Despite their tiny size and short lifespan, fruit flies are familiar test subjects in labs because they can show us a lot about ourselves, particularly in terms of genetics. And in a study for Current Biology, a team led by Anita Devineni found that the insects have another thing in common with people—they like alcohol, sometimes a little too much.
The scientists started by giving their test subjects a choice. Flies held inside vials could sip from thin tubes holding either liquid food spiked with 15 percent ethanol or plain liquid food. The researchers measured the descent of the liquids inside each tube to get a readout of which food the flies preferred [Science News]. It was no contest: The flies preferred the alcohol-spiked food, and the more they had it, it seems, the more they craved it—the flies’ tipples grew more frequent over time [National Geographic News].
Researchers found other signs of addiction similar to human alcoholism. When they upped the alcohol content from 15 to 25 percent, flies who hadn’t been drinking didn’t care for the harder stuff, but those already accustomed to alcohol slurped it up. When the researchers laced the booze-food mix with small amounts of the toxic chemical quinine, those flies continued to drink, even though fruit flies normally avoid the chemical. “I was actually pretty surprised when they continued to drink it,” Devineni says [Science News].
That alcohol has strong effects on fruit flies is unremarkable; other studies have shown that. But Devineni’s study offered the flies a choice to drink or not, which revealed some new ways it can change them. Her team found that flies even relapse: those allowed to drink for a few days and then forced to abstain for a day or two went right back to boozing at peak levels when the scientists offered the spiked food again. The team hopes to investigate the genetics behind this behavior in the future, in hopes of zeroing in on the genetic component of alcoholism in humans.
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Image: Edward Dougherty