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There’s a reason that fruit flies are called fruit flies, and not “beer flies”. Fruit flies like sugar: we see them hovering around our over-ripe bananas, or jostling like crazed groupies for an autograph from a rotting peach. We also know some of the molecular mechanisms underlying this sugar preference.

But what are we to make of those fruit flies hanging around the beer keg? Beer has relatively low sugar content, so what’s their deal? Maybe we should we call a clinic and stage an intervention? Not so fast. According to a new study by Zev Wisotsky, Adrianna Medina, Erica Freeman, and Anupama Dahanukar of the University of California, Riverside, those Drosophila species harboring a copy of the Gr64e gustatory receptor gene are hardwired to hit the sauce. But don’t judge: they’re not chasing the buzz, but rather the glycerol, a sugar alcohol and yeast fermentation byproduct that is also used as an additive in many food products.

F1000 Faculty Member Paul Garrity of Brandeis University writes in his evaluation of the paper:

This very nice study identifies a likely molecular basis for … the predilection of most Drosophila species (like the ever-sensible Drosophila melanogaster) for foods rich in glycerol, which include yeasty concoctions like beer, and it probes why not all Drosophila species share this affinity. The difference appears to reside in the Gr64e gustatory receptor locus.

The authors found that flies with the Gr64e gene exhibited both cellular and behavioral reactions to glycerol. On the behavioral side, the investigators found that proboscis extension was “robust” in reaction to glycerol as opposed to sugar, as long as the Gr643 receptor locus was functional, and that the flies preferred glycerol to sugar across a range of glycerol concentrations.

On the cellular side, the researchers were also able to express Gr64e in non-gustatory, olfactory neurons. When they did so, the altered neurons reacted to glycerol, where they had not before. The authors also tested whether fruit flies without a sense of smell (ΔOrco mutant flies) would still be attracted to beer. They were, pointing to the fact that flies’ preference for Bass Pale Ale is a gustatory, not an olfactory phenomenon.

To quote my favorite heading from the paper’s Results section, “Beer drives a strong ingestion response.”

This paper points to an interesting potential evolutionary shift in appetite preferences in fruit flies. So does that mean that the next time you’re presented with a choice between a candy bar and a glass of zinfandel, and you choose the zinfandel, you can chalk it up to your DNA? Until we know for sure, at least we can take heart in having something in common with fruit flies besides a mutual affection for bananas.