A new study published in the journal Proceedings of the National Academy of Sciences suggests that bumblebees exhibit 'emotion-like' behaviors, captured in slow-motion video. When bees taste something good, they reach out their glossa (insect tongue) for a while afterward, akin to licking their lips. In contrast, they respond to unpleasant substances by shaking their heads and wiping their mouths.
Study Methodology and Findings
Researchers from Macquarie University and Southern Medical University in China presented bumblebees with droplets of various solutions: 60% sugar, 20% sugar, plain water, 5% salt, or quinine at 1 millimolar concentration. They recorded the bees' reactions using slow-motion video. Under normal conditions, bees displayed 'post-consumption glossa' after tasting sweet solutions—they kept licking even after finishing. For salt or quinine, they showed clear distaste.
Prof Andrew Barron, co-author and insect behavior researcher at Macquarie University, stated: 'Facial expressions are an important window into the internal states of animals. What we found is that bees show responses with their mouthparts to solutions that indicate their subjective like or dislike of those solutions. It tells us there is an inner life to the insect.'
Comparison with Mammalian Behavior
Previous studies have shown that mammals like primates and rats display clear signs of 'liking'—such as licking and tongue protrusion—and 'disliking'. Barron noted: 'If a rat gets a salty taste it doesn’t like, it wipes its mouth parts, wipes its whiskers, wipes its tongue. And we see something similar in a bee.' However, similar findings in insects remain 'highly controversial'.
To rule out chemical reflexes, the scientists tested responses across 18 colonies under various conditions: heat stress, satiety, and after drug doses. The bees' reactions depended on context. For example, heat exposure changed their response to water or salty solutions from neutral or averse to positive. Barron compared this to a person's desire for an electrolyte drink after intense exercise.
Implications for Insect Sentience
Associate Prof Thomas White, an entomologist from the University of Sydney not involved in the study, called the research 'a fast moving field'. He highlighted its focus on positive experiences, as most research investigates negative feelings like pain or fear. 'The picture is increasingly pushing towards a view that insects, or many insects, have some simple capacity to feel the world, not just to assess it and detect it and process information but to actually have a point of view,' White said.
This challenges conventional views about where to draw the line in the animal kingdom regarding pleasure and pain, and the ethical responsibilities toward those animals. Barron concluded: 'There’s always been a tension between thinking of insects as animals, or some sort of mini robots. This is another step towards showing there’s an inner life to being a bee.'
