Tilman Triphan and Wolf Huetteroth via New Scientist

Dear Readers, if I told you that the image above showed a fruit fly voluntarily riding a carousel, I’m sure you’d be surprised.

“Surely, Bug Woman”, I hear you say, “While fruit flies have been extremely useful in genetic studies, surely they barely have two synapses to rub together, so why are they playing?”

And indeed it is a puzzle, but then we are learning that insects and other invertebrates have far more complex lives and emotions than we ever thought. Last year, researchers found that bumblebees left with a wooden ball would roll it about just for the hell of it, without any reward other than the joy of manipulation. Interestingly, young bumblebees ‘played’ more than adults, and male bees (presumably with more time on their appendages) played more than females (who have many, many hungry mouths to feed).

But a fruit fly? Tilman Triphan and Wulf Huetteroth of the University of Leipzig built little arenas for the fruit flies, with food and a carousel, and then popped one fly into each compartment for a few days. In some compartments, the carousel moved, and in others it was stationery. Flies with a spinning carousel would spend up to 5 minutes at a time on it, and would visit it several times during the course of their ‘stay’.

“We were all astonished,” says Huetteroth. “My expectation was that the flies would completely avoid it and wouldn’t like it at all.”

Drosophila melangaster – the fruit fly (Photo By Sanjay Acharya – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=63862733)

However, as with the bees, not all the individual flies liked the carousel – some did avoid it altogether, which brings in another point: even at the level of a fly, there are different ‘personalities’. Some flies like a bit of vertigo-inducing activity, others would rather not. It’s a bit like me standing back whenever I’m at a fairground and someone suggests the Waltzer.

To be considered play-like behaviour, an activity must have no immediate relevance for survival, and it must be voluntary and intentional. The flies (and the bumblebees) seem to be engaging in an activity just for the hell of it. It makes me wonder what other similarities between ourselves and other animals are out there, if we just chose to look.

You can read the whole paper here. The bumblebee paper is here.