For years, scientists believed abstract geometry was one of the skills that separated humans from every other animal. Understanding ideas like symmetry, right angles, and parallel lines seemed to require a uniquely human brain. A new study now tells a very different story.
Researchers have found that monkeys and young children share the same basic grasp of abstract geometry. The findings suggest that this ability did not suddenly appear in humans. Instead, it may have been part of the primate brain for millions of years, long before schools, textbooks, or written mathematics existed.
The research, published in the Proceedings of the National Academy of Sciences, was led by cognitive neuroscientists at Carnegie Mellon University. Their work challenges a long-held belief about the origins of mathematical thinking and opens the door to a new way of understanding how intelligence evolved.
The study focused on one simple question. Can monkeys recognize geometric relationships without relying on obvious visual clues like size, color, or direction?
To find the answer, researchers designed a touchscreen game that tested abstract thinking instead of simple pattern matching. Participants looked at a two-dimensional shape and then selected the matching shape from several choices. The correct answer was never an exact copy because the shapes changed in size or rotated into different positions.
That forced every participant to ignore surface details and focus on the shape itself. They had to recognize properties like symmetry, parallel lines, and right angles instead of picking the option that simply looked the same.
The experiment included olive baboons, rhesus macaques, preschool children between three and six years old, adults from the United States, and adults from Bolivia’s Indigenous Tsimane’ community. This mix allowed researchers to compare people with very different educational backgrounds while also studying two monkey species.
Monkeys and Children Solved the Puzzle the Same Way
Researchers described the findings as showing “a clear continuity across all groups.” That means the basic process used to recognize geometry appeared remarkably similar in monkeys, young children, and adults.
Senior author Jessica Cantlon said the biggest surprise was not that monkeys completed the task successfully. Instead, it was the fact that every group seemed to process geometric information using the same mental framework.
However, adults still performed better overall, but that difference was expected. Years of education and experience give adults stronger mathematical skills and better strategies for solving visual problems.
Geometry May Be Built Into the Primate Mind
One of the biggest takeaways from the research is that humans may not learn geometry from a blank slate. Children appear to arrive with an early understanding of shape and space that develops naturally as they grow. That changes the way scientists think about education. Instead of introducing completely new ideas, teachers may actually be strengthening abilities that children already possess.
The researchers believe these geometric instincts are part of the basic architecture of the primate brain. They describe this as an evolutionarily ancient ability that has survived across different species over millions of years.
Another important finding involves something called ‘rotation-invariant encoding.’ In simple terms, the brain recognizes a shape as the same object even after it turns or changes size. This allows people and monkeys to focus on the important geometric features instead of getting distracted by appearance.
What This Means for Human Learning
Early learning may become more effective by connecting classroom activities with the natural ways children already recognize patterns and shapes. That could make geometry easier to understand and more enjoyable to learn.
The study also adds another piece to the puzzle of human evolution. Scientists have long sought the origins of mathematical thinking, and this research suggests those roots extend much further back than previously believed.
Archaeological discoveries support that idea. Researchers pointed to a 70,000-year-old stone etched with parallel lines and a 35,000-year-old mammoth tusk marked with carefully organized notches. These ancient objects show that humans have noticed geometric patterns for tens of thousands of years.