PARIS - When peanuts are dropped into a pint of beer, they initially sink to the bottom before floating up and "dancing" in the glass.
Scientists have dug deep seeking to investigate this phenomenon in a new study published on Wednesday, saying it has implications for understanding mineral extraction or bubbling magma in the Earth's crust.
Brazilian researcher Luiz Pereira, the study's lead author, told AFP that he first had the idea when passing through Argentina's capital Buenos Aires to learn Spanish.
It was a "bartender thing" in the city to take a few peanuts and pop them into beers, Pereira said.
Because the peanuts are denser than the beer, they first sink down to the bottom of the glass.
Then each peanut becomes what is called a "nucleation site". Hundreds of tiny bubbles of carbon dioxide form on their surface, acting as buoys to drag them upwards.
"The bubbles prefer to form on the peanuts rather than on the glass walls," explained Pereira, a researcher at Germany's Ludwig Maximilian University of Munich.
When the bubbles reach the surface, they burst.
The peanuts then dive down before being propelled up again by freshly formed bubbles, in a dance that continues until the carbon dioxide runs out -- or someone interrupts by drinking the beer.
In a series of experiments, the team of researchers in Germany, Britain and France examined how roasted, shelled peanuts fared in a lager-style beer.
Of course, science is never settled -- particularly when beer is involved.
Hoping to create a better model of the dancing peanut phenomenon, Pereira said the scientists will continue to "play with the characteristics of different peanuts and different beers".