Sequence alignment of folk song melodies reveals cross-cultural regularities of musical evolution

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ISMIR 2015, 2015: 162-168Google Scholar allows us to quantitatively test for the presence of cross-cultural regularities using a sample of 10,062 melodies from musically divergent Japanese and English (British/American) folk song traditions.17Machida K. 日本民謡大観 [Japanese folk song anthology]. NHK (Nippon Hōsō Kyōkai), 1944Google Scholar,18Bronson B.H. The Traditional Tunes of the Child Ballads: With Their Texts, According to the Extant Records of Great Britain and America. Princeton University Press, 1959Google Scholar Our analysis identifies 328 pairs of highly related melodies, finding that note changes are more likely when they have smaller impacts on a song's melody. Specifically, (1) notes with stronger rhythmic functions are less likely to change, and (2) note substitutions are most likely between neighboring notes. We also find that note insertions/deletions ("indels") are more common than note substitutions, unlike genetic evolution where the reverse is true. Our results are consistent across English and Japanese samples despite major differences in their scales and tonal systems. These findings demonstrate that even a creative art form such as music is subject to evolutionary constraints analogous to those governing the evolution of genes, languages, and other domains of culture.