My iPod playlist as a metaphor for evolution

I've talked about my awesome iPod playlist in great detail before, so I won't bore you with the details again, but in a nutshell I have a playlist on my iPod that I listen to while driving and while working. It is a smart playlist, which means it updates itself, and when I listen to a number of songs from it and then sync my iPod again, iTunes removes those songs I've listened to and replaces them with new songs at the end of the list. All the songs are rated, so 5-star songs show up more often and 3-star songs show up infrequently. I posted about this on a board that both I and Kevin Sheath (writer of Lightshade and The Sundays) post on, and he pointed out that the playlist is based on "performance, feedback, revision" and is a metaphor for natural selection.

I had never thought of it that way before, but it works. Essentially, natural selection is the guiding force (or one of the major guiding forces) behind the theory of evolution. Every generation, random mutations in DNA cause tiny changes in offspring; it might be a slightly longer neck in a giraffe or slightly sharper eyes in an eagle. But if the mutation causes the organism to survive better in its environment (to get more food than others of its species or to live longer), it has a higher statistical probability of passing on its genes to the next generation; in other words, havin' sex and makin' babies. Over the course of many many generations (ie., millions of years for a mammal or perhaps several decades for bacteria and other single-celled organisms), individual species can undergo so many changes that they no longer closely resemble their distant ancestors, and become classified as a completely different species. This is evolution, which means "change over time."

When I started using my playlist about a year ago, most of the songs that showed up in it were completely random, because I didn't have a lot of songs rated. Over the course of months, songs that I loved (ie., 5-star songs) started having a higher chance of showing up in the playlist than those I didn't like very much (ie., 3-star songs). And songs I hated altogether, such as 1-star tracks, had zero chance of showing up in the playlist. The playlist got better and more enjoyable for me to listen to, because the ratio of songs I liked to songs I didn't like became higher and higher.

This is natural selection, or more accurately, artificial selection (selection of genes by human rather than nature, such as selective breeding in dogs or food crops). Genes (songs) that are better adapted to their environment (more likely to be pleasing to my ear), are more likely to procreate (show up again in my playlist on a frequent basis), and the structure of the species (my playlist) changes over time. The playlist is very different than it was a year ago, when songs I didn't like very much showed up often. Over time I rated these songs poorly or deleted them from my iTunes library outright, and the chance that they'd come back dropped dramatically. Songs I like started showing up more and more, and songs I love started showing up very frequently.

Science is all around us.

EDIT: Kevin informs me this idea is touched on briefly by rapper Baba Brinkman on his song "Unity of Common Descent," from his album "The Rap Guide to Evolution." You can listen to it streaming here.