Full Breakdown
Monkeys Demonstrate Human-Like Geometric Intuition, Study Finds
7/22/2026, 12:20:41 PM
Core Findings: Monkeys Match Human Geometric Reasoning
Researchers led by Jessica Cantlon and Jialin Li at Carnegie Mellon University tested eight adult non-human primates—four olive baboons (*Papio anubis*) and four rhesus macaques (*Macaca mulatta*)—on a touchscreen task that required matching pairs of two-dimensional shapes that were geometrically identical despite changes in size or orientation. The same task was given to preschool-aged children, U.S. adults, and adults from the Indigenous Tsimane’ community in Bolivia. Across all groups, behavior was best explained by models of abstract geometric reasoning (symmetry, parallelism, right angles) rather than simple pixel similarity. Monkeys relied on these “symbolic” cues, though less strongly than adult humans, and showed a marked increase in symbolic reliance when shapes were rotated—an effect comparable to that observed in preschoolers. The results indicate a graded continuity in geometric intuition across primates.
Background & Context
Psychologists have long argued that encoding geometric rules such as “four equal sides” is uniquely human, a view reinforced by a 2021 study showing poor baboon performance on an “odd-one-out” geometry task. The new study, published in *Proceedings of the National Academy of Sciences*, challenges that hypothesis by demonstrating that non-human primates can employ the same abstract representations that underlie human geometric reasoning.
Key Figures & Groups
- Jessica Cantlon – senior author, Carnegie Mellon University.
- Jialin Li – co-first author, Carnegie Mellon University.
- Olive baboons – one of the two primate species tested.
- Rhesus macaques – the second primate species tested.
- U.S. preschoolers (ages 3–6) – recruited through Carnegie Mellon’s Children’s School.
- American adults – participants with typical U.S. schooling.
- Tsimane’ adults – members of a Bolivian farmer-forager community with little formal education.
Data & Statistics
- Monkeys: 8 individuals (4 baboons, 4 macaques).
- U.S. preschoolers: reported as 55–58 participants.
- American adults: 21 participants.
- Tsimane’ adults: reported as 77–80 participants.
- Task performance: All groups succeeded above chance; monkeys’ symbolic-model scores rose roughly threefold on rotated trials, matching the increase seen in preschoolers. Adults showed the strongest symbolic scores overall.
Why It Matters
The findings suggest that basic geometric intuition is an evolutionarily ancient capacity shared by primates, with formal education refining rather than creating symbolic geometric reasoning. This challenges curricula that treat geometry as a wholly novel construct and supports educational approaches that build on innate spatial intuitions. The cross-cultural testing highlights the value of isolating biological versus cultural contributions to cognition.
Official Statements & Responses
Li noted that the monkeys’ performance “surprised us” because it revealed a shared underlying mental architecture rather than a simple visual-matching strategy. The researchers emphasized that the touchscreen task removed obvious visual cues such as color or size, forcing reliance on abstract shape properties.
Verbatim Quotes
- “What surprised us wasn’t just that monkeys could do the task,” — Jessica Cantlon
- “The most surprising finding is that young kids, before receiving any formal math education, are struggling with the task as monkeys do," Jialin Li, a psychology researcher and the paper's co-first author, told ScienceAlert.” — Jialin Li
Conflicting Reports & Gaps
Sources differ on the exact numbers of human participants. Preschooler counts vary between 55 and 58, while the Tsimane’ adult sample is described as 77, 79, and “nearly 80.” The study’s methodology and overall conclusions are consistent, but the participant-count discrepancies highlight a gap in publicly available detailed rosters. No source provides a precise timeline for data collection, and the long-term implications for educational practice remain to be empirically tested.
