In the lowlands of Bolivia, the most isolated of the Tsimané people live in communities without electricity; they don’t own televisions, computers or phones, and even battery-powered radios are rare. Their minimal exposure to Western culture happens mostly during occasional trips to nearby towns. To the researchers who make their way into Tsimané villages by truck and canoe each summer, that isolation makes the Tsimané an almost uniquely valuable source of insights into the human brain and its processing of music.
Most studies about music perception examine people accustomed to Western music, so only a few enclaves like these remote Tsimané villages allow scientists to make comparisons across cultures. There they can try to tease apart the effects of exposure to music from the brain’s innate comprehension of it — or at least start dissecting the relationship between the two. “We need to understand that interplay between our genes and our experience,” said Josh McDermott, an associate professor of brain and cognitive sciences at the Massachusetts Institute of Technology. He is the senior author of a recent paper involving the Tsimané in the journal Current Biology which suggests that a feature of music most of us might consider to be intrinsic — the perceived organization of musical pitches into octaves — is a cultural artifact.
Musical systems around the world and across historical eras have been diverse, but octaves are commonly a feature of them. The acoustic structure of octaves is always the same: The frequency of a note in one octave is half the frequency of the same note in the octave above. For example, middle C, or C4, is 261.63 hertz, while C5, one octave up, is 523.25 hertz. These physical qualities of sound in the ear have routinely led to assumptions that octave equivalence — the perception of pitches in different octaves as variations on the same note — is universal, according to Elizabeth Margulis, a professor of music at Princeton University. [Continue reading…]