Humpback whales, which have a sonic range of at least seven octaves, create songs between the length of a modern ballad and a symphony movement, possibly because their attention span is similar to that of humans. Their tunes also contain repeated refrains that form melodic rhymes, suggesting that, like humans, they use these as mnemonic devices.

Irving Berlin composed most of his songs in F-sharp major; the six sharp notes in the scale meant he could play the black keys of the piano almost exclusively. Eventually, for purposes of technical variety, he had a lever mechanism installed that allowed him to modulate into other keys without changing his playing.

Researchers working with the Tsimané of the Amazon found that tribe members could tell the difference between consonance and dissonance but took them to be equally pleasant, giving credence to the idea that Western preference for consonance is not biological. “The Greeks were really into ratios,” speculated the lead researcher. “It’s possible they started making music that way and we’ve been stuck with it ever since.”

Hoping to encourage hostages held by FARC during Colombia’s civil war, state negotiators commissioned a local producer in 2010 to create a pop song embedded with a Morse-code message and had it broadcast repeatedly on the radio in rebel-controlled areas. After the lyrics “Listen to this message, brother,” the code sounded as a synth interlude: “Nineteen people rescued. You are next. Don’t lose hope.”