The honeybee’s brain has about 1 million neurons. While that may sound like a lot, it’s pretty tiny compared to other species. A mouse brain has about 75 million neurons. Humans have 100 billion, or 100,000 times more.
Yet even with this small hardware, the bee brain is capable of accomplishing many complex tasks. One of them is basic math.
In a new study in Scientific Advances, scientists in Australia have shown that honeybees can add and subtract if trained to do so. It shows animals don’t need a huge brain — or anything even resembling human language — to think in terms of numbers. “We propose that language and prior advanced numerical understanding are not a prerequisite necessary for the ability to calculate addition and subtraction solutions,” the study’s authors conclude.
It’s often hard to probe and access animals’ cognitive abilities. So this study gives us some more insight into what type of thinking many animals may be capable of.
How to teach a bee to add or subtract
The 14 bees in the study weren’t given a sheet of math problems to solve. No, to get a bee to add or subtract, the researchers first had to teach them the rules of arithmetic.
To do that, they set up a few L-shaped apparatus. They looked like this.
When the bees approached the structure, they were greeted by an array of either blue or yellow shapes (bees have pretty robust color vision to spot nectar-laden flowers). The number of shapes on the array varied — some had two, others three. The bees then would enter another chamber, where they had a choice to fly next to an array with more squares than the one they previously saw, or fewer.
If the shapes in the first chamber were blue, that meant the researchers wanted the bees to add by 1. The bees were rewarded with delicious sugar for choosing the array with more shapes in the second chamber. If they chose incorrectly, they were punished with acrid quinine.
The same went for subtraction. When the original shapes were yellow, the bees were rewarded for subtracting by 1, and punished for choosing the higher number.
Over the course of 100 training trials, the bees got better and better at the task. They improved at realizing, for example, that three shapes are more than two, and two shapes are fewer than three. It’s rudimentary, but also the basic building block of understanding the value of numbers and math.
But to test if the bees had truly learned these rules, the experimenters set up a new testing arena that had no punishments or rewards, and alternated which side of the arena the correct answer was on. (This served as a control for the possibility that bees might just prefer one side over the other.)
Across four trials (two addition and two subtraction), the 14 bees chose the correct answer between 63 and 72 percent of the time.
Okay, so bees aren’t great at math. If you scored 63 percent on a math test, you might fail it (though try to ask for extra credit). Also, the bees were only adding or subtracting by 1. These aren’t super-hard problems.
But the bees were making better-than-chance decisions, which is evidence that they have some mathematical ability, or at least a sense of less than and greater than. And this means they join the ranks of humans, chimpanzees, pigeons, and even spiders(!) as animals that science has shown can add and subtract by at least 1.
Bees are incredible thinkers. What can we learn from them?
In previous work, this same lab has shown bees are capable of an amazingly complex array of tasks. For instance, the scientists found in 2010 that bees can be trained to learn and remember human faces, and they do it in a manner that’s not entirely different from how we do it.
Somewhat incredibly, this lab also showed that bees are capable of understanding the concept of the number zero — which is something human children generally can’t grasp until kindergarten. Bees’ and humans’ last common evolutionary ancestor lived more than 600 million years ago. But somehow, separately, both vertebrates and insects developed these similar skills.
This isn’t just delightful biology. It’s possible that in deconstructing how the bees compute numbers, we could make better, more efficient computers one day.
Our computers are electricity-guzzling machines. The bee, however, “is doing fairly high-level cognitive tasks with a tiny drop of nectar,” Adrian Dyer, the Royal Melbourne Institute of Technology researcher who has spearheaded much of this research, told me last year. “Their brains are probably processing information in a very clever [i.e., efficient] way.”