Guest post by Luke Bowles
Reference: Romero-González, J. E., Zhuo, Z., Chen, L., Peng, C., Solvi, C., & Peng, F. (2025). Positive affective contagion in bumble bees. Science, 390(6771), 377-380.
A shift in mood is a powerful, often contagious phenomenon, a dynamic familiar to anyone who has seen a grumpy coworker darken an office atmosphere.
Now, a new study published in the journal Science reveals that this kind of emotional contagion, long thought to be exclusive to complex social vertebrates such as humans and dogs, also occurs in animals with brains the size of a poppy seed: bumblebees.
This discovery could prompt the public to reconsider long-held assumptions about insect behavior and emotional capacity, with potential implications for conservation, pesticide use, and animal welfare discussions.
In a finding that pushes the boundaries of animal emotion, researchers at Southern Medical University in Guangzhou, China, revealed that bumblebees, whose lineage diverged from social vertebrates over 600 million years ago, also spread positive feelings.
Scientists used a judgment-bias test to gauge the bees’ outlook. In the training phase, bees learned to associate a blue flower with a sugar reward and a green flower with none. The trick was presenting the bees with an intermediate, ambiguous blue-green flower: a quick approach indicated optimism (the bee expected sugar), while a slower approach indicated pessimism.
After training, the researchers gave half of the bees an unexpected reward right before introducing them to the intermediate color: a hit of sugar water. They found that these bees approached the blue-green flower much more quickly than the control, indicating their optimism about an uncertain outcome.
Then, the researchers introduced a new twist: after one bee experienced this hit of sugar-water, they introduced another bee into their enclosure. A transparent film separated them, so they could only see each other, but not touch or smell.
These new bees performed almost equally as optimistically on their emotional test, even though they never received any sugar themselves.
“These behaviors are hallmarks of an affective shift, not simply arousal or social copying,” said Fei Peng, a neuroscientist at Southern Medical University and the study’s corresponding author.
She emphasized that the control experiments, in which observer bees watched unrewarded bees, confirmed that the shift was a true emotional contagion, not simple arousal. In essence, a bee needed to see a happy bee to feel happy themselves.
These results suggest something more profound: a rudimentary form of empathy. Affective contagion—the sharing of emotional experiences with others—is recognized as the first building block of empathy in animals.
“This work expands what I call the ‘biodiversity of sentience’ to invertebrates who possess tiny brains and often are written off as being insentient,” said psychologist Mark Bekoff, who was not associated with the study.
Bekoff points to a growing body of research from the past decade suggesting that insects can experience pain and emotions.
As people increasingly farm insects for food due to their high protein content and climate change-induced strain on our agricultural systems, investigating insect pain and emotion is more relevant than ever.
The public’s understanding of insect sentience could directly shape food policy and industry standards. If more evidence supports the idea that bees and other insects can feel and share emotions, it could drive demand for more humane conditions in insect farming, influence consumer choices for pesticide-treated foods, and spur governments and businesses to reconsider how insects are treated in research and agriculture.
“This perspective suggests that welfare in managed or agricultural settings involves more than nutrition and disease control. A calmer, low-stress atmosphere might matter just as much, especially if the mood of a few bees can subtly nudge the whole group,” said Chelsea Haney, a science writer not involved in the study.
Altogether, these findings suggest that the inner lives of insects deserve greater attention and may warrant a reconsideration of how we treat them. Though invisible to us, these inner experiences shape the miniature worlds of bees, showing that even a tiny brain can harbor empathy and positivity.
Luke a is a Biology PhD student at the University of Missouri studying plant acoustics in the Cocroft Lab. Specifically, his research explores how plants use the sounds of bees to regulate their nectar production to alter pollinator learning. He grew up on a goat farm in a small town in Mississippi and graduated from the University of Georgia with degrees in philosophy and cognitive science where he combined his love for psychology, philosophy, and nature by studying collective behavior and personality in various ant species.
Luke also has a deep passion for sharing his love of animal cognition and insect behavior, and you can find him on Instagram @BowlesBugs. In his free time, you can find him hiking (aka looking for bugs), rock climbing, or making art.
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