The Unlikely Genius of Fruit Flies

There’s  a reason we don’t generally compliment someone by saying they’re smart as a fruit fly. There’s no evidence that individual fruit flies can demonstrate higher-order cognitive function—or much lower-level cognitive function, for that matter.

But as we’ve learned with bees, groups of insects can sometimes demonstrate a downright creepy amount of intelligence. Get enough of them in a room together, and they’re capable of something approaching telepathy. But are fruit flies among those insects? After all, their 100,000-neuron brains are much simpler than those of other social insects, such as ants (avg. 250,000 neurons) and bees (avg. 960,000 neurons). 

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Swiss biologist Pavan Ramdya has studied the social habits of fruit flies and, as science writer Ed Yong explains, his research paid off:

Ramdya suspected that the supposedly anti-social flies might also show collective behaviour.

He was right. Through a impressive series of experiments, involving a smorgasbord of cutting-edge techniques, Ramdya showed that flies can collectively flee from a bad smell faster than any individual can by itself. Alone, each fly is only slightly repelled by the odour; together, they run away decisively. Even mutant flies that can’t smell the odour at all can escape if they’re in the presence of smell-sensitive peers.

If the idea of insects solving problems in groups seems unimpressive, remember that our own brains consist only of an average of 86 billion neurons working together—not too far removed from being itself a big, wet swarm of cooperative microorganisms. The line between a human brain and the brain of a siphonophore, or between the brain of a siphonophore and the collective brain of a community of social insects, is a little blurry. And as we continue to study the hive minds of social insects, that line may become blurrier still.     

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