The Mind of a Bee
A review of Lars Chittka’s Book
I’ve long appreciated that, with social insects, the colony can solve problems an individual can’t. When it comes to picking a place for a hive, bees engage in a surprisingly sophisticated form of decision-making (detailed in Thomas Seeley’s book Honeybee Democracy). Scouts investigate different sites and return to the swarm to “campaign” for the best site, convincing other scouts through their waggle dances. The swarm gradually converges to a consensus, consolidating information from the different sites even though no single bee may have visited all of them, and the swarm picks its new home.
What I didn’t appreciate, until I read The Mind of a Bee, is how smart individual bees are.
For one thing, I didn’t realize how sophisticated the senses of a bee are.
Their senses of smell, for example, are quite good, to the point where some researchers have tested them to detect explosives and other substances as an alternative to sniffer dogs. Aren’t airports bad enough without bees? (Insert Seinfeld riff here)
Flowers, of course, are important for a bee. They use their senses to assess flowers in surprising ways. For example, they can detect electrical charge. When bees fly, they shed some electrons to the air, becoming positively charged. Thus when they visit a flower, they take some of the flower’s electrons, giving the flower a brief positive charge. Bees can detect this charge, and don’t waste their time on those flowers likely already emptied by another bee.
Bees see in much lower resolution than we do. They have compound eyes, made out of a combination of smaller visual units (called “ommatidia”), giving their vision a sort of pixelation. Based on the number of ommatidia bees have, their vision of what’s in front of them would be a bit like seeing a 30x30 or 60x60 image.
Despite this, vision is extremely important for bees. They can navigate by landmarks and find their way back to the nest based on familiar surroundings. But more importantly, bees rely on their sight to spot flowers.
Bees burn a lot of energy. Flying around is exhausting, and the nectar of flowers is often hidden away and difficult to access. Bees need to be able to tell from afar what flowers are worth investigating.
Bee eyes are sensitive to different wavelengths of light than ours. They can’t see red, but they do see ultraviolet, and so flowers look different to them than they do to us, often revealing additional patterns we can’t see.
Surprisingly, analysis of the spread of genes through the insect kingdom suggests that bees’ color vision came first, before flowers. It wasn’t that bees developed color vision to detect flowers, but flowers became colorful to attract bees.
Without landing on them, bees can assess flowers. They learn, through watching other more experienced bees or through their own experience, what types of flowers are worth foraging from, and assess them from afar.
This social learning in particular surprised me. It’s easy to think of bees as little robots, with maybe a bit of isolated learning ability, but mostly running on hardwired rules. They live seemingly pretty simple lives, so it seems plausible that they wouldn’t have sophisticated learning abilities. It turns out that’s far from reality.
Learning in bees
Social learning from other bees doesn’t stop at learning what kind of flowers to land on. Some flowers are “deep-tubed”, keeping their nectar out of reach of any short-tongued bees. Some bees learn that they can bite the base of the tube and suck the nectar out, without going the “usual” route of putting their tongue down the tube. There’s evidence that bees can learn this technique from each other, and that there’s even a sort of cultural transmission—in different areas, there are different local “traditions” of biting either the left or the right side, for example.
In the lab, a task was set up that required a bee to pull a rope to expose a “flower” filled with sugar water. Of the 100 bees tested, only 2 were able to learn this task on their own. But the other bees became able to do it after just watching another bee perform the task.
There’s no obvious “in the wild” analogue of this sort of behavior. Bees don’t pull ropes to make their hives. Their learning is surprisingly flexible.
In the lab, you can test bees by setting up artificial “flowers” and filling some of them with sugar water. Bees can quickly learn that certain characteristics of the artificial flowers get them the sugar water reward. For example, if you only put sugar water in the artificial flowers of certain colors, they’ll quickly learn which colors are rewarded—unsurprising since this is the sort of cue they would encounter out in the wild.
Other cues they can learn are more surprising. Bees can detect magnetic fields, most likely to help them navigate, but they can learn to associate magnetic stimulation with a reward. They can even learn to associate threat pheromone—normally a danger signal to other bees—with reward. This flexibility in what bees can associate with reward cuts against a view of bees as driven by simple hardwired instincts.
Bees can also associate cues with actions they need to take. They can learn that a blue entryway to a tube means they have to turn left to get to the reward, while a yellow one means they need to turn right. They can make associations not just between a color and a reward, but between a color and the rule they need to follow.
But what I found most surprising is that bees can learn abstract concepts, like “same” versus “different”. In one study, bees were trained on what’s called a “delayed match to sample task”. Bees would encounter an entryway that had a color on it, and then inside the tunnel there was a fork where the bees had to pick whether to turn left or right. The two directions they could turn were themselves labeled with a color. The experimenter could then decide on a rule—like having the bees learn that if the entry was yellow, they should take the yellow branch, a “sameness” rule, or if the entry was yellow, they should take the blue branch, a “difference” rule.
Bees were able to learn these sorts of rules. But what was more impressive is they were able to generalize it. If they were trained on finding the matching or differing color, they could then be tested on a matching or differing pattern, like horizontal versus vertical lines. Bees trained to look for the same color (yellow to yellow) would look for the same pattern (horizontal to horizontal), while those trained to look for the different color (yellow to blue) would look for the different pattern (horizontal to vertical). The bees had learned the abstract concepts of “same” and “different”.
Despite their tiny brains, bees are able to learn abstract concepts, learn from each other, and behave flexibly in a way that defies the view of them as hardwired little robots. This all seems to raise a question: if such a wide cognitive repertoire is possible in such a little brain package, why do we larger animals bother with such large brains?
If bees are so smart, why do we bother with big brains?
At multiple points in the book, Chittka makes the point that the question isn’t how bees are capable of so much with such small brains—it’s why we bother to have such large brains if small brains are so effective.
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