Evolution of musical scales

Author / Creator

Cultural Evolution Society 2021 (2021)

Conferences

Cultural Evolution Society 2021 Q&A session 24: Language and music (2021)

Available as

Online

Summary

Musical scales, defined as a set of discrete pitches from which melodies are constructed, are one of the most universal features of music. Some important analogies can be drawn between the evolutio...

Musical scales, defined as a set of discrete pitches from which melodies are constructed, are one of the most universal features of music. Some important analogies can be drawn between the evolution of scales and biological evolution: they both entail evolution of a linear sequence of discrete units; their study is focused on extant species; they exhibit large variations in mutation rates (e.g. vocal scales vs. metallophone scales). In comparison to the seemingly infinite space of biological sequences, however, the space of possible scales (typically 7 or fewer notes, just-noticeable-differences of at least ~5 cents) is comparatively tiny; and little is known the relative effects of drift and selection in scales. Despite these properties of scales, quantitative studies of the evolution of scales are scant. To study of the evolution of scales, we first create a sample of extant scales, by scouring the ethnomusicological literature of the last century to assemble a cross-cultural database of scales. This allows us to first consider the 'drift' forces inherent due to imperfections in both vocal production, and pitch perception. We then consider a set of selection biases, and test which hypotheses may best predict the distributions of extant scales. Finally, we think about how the different forces (physical, perceptual, cultural) involved in drift and selection, in comparison to biological evolution, may vary considerably across populations and histories in what sometimes may appear an arbitrary fashion.

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