A Head for Shapes

Crows have long been hailed as some of the cleverest creatures to exist: For example, they can “count” and even build fortified nests. 

Now, scientists discovered that the avian species has a knack for geometry.  

In a new study, researchers at the University of Tübingen in Germany found that crows can recognize geometric regularity in shapes – a cognitive ability previously thought to be unique to humans. 

“Claiming that it is specific to us humans, that only humans can detect geometric regularity, is now (incorrect),” co-author Andreas Nieder told NPR, adding, “because we have the crow.” 

Nieder’s team trained two carrion crows to spot the “odd one out” among six geometric shapes on a computer screen. The birds were first given easy tasks, such as picking out a flower among moons, and rewarded with mealworms when they got it right.  

But then came the real test: Sets of subtly different four-sided shapes, some perfectly regular – such as squares – others more lopsided. 

The findings showed that the birds were not randomly picking the outlier shapes. They easily detected the outlier shapes among the four-sided shapes with regular features. 

The crows were the most challenged while attempting to spot differences between irregular shapes, such as rhombuses. The team explained that this difficulty is also present in humans. 

“This highlights the similarities of the geometric capabilities between crows and humans,” Nieder told ScienceAlert.  

Yet despite the challenge, the birds’ success rate showed they had an innate sense of angles, parallel lines, and symmetry.  

The study raises big questions about the roots of geometric intuition in the animal kingdom. Previous research has suggested that even primates like baboons struggled with this task, making the crows’ abilities even more surprising.  

As scientists begin to look beyond traditional models for mathematical ability, researchers believe that the animal kingdom may have more hidden talents than once thought.  

“We humans – based on our unique formal and symbolic understanding – take geometry to a whole different level,” Nieder told ScienceAlert. “But the very foundation of it, from a visual point of view, seems to be rooted in evolution.”