Monday, May 23, 2011

Music and Evolution

Mark Changizi is an "evolutionary neurobiologist" and has a brand new book out called Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man. Because what he seems to be saying overlaps so nicely with my idea that physical gesture is a primal constituent of music, the book jumps to the top of my to read list.

Here are some excerpts from an interview published in today's WSJ:

. . . My research suggests that when we listen to music without any visual component, our auditory system—or at least the lower-level auditory areas—"thinks" it is the sounds of a human moving in our midst, doing some sort of behavior, perhaps an emotionally expressive behavior.

The auditory system "thinks" this because music has been "designed" by cultural evolution to sound like people moving about. That is, over time, humans figured out how to better and better make sounds that mimicked (and often exaggerated) the fundamental kinds of sounds humans make when we move. . . 

 . . . Just to give one example of a fit between music and movement, consider that when people move faster (i.e., have greater tempo), their Doppler shifts are amplified, and so the difference between the highest (going toward you) pitch and the lowest (going away from you) pitch is greater. If music sounds like moving people, then we expect that faster tempo music should have melodies with a greater pitch range. And, indeed, that's what we found in our data. . . .

. . . Not all music induces dancing. What one wants to explain is why any music should induce this (and yet no other kind of thing induces movement time-locked to it).

If music has come to sound like someone moving in your midst, and probably moving evocatively in some way, then it is not very surprising. Lots of human behaviors are contagious. Dancing amounts to just another case of humans moving in reaction to, or following, the behavior of other humans. . . 

Two previous posts on Changizi are here and here. I really think he's on to something, but wonder if he's overstating his case. On down the line, when I've had a chance to actually read the book, will post again. 

Update - Jonathan West wanted to make the following comment, but Blogger, which has been more than a little buggy lately, keeps being stuck in "preview" rather than "post", so here is the comment as Jonathan emailed it:

I'm seriously skeptical.

First, the Doppler explanation just doesn't hold water at all. At the speeds unassisted humans move about, doppler effects on sound are all but undetectable to the human ear. That is why the Doppler effect wasn't discovered until the 19th century, when we started having machines (i.e. railroad engines) that could move fast enough for doppler effects to be heard.

Also, the conclusion that faster music has a wider pitch range I would want to examine very closely. What music was chosen in order to make the comparison? How was the sampling scheme set up? What kinds of music were included (or excluded) and why?

It sounds very much as if a superically plausible theory (doppler effect) was dreamt up, and then the data (different kinds of music) cherry-picked to match. Unless you take great care to prevent it, this sort of thing can happen without any intent to deceive anybody.

That there is a link between music and movement is beyond doubt. How much of it is culturally determined and how much is genetic is an interesting question - but I suspect that the answer, when it finally appears, will be to the effect that it is all intertwined to an extent that makes it hard to describe the contributions in terms of proportions.

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