Giraffes Just Passed A Math Test That Stumps Toddlers

Four giraffes at Barcelona Zoo have done something that would trip up plenty of five-year-olds: they mentally added numbers they could not see. A study published in the journal ‘Scientific Reports’ by researchers from the University of Barcelona and the University of Leipzig found that giraffes named Nakuru, Njano, Nuru and Yalinga could track hidden food quantities and combine them accurately, choosing the container with more food roughly 68% of the time.

The test worked like this: researchers placed carrot pieces into two covered containers, letting the giraffe see how many went into each before the lids closed. A third container, holding more carrots, was then emptied into one of the covered ones. To pick correctly, the giraffe had to remember the starting amounts, add the new pieces mentally, and compare the final totals without ever seeing them side by side.

The giraffes handled this ‘combination’ task well, successfully keeping track of totals up to five items and mentally adding as many as three new pieces to an existing hidden amount. But addition was clearly easier than subtraction. When researchers reversed the setup and visibly removed carrots from a container instead of adding them, giraffe accuracy dropped to about 57%, which the team considered close to random chance.

That imbalance mirrors a pattern seen in human children, who typically grasp addition before subtraction, and in some primates, including chimpanzees, which show the same skew. Researchers say it suggests a deeper, shared cognitive tendency rather than a giraffe-specific quirk.

To rule out the animals simply reading human cues rather than actually calculating, the researchers guarded against the so-called Clever Hans effect, in which an animal appears to solve a problem by picking up on a trainer’s body language instead of reasoning it out. The experimenter wore sunglasses and kept a neutral expression throughout. Even when testers tried directing the giraffes toward the wrong container with hand movements, two of the four, Nuru and Njano, still chose the larger true total, indicating they were tracking quantities in their heads rather than just following hints.

Giraffes have comparatively small brains relative to their body size, and researchers say the finding challenges the long-held assumption that arithmetic-like ability requires a large brain-to-body ratio, as seen in primates, dolphins or parrots. Instead, they point to the giraffe’s social and feeding life, tracking shifting groups and estimating which distant trees hold more leaves, as a more likely driver of this kind of numerical skill.

Wikimedia Commons/by Charles J. Sharp