“We think of [music] as the product of genius — your Bach or your Lennon,” said Leroi, who studies the worm C. elegans at Imperial College London. “But . . . if science makes it clear that natural selection can make all of nature, surely it might play a role in making music as well?”
For years, this question had intrigued MacCallum, who is also at Imperial College, where he uses computational technology to study the mosquito genome. Together, he and Leroi launched the online program “DarwinTunes” in 2009, to commemorate Charles Darwin’s 200th birthday.
In the natural environment, organisms compete to survive, reproduce and pass on their genes to the next generation. In the DarwinTunes world, only the most musically appealing — the fittest — tunes would survive.
The scientists unleashed an original “population” of 100 eight-second loops composed of random electronic tones into a virtual environment by posting them online at www.
darwintunes.org/evolve-music. Listeners were invited to rate them on a five-point scale, and the 50 that got the best rating were allowed to survive and pass on their “musical genes,” as Leroi put it in an interview.
To simulate the natural mutations that change an organism’s genome over its lifetime, Leroi and MacCallum did some random auditory tweaking to each of the loops. Then they randomly paired the surviving loops to “mate,” or swap bits of computer code, to produce two slightly different “baby” loops that took their parents’ place in the next generation. Listeners then rated the loops in that generation, and the evolution continued.
For the first 1,000 generations of mating, the authors’ Darwinian hunch held: The original “rubbish-sounding” loops had evolved into pleasing, eight-
second ditties with identifiable Western chords and rhythmic structures that sounded like ring tones. Listeners consistently rated these new generations as more pleasing.
After about 2,500 generations, the increase in the loops’ appeal began to plateau — an effect the scientists attribute to the mating process, which could scramble the elements of late-generation tunes in a way that destroyed the complexity that had made earlier loops appealing.
To date, the DarwinTunes Web site has drawn close to 19,000 unique participants; votes have been cast for more than 20,000 evolving loops.
Composer and computer scientist David Cope of the University of California at Santa Cruz, who wasn’t involved in the study, said that despite its simple design, DarwinTunes reveals the importance of audience feedback in driving the evolution of a com-
poser’s style — even if the composer is only a computer program.
“Composers grow by letting some of their musical ideas live and letting others die. We always have,” Cope said.
He added that in an “increasingly digital and democratic era of music,” audience reaction in the form of “likes” and tweets influences pop artists to cater to listeners around the world.
Next, the DarwinTunes team wants to create a mobile app aimed at drawing millions of people to vote on loops and generate what MacCallum envisions as “an ecosystem of digital songs.”
“But first, planning and funding — and to do that, we are going to have to liberate Bob from mosquito bioinformatics,” Leroi said.