 and mutation (gold) produce )
MUSICAL REPRODUCTION: Recombination (red and blue) and mutation (gold) produce "daughter" tunes for an audience to rate.
Image: MacCallum, Mauch, Burt, Leroi, PNAS
Public tastes may exert a kind of "natural selection" that improves music's appeal—up to a point—finds a study published this week in Proceedings of the National Academy of Sciences. The research supports the theory that culture and art are shaped by processes similar to those in biological evolution.
Whereas past research using computer models has probed whether popular songs could evolve by selecting for particular musical attributes, "the real difference here is the selection process," says Armand Leroi, professor of evolutionary developmental biology at Imperial College London and a co-author of the paper. Instead of using a computer program or an individual to select which songs "reproduce," "we just let public taste decide," Leroi adds.
He says that people are very comfortable with the idea of natural selection in organisms, but when it comes to music they fail to recognize the creative power of consumer preferences on which songs survive. There is a perception that only the composer and performer are the innovators.
In the experiment, the researchers first populated their "tune world" with short clips of sound encoded by a computer program. They mimicked sexual reproduction by exchanging code between two "parent" clips, analogous to genetic recombination, and by adding random mutations to create "daughter" clips, after which the parent clips would "die." For each generation, they kept 100 songs.
After the researchers used random processes to develop a "gene pool" with sufficient diversity, members of the public were invited to the DarwinTunes Web site and rated the songs on a five-point scale from "I can’t stand it" to "I love it." The computer program then recombined the codes of the top-rated songs, and new songs emerged to be rated in the next generation.
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- Darwin Medley at 0 Generations
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- Darwin Medley at 150 Generations
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- Darwin Medley at 600 Generations
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- Darwin Medley at 3000 Generations
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As the generations "evolved" and progressed, the clips started sounding like music. "What we're making here sounds kind of like electronica dance music," Leroi says. In part, the style might have been influenced by the type of people who would choose to visit a Web site such as DarwinTunes. "I wouldn't be surprised if it's a whole lot of little ravers generating the kind of music that they really like," Leroi says. The results have proved popular among the scientists, too: "We've had some informal little parties in which we've played some DarwinTunes," he says. "Well, you don't want to listen to them all night, but it's definitely listenable to, and certainly danceable to."
After DarwinTunes had evolved for about 2,500 generations, users rated songs from different generations side by side to produce data about the way the songs' musical appeal changed over time. The researchers found that the average likability increased rapidly for about 600 generations and then settled into a kind of equilibrium, or stasis.
Using previously existing music-analysis technology, researchers compared two musical traits, chord clarity and rhythmic complexity, with the users' ratings of the clips' appeal. They found that both were correlated with maximal listener appeal, and that all three characteristics entered stasis around the same time. Researchers estimated an "evolutionary peak" of maximal appeal based on chord clarity and rhythmic complexity and found that the tunes had not reached that peak. Rather, using a variety of statistical techniques, the group determined that the most likely cause of stasis was "low transmission fidelity"—in other words, the children were "too different" from their parents, so the favorable musical qualities were not being passed down intact.
Further analysis indicated a couple of likely reasons for the low transmission fidelity. Recombination, the process by which the genetic material of the two parents is blended, might break up genes that positively influence each other. Alternatively, the delicate structures that make music pleasing could be very sensitive to mutation. The researchers could change the computer programs to overcome these difficulties. Leroi says, "We want to fiddle with the mutation rates, fiddle with the recombination rates." He wants to see if they can get closer to a peak in musical appeal.
The paper notes that although this study suggests that individual consumers' tastes shape music produced by DarwinTunes, the evolutionary process in human-composed music is more complex. Composers and musicians themselves are responsible for a large amount of musical development, and social groups influence individual ratings as well. The researchers want to incorporate these other influences into musical software. "This could be much, much bigger," Leroi says. He imagines modifying DarwinTunes, even turning it into an iPhone game with not thousands but millions of users. "You could produce a whole new musical ecosystem, as it were."
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11 Comments
Add CommentEconomics and natural selection failed to keep decent melody in classical music (since about 1900). Can anyone explain this?
Reply | Report Abuse | Link to thisYes, exactly! The listeners are as much a part of the creative process as the performers are. Great article!
Reply | Report Abuse | Link to thisDarwin Medley at 600 generations reminds me of "In C". Darwin Medley at 3000 generations sound like an "In C" remix.
Reply | Report Abuse | Link to thisanother mickey mouse article
Reply | Report Abuse | Link to this>Leroi says, "We want to fiddle with the mutation rates, fiddle with the recombination rates."<
Reply | Report Abuse | Link to thisWould it be rude to point out that the computer and its program are intelligently designed to produce the result that it does? How can they seriously claim that this mimics evolution when they are tinkering with the algorithms and parameters to "get closer to a peak in musical appeal?" Darwinian evolution is not goal-directed.
