Playing with a guitar or other string instrument, it's possible to note how the string has several points in which another kind of sound appears without pressing the string as usual. It's called a natural harmonic, and mathematically would be represented as an integer, multiple of the fundamental frequency.
This provides intervals of maximum importance in music, and the methodology to create modes and chords. For this reason, music doesn't seem exclusive to some particular species that have enough intelligence to discover it. We could assume that classical music and its symmetric or logical substitutions would be exactly the same in other planet around the Universe or after a complete deletion of culture and relearning here, on Earth.
At the same time fits with the inherent interpretation of a brain that processes music naturally, feeling how has the power to modify and create sensations at the lowest level. There's no experience in a human life that cannot be accompanied with music, thus the orchestra performing the soundtrack doesn't stop, in another example of natural perfection that fits really, really bad with the consideration of the “survival of the fittest”, an evolution without director and a supreme set of ideas.