Leipzig Zoo in central Germany is a world-leading centre of great ape research. Recent studies have seen chimpanzees there using touchscreen controls to navigate virtual forests and locate food rewards – applying similar techniques to what they would use in the wild.
Other research (of which I was part) has investigated chimpanzees’ social curiosity. We discovered they actively seek out information about others’ interactions, even if it means forgoing food rewards. Keeping track of their peers’ latest social developments appears central to these great apes’ social wellbeing.
But in my decade working with Leipzig Zoo’s chimpanzees and bonobos, one question came up repeatedly. Were differences in how each great ape would cooperate and resolve conflicts simply down to its mood on a particular day? Or were there longer-term explanations – deep-rooted personality traits, for example, or their relationship history with other apes?
Long-term questions like this are very difficult to tackle in single studies, which often draw on just a handful of participants. So, my colleagues and I have developed EVApeCognition: a standardised database of 18 years’ worth of great ape experiences, decisions and relationships.
This lays the groundwork for answering many more questions about these extraordinary creatures’ cognition, intelligence and social behaviour. If a bonobo showed striking generosity towards a partner in 2008, for example, we can piece together whether that behaviour was linked with their stable disposition, a particular relationship, or some other factor.
Changing how we study great apes
In all, EVApeCognition comprises 262 experimental datasets from 150 scientific publications between 2004 and 2021. These were all overseen by the Wolfgang Köhler Primate Research Centre, headquartered at Leipzig Zoo. Eighty-one great apes participated in these studies, with the vast majority (78) taking part in more than one.
These wide-ranging social cognition studies have assessed how great apes think about other apes, how they cooperate, and to what extent they are motivated to help their peers. But there have been limitations to this research.
The Otters/Wikimedia Commons, CC BY-NC-SA
In the wild, great apes are social animals who live in stable groups with histories, hierarchies and relationships that change over time. In contrast, a large majority of the studies in our database were with apes in pairs that imposed strict control conditions.
So, moving to larger-group studies could offer a more ecologically relevant window on their cognition and social behaviour. Group settings can present apes with different problems that map more closely on to the social challenges they face every day in the wild.
Our most recent study, led by Kirsten Sutherland at the Max Planck Institute for Evolutionary Anthropology, found that great ape quartets maintained access to a pool of yoghurt for significantly longer than pairs did. Social tolerance played a key role, with more tolerant quartets maintaining access to the yoghurt for longer periods.
We found that cooperation was strongest when the highest-ranking individual showed restraint, emphasising the importance of tolerant leadership.
The new database also highlights an imbalance running through captive great ape research: chimpanzees dominate the record, while bonobos, gorillas and orangutans remain comparatively underrepresented.
Bonobos – which, unlike chimpanzees, are known to cooperate in the wild outside the limits of their group’s territory – would be particularly compelling subjects for this research shift towards studying larger groups.
Closing the gap with wild settings
Experimental performance does not occur in a social vacuum. A great ape’s willingness to cooperate on a task on a given Tuesday may not only reflect its intelligence, but whether it groomed its partner that morning, or if its status had changed within the group.
Providing this context is essential to understanding how everyday experience and social relations shape their cognitive development. Fortunately, the field is moving in promising directions, with the EVApeCognition database one piece of a larger picture.
The global ManyPrimates project, established in 2017, has already produced the most comprehensive overview of primate short-term memory. This shows that genetic lineage has played a larger role than ecology or sociality in the evolution of their short-term memory.
At the level of higher-order reasoning, we now know that chimpanzees update their beliefs by considering all sources of information before making a choice. A 2025 study showed they remained committed to an initial belief when counter-evidence was weaker, but revised this when the supporting evidence became stronger – a pattern long thought to be distinctly human.
Perhaps most ambitiously, the divide between captive and wild settings is also beginning to close. Research led by Sofie Forss at the University of Zurich, for example, has found a systematic “captivity effect” when presenting the same new stimuli to both wild and captive orangutans. The wild individuals responded far more cautiously to novelty than their zoo-housed counterparts.
Taken together, these efforts point in a common direction: toward an understanding of great ape cognition that is at once broader in scope, richer in context, and more faithful to the complexity of their social lives.
Alejandro Sánchez-Amaro does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
