The system they developed to test this they call "DarwinTunes." With this system they turned the selection process over to listeners.
...we constructed a Darwinian music engine consisting of a population of short audio loops that sexually reproduce and mutate. This population evolved for 2,513 generations under the selective influence of 6,931 consumers who rated the loops’ aesthetic qualities. We found that the loops quickly evolved into music attributable, in part, to the evolution of esthetically pleasing chords and rhythms. Later, however, evolution slowed.Fitness was defined by appeal to public taste; the tunes the public liked best "got to have sex, got to have babies," and the tunes the public disliked died. Here's a video of one of the authors explaining the experiment, with musical examples, and here's a link to a demonstration.
So, the argument is that they've demonstrated Darwinian evolution, and, incidentally, that good music doesn't require composers. But of course both arguments are patently false. The only halfway credible way to demonstrate the latter is to do the same experiment with people who've grown up with zero exposure to music because exposure -- to music written by human composers -- shapes the consumer's taste and people's tastes shaped the outcome of this experiment. So whether or not a composer actually wrote the notes to the tune that consumer forces determined to be the fittest one here, centuries if not millennia of composers wrote the notes that shaped the taste that determined the selections made by the consumers of the music. That's the most important loop here.
And of course this experiment doesn't demonstrate Darwinian evolution by natural selection because the selective force was artificial. But more importantly it was teleological, goal directed, the goal being music that people like, and that has been shaped by years of listening to music. Western music at that. You don't hear eastern influences in the final generation of acceptable tunes. The evolution of this music was clearly headed in a predetermined direction from the start, with among other requirements, whole and half steps and little or no dissonance.
And, who's to say that consumer taste has always driven musical style? It may be a powerful force now in our Top 40 marketing age, but even in the age of marketing The Beatles really did change the kind of music people wanted to hear.
None of this is meant to take away from the cool factor of this experiment. But why ruin that with the inappropriate Darwinian analogy that will only serve to further confuse a public that already has a dim enough understanding of evolution? And what does it say about PNAS that its reviewers didn't spot this egregious mistake and/or permitted the study's misrepresentation as 'Darwinian'? Is this model so deeply ingrained in today's culture that 'evolution' is confused with Darwinian natural selection, or is it that using Darwin's name was another example of hype or marketing for the study?
And ok, it's conceivable that an internet full of musical consumers could eventually produce something like J.S. Bach's Suite for Lute in G minor (the beginning of the Prelude to which is to the left), just as it's possible that a roomful of monkeys at typewriters could eventually hammer out a Shakespearean play random typing, but the idea that composers are not needed to create music belittles the complexity of great music, and the role of the composer in its creation. Really, how much more Muzak do we need?
The study constitutes science of a sort, and is certainly cute and even interesting. But it says nothing about Darwinian evolution and should not have been portrayed that way. If our taste really did evolve in a way that makes Bach pleasant (to the educated elite, anyway), this may reflect the way we are, but it says nothing about how we got that way.