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蝦米?果蠅也愛啤酒?不曉得它們會不會喝醉?

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Beer Or Sugar Water?

For Flies, The Choice Is Pale Ale

by Joe Palca

LINDA WERTHEIMER, HOST:

There are certain scientific studies that call out to NPR science correspondent負責跑科學新知相關新聞的記者 Joe Palca, because they reveal something fundamental基礎的 about the natural world. For example, a recent study from scientists at the University of California in Riverside reveals why fruit flies果蠅 like the taste of beer. Surely that's a fundamental fact of nature. Here's Joe.

JOE PALCA, BYLINE: I've drunk my share of beer, but I have to admit I was surprised to learn that fruit flies like beer. Apparently I shouldn't have been.

ANUPAMA DAHANUKAR: The attraction of flies to beer was first reported in the early 1920s.

PALCA: That's Anupama Dahanukar. She's not in the school of bartending science酒保學 at the University of California Riverside. There isn't one. No, she's part of an inter-disciplinary program跨領域計畫 involving neuroscience神經科學 and entomology昆蟲學.

DAHANUKAR: We're interested in how flies recognize chemicals.

PALCA: So answering the question of why flies like beer is actually quite relevant有相關性的 to her research. It's not a simple question. Scientists are only just beginning to understand the basics of smell and taste in humans. So research on flies has been extremely helpful with that.

Now, as everyone, including me, knows, flies like sugar. So it could just be that flies like beer because they can detect發現 some residual殘留的 sugar in the beer. But Dahanukar suspected that might not be the case懷疑那可能不是真正原因, so she planned a beery experiment. She would give the flies a choice between beer and sugar water and see which they preferred.

DAHANUKAR: We selected a pale ale一種顏色呈現琥珀色，味道較苦且較為不甜的啤酒, and the main reason was because pale ales have very lower sugar content. And so we were trying to identify other chemicals, chemicals other than sugars, that taste good to flies.

PALCA: It would be a thrilling令人振奮的, dare I say unforgettable, moment in science to prove that it was something other than sugar that attracted flies to beer.

ZEV WISOTSKY: I remember, it was a Saturday.

PALCA: Carrying out the experiment fell to graduate student Zev Wisotsky.

WISOTSKY: I grabbed the beer at the grocery store, came into lab, and performed the two-choice assay分析.

PALCA: The two-choice assay is where the flies get to choose between a sip of beer and a sip of sugar water.

WISOTSKY: They surprisingly went for the beer.

PALCA: Now that that was established, Wisotsky and Dahanukar went about trying to figure out which compound(化學) 化合物 in the beer was attracting the flies.

DAHANUKAR: And the answer, as it turns out, was quite simple. It's a molecule分子 called glycerol(化學) 甘油, which is made by yeast酵母 during fermentation發酵.

PALCA: Glycerol is the stuff that's used in antifreeze防凍劑/液. It actually tastes sweet, but it's not a sugar. Dahanukar and Wisotsky even found the particular gene基因 responsible for flies' ability to detect glycerol. When they created flies missing that gene and gave them the sugar water or beer choice, they went for the sugar water.

The research appears in the journal, Nature Neuroscience.自然神經科學期刊

There are practical applications that may result from understanding how insects taste and smell. For example, other scientists are developing powerful insect repellents驅蟲劑 based on what they've learned about insects' preference in the odor arena氣味庫. You see, learning why flies like beer is both fundamental and practical.

Joe Palca, NPR News, Washington.

STEVE INSKEEP, HOST:

Did he say the odor arena? Yes, he did. From flies drinking beer to good old fashioned bar flies. While most Americans were celebrating Thanksgiving, in Paris some were celebrating the 100th anniversary of a legendary watering hole傳奇酒吧.

Harry's Bar, originally called the New York Bar, opened on Thanksgiving Day in 1911. Its American founder wanted it to be a slice of Manhattan一點曼哈頓風格(味道), so much so that he had a New York saloon酒吧 dismantled拆解下來 and shipped to the City of Lights. 光之城是巴黎的暱稱，法文La Ville-Lumière" ("The City of Light" or "The Illuminated City)

In the '20s, Harry's Bar was a favorite of expatriates流浪在國外的人 like F. Scott Fitzgerald費茲傑羅(美國文學家)

and Gertrude Stein旅法美國女詩人與作家葛楚德史坦. Many years later, Clint Eastwood would visit. The bar remains a favorite of expats and Parisians巴黎人 alike and is likely to stay that way as it enters a second century.

This is NPR News.