In a paper published in the journal Current Biology, researchers from Harvard University in the US and New Zealand’s Victoria University of Wellington say songs with a similar purpose – love songs, lullabies or dance music – tend to sound similar, no matter which culture they come from.
The findings are consistent with the existence of universal links between form and function in vocal music, the researchers say.
"Despite the staggering diversity of music influenced by countless cultures and readily available to the modern listener, our shared human nature may underlie basic musical structures that transcend cultural differences," says the report’s lead author, psychologist Samuel Mehr, from Harvard.
"We show that our shared psychology produces fundamental patterns in song that transcend our profound cultural differences," adds co-author Manvir Singh, also from Harvard. "This suggests that our emotional and behavioural responses to aesthetic stimuli are remarkably similar across widely diverging populations."
The researchers say they have found evidence of recurrent, perceptible features of three domains of vocal music across 86 human societies. These inform the striking consistency of understanding across listeners from around the globe – "listeners," the add, "who presumably know little or nothing about the music of indigenous peoples".
Among non-human animals, there are links between form and function in vocalisation. For instance, when a lion roars or an eagle screeches, it sounds hostile to naive human listeners. But it wasn't clear whether the same concept held in human song.
Many people believe that music is mostly shaped by culture, leading them to question the relation between form and function, Singh says, explaining, "We wanted to find out if that was the case."
In their first experiment, the researchers asked 750 internet users in 60 countries to listen to 14-second excerpts of songs. The songs were selected from 86 predominantly small-scale societies, such as the Fulani people in Africa and the Blackfoot Indians from North America. They also spanned a wide array of geographic areas designed to reflect a broad sampling of human cultures.
After listening to each excerpt, participants answered six questions indicating their perceptions of the function of each song on a six-point scale. The questions evaluated the degree to which listeners believed that each song was used.
The possible uses offered were: dancing, soothing a baby, healing an illness, expressing love for another person, mourning the dead, and telling a story.
In fact, none of the songs were used in mourning or to tell a story. The options were included to discourage listeners from assuming that only four song types were actually present.
Participants listened to more than 26,000 excerpts and provided more than 150,000 ratings. Despite listeners’ unfamiliarity with the societies represented, the random sampling of each excerpt, short duration, and the enormous diversity of the music, the ratings demonstrated accurate and cross-culturally reliable inferences about song functions on the basis of their forms alone.
In a follow-up experiment designed to explore possible ways in which people made those determinations about song function, the researchers asked 1000 internet users in the US and India to rate the excerpts for three "contextual" features: number of singers, gender of singer(s), and number of instruments.
They also rated them for seven subjective musical features: melodic complexity, rhythmic complexity, tempo, steady beat, arousal, valence (or "goodness"), and pleasantness.
Analysis found some relationships between various features and song function, but not enough to explain the way people were able to so reliably detect a song’s function.
Mehr and Singh say that one of the most intriguing findings relates to the relationship between lullabies and dance songs. "Not only were users best at identifying songs used for those functions, but their musical features seem to oppose each other in many ways," Mehr says.
Dance songs were generally faster, rhythmically and melodically complex, and perceived by participants as "happier" and "more exciting". Lullabies, on the other hand, were slower, rhythmically and melodically simple, and perceived as "sadder" and "less exciting".
The researchers say they are now conducting these tests with listeners who live in isolated, small-scale societies and have never heard music other than that of their own cultures. They are also further analysing the music of many cultures to try to understand how their particular features relate to function and whether those features themselves might be universal.
The study asks: Why do songs that share social functions have convergent forms? If dance songs are supposed to indicate unity, their context and musical features should amplify that signal. The research supports this idea: "Dance songs tend to have more singers, more instruments, more complex melodies, and more complex rhythms than other forms of music," the authors write.
Meanwhile, they add, if lullabies are supposed to signal parental attention to infants, their acoustic features should amplify that signal. Indeed, lullabies "tend to be rhythmically and melodically simpler, slower, sung by one female person, and with low arousal relative to other forms of music."
The researchers say their study raises two key questions about the basic facts of music.
They note that despite the geographic spread of the experiment participants, all could read and write English, and all had access to a wide range of music through the Internet.
This raises the question of whether the same assumptions about form and function will be found among people who are familiar only with music from a single culture. The authors suggest exploring this idea would result in "a stronger test of universality".
Second, they believe a stronger demonstration of universals in music would require "in-depth analyses of a cross-culturally representative sample of music from small-scale societies, informed by expert listeners, music information retrieval, and modern approaches from data science".
Nevertheless, they conclude, the present work demonstrates that cross-cultural regularities in human behaviour results in music that fits into recurrent, recognisable forms while maintaining a profound and beautiful variability across cultures.
