How Did Music Evolve?

Is music just "auditory cheesecake" or can it provide deep insights into the workings of the brain and the evolution of language? From the New Zealand haka to raves and dancing birds, The Guardian's James Randerson investigates why music evolved, how it is linked to language, how it is understood by the brain and how it can be used to treat patients.
Scientists have learned that we are not the only species that can dance to a beat. Birds that engage in mimicry can be entrained to bob their heads in time with a beat, even as the beat changes. Since this musical awareness does not seem to occur spontaneously in the wild, scientists theorize that, in humans, it emerged through natural selection as a byproduct of another skill such as vocal imitation. In other words, perhaps music originated as a series of taking one capacity and using it for another purpose it wasn't originally designed for.
Whatever way it originated, musical grammar is processed in the same part of the brain as linguistic grammar. Expectation of what comes next in a musical sequence or in a sentence is a large part of what establishes meaning. Musicians play with our sense of expectation, sometimes satisfying it and sometimes surprising us, which engages our emotions. Across cultures, music is used in a way that promotes and sustains sociality, perhaps suggesting why it evolved. We use music to reinforce our sense of self and to help establish relationships within a group.
My own belief, which is the theme of my collection of stories on the Song of Fire website, is that music connects us with something essential that defines the universe. Musical patterns, rhythms and sequences infuse everything around us. In a fundamental way, we are music.