From the earliest of civilisations, humans have found ways to make music, whether through makeshift drums or artfully drilled bone flutes. But how did music – effectively little more than a series of certain tones and rhythms – become so integral to the human experience? Untangling the curious links between notes and number, musical perception, psychology and physics, David Darling examines the fascinating science behind music, from its Palaeolithic origins to the present. Revealing surprising connections and busting pervasive myths, A Perfect Harmony asks: Why do musicians tend to be better at maths than non-musicians? Why do we find some pieces sad and others happy? Will playing Mozart to babies predispose them to genius? Could an AI write the perfect symphony?