The coming together of rhythm and melody bridges our cerebellum and our cerebral cortex. - Daniel Levitin

The best estimates are that it takes a minimum of fifty thousand years for an adaptation to show up in the human genome. This is called evolutionary lag... Our hunter-gatherer ancestors had a very different lifestyle...

Paul McCartney may be the closest thing our generation has produced to Franz Schubert -- a master of melody, writing tunes anyone can sing, songs that seem to have been there all along. Most people don't realize that "Ave Maria" and "Serenade" were written by Schubert (or that his "Moment Musical in F" so resembles "Martha My Dear"). McCartney writes with similar universality. His "Yesterday" has been recorded by more musicians than any other song in history. Its stepwise melody is deceptively complex, drawing from outside the diatonic scale so smoothly that anyone can sing it, yet few theorists can agree on exactly what it is that McCartney has done.

The emerging picture from... studies is that ten thousand hours of practice is required to achieve the level of master associated with being a world-class expert—in anything.