Getting a Bee in Math: Honey Bees Can Distinguish Between Odd and Even Numbers

Honey bees know nothing. Literally. Honey bees have previously demonstrated to scientists they understand the concept of zero by selecting dotted paper based on a reward of sweetened water. Eventually, the paper with no dots that provided the treat was recognized.

Apparently, their aptitude for math is even more impressive than initially believed. A new study has revealed honey bees can tell the difference between odd and even numbers, a concept more than a few humans may struggle with.

The research, published in Frontiers in Ecology and Evolution, examined honey bee math prowess by “recruiting” free-flying and hive bees in Toulouse, France, and encouraging them to visit a vertical screen.

There, researchers presented their striped subjects with a series of cards that had odd and even amounts of shapes on them—circles, triangles, squares, and diamonds. If a bee landed on an even-numbered card, they got a treat—sugar, naturally. If they landed on an odd-numbered card, they received quinine, a bitter substance bees dislike. A second group got the reverse: Odd-numbered cards had a reward, while even-numbered cards delivered bitterness.

The bees learned—quickly. Even as researchers raised the number of shapes per card to 11 and 12, the bees generally maintained an ability to understand which set delivered the goods, all by recognizing whether a card had odd or even numbers of shapes. With some experience, the bees got the right answer roughly 80 percent of the time.

Because the surface was washed regularly, olfactory cues didn’t appear to play any part in their evaluation; the position of the cards was also changed so bees didn’t take location cues.

The bees’ ability to discern between odd and even numbers is all the more remarkable given that they have no cortex and fewer than 1 million neurons, compared to a human’s 86 billion. It's an indication other parts of the brain can seemingly handle processing tasks like this one.