Music, you might think, is an innately human pursuit; something which can only truly be written by us, the most intelligent of creatures. But a team of researchers has demonstrated that, actually, it's possible for digital music to evolve by itself, without any creative input from a composer.
"We don't often think of music as evolving, but everybody knows it has a history and it has traditions. But if you think about it, it really has evolved, it is changing continuously. We believe music evolves by a fundamentally Darwinian process - so we wanted to test that idea."
To do that, Leroi and his team created a computer program that could both create and combine noise. In the first instance, it spat out two random streams of noise, with notes and sounds all over the place. Then, those two were combined by the program—in an act of digital reproduction—to create four new loops. And so on, creating more and more offspring.
Then, when they'd amassed a hundred tracks, volunteers were asked to rate them on a scale of "love" to "hate". The best-liked pieces survived, while the disliked ones were killed off. "In the beginning, [the loops were] pretty horrible," says Bob MacCallum, one of the researchers, to the BBC. "But occasionally, one was slightly less horrible."
The survivors went on to be combined, breeding another generation of tracks. The process went on for thousands of iterations and, slowly, the clashing chord disappeared, being replaced with charming rhythms and, in some cases, even the odd melody. You can listen to the different generations of the music below. Eventually, though, something weird happened. MacCallum explains:
"After about 3,000 generations had been listened to, there starts to be a kick drum or a bass drum, and that just spontaneously came, we didn't put any drum sounds into the algorithm."
Huh! That's crazy, but not unexpected: the music was edging ever closer to what the listeners wanted, and eventually it was able to combine the sounds it had at its disposal to create a drum beat, something clearly desirable in modern music. In fact, not long after the evolutionary process began to slow, and the improvements became more and more subtle—not unlike evolution in the animal kingdom. The results are published in PNAS.
Of course, while this all suggests that music can itself evolve without any help from an external composer controlling how notes are arranged, it's also worth pointing out that consumer choice—in this case, the volunteers choosing the best and worst loops—acts as a form of creative force. Good music, then, can't be created from nowhere: there needs to be at least some input, and it almost certainly needs to come from humans.
Given long enough, with enough processing clout, there's no reason some decent tracks couldn't come out of algorithms such as these—it'll just never surpass the musical genius we're used to, be it Bach or Bob Dylan. [PNAS, Darwin Tunes]
Image by Andy Buscemi under Creative Commons license