Well it's been in western classical music since before Bach's time.
They were trying to make melodies and lines more interesting.
Moazrt and Chopin used it very heavily among others.
Basically alot of that music is very similar to jazz except that:
1) Rhyhmically it's different.
2) The harmony uses triads more than seventh chords
3) No blues.
However melodically it's very similar.
Play through the mozart sonatas or almost any of Chopin's music
and you'll see alot of the same things Charlie Parker does.
For some reason it didnt show up in Jazz until Bebop.
You don't hear it in dixiland or early swing like Benny Goodman .
Benny Goodman thