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A little girl and an olive baboon interact with each other through the glass at the Seneca Park Zoo, where the Primate Portal is housed. Credit: Rochester Institute of Technology
Nonhuman primates are viewed as among the smartest animals due to tool use, face recognition and sign language learning. Yet geometry has long been considered beyond their reach.
A new study in Proceedings of the National Academy of Sciences challenges that view.
“What surprised us wasn’t just that monkeys could do the task,” said Jessica Cantlon, a cognitive neuroscientist at Carnegie Mellon University and 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.”
Cantlon’s team gave olive baboons and rhesus macaques fruit snacks for completing a touchscreen matching task with two-dimensional geometric shapes.
“That might seem easy, but it’s actually pretty difficult, because there are no distinctive features among the objects, no major differences in color, size or form,” said Cantlon.
The monkeys had to match shapes based on geometric similarity alone.
“You’d get tripped up, too,” Cantlon noted when asked if adults would struggle.
The same test was given to preschoolers aged 3-6 at CMU’s Children’s School, 79 adults from Bolivia’s indigenous Tsimane’ people and 21 American adults.
“That allowed us to sort of tease apart age and cultural experience,” said Cantlon.
Results showed clear continuity across nonhuman primates, children and adults in basic geometric thinking.
“Geometric intuition is something humans eventually turn into mathematics and science,” said Cantlon. “This study suggests that children start with deep, evolutionarily ancient intuitions about shape and space.”
The work comes from Cantlon’s lab and the Primate Portal at Seneca Park Zoo, an enclosed touchscreen for captive olive baboons.
“One of the baboons, named Kalamata, was the hardest-working monkey that I’ve ever seen,” said lead author Jialin Li.
The portal provides open access to data, code and video for studying animal minds.
