Scientists Discover Giraffes Can Silently Do Math In Their Heads

A study published in ‘Scientific Reports’ has found that giraffes possess a talent researchers describe as a basic form of arithmetic: mentally combining quantities they cannot see. The work, carried out by scientists from the University of Barcelona and the University of Leipzig, tested four giraffes, Nakuru, Njano, Nuru and Yalinga, at Barcelona Zoo.

During the test, researchers showed each giraffe two covered containers holding different numbers of carrot pieces before sealing them. They then added more carrots from a third container into one of the sealed ones. To choose the correct, bigger total, the giraffe had to remember both starting amounts, mentally add the newly poured-in pieces, and compare final totals that it never actually saw.

The giraffes chose the container with more food correctly around 68% of the time and could track totals as high as five items, successfully adding up to three new pieces to an already-hidden amount. Subtraction was a different story: when carrots were visibly taken away instead of added, giraffe accuracy fell to about 57%, a figure the researchers regard as effectively random guessing.

This gap between addition and subtraction skills is not unique to giraffes. Human children generally find subtraction harder and learn it later, and earlier research on chimpanzees found the same asymmetry, with primates handling addition better than removal tasks.

To make sure the giraffes were not simply reading cues from their human handlers, a bias known as the Clever Hans effect, researchers wore sunglasses and kept a blank expression throughout testing. Even when hand movements were used to point toward the wrong container, two giraffes, Nuru and Njano, still chose the container with the genuinely larger total, suggesting real mental tracking rather than cue-following.

Giraffes carry relatively small brains for their body size, and the researchers say this finding challenges the assumption that arithmetic-like reasoning requires a large brain-to-body ratio, as commonly assumed in primates, dolphins and parrots. They instead point to the giraffe’s complex social structure and habit of assessing food-rich trees from a distance as possible drivers behind the skill.

Wikimedia Commons/by Charles J. Sharp