Honeybees have become the first invertebrates to exhibit pessimism, a benchmark cognitive trait supposedly limited to "higher" animals.
If these honeybee blues are interpreted as they would be in dogs or horses or humans, then insects might have feelings.
Honeybee response "has more in common with that of vertebrates than previously thought," wrote Newcastle University researchers Melissa Bateson and Jeri Wright in their bee study, published on June in Current Biology. The findings "suggest that honeybees could be regarded as exhibiting emotions."
Bateson and Wright tested their bees with a type of experiment designed to show whether animals are, like humans, capable of experiencing cognitive states in which ambiguous information is interpreted in negative fashion.
Of course, unlike unhappy people, animals can't say that the glass is half-empty. Researchers must first train them to associate one stimulus -- a sound, a shape, or for honeybees, a smell -- with a positive reward, and a second with a punishment.
Then, by prompting the animals with a third, in-between stimulus, it's possible to assess their outlook. Like a depressed person seeing hostility in a neutral gaze, pessimistic animals tend to treat that uncertain stimulus like a punishment.
Such tests might seem simplistic compared to the richness of human emotion, but they're the most objective available tool for comparing cognition across species. And pessimism is no mean feat: It's a form of cognitive bias, considered in humans to be an aspect of emotion. You can't be pessimistic if you don't have an inner life.