emerged earlier in primate evolution. The evidence we gather will help clarify how sensitive communication and emotional regulation evolved as adaptive responses to the challenges of group living.
Importantly, our field site lies in a heavily human-impacted area, where geladas must coexist with agriculture and livestock. This gives us the opportunity to investigate not only their natural conflict-resolution strategies, but also their behavioral flexibility and adaptability in response to anthropogenic pressures—an issue highly relevant to conservation and to understanding how primates, including humans, adjust to rapidly changing environments.
In this sense, geladas are more than a fascinating primate species: they are a window into our past, helping us understand how the capacity to manage conflict and restore harmony may have shaped the evolution of human societies.