Sensitive Male Fruit Flies Sing Songs Tailored to the Fly Ladies Near Them - Atlas Obscura
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Sensitive Male Fruit Flies Sing Songs Tailored to the Fly Ladies Near Them

Female fruit flies listen to many minutes of male song before deciding whether to mate.

Fruit flies are the only creatures outside of humans and songbirds to have displayed the ability to adjust the intensity of their acoustic signals based on distance of the receiver. (Photo: U.S. Department of Agriculture/Public Domain)

The pesky little critters that emerge when you’ve left your bananas out on the kitchen counter too long are smarter than you think. Though fruit flies have only 100,000 neurons, which is one-millionth that of a human brain, recent research shows that they are able to carry out highly complex adjustments to their courtship songs.

The ability to adjust the intensity of acoustic frequencies based on the distance of the receiver was previously thought to be exclusive to humans and songbirds, but researchers at Princeton have found that male fruit flies demonstrate the same ability during their courtship rituals. During courtship, the male fruit fly attracts a female by extending and vibrating one wing to produce a song.

You may not have realized that the fruit fly near your wineglass sings romantic songs, likely because those songs are extremely quiet. Indeed, they need to be amplified one million times in order to be heard by humans. The below video shows a fruit fly running on an air-supported ball, with audio traces of the song it produces.

“Females listen to many minutes of male song before deciding whether to accept him,” said Mala Murthy, the professor in charge of the research at Princeton. “There is thus enormous evolutionary pressure for males to optimize their song to match the female’s preference.”

In order to conserve energy during the courtship ritual, the male fruit fly changes the amplitude of its song depending on how far away the female is, allowing him to continue singing for longer periods of time. 

Here’s what it looks like when a pair of courting fruit flies meet in the recording chamber:

Since fruit flies have relatively simple neural networks, the recent findings imply that such complex acoustic manipulation could be possible in other interactions across the animal kingdom, too.