Do they know it’s Christmas?

What all of these hypotheses have in common is the ability of music to manipulate the emotions, and this is the most mysterious part of all. That some sounds lead to sadness and others to joy is the nub of all three hypotheses. The singing lover is not merely demonstrating his prowess; he also seeks to change his beloved’s emotions. Partly, that is done by the song’s words, but pure melody can also tug at the heart-strings. The chords of martial music stir different sentiments. A recital of the Monteverdi Vespers or a Vivaldi concerto in St Mark’s cathedral in Venice, the building that inspired Gould to think of the non-role of spandrels, generates emotion pure and simple, disconnected from human striving.

Part of that accident may be the fact that many natural sounds evoke emotion for perfectly good reasons (fear at the howl of a wolf, pleasure at the sound of gently running water, irritation and mother-love at the crying of a child). Sexually selected features commonly rely on such pre-existing perceptual biases. It is probably no coincidence, for instance, that peacocks’ tails have eyespots; animal brains are good at recognising eyes because eyes are found only on other animals. It is pure speculation, but music may be built on emotions originally evolved to respond to important natural sounds, but which have blossomed a hundred-fold.