Musical styles have a way of evolving. They change with the times.
But who drives that process? Composers? Musicians?
The answer, says a team of British scientists, is consumers.
The scientists conducted an unusual experiment using what the researchers call a Darwinian Music Machine. It is a computer program designed by evolutionary biologist Armand Leroi of Imperial College London and his colleagues.
The program creates a population of short medleys, each about eight seconds long. "They're just random bits of noise," says Leroi.
Leroi says the program started off with a population of about a hundred such tunes. He and his colleagues then posted those tunes on a website and invited people to rate each tune on a five-point scale, ranging from "I can't stand it" to "I love it."
As people rated the music, the program picked the most popular medleys and allowed them to procreate.
"These songs — they get together, they have sex, as it were," says Leroi. "The code gets mixed up, and then they have baby songs."
The "baby" songs sound similar to their parents and yet are distinct musical entities.
In the experiment, those babies were then sent back online to be rated by the public. The process continued for generation after generation.
"So you have a system that is directly analogous to natural selection in organisms," says Leroi. "The population evolves."
In organisms, natural selection drives evolution. In this case, consumer choice was the selective force. Leroi says that the striking thing is how quickly the noise turned into music.
"Even within a couple dozen generations, we found that they were already much more musical," he says. "By 500 to 600 generations, they were sounding really good."
Take for example, the cacophonous medley you heard earlier.
Here's how it sounded after a 150 generations.
"In effect, we're evolving music out of noise, but there's no creator there, there's no composer," says Leroi. "It's just pure market forces there, or pure consumer choice that is doing it."
So what's the point of this experiment?
Leroi says people generally think that musical styles are determined by composers and musicians.
"You know, there's the Beatles and there's Nirvana," he says. "It's all one bunch of musical geniuses handing the baton down to the next set of musical geniuses. But what we forget is that the public are exerting a choice upon this, and that choice itself is a creative force."
In other words, it's the public that chooses which songs succeed in the marketplace and go on to influence the next generation of artists.
McGill University neuroscientist Daniel Levitin, author of The World in Six Songs: How the Musical Brain Created Human Nature, says the new study offers a compelling illustration of the role consumers play in shaping music.
But he says the experiment doesn't represent the real world because musicians also shape what the audience finds pleasing.
"In the real world, the composer may just draw a line and say, 'No, I think this is better, and I'm going to stick with it,'" he says. "'And maybe people don't like it now, but maybe they'll come around.'"
Take, for example, the American rock band the Talking Heads.
"Their first few records didn't do very well," says Levitin. "And they didn't change anything. They just kept doing what they were doing. And suddenly, the whole world comes around to them, and says, 'Yea, you were right. That's a good sound. We love it now.'"
So, says Levitin, when it comes to musical evolution, natural selection is important. But you can't dismiss the role of the creator.
Here is something I didn't get to include in the broadcast version of my story about musical evolution.
Neuroscientist Daniel Levitin, who I spoke to for this story says the new study illustrates something that scientists have known for a while–that music evolved out of noise, and we human beings shaped the direction of musical evolution.
However, he notes that the distinction between the artist, or the composer and the audience is a relatively new one in the history of music.