Inspired in part by long-running experiments probing the evolution of bacteria, computational biologist the researchers decided to see if pleasant music could evolve from a cacophonous mess when human listeners acted as the force of natural selection. The researchers started with a loop of simple audio wave forms and let it randomly evolve to generate a starter population with variation on which selection could act. Then more than 6,000 people listened to the audio loops and rated how much they liked the sounds on a five-point scale. The audio loops rated more favourably were allowed to mutate or combine with others to make a next-generation clip; the bad ones died off.

By 500 generations, the pieces developed into pleasant little ditties with chord structure and rhythm, the team report.

Now the researchers are running experiments with stricter, more realistic sources of variation. They also want to scale the project, called DarwinTunes, up to millions of users.