Are We Wired for Music?
I was recently leafing through Jared Diamond’s bestseller “Guns, Germs, and Steel” and was reminded of the prevailing idea in biological anthropology that humans first colonized the Americas around 15,000 years ago (give or take a couple thousand years). I had just posted on this site about Leonard Bernstein’s Harvard lectures and his thoughts concerning the universality of the five-note “pentatonic scale,” so I began to think about Native American music and its pentatonic nature.
The centrality of the flute in Native American music then reminded me of a study in Nature published last year, that reported the oldest ever archeological evidence of music: A 35,000 year old flute carved from the bone of a vulture. While the exact tones produced by the flute remain unknown, it had a curious number of holes: 5. I also recently stumbled on a research article in the journal Infant Behavior and Development on the language of mothers and their infants – the authors showed that infants and their mothers coordinate their pitches harmonically while they speak, and the go-to pitches were often within a pentatonic scale. Throw in the pentatonic’s ubiquity in Eurasian and African traditional music and the picture is pretty clear – these 5 notes are genetic.
The universality of the pentatonic scale in world music is not a new idea. However, the idea that it could be biological is more controversial.
The acoustic signatures of human speech have been attributed to the efficacy of a harmonic series, which is a tone that resonates with a fundamental frequency (the ‘note’) and a group of overtones that are proportionally spaced apart. A harmonic series is elicited by structures like human vocal chords, a bird’s syrinx (their singing organs) and a guitar string – the regularity of a harmonic series allows animals to differentiate their friend’s communications from the disordered noise of everyday life. In other words, we speak in notes. But why arrange these notes into a scale?
Kamraan Gill and Dale Purves argue that humans are drawn to musical scales because scales represent a harmonic series similar to human speech:
“The component intervals of the most widely used scales throughout history and across cultures are those with the greatest overall spectral similarity to a harmonic series. These findings suggest that humans prefer tone combinations that reflect the spectral characteristics of conspecific vocalizations (Gill and Purves, 2010).”
In other words, we are drawn to scales because they acoustically resemble speech, and we are drawn to speech for obvious reasons. But what do notes arranged in scales (music) communicate that speech doesn’t?
Another line of new research suggests that this question is misguided. Instead of separating music from speech and finding obvious functional differences, we have to look deeper at the similarities. In a new article in the psychology journal Emotion, Megan Curtis of Tufts University argues that the defining pitch intervals of both sad, “minor,” and happy, “major,” music can also be heard in normal speech.
Curtis recorded professional actresses speaking neutral two-syllable phrases (i.e. “Let’s Go”) with various emotional signatures, like “sadness” and “pleasantness.” The actresses typically uttered a minor 3rd interval when expressing sadness and the major 3rd interval when expressing happiness. Furthermore, listeners overwhelmingly heard “sadness” in the minor third and “pleasantness” in the major third – it appears that the pitch of spoken words communicates emotion in the same way music does.
Intriguingly, these intervals play an important role in differentiating the major and minor pentatonic scales.
Noam Chomsky put forth the idea of a “universal grammar” in language – a cross-cultural, biologically ordained set of syntactical rules that turn words into sentences. I suspect that a “universal musical grammar” will eventually be added to his model. Subjects and verbs are universals in human language, perhaps the pentatonic scale is one too.