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How Insects Might Be The Reason Beer Smells So Damn Good

Fruit flies may be gross, but they give yeast a helping leg.

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New research shows that fruit flies may be partially responsible for that intoxicating beer smell.

We’re more like fruit flies than you'd believe: They’re just as drawn to beer’s smell as we are. Beer's scent partially comes from the common brewer's yeast that's used to make it.

A new study published in Cell Reports shows that the aroma of yeast attracts fruit flies, who then help disperse it before it's beer in your glass.

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Fruit fries love overripe fruit, so the fruity smell of yeast draws them to it. Two Belgian scientists accidentally made the discovery after leaving a flask open and finding it infested with fruit flies. Another beer, which had a specific aroma gene eliminated, didn't have the same fly party.

After flies munch on a yeast colony, the yeast remnants cling to fruit flies' bodies like a train hopper.

Here you can see the fluorescent yeast cells on the leg of a fruit fly. (Sorry if it made you a bit squeamish.) Yeast is a fungus that's commonly found in nature that eats starches and sugars and poops carbon dioxide, which is where fizz comes from in drinks like champagne and beer (and what makes bread rise).

Yeast can also have a symbiotic or parasitic relationship with animals. The flies scatter it during their tiny travels, flinging yeast bits far and wide so it can colonize.

The researchers found that one yeast gene in particular, called ATF1, entices fruit flies.

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Using a combination of molecular biology, neurobiology, and behavioral tests, the scientists showed that fruit flies were significantly less attracted to a mutated form of ATF1 (short for alcohol acetyl transferase).

Basically, mimicking the scent of fruit helps yeast attract its winged comrades.

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The researchers write: "For the yeast, dispersal is essential to reach new niches, especially when nutrient levels are running low."

They suspect this isn't the only microbe-insect symbiotic relationship. And the yeast might even have salacious relations with other insects, too.

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