Waxing Drosophilosophical: Why I Study Fruit Flies

Waxing Drosophilosophical: Why I Study Fruit Flies

Whenever I tell someone the focus of my research is flies, a strange look usually passes across their face.

“No no,” I hastily add, “not the big ones you’re probably thinking about — fruit flies. Tiny things.” At this point I usually hold up my hand and show a gap of a few millimetres between index finger and thumb. “House flies are quite big, really, in the scheme of things. And blowflies… well, blowflies are even bigger, you know that. Pretty disgusting, if you ask me. Their larvae are maggots, after all. I guess fruit fly larvae are kind of maggots as well, now that I think about it…”

The person I’m speaking to didn’t need to be reminded of maggots. I’m not doing a good job.

“But anyway,” I continue, trying to salvage the conversation, “fruit flies aren’t the same as blowflies and houseflies. They don’t eat meat, just fruit. It’s in the name. Harmless creatures, really, and quite pretty… if you’re into that sort of thing.”

Most people aren’t into that sort of thing, and I usually don’t succeed in convincing those I chat with about the beauty of flies. I chalk that up to my own persuasive abilities, not any sort of aesthetic void in the vicinity of insects. Ah well, we can’t all be passionate about the same things.

Me again: “I keep them in small plastic vials. Solid food at the bottom — a sort of yeast mixture I think, I don’t make it — and cotton wool at the top so they don’t escape. They live quite happily in there, laying their tiny eggs in the food, letting the larvae hatch out and crawl around, eating everything in sight. When they’re ready, they climb up the side of the vials and pupate — turn into adults. Circle of life!”

I haven’t seen The Lion King in 15 years, so I spare them a musical number.

“So, uh, yeah. That’s what I do. I study flies.”

Smooth, Scanlan. Another win for science communication. Whoever I’ve been chatting to just couldn’t get enough.

I often wonder how other fruit fly geneticists handle this sort of thing. I mean, Drosophila melanogaster — my species of interest — has been studied for over 100 years: that’s a lot of potential awkward conversations. Did Thomas Hunt Morgan, who won a Nobel Prize in 1933 on the back of millions of fruit flies, ever have to explain his passion to a slightly disinterested neighbour? He probably could have saved himself by revealing his shiny medallion — I don’t have that luxury.

Maybe scientists in the past were more hardcore than I am, able to slog through their scientific life without involving the general public — aka. family, friends and casual acquaintances — in their professional pursuits.

Or maybe not. Most scientists are pretty passionate about their work: after all, a lot of day-​​to-​​day science is rather boring and repetitive (accuracy and rigour comes at a cost, everyone), so you need to care deeply about the questions you’re trying to answer in order to get through each day. I bet Ol’ Tommy Morgan was almost as bad as a Doctor Who fan after a regeneration most of the time, when it came to his flies.

I’m a bit the same. Although, as I’m a fruit fly geneticist and a Doctor Who fan, you should steer clear of me after we get a look at Peter Capaldi’s Doctor, because I’m going to be insufferable.

So why do I study fruit flies, anyway? That’s probably something that I should address, I imagine: the title of this little bundle of words might have hinted at that.

The simple answer is that fruit flies are one of the best genetic models currently available. There’s a reason Tommy Morgan was messing about with them while trying to undercover the secrets of chromosomes and genes — they’re ridiculously easy to breed. Screw Homo sapiens with our 9 month gestational periods! Individual female fruit flies can give rise to nearly 300 offspring in a two week period. This makes doing genetic crosses — the backbone of classical genetics — a relative walk in the park. Well, a walk in a park brimming with flies. Don’t breathe them in.

This reproductive flexibility, along with their humble food and storage requirements (remember the vials?), makes them a breeze to keep in a lab. The only things easier to deal with are probably bacteria, but they just sit on plates doing nothing, so I’m not sure they should count.

Starting from this attractive base, fruit fly research exponentially exploded at the start of the 20th century, and because scientific knowledge is cumulative, by the end of the century we almost knew more about fruit flies than we did about ourselves. The genome sequence of Drosophila melanogaster was published in 2000, three years before the human genome, and there now exist extensive fruit fly genetics resources quite literally at every geneticist’s fingertips.

I am, of course, talking about the Internet.

Want the actual, physical DNA of a particular fruit fly gene (and nothing else)? Yours in just a few clicks! Want to knock down a pesky gene you’re interested in characterising? You can order flies that will let you do that! Want to go the whole hog and just delete sections of chromosomes? No worries, someone’s already done that for you.

Amazon has nothing on fruit fly genetics. (All we need now are fruit fly drones and we’re set.)

Yes, fruit fly research is convenient, but that’s surely not a completely compelling reason to study them, right? After all, a boring fruit fly is a boring fruit fly: they don’t spread diseases like malaria, they don’t eat our economically important crops, and they’re not an invasive pest species…

Ah-​​hah! Thought you had me cornered, didn’t you? Thought I’d have to play my “But you don’t understand how cooooooool they are!” geek trump card? Well, you were wrong. Fruit flies aren’t actually that cool.

Yep, I said it.

Fruit flies are kinda boring. And yet, to me, that makes them more interesting than almost every other organism on the planet.

I promise I’m not having a stroke right now.

Molecules are my jam. I love the microscopic nature of life — we’re all made up of tiny proteins, sugars, fats and strings of DNA, and that’s fascinating. I could sit down and think about all the subcellular processing going on in my hands for about three hours, no lie. (Also, no illicit drugs need be involved, I must point out.)

Model organisms like the fruit fly are vessels for these molecules. I mean, every life form is, but things like wasps and eagles and microbes that can grow at 121ºC — you know, the really cool creatures — are distracting. Boring vessels flatter the goods within. Flashy vessels get all the glory and have a serious negative influence on the goods’ self esteem.

If that sounds stupid, maybe it is, but that’s just the way my brain works.

Fruit flies are simply tools I use to study the nature of life — how genes evolve, what proteins do, how systems interact. If their brains were more complex, they might be offended by that. No offence intended, little fellas! Keep doin’ what you’re doin’. I might be using you for your bodies, but it doesn’t mean I don’t appreciate them.

Sorry, that was gross.

Of course, in reality, fruit flies have lead to extremely important scientific discoveries about the relationship between genes and DNA, insect adaptability to climate change, and even human diseases like Alzheimer’s. As a model insect, they’ve also opened windows on more “important” species, like mosquitos and crop pests. They’ve been invaluable to humanity for many reasons.

So there are plenty of reasons to study fruit flies. Mine probably aren’t the most rational, but hey, whatever gets you into the lab is just fine.

Unless it’s a pathological need to kill insects. Then you should probably seek help.

[Creative Commons licensed Flickr photo by lagrimon]