Summary: Great ape cognition is highly individualized, dynamic, and organized differently from human intelligence. In an 18-month longitudinal study of 48 animals — chimpanzees, bonobos, gorillas, and orangutans — researchers found that individual cognitive profiles remain stable over time and are strongly shaped by factors such as rearing history, sex, and social group membership.
Crucially, while human social abilities often develop in cohesive clusters, the apes in this study showed no statistical correlation between different social tasks. This indicates a distinct cognitive architecture in great apes and challenges assumptions based on human-centered models of cognitive evolution.
Key Facts
- Individual Profiles Over Species Averages: Intelligence in great apes is not uniform within a species. Individual apes show stable cognitive strengths and weaknesses that persist across time.
- 18-Month Longitudinal Study: The research tracked 48 individuals from four species across ten testing sessions during a year and a half, using repeated measures to assess stability.
- Predictors of Performance: Cognitive performance was strongly predicted by stable environmental and demographic factors, including social group, sex, rearing history, and prior research experience.
- A Different Structure Than Humans: Tasks that depended on social cues did not correlate with one another, in contrast to human patterns where social skills tend to cluster together.
- Need for Primate-Centered Tools: The findings highlight that many common assessment methods are tailored to human cognition, underscoring the need for measurement tools developed specifically for apes.
Source: APS
Background: For decades, scientists have studied great ape cognition to trace the origins of human cognitive abilities. A common assumption has been that cognitive traits appearing only in species closely related to humans must have emerged relatively late in our evolutionary history. That perspective tends to treat cognition as static and uniform within species. In contrast, this study approached ape cognition as a dynamic set of abilities that vary across individuals and through time, shaped by personality, experience, and developmental history.
“Many experiences contribute to the precise way an individual’s cognition is structured,” said Manuel Bohn, a developmental psychologist at Leuphana University of Lüneburg. “In human research, developmental and individual differences are central. We wanted to bring the same perspective to great ape cognition.”
Published in Psychological Science and building on earlier work by Bohn and colleagues, the new study explored individual differences across multiple cognitive domains over an extended period. The goal was to assess stability, structure, and predictability of cognitive traits in great apes rather than assuming a single species-wide profile.
The sample included 48 individuals across four species: bonobos, chimpanzees, gorillas, and orangutans. The animals, varying in age and sex, completed six tasks across domains such as social cognition, reasoning, and executive function. Tasks assessed abilities like following a human experimenter’s attention, interpreting communicative cues, and recalling locations where they had searched for food. These procedures draw on established comparative psychology methods but were applied longitudinally to evaluate individual trajectories.
Results revealed substantial individual variation, even within species. Group membership, prior research experience, sex, and rearing history emerged as strong and consistent predictors of performance. For most tasks, individuals’ scores remained reasonably stable over the 18-month period, indicating that these cognitive differences behave like traits rather than fleeting states.
When the team examined correlations between tasks to infer the internal organization of ape cognition, a striking pattern appeared: nonsocial tasks (for example, reasoning tasks) tended to correlate positively with one another, but social tasks did not correlate with each other or with nonsocial measures. In other words, being good at one social test did not predict being good at another. This contrasts with human developmental data where social abilities typically cluster together.
“We did not find the clusters we would expect based on human cognitive organization,” Bohn said. “That raises fundamental questions about how cognition is structured in other primates and what alternative organizational principles might apply.”
Bohn acknowledged the study’s modest sample size and urged caution, but he emphasized the study’s contribution in opening new lines of inquiry. He suggested future work should focus on refining assessment tools specifically for ape cognition and conducting more longitudinal research to map developmental trajectories and individual variability in greater detail.
Longitudinal studies are challenging, yet they are essential to document how cognitive capacities emerge, change, and interact over time. Comparing such developmental profiles with human patterns could illuminate which processes are shared across species and which are unique, clarifying the evolutionary pathways that shaped cognition.
“Thinking about alternative structures of cognition beyond human-centered frameworks is vital,” Bohn said. “This study invites researchers to explore non-anthropocentric models of cognitive organization and to develop tools that measure cognition on the species’ own evolutionary terms.”
Key Questions Answered:
A: Like humans, individual apes have distinct personalities, genetic backgrounds, and life experiences that shape their cognitive development. Treating the entire species as having a single, fixed intelligence level ignores the dynamic nature of cognition: abilities develop, peak, and change across an individual’s life. Recognizing individual differences reveals cognition as a flexible, living system rather than a single evolutionary snapshot.
A: In human developmental research, social skills often cluster—strong performance in one social domain tends to predict strength in another. In this study of apes, those links were absent. An individual might excel at following gaze but perform poorly at interpreting a direct communicative gesture. This indicates that ape social cognition may be organized along different evolutionary lines than human social cognition.
A: Two major obstacles are limited sample sizes and the lack of assessment tools designed specifically for apes. Longitudinal studies are difficult to run but necessary to capture developmental trajectories. Many existing comparative psychology tools were developed with human milestones in mind; to understand ape cognition fully, researchers must create non-anthropocentric instruments that measure cognition on terms relevant to apes.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by staff to clarify implications for comparative cognition research.
About this social and evolutionary neuroscience research news
Author: Hannah Brown
Source: APS
Contact: Hannah Brown – APS
Image: Image credit: Neuroscience News
Original Research: Open access. “Individual Differences in Great Ape Cognition Across Time and Domains: Stability, Structure, and Predictability” by Bohn, M., Völter, C. J., Hanus, D., Eisbrenner, N., Eckert, J., Holtmann, J., & Haun, D., published in Psychological Science. DOI: 10.1177/09567976261434817
Abstract
Individual Differences in Great Ape Cognition Across Time and Domains: Stability, Structure, and Predictability
Understanding variation in cognitive abilities is essential for studying both the evolution and development of cognition. This study examined the stability, structure, and predictability of individual differences in cognition across domains that include social cognition, quantitative reasoning, executive function, and inferential reasoning. Six tasks were administered to 48 individuals from four species across ten sessions spanning 1.5 years. Task performance was most strongly predicted by stable, individual-specific characteristics rather than transient group-level variables. Using additional data from the same individuals, researchers observed substantial positive correlations among nonsocial tasks, while tasks that measured social cognition did not correlate with one another or with nonsocial measures. The authors recommend future work aimed at building mechanistic models of great ape cognitive processes and developing assessment tools suited to ape biology to advance our understanding of cognitive evolution.