Although summer has ended, the memories of sitting in a beer garden, swatting flies away from your pint, have far from faded. But why do flies like beer?
Scientists working at the Flanders Institute for Biotechnology and the University of Leuven have the answer. Yeast cells produce aromas that are highly attractive to flies.
This is no accident; it is evolutionarily advantageous for yeast to do so. The attraction allows some yeast cells to latch onto the insects and be taxied to fresh food sources. This process is vital for the otherwise immobile cells to prosper. Over time, the yeast that makes the most appealing scent is naturally selected to survive.
The team found that when the gene in yeast that produces these aromas was removed, the flies became disinterested. The flies’ brain activity also differed greatly depending on whether they’d been exposed to the aromas or not.
“Flies are strongly attracted to normal yeast cells, when compared to mutant yeasts that don’t produce [aromas],” says Dr Emre Yaksi.
Perhaps more interestingly, though, is that it is the exact same yeasty aromas that make beer and wine taste good to humans, to a degree which “has long been underestimated,” says Dr Kevin Verstrepen.
“In fact,” he adds, “yeasts may even be responsible for much of the terroir, the connection between a particular growing area and wine flavour, which previously often was attributed to differences in the soil.”