Thank you Featherstonehugh. As a former Director of Music in three churches and an amateur composer since age 14, including a 25 minute electronic 4-movement symphony, I would like to add a musician's viewpoint. I love most of the music composed since 1900 and would be outraged if anyone tried to censor it, but minimalism is one genre in which most of the results bore me to sleep. If the definition of music is an "audial art form in which tones, harmonies and rhythms move and develop through time" then minimalism doesn't even qualify as music. No matter what the AI program does, these beeps and twitters still sound like the chatterbox of minimalism. But it's Interesting that the only one of these sequences I found even remotely worth listening to was the second one on the "change" list, the one right after the start. The ones that came afterward were all downhill, and when they started to sound like cheap pop elevator music I gave up!
Reply | Report Abuse | Link to thisI'm getting tired of readers dismissing these articles as "mickey mouse"—usually, I suspect, because they don't like the findings. It should be obvious from the relative lengths that these articles on the website are not intended to be as weighty as those in the published magazine. But they always include some data that points in the direction of the suggested conclusions. They are reports of scientific work-in-progress, giving us a glimpse of front-edge research.
Reply | Report Abuse | Link to thisRude Featherstone? No. Ignorant ... perhaps. I'm not all that surprised someone form the I.D. camp felt they they needed to chime in here. Nor am I all that surprised they used a straw man argument to do so. Feastherstone, look back in the article's text and you will not find the word 'MIMIC' anywhere. What they did say was 'SIMILAR'.
Reply | Report Abuse | Link to thisadjective 1. having a likeness or resemblance, especially in a general way.
The Darwinian process that is 'similar' to, but not identical to the process they refer to in the article is 'SEXUAL SELECTION'. And while a physical agent is involved in the selection process ... no high mental functions are necessary.
Sexual selection - Wikipedia, the free encyclopedia
Concept|Modern...|Criteria for...|Example:...
Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection.
In this case, I think 'SENSUAL SELECTION', would be an an appropriate title. In that what is pleasing to one's (well, more than one's, in this case) ear controls the feedback.
The 'Tinkering' you object to so strenuously is also somewhat analogous to random mutation and sexual selection. In a sense, it is similar to goal oriented searches, but only in that it can arrive at the same destination. Where it arrives, however, is not a 'predetermined' point. It's just playing it 'by ear', as the saying goes. :)
Steve
Alas or fortunately music is still completely escaping the scrutiny of science although the experiment is quite fun and may demonstrate something valid for genetics. It would take a dissertation to explain why, since music is essentially a cognitive mathematic of the vibrations velocity, such process would lead to acceptable musical results, by those scientists standards.
Reply | Report Abuse | Link to thisPeople without a personal experience in playing , improvising and/or composing music depend on "taste" to judge music, a highly unreliable form of measurement, for an art which is all about fine measurements.
Fortunately for the most delightful composers, they hear the resonances in forms and shapes, they do not try to shape the natural world. Music precedes people: we are in a sea of music that we are trying to hear. Our vision is segmented by the limitation of our senses so we tend to love fragmented reality as a mirror of ourselves.
Unfortunately this leads us to be easily subjected to purely mathematical music, which can manipulate our feelings or energy: that has been proven dangerous at times.
Great, soulful composers/musicians try to render what they hear in the magnificent world of resonances which is not fragmented, in which energy never disappears but is reingurgited in harmonics above and below. Science has much to learn in continuing it's seminal relationship with music.
Perhaps the problem here is with the article's title. If listeners truly did shape the evolution of popular music, creative experts would not be needed. Interestingly, humans are actually a much less important factor in the recording process today. A tune is designed for popular consumption: the beat is quantized, the voices auto-tuned. It is then subjected to appraisal by a 'producer program' in the control room that checks the level of conformity to established 'norms' for popular music, these norms being the parameters common to the top-selling singles of the moment. Finally, the dynamics are compressed to compensate for low-bandwidth streaming, the music goes round and around and it comes out of your mobile device as a ringtone. Welcome to the brave new world of the lowest-common denominator, where a million ape-descendants with a million computer keyboards will make all of the musical decisions for the next generation.
Reply | Report Abuse | Link to thisThe rise of the Modernist aesthetic introduced a new acceptance of dissonance and tone clusters that replaced the teleology of the final Romantic compositions. The new music of the 20th century began to alter in complexity, note duration and scale as composers raced towards technical supremacy over emotional qaulity. The outcome of this change displays itself in the musics of the Second Vienese School in comparison to Romantics such as Wagner for example. Hope this is of any use!
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