Fruit flies are far from human, but not as far as you might think.

They do many of the same things people do, like seek food, fight and woo mates. And their brains, although tiny and not set up like those of humans or other mammals, do many of the same things that all brains do — make and use memories, integrate information from the senses, and allow the creature to navigate both the physical and the social world.

Consequently, scientists who study how all brains work like to use flies because it’s easier for them to do invasive research that isn’t allowed on humans.

The technology of neuroscience is sophisticated enough to genetically engineer fly brains, and to then use fluorescent chemicals to indicate which neurons are active. But there are some remaining problems, like how to watch the brain of a fly that is moving around freely.

It is one thing to record what is going on in a fly’s brain if the insect’s movement is restricted, but quite another to try to catch the light flash of brain cells from a fly that is walking around.