16 August 2010

Song memes

ResearchBlogging.orgOver thirty years ago, Richard Dawkins coined the term “meme” in his classic book The Selfish Gene. A meme was analogous to a gene. A gene is a physical replicator that multiplied itself (but with variations), in such a way that permitted selection and evolution. A meme, Dawkins wrote, was an intellectual replicator that could also multiple itself, creating variants as it did so, allowing evolution.

About two years ago. Susan Blackmore complained that people weren’t taking mimetics seriously, and I argued that mimetics is nowhere near being serious science.

A new paper by Cardoso and Atwell uses the meme concept in describing birdsong. On the face of it, bird song is not a bad model to use the meme concept. Some songs are easily measured; and there are distinct varieties, that are subject to some variation as they are learned.

Cardoso and Atwell looked at the songs of dark eyed juncos (Junco hyemalis) in California, where there has only been a population for about 30 years. In that time, their songs have gotten higher in pitch, which is something that tends to happen to birds in environments with lots of human created sound. They compared those to an older, more established population further from urban centers.

They’re trying to figure out if the number of modifications the birds introduce is enough to explain the change in the songs (like mutation for a gene). If it isn’t, that suggests there is another process going on, like a selective process as birds discard some songs.

If I’m understanding the authors right*, the birds change their songs slightly, but those modifications are only enough to account for about half the difference between the two populations.

The remaining difference between the two populations, they argue, came because the high frequency songs “outcompeted” the low frequency songs. But I think* they are also arguing that no selection for high pitched songs is going on right now. They say this because they reckon that if there was selection going on right now, it would be expressed by more males learning, and singing, higher-pitched songs than lower pitched songs – which isn’t the case.

In other words, the song situation appears to have stabilized. This is slightly frustrating for me as a reader, because I was hoping to get a sense of the process of song change, but it seems most of the action happened decades ago.

What I am not seeing is how characterising songs as memes leads to distinctly different hypotheses or explanations than plain old learning and communication theory does. Cardoso and Atwell are able to couch their descriptions in terms of mimetics, but I would be more impressed if they were about to use mimetics to make a explicit prediction that differed from some theory.

I haven’t changed my mind about mimetics yet.

* I have to put in that caveat that I may be getting it wrong, because this paper assumes a lot of background knowledge. For instance, me being a novice in birdsong, it’s not clear how you would group over 1,000 sound recordings into about 100 song types, or memes. There several points like that in this paper.


Cardoso G, & Atwell J. 2010. Directional cultural change by modification and replacement of memes. Evolution. DOI: 10.1111/j.1558-5646.2010.01102.x

Photo by pheanix300 on Flickr, used under a Creative Commons license.

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