Do bees have inner lives? Slow-motion video reveals bumblebee behaviour similar to ‘liking’ or ‘disliking’ | Bees

When bumblebees taste something nice, they extend their glossas (or insect tongues) after a moment, as if they were licking their lips. And when they don’t like something, insects shake their heads and wipe their mouths.

Scientists who recorded miniature facial expressions on slow-motion video say this behavior is consistent with the “like” and “dislike” responses observed in mammals. Their results were published in the Proceedings of the National Academy of Sciences.

In the study, conducted jointly between Macquarie University and the Southern Medical University in China, researchers presented bumblebees with droplets of different solutions: 60% sugar, 20% sugar, plain water, 5% salt or quinine (at a 1 millimolar concentration) and recorded their responses.

Professor Andrew Barron, who researches insect behavior at Macquarie University and co-authored the paper, said that under normal conditions, bees exhibited something called “postconsumptive glossa” after tasting the sweet solution: They continued licking even after they had finished drinking it.

In contrast, they showed a clear aversion to salt or quinine solutions.

“Facial expressions are an important window into the internal state of animals,” he said. “What we found was that the bees respond to solutions with their mouthparts, indicating whether they like those solutions or not. This tells us that the insect has an inner life.”

Without language, it is difficult to establish evidence of pleasure or pain in other animals. That’s why scientists are studying behavioral markers, such as facial expressions, to measure positive and negative experiences.

Previous studies have shown that mammals such as primates and rats display clear signs of “liking,” such as licking and sticking out their tongues and “disliking.”

“If a mouse gets a salty taste that it doesn’t like, it will wipe its mouthparts, its whiskers, its tongue,” Barron said. “And we see something similar in the bee.”

But while similar findings in mammals are easily accepted, the concept of internal life in insects such as bees remains “quite controversial,” he said.

To ensure they were not simply observing a chemical reflex, the scientists tested the responses of 18 colonies under various conditions, including when the bees were heat stressed, already saturated, or given different doses of medication.

The bees’ responses depended on the context. For example, heat exposure changed the response to water or saline solutions from neutral or negative responses to positive.

It’s like someone offered you an electrolyte drink, Barron said. “You’ll probably be ‘blegh’ most of the time. Unless you’ve gone out on a really hot day and gone for a massive run, then an electrolyte drink is exactly what your body needs, and it tastes great.”

Entomologist Assoc. Prof. from the University of Sydney, who was not included in the article. Thomas White said research into insect behavior and sentience was a “fast-moving field.”

What made this study fascinating, he said, was the focus on “the positive side of life,” since the vast majority of research investigated negative emotions, such as pain or fear.

“This picture is increasingly pushing towards the view that insects, or many insects, have a rudimentary perceptual capacity to not only evaluate, detect, and process information about the world, but also to have a point of view,” White said.

He said this can be challenging for some people. “This goes against a lot of people’s intuitions about where we can draw the line in the animal kingdom, what can feel pleasure and pain, and therefore what ethical and moral responsibilities we have to those animals.”

“There’s always been a tension between thinking of insects as animals and as sort of mini-robots,” Barron said. “This is another step towards showing that being a bee has an inner life.”