Image: Sound clip
DarwinTunes.org
DarwinTunes listeners can add annotations to musical clips, such as this medley that has evolved through 3,520 generations.
By ISNS contributor
Inside Science News Service
updated 6/20/2012 12:20:14 AM ET 2012-06-20T04:20:14

In music, as in evolutionary biology, it could be the survival of the fittest.

Using loops of computer sounds as building blocks, scientists have found that by obtaining small contributions from many people, or crowdsourcing, they can create pleasant-sounding music, just the way biology produces adapted organisms.

In a paper published in this week's Proceedings of the National Academy of Sciences, Bob MacCallum of Imperial College, London, and his colleagues demonstrate how evolutionary pressure from audiences can shape music.

"What interests us is not that we can do a composer's job," he said. "What interests us is that we can quantify the consumer or listener's creative role."

Music research is not MacCallum's day job. He actually is an expert on the genetics of mosquitoes. He also loves music. His paper is full of biological references, describing how music is changed by the same mechanisms that organisms and languages use to evolve.

MacCallum wrote a program called DarwinTunes and posted it on the web.

DarwinTunes began with a series of sound loops, eight seconds long, consisting of sounds produced by computer from sine waves — not very natural-sounding. Any melodies are purely coincidental.

The researchers did set limits. MacCallum said. They designed the loops to have four beats to the bar, to continue for four bars, and used the conventional Western 12-tone scale so it would not sound alien to their Western subjects.

The sounds are entirely artificial, MacCallum said, because if he used real instruments the personal preferences of the listeners might alter their decision. There are people, for instance, who hate accordions.

Participants in the study vote on a scale of one to five on whether they like the loops or not. Every time 20 loops have been rated, the top 10 are paired with each other randomly, and the bottom 10 are dropped from the program.

"If it's good music, it survives, makes babies, and if it's bad music according to the audience, then they just die off," MacCallum said.

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The loops periodically replicate (MacCallum calls it "having sex") and produce new loops ("babies"). The second generation is not identical to the first because they are formed by the combination of two loops, and there is some random mutation, just like in life.

At any time, there are 100 loops in the program.

So far, he reported, 6,931 listeners made 85,533 ratings over the course of 2,513 generations. In all, 50,480 loops were created. A few short melodies accidentally evolved. The results sound something like the kind of minimalist music that gained attention from critics toward the end of the last century.

But, as each generation evolved, the changes diminished, which became noticeable about a third of the way in, and the result now appears to have stopped evolving.

MacCallum said this is mirrored in nature. There are some species of reptiles, for instance, which essentially haven't evolved in 100 million years, probably because they didn't need to for survival. Their environment stabilized. Also, there were a lot more of the reptiles than tones in his program — and with large populations, you need only a small fitness advantage.

MacCallum said he and his colleagues were changing the program to take it off its plateau and resume evolution. The process also happens in life. A thousand teenage bands practice in garages, he said, and sometimes a few are so good they are encouraged to play publicly. The really good ones become popular around the country and the world. Their success breeds imitators.

Is what the program produced real music?

Seems like a stretch, says Sharon Levy, who teaches music literature at the Juilliard School in New York and the Peabody Institute at Johns Hopkins University.

"Certainly, as the authors note, this kind of program can only evolve so far. That's partly due to the limited choice within the program itself, as it's about very short segments of musical material, whereas some of what's considered the most important musical contributions, at least in the West, has to do with how such materials are arranged, manipulated and transformed across a much larger unit of musical time," Levy said.

"Another issue," Levy said, "is that everyone — brilliant musician or not — plays an equally limited role. If the authors wanted to continue the evolutionary model, then perhaps folks like Bach or Beethoven might be seen as kinds of musical meteors who dramatically altered the evolutionary process, which, if nothing else, is a nice metaphor."

MacCallum thinks it's music within a limited definition.

"It's a fact we've made music that is more pleasing to Western people," said MacCallum. "But more pleasing is not the same as a Mahler symphony."

More about the science of music:

Joel Shurkin is a freelance writer based in Baltimore. He is the autor of nine books on science and the history of science, and has taught science journalism at Stanford University, the University of Californbia at Santa Cruz and the University of Alaska at Fairbanks.

This report was originally published by Inside Science News Service on June 18 as "Evolution Produces Tasteful Tunes." Copyright 2012 American Institute of Physics.

Explainer: The 2012 Weird Science Awards

  • Our annual Weird Science Awards pay tribute to the strangest scientific tales of the past year, and you just know the 2012 edition had to be a doozy. While we're waiting for the Maya apocalypse — and we may be waiting a long, long time — let's count down the top 10 Weird Science stories, as determined by an ironically unscientific Live Poll.

    No. 10 is the discovery that having a painful need to urinate can impair your judgment. "When people reach a point when they are in so much pain they just can't stand it anymore, it was like being drunk," says Brown University neurologist Peter Snyder. "The ability to hold information was really impaired." To say nothing of the ability to hold water.

    The research won Snyder and his colleagues a share in one of 2011's Ig Nobel Prizes, which honor science that makes you laugh, and then makes you think. Watch Snyder explain the study in this YouTube video, then click the "Next" button for more laugh-provoking science — or scroll quickly all the way down to the bottom if you have a painful need to go.

    — Alan Boyle, msnbc.com science editor

  • 9. Flies hooked on meth ... and sugar

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    Botaurus via Univ. of Illinois
    Researchers have found that the fruit fly is a useful model organism for studying the whole-body effects of methamphetamine exposure.

    When researchers noticed that meth addicts often take in large amounts of sugary drinks, they decided to do a little experiment: First, they got fruit flies hooked on methamphetamine. Then the scientists fed some of the flies a diet heavy on trehalose, an insect blood sugar. They found that the sugar-gobbling flies outlived the flies who didn't get the sweet stuff. Maybe sugar metabolism plays a role in meth's toxic effects. "Hopefully, some of these insights might lead to opportunities to deal with the problems associated with the drug," says University of Illinois toxicologist Barry Pittendrigh. But more research is required to trace the effects on mammals. In the meantime, watch out for those meth-head fruit flies.

  • 8. Monster pictures make a splash

    Courtesy of Discovery News
    A photo from a video that claims to show Alaska's own version of a sea monster.

    2011 saw a double-header (so to speak) in the marine-monster category. The most popular Loch Ness monster-like picture came from Alaska, where Andy Hillstrand of the "Deadliest Catch" TV show captured the footage for the Discovery Channel. Some might suggest that the creature is an eel, or a fish, or even a trick of light on the water. Not Hillstrand. "I've never seen anything like it," he told Discovery News. He suspects that the picture shows a Cadborosaurus, a legendary beast that has long been said to frequent Alaska's waters. Meanwhile, another picture purporting to show a creature that's been nicknamed "Bownessie" made waves in England.

  • 7. Glowing dog has an on-off switch

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    Photos demonstrate the inducible glow-in-the-dark effect in a genetically modified dog: The left images shows the dog's paw in normal light (upper left) and under ultraviolet light (lower left) after doxycycline is added to the dog's food. The right-hand images show the dog's paw in normal and ultraviolet light after scientists stopped administering the drug.

    In past years, our Weird Science Award winners have included glow-in-the-dark kitties and glow-in-the-dark puppies. How could scientists possibly top that? Would you believe a dog with a gene that turns the fluorescence under UV light on or off, depending on whether a particular drug is added to its food? That's exactly the kind of dog that South Korean scientists produced in 2011. Why, you ask? Well, the ultimate aim of these glow-in-the-dark exercises is to splice in genes that can help treat diseases — and having an on-off switch would give physicians more control over the treatment. That feat would make other researchers turn green ... with envy.

  • 6. Just this once, Samoa skips a Friday

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    Hannah Johnston  /  Getty Images
    Samoa and New Zealand-administered Tokelau skip a day as they jump over the international date line in an attempt to improve trade and tourism.

    For more than a century, Samoa was on one side of the International Date Line, and Australia and New Zealand were on the other. When the Samoans were at Sunday church, the Aussies were starting their business week on Monday. And when Samoa was trying to finish up its own business week, the Kiwis were settling into the weekend. To remedy that, the Samoans switched over to the Australia-New Zealand side in 2011, going directly from Thursday, Dec. 29, to Saturday, Dec. 31. To top it all off, workers were paid for the non-existent Friday. If only we could all get to the weekend that quickly ... and spend it on a tropical island.

  • 5. Pole shift forces airport makeover

    Might as well face reality: Shift happens. Earth's shifting magnetic poles are not a sign of the apocalypse. They're just a fact of life on our dynamic planet. We do have to cope to the shift that life throws at us, though. For example, in early 2011, Tampa's airport had to repaint the numbers on its runways to reflect their shifting orientation with respect to magnetic north. The good news is that even dramatic changes in the poles' position would have no effect on life on Earth, despite what the doomsday prophets say.

  • 4. Corpse-dissolving machine invented

    "Build a better mousetrap and the world will beat a path to your door." Does that old saying apply to building a better corpse-dissolving machine as well? Resomation Ltd. hopes so. The Scottish company installed its machine in a St. Petersburg, Fla., funeral home and hopes the system will be legalized in other jurisdictions. The alkaline hydrolysis unit liquefies a body's soft tissues and flushes the sterile liquid into the municipal water system. The bones and other hard parts are left behind to be crushed. Company founder Sandy Sullivan says the machine lets people express their environmental concerns "in a very positive and I think personal way." Sounds good, as long as they don't put a Soylent Green factory next door.

  • 3. Preacher gets doomsday wrong ... twice!

    First, figure out exactly when Noah's Ark was floated by the Flood, and exactly when Jesus was crucified. Then come up with an arcane biblical numerology to add 7,000 years to the former, and 722,500 days to the latter. That was California preacher Harold Camping's formula for determining that May 21 was the date for the beginning of an apocalyptic Rapture. When May 21 didn't work out, he said Oct. 21 was the fallback date for the end of the world. And when that didn't work out ... well, now Camping says he's rethinking this whole doomsday business. But what about the 2012 apocalypse? That's too kooky, even for Camping. "Mr. Camping does not believe the Mayan calendar holds any significance at all," a spokeswoman says. Camping's mathematical acumen earned him a share in one of 2011's Ig Nobel Prizes.

  • 2. 'Aflockalypse' is for the birds

    Image: A dead blackbird on the ground in Beebe, Arkansas,
    Warren Watkins/The Daily Citizen  /  EPA
    A dead blackbird on the ground in Beebe, Arkansas.

    The year 2011 was rung in with a series of reports about mass die-offs, involving blackbirds (the so-called "Aflockalypse" in Arkansas), fish, crabs and other creatures. Some wondered whether a global environmental crisis was in the offing, but experts said the Aflockalypse was simply a case of people connecting the dots between unrelated events, facilitated by global communication systems. Die-offs can happen for a variety of reasons. The Arkansas blackbird deaths, for example, took place after the birds were spooked by New Year's Eve fireworks. And wouldn't you know it? The Aflockalypse happened again to kick off 2012.

  • 1. Fungus turns ants into zombies

    David P. Hughes
    A dead ant, after being zombified by a species of parasitic fungus. The brain-controlling fungus turns ants into zombies that do the parasite's bidding before it kills them.

    If books like "Pride and Prejudice and Zombies" and video games like "Resident Evil" can generate billions of dollars in sales, it shouldn't be surprising that the top Weird Science honors go to a story about zombie ants being taken over by a brain-controlling fungus. The fungus apparently uses temperature cues to decide when to have the ant clamp down on a cool leaf with a death grip. Pennsylvania State University's David Hughes speculates that the fungus does its thing to ensure it "has a long cool night ahead of it, during which time it can literally burst out of the ant's head to begin the growth of the spore-releasing stalk." It's the perfect plot for a horror movie directed by one mean mother: Mother Nature.

  • Honorable (?) mention

    Other weird tales that almost made the top 10:

    Does 13th zodiac sign mean your horoscope is wrong?
    Was the Shroud of Turin created in a blinding flash?
    Science reveals how to win at 'Rock, Paper, Scissors'

    Previous Weird Science winners:

    Cricket testicles and 2011's other Weirdies
    Kinky fruit bats and other Weirdies from 2010
    2,700-year-old marijuana and other 2009 Weirdies
    Glow-in-the-dark kitties and other Weirdies from 2008

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