Summary: A research team has shown that an intuition for two-dimensional geometry is shared across species and ages: olive baboons, Rhesus macaques, young human children, and adults all rely on the same basic mental processes to judge geometric similarity. By comparing touchscreen data from free-ranging primates with performance from U.S. preschoolers, American adults, and 79 adult members of Bolivia’s indigenous Tsimane’ farmer-forager community, the study demonstrates that this geometric sense is a deep, evolutionarily ancient cognitive capacity that exists prior to formal schooling and much human cultural variation.
Key Facts
- Cross-species geometric continuity: Olive baboons, Rhesus macaques, preschool children (ages 3–6), and adults assess two-dimensional shape similarity using fundamentally comparable cognitive strategies.
- Separating culture and schooling: Testing Tsimane’ adults—who typically lack U.S.-style formal schooling—helped the researchers isolate biologically rooted geometric intuitions from learned, education-driven skills.
- Feature-free similarity matching: The touchscreen tasks were designed so matches could not rely on obvious visual cues such as color, size, texture, or salient surface features; participants had to base choices on abstract geometric relationships.
- Foundational STEM architecture: The results indicate that formal geometry education builds on preexisting, evolutionarily ancient cognitive foundations rather than creating geometric understanding from scratch.
- Primate Portal data collection: Part of the data came from a public, touchscreen research kiosk at a zoo that lets baboons voluntarily perform cognitive tasks while providing open access to data and code for education and research.
Source: Carnegie Mellon University
Non-human primates are already known for complex abilities such as tool use, facial recognition, and flexible communication, but many have assumed that sophisticated geometric reasoning is unique to humans. A new study, to be published in Proceedings of the National Academy of Sciences, challenges that assumption by showing continuity in geometric intuition across primates and humans.
“What surprised us wasn’t just that monkeys could do the task,” said Jessica Cantlon, a cognitive neuroscientist at Carnegie Mellon and the study’s senior author. “It was that monkeys, children and adults seemed to think about geometric relationships in fundamentally the same way. That suggests these intuitions are part of the basic architecture of the primate mind.”
To investigate geometric perception, the researchers used a match-to-sample touchscreen task that removed conspicuous visual cues. Monkeys received small fruit snacks when they participated, and human participants—preschoolers, U.S. adults, and Tsimane’ adults—completed analogous versions of the task. Because the shapes lacked distinctive colors, textures, or scale differences, success depended on evaluating abstract geometric relationships such as relative angles, parallelism, and overall shape structure.
The team tested dozens of preschool-aged children at Carnegie Mellon’s Children’s School, 21 American adults, and 79 adults from the Tsimane’ community. Including the Tsimane’—a population with little exposure to Western formal education—allowed the researchers to determine whether geometric reasoning depends on schooling or reflects a more universal, biologically based capacity. The consistent patterns across species and cultures indicate that basic geometric intuition does not require formal instruction.
Cantlon explained that recognizing what children already know about shape and space matters for education. “Geometric intuition is something humans eventually turn into mathematics and science,” she said. “If we want to understand how children learn geometry, we need to know what they bring to the table before formal instruction begins. This study suggests that children start with deep, evolutionarily ancient intuitions about shape and space, and education can build on those intuitions.”
The Primate Portal
A portion of the monkey data was collected via the Primate Portal at Seneca Park Zoo, a collaborative touchscreen kiosk developed by researchers at Carnegie Mellon University and the Rochester Institute of Technology. The enclosure allows captive olive baboons to interact voluntarily with cognitive tasks during their daily routines. The portal shares raw data, code, and video to support research transparency and K–12 STEM education.
Lead author Jialin Li, a Ph.D. student, highlighted the engagement of individual animals: one baboon, nicknamed Kalamata, frequently returned to the kiosk and spent hours completing mathematical tasks. Beyond research, the Primate Portal has been adapted for classroom use: elementary students learn to code game tasks for the zoo kiosks, visit the animals, and gain hands-on experience that the researchers say correlates with increased interest and achievement in STEM subjects.
The origins of human thought
Archaeological findings—such as engraved stones and notched bone artifacts—show that sensitivity to geometric patterns has deep roots in human history. The current study suggests that the cognitive processes underlying those geometric insights are not uniquely human but are shared, at least in part, with other primates. By demonstrating that monkeys and humans rely on similar abstract representations to judge shape similarity, the research challenges theories that attribute human geometric reasoning solely to symbolic or culturally acquired systems.
Key Questions Answered:
A: When distinctive visual features are removed, matching shapes depends on abstract, high-level perceptual processing. Participants must ignore superficial differences and evaluate mathematical relations between shapes—an ability that requires more abstract cognitive representation than simple feature-based matching.
A: Including Tsimane’ adults, who generally lack exposure to Western formal schooling, allowed the researchers to rule out formal education as the primary source of geometric reasoning. Similar performance across culturally diverse groups indicates the trait is a natural biological capacity shared across primates.
A: The Primate Portal is a public touchscreen research kiosk where captive baboons can voluntarily engage with cognitive games. The project shares data and materials with classrooms so students can design tasks, observe animal behavior, and learn coding skills—an approach linked by the researchers to increased STEM interest and improved learning outcomes.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by staff.
About this evolutionary neuroscience research news
Author: Jason Bittel
Source: Carnegie Mellon University
Contact: Jason Bittel – Carnegie Mellon University
Image: The image is credited to Neuroscience News
Original Research: Open access. “Continuity in Geometric Intuition Between Humans and Monkeys” by Jialin Li, Isabelle Boni, Logan R. Sandwick, Emily M. Sanford, Caroline M. DeLong, Li Wenjie, Margaret M. Henderson, Steven T. Piantadosi, Jessica F. Cantlon. PNAS
DOI: 10.1073/pnas.2532934123
Abstract
Continuity in Geometric Intuition Between Humans and Monkeys
Geometric intuition has long been considered a hallmark of human cognition, often linked to advanced mathematical thought and the ability to represent Euclidean features such as parallelism and symmetry. A common explanation posits a qualitative divide: humans use discrete, symbolic encodings for geometry while other primates rely on continuous perceptual cues. This study offers evidence against that strict divide.
Using a match-to-sample paradigm, the researchers found that monkeys and humans both combine high-level perceptual representations with more abstract, rotation-invariant encodings to judge two-dimensional geometric similarity. Rather than a categorical difference, the findings point to a graded, quantitative continuity in geometric intuition across species. Monkeys demonstrated particularly strong rotation-invariant processing in some conditions, suggesting that what appears to be symbolic representation can arise from abstract perceptual encoding. These results imply that the roots of human geometric reasoning are shared with other primates and predate formal education and many cultural practices.