Four giraffes at a Spanish zoo just did something scientists had never tested in the species before: they added numbers together in their heads.

Researchers at Barcelona Zoo hid carrots inside opaque boxes and tracked whether the animals could keep a running tally, a test nobody had thought to try on this species before. Two of the four cracked it without leaning on a single shortcut. Here’s how the carrots gave them away.

Giraffes passed addition but failed subtraction

A team led by Iker Loidi at the University of Barcelona ran four giraffes, Nakuru, Njano, Nuru, and Yalinga, through carrot-based memory games. In the combination task, keepers showed two hidden piles, then moved up to three more carrots into one of them while the final total stayed hidden from view.

The giraffes picked correctly 68% of the time, well clear of the 50% chance line, which meant they had held both piles in memory and tracked the total after it disappeared. Flip the task around and ask them to subtract carrots from a hidden pile instead, though, and accuracy fell straight back to a coin flip.

Nuru and Njano kept succeeding even once researchers removed the obvious shortcut of picking whichever dish a human had touched last, and that detail is what makes the result stick rather than look like a lucky streak. Nakuru and Yalinga only won when that shortcut was available, so their math credentials stay a little shakier.

The team also flagged that carrots differ in mass as well as number, so a giraffe that judges “more carrot” might be reading bulk rather than counting pieces. Addition still beat subtraction by a wide margin, a pattern researchers have already clocked in toddlers, pigeons, and primates.

Giraffes have made headlines for less cerebral reasons too, including the Texas runaway who had an entire ranch stumped for weeks, and animal stories keep getting stranger, like the recent bust of a ring caught selling stolen pets for food.

-Dexerto