There’s a quirky little item in the science news today: some researchers in Germany have been studying fruit flies, and have observed that their behavior seems surprisingly flexible.

The fruit fly, Drosophila melanogaster, is a simple little fellow, tiny, short-lived, and with few pretensions to grandeur. In particular, being only a couple of millimeters long, he has an itty-bitty brain, and is not assumed to possess a supple mind. But Dr. Björn Brembs and his colleagues spent some time examining the activity of flies that had been attached to a tether in a featureless white enclosure, and contrary to their expectation — that given a perfectly uniform environment, the fly’s behavior would be robotically repetitive as well — the flies zoomed around in patterns that varied in interesting, nonrandom ways. This is an intriguing result: the fly’s brain, even though it is a pretty simple one, as brains go, is still able to generate innovative, difficult-to-predict patterns of movement.

This is all good, interesting science. I have a problem, though, with the way it is being reported. I first got wind of the story from a news screen in the elevator at my office (a service that calls itself, forthrightly but rather depressingly, the “Captivate Network“). The headline said something like “Fruit Flies Found To Have Free Will”, which, as you can imagine, certainly got my attention. I found the story online a few minutes later, and the spin was the same. This is most unfortunate, as this tagline will predictably be picked up again and again, by legions of earnest-looking local news reporters and chuckleheaded bloggers. You can hear it now:

“Well, that’s it for the weather. Back to you, Bob.”

“Thanks, Jessica. And now, one last item. In what just might settle an age-old philosophical controversy, researchers in Germany are reporting that they have found evidence that fruit flies have ‘free will’.”

“Well, I flunked philosophy in college, Bob, but I guess if fruit flies have free will, that means we must too, right?”

“Not me, Jessica. I’m a married man!”

[Laughter. Fade. Music up. Credits roll.]

What it appears that the researchers have found is a feature in the fly’s brain that generates movement that is, while nonrandom, difficult to predict. It is simple to imagine why this would be useful; anyone who has tried to snatch a fly out of the air has been frustrated by its ability to move, at quite ordinary speeds, in ways that are maddeningly elusive. To be able to do this is strongly adaptive: a fly that lacked this ability, and moved always according to foreseeable patterns, would be easy prey. This is a remarkable accomplishment for a brain so tiny, and it will be enlightening to learn how the trick is done, but it is certainly not “free will” in the traditional philosophical sense, even though it may have a great deal to tell us about why we seem to have free will. The researchers are quite clear about this themselves. Says one of the authors, George Sugihara:

“The results of our analysis indicate a mechanism which might be common to many other animals and could form the biological foundation for what we experience as free will”.

Note the language. A “mechanism”. “The biological foundation for what we experience as free will.”

I’m what you’d call a “compatibilist”, which means that I think two ideas that are usually thought to be contradictory actually aren’t: I believe that our minds, and our choices, are solely the product of physical processes in the brain, but I also think that this fact is compatible with our being every bit as free, and as responsible, as we could coherently wish to be (this is a topic I should return to in future posts). But the subject is confusing and elusive enough to give even competent, hardworking philosophers a nagging headache, and after reading that headline in the elevator, I don’t look forward to seeing how this story is going to bumble its way through the popular culture.

You can read the media reports here, or here, but for Dr. Brembs’s own account, see his own website, here. One amusing note: the facility where the work was done? The Free University of Berlin.


  1. Hey, you really paid attention to what we wrote, very impressive! As you noted, the professional journalists either paid less attention or they felt the pressure to sell their article. In a radio (CBC) interview they even cut out the section where I explicitly stated that fruit flies of course do not have the same impression of free will as we have.
    Keep up the good blogging!


    Posted May 22, 2007 at 9:45 am | Permalink
  2. Malcolm says

    Hi Bjoern,

    What a delightful surprise that you would drop by to comment. This is what I love about the “blogosphere”: that a conversation can span the globe as easily as it once would span a living room or railway car.

    Your work sounds fascinating, and is bound to shed light on a number of topics about which I have abiding curiosity. We’ll be following its progress with keen interest.

    Thanks for visiting! And thanks also for the link you attached to your name; I have added it to the text above.

    Posted May 22, 2007 at 10:14 am | Permalink

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