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

Abstract

Melodies are culturally transmitted sequences of notes that evolve through time in a manner that broadly parallels the process of molecular sequence evolution. While gene sequencing and the identification of general mechanisms of DNA transmission and mutation have revolutionized our understanding of biological evolution, the nature - and even the existence - of cross-culturally universal mechanisms of musical evolution remains debated. Here we adapt sequence alignment algorithms from molecular genetics to analyze musical evolution in a sample of 10,062 melodies from musically divergent Japanese and English folk song traditions. Our analysis identifies 328 pairs of highly related melodies, within which rates of musical evolution vary in ways predicted by general principles of music cognition and cultural evolution. Note changes are more likely when they have smaller impacts on a song's melody, specifically: 1) notes are most likely to change to neighboring notes, 2) rarer notes are more likely to change, and 3) notes with stronger functional roles are less likely to change. These results are consistent across samples despite using different scales with different probabilities of change between notes, suggesting they may apply universally. Our 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.

Cultural evolution and music

“…For example, some types of melodic modi cations may be more likely than others because they are easier to sing or less noticeable to listeners. In a recent study of over 10,000 Japanese and English folk melodies, Savage et al (2020) found that modi cations that have a smaller impact on the melody are more likely to change and have those changes persist in the population. This nding was consistent despite striking di erences in the scales used in Japanese and English folk music.…”

Studying the Effect of Oral Transmission on Melodic Structure using Online Iterated Singing Experiments

“…Naively, one might expect that oral transmission just introduces random noise into the sung production. In practice, however, it is thought that oral transmission shapes musical systems in systematic ways that reflect human reproduction biases (Mehr, Krasnow, Bryant, & Hagen, 2020; Savage et al, 2022). With cultural exposure, people internalize these regularities and, in turn, are more likely to feature them in future productions.…”

The role of population size in folk tune complexity

“…The optimal balance between familiarity and innovation in artistic domains will depend, further, on distinct features of specific artistic genres and social contexts. While improvisation is important in, for example, jazz and North Indian classical music, folk music is by nature relatively conservative, with individual innovation limited by an emphasis on preserving traditional tunes (Vallely, 2011) and by the constraints of typical folk tune structure, phrasing and tonality (Savage, Chiba, Currie, Suzuki, & Atkinson, 2020). The finding that session tunes of intermediate complexity are most popular is consistent with previous evidence that preferences for novelty in music trade off against preferences for predictability (Chmiel & Schubert, 2017;Delplanque et al, 2019;North & Hargreaves, 1995;Van Geert & Wagemans, 2020), confirming the suggestion of folk scholars that tunes with an optimal balance of playability and aesthetic interest are most likely to become established favourites (Hillhouse, 2013;Vallely, 2011).…”