Bumblebee tongues reveal 'liking' vs 'wanting' split
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- Andrew Barron at Macquarie University and colleagues offered buff-tailed bumblebees sugar, salt, and bitter droplets under high-resolution video to find a behavioral readout of inner state in an insect with a rigid face.
- After tasting sugar water, bees repeatedly protruded their glossa (hairy tongue); after salty and bitter samples they wiped their mouths and shook heads — though Barron noted both responses could have been reflexive chemical reactions.
- When bees were dehydrated at 40°C (104°F), they switched to repeatedly extending their glossa at salty droplets they had previously rejected — the same way a person would only enjoy an electrolyte drink after exercise, Barron said.
- Dopamine treatment (which drives food-seeking 'wanting' in mammals) did not increase glossa protrusions, but endocannabinoid treatment (which drives food 'liking' in mammals) did — the first time 'wanting' and 'liking' have been separated in a bee, per Jonathan Birch at the London School of Economics.
- Ralph Adolphs at the California Institute of Technology called the work 'an important and innovative study on a difficult topic' but cautioned it does not show pleasure as mammals know it, concluding bees have 'bee emotions, not mammal emotions.'
Why it matters: By separating the 'wanting' and 'liking' circuits in a bumblebee — the same split documented in mammals — the study challenges the assumption that subjective evaluation requires a mammalian brain. For scientists who argue insect sentience matters for welfare policy, this is the kind of mechanistic evidence that has previously been missing.
