Steven pinker wrote about overtones, the fundamental note.
U see in nature when a monkey makes his mating call, u only preseeve the one note, The fundamental. But in way he sang out 8 notes at once, each one double the frequency of the last(why? becauce it proved to be easy for evolutionaryly construct voice box to reproduce) these notes are mind compreend on a sub concience level. These overtones can be heard on they´re own. Theses notes have been re-arranged and now comprise our scales. You probably got more then what u baggined for but this point zero on why we have the inventory of notes that we do.
This is a very incomplete explantion, i´m sorry. And my english is pretty bad, i´ve been attending a brazilian school for the last 3 years.
