Researchers hatch theory that chickens count just like humans

Chickens — they’re just like us!

When humans are asked to visualize numbers, they usually put them on a mental number line from left to right. Zero is to the left, one is to the right, and so on. But why? Sometimes it seems like a cultural thing, since humans who use languages that read from right to left are more likely to have reversed mental number lines. But studies have shown that even babies — too young for reading to influence them — have a bias for left-to-right counting.

The best way to see if something is truly innate? See if other species do it, too.

In a new study published in Science, researchers did just that. They trained three-dayold chicks to look for food behind a little panel with five squares on it. The researchers then swapped this one panel out for two panels, each showing an identical number of squares — either two or eight.

When the panels had two squares, the chicks would go toward the left one 70 per cent of the time looking for food. When the panels both had eight squares, their preference flipped: they went to the right 70 per cent of the time.

In other words, the chicks went to the left when the panels showed a smaller number than the one they’d been trained with, and headed right if they saw a bigger number. The researchers believe this shows that the chicks were comparing the numbers’ relative sizes, assuming that a small number “belonged” on the left and a large number belonged on the right. They figured that the “correct” number placement was hiding the food reward.

This is the first study to suggest that humans aren’t the only ones who count this way.

But why do humans — and chicks have this brain quirk? From Ed Yong for National Geographic:

“There might not be a why. The direction of the line might be totally arbitrary. Then again, in many animals including chicks and humans, the right half of the brain takes the lead in visual, spatial and numerical tasks. And since the right hemisphere directs our attention to the left side of space, perhaps that’s why the number line begins on the left.”

One thing is for certain, in any case — counting chicks are adorable, and we’re all for further testing.