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How did humans evolve to be musical?

I just came across interesting stuff relating to two questions about music and evolution. How did humans evolve to be musical? and How does music evolve?

For this post: How did humans evolve to be musical?

There’s a paper by Geoffrey Miller (no relation) Evolution of human music through sexual selection (ftp://ftp.repec.org/RePEc/els/esrcls/draftfin.pdf), which works through the idea being musical and producing music might give the mating advantage, and so evolve through sexual selection.

One thing I like about this paper is that it carefully works through the mechanisms and criteria for thinking that of behaviour or characteristic can be evolutionarily selected, rather than just making up a sort-of convincing story that some characteristic could be a mating advantage and leaving it at that. It does give you a sort-of convincing story as well:

Consider Jimi Hendrix, for example. This rock guitarist extraordinaire died at the age of27 in 1970, overdosing on the drugs he used to fire his musical imagination. His music output, three studio albums and hundreds of live concerts, did him no survival favours. But he did have sexual liaisons with hundreds of groupies, maintained parallel longterm relationships with at least two women, and fathered at least three children in the U.S., Germany, and Sweden. Under ancestral conditions before birth control, he would have fathered many more. Hendrix’s genes for musical talent probably doubled their frequency in a single generation, through the power of attracting opposite-sex admirers. As Darwin realized, music’s aesthetic and emotional power, far from indicating a transcendental origin, point to a sexual-selection origin, where too much is neverenough. Our ancestral hominid-Hendrixes could never say, “OK, our music’s good enough, we can stop now”, because they were competing with all the hominid-Eric-Claptons, hominid-Jerry-Garcias, and hominid-John-Lennons. The aesthetic and emotional power of music is exactly what we would expect from sexual selection’s arms race to impress minds like ours.

…which is great, but he then goes on to carefully work through the mechanisms of selection to build up quite a convincing argument. He also points out that Darwin suggested much the same idea, though it wasn’t taken up in mainstream evolutionary thought.

It’s quite a long and detailed paper, but I think well worth reading, if only as an example of careful thought that I think is often missing in evolutionary psychology. There’s also a bit later on which I found fascinating about possible runaway effects in sexual selection – the kind of thing which leads to hyper exaggerated characteristics which don’t seem very adaptive, like the enormous antlers of the Irish elk or the peacock’s ludicrous tail. You may be able to think of human equivalents. Miller cites mathematical models for the effect, and notes: “Only when the courtship trait’s survival costs became very high might the runaway effect reach an asymptote.”

The power of the runaway theory is that it can explain the extremity of sexual selection’s outcomes: how species get caught up in an endless arms race between unfulfillable sexual demands and irresistible sexual displays. Most relevant for us, the preferences involved need not be cold-blooded assessments of a mate’s virtues, but can be deep emotions or lofty cognitions. Any psychological mechanism used in mate choice is vulnerable to this runaway effect, which makes not only the displays that it favors more extreme, but makes the emotions and cognitions themselves more compelling. Against the claim that evolution could never explain music’s power to emotionally move and spiritually inspire, the runaway theory says: any emotional or spiritual preferences that influence mate choice, no matter how extreme or subjectively overwhelming, are possible outcomes of sexual selection (cf. Dissanayake, 1992). If music that emotionally moves or spiritually inspires tended to sexually attract as well, over ancestral time, then sexual selection can explain music’s appeal at every level.

Although I’m usually very suspicious of evolutionary explanations of psychological phenomena (mainly because they often seem to me to be based on sloppy evolutionary theory), I think Miller makes a good case. There is one thing that worries me, though. The explanation is based on the mate selection, which is Miller says is primarily females selecting males. The peacock and Irish elk examples show characteristics developed in males than females. So this looks like an explanation for why human males develop musicality and the ability to produce music, while human females need only develop musicality – the ability to appreciate the music that males are producing to improve their chances of being selected. So where’s the explanation for women’s musical skills? Many of my favourite musicians, and most of my favourite singers, are women. Is this musical skill an epiphenomenon? Just a matter of gene leakage from the male-selected characteristic?

The other question is how does music evolve? See the next post for that.

Reference:
Miller, G. F. (2000). Evolution of human music through sexual selection. In N. L. Wallin, B. Merker, & S. Brown (Eds.), The Origins of Music, MIT Press.

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