Natural selection expresses the idea that organisms (i.e. their genes) vary and that variability has consequences. Some variants are unfit and go extinct, others adapt and do well. This process, repeated over millions of years, has given us the variety of life on earth.
Many authors have played with the idea how to combine these insights from evolutionary biology to changes in culture, the notion of ‘memes’ being one of them. Richard Dawkins proposed that human culture is composed of a multitude of particulate units, memes, which are analogous to the genes of biological transmission. These cultural replicators are transmitted by imitation between members of a community and are subject to mutational-evolutionary pressures over time.
This week an interesting study appeared in PNAS (early edition) showing that a simple Darwinian process can produce music. Inspired by cultural transmission theory, the study suggests that the evolution of music can be viewed and analyzed in terms of selection-variation processes, and, as such, may shed light on the evolution of real musical cultures.
The experiment described in the paper works as follows: An algorithm maintains a population of tree-like digital genomes, each of which encodes a computer program. Each genome-program specifies note placement, instrumentation, and performance parameters (with tempo, meter, and tuning system fixed for all loops). Loops periodically replicate to produce new loops. The selective pressure on the music that is generated comes from a population of consumers who listen to samples of the loops via a Web interface (DarwinTunes) and rate them for their appeal. These ratings are then the basis of a fitness function that determines which loops in a given generation will be allowed to mate and reproduce.
Robert M. MacCallum, Matthias Mauch, Austin Burta, & Armand M. Leroi (2012). Evolution of music by public choice. Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1203182109
(See also earlier blog entry).