Bees have a lot going on in their teeny brains; with less than a million neurons compared to the 86 billion that humans boast, they can achieve an impressive array of tasks from basic maths to connecting numbers and symbols.
Now scientists have shown they can perform a complex cognitive feat thought to be unique to humans and a select group of animals such as apes, rats and dolphins: transfer information about an object from one sense to another.
This ability, termed “cross-modal object recognition”, is what helps us find things in the dark, like fumbling around in a cluttered handbag for a set of keys. We can store visual information about the keys and transfer this knowledge to how they feel.
Researchers at Queen Mary University of London, UK, and Macquarie University in Australia, have shown that bumblebees (from the genus Bombus) can also find things in the dark that they’ve only seen before.
As described in the journal Science, the bees were trained to find sugar water in a cube or sphere and a bitter quinine solution in the other shape using only vision (in a light room where they couldn’t touch the outside of the objects) or touch (in a completely dark room).
When those bees trained in the light were tested in a dark room, they hung around the object that had previously rewarded them with sugar water, evidencing a transfer of visual information to tactile sensations.
They also achieved this task the other way around – after learning to find the rewarding shape in the dark, they preferred that one when tested in the light.
Importantly, the shapes and testing area were cleaned after the training so the bees couldn’t use smell or chemical cues to detect those that had previously contained the reward.
As a control, the researchers ran the same experiment in the dark room, but the bees couldn’t touch the shapes.
Later, when tested in the light, the bees showed no shape preference, confirming they had indeed previously transferred information from tactile to visual senses.
“This suggests that similar to humans and other large-brained animals, insects integrate information from multiple senses into a complete, globally accessible, gestalt perception of the world around them,” the authors write.
It doesn’t mean bees experience the world in the same way as us, says lead author Cwyn Solvi, “but it does show there is more going on in their heads than we have ever given them credit for”.
Senior author Lars Chittka notes that although it’s well established that bees can remember the shape of flowers, this doesn’t necessarily demonstrate awareness; a smartphone can recognise your face, for instance.
“Our new work indicates that something is going on inside the mind of bees that is wholly different from a machine – that bees can conjure up mental images of shapes.”
How the bees do it isn’t entirely clear, note Gerhard von der Emde, from the University of Bonn, Germany, and Theresa Burt de Perera, from the University of Oxford, UK, in an accompanying commentary, but they are similarly impressed.
“Cross-modal recognition … is a highly complex cognitive capacity that was thought to be limited to vertebrates.
“Solvi et al. show that this capability exists in an insect brain, which contains a small fraction of the numbers of neurons in vertebrate brains.”
Looking at the bigger picture, Solvi’s work is driven by a curiosity about how the brain generates complex cognitions like emotion, metacognition (knowledge about knowledge) and consciousness.
“By investigating the cognitive capacities of very small brains,” she says, “we may be able to shed significant light on how our brains produce the things we feel make us so special.”
Natalie Parletta is a freelance science writer based in Adelaide and an adjunct senior research fellow with the University of South Australia.
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