Bees arrange numbers in increasing magnitude from left to right, a study has shown for the first time, supporting the much-discussed theory that this direction is inherent in all animals, including humans.
Western research has found that even before children learn to count, they begin to organize increasing sets from left to right in what is called the “mental number line.”
However, the opposite direction has been found in people from cultures that use an Arabic script that reads right-to-left.
“The issue is still debated between those who believe the mental number series has an innate character and those who say it is cultural,” said Martin Giurfa, a professor at the Research Center for Animal Cognition at the Paul Sabatier University. University of Toulouse, France.
There is recent evidence that newborns and some vertebrates, including primates, organize numbers from left to right. Giurfa led a study published last week in the journal Proceedings of the National Academy of Sciences (PNAS) aiming to find out if the same is true for insects, through an experiment on bees. “Bees have already been shown to be able to count – at least to five,” Giurfa told AFP.
They also process information differently in the two cerebral hemispheres, he added. This trait they seem to share with humans, and it’s thought to be a possible reason for the “existence of the mental number line,” Giurfa said.
A numbers game
For the experiment, the researchers let individual honey bees fly into the first of two compartments of a wooden box. Sugar water was then used to trick the bees into picking a number that was placed in the middle of the back of the second compartment.
The number remained the same for each individual bee, but varied randomly across the group from one, three, or five in the shape of circles, squares, or triangles. Once the bees were trained to fly toward their designated number, the researchers removed them and placed a different number on either side of the second compartment, leaving the middle blank.
ALSO READ: Europe’s bees stung by climate, pesticides and parasites
Then they removed the sugar water treat and observed which way the bees went. For example, if the bee was trained to pick the number three and was now faced with two number ones on either side and nothing in the middle, which way did they fly?
About 80 percent of the time, the bees chose the option on the left — the “right choice” when the brain orders the numbers from left to right, Giurfa said. But when those same bees had two fives to choose from, they got it right, again supporting the mental number line.
And bees that were trained for number one went right for number three, while bees that were aiming for a five went left for their three. So if animals do think numbers from left to right, why can’t all humans do the same?
Giurfa said it was more complicated than choosing directly between nature and nurture. Even if the mental number line “is innate, culture can still modify it, even reverse it — or, on the contrary, accentuate it,” he said.
Bees, on the other hand, have to do what nature dictates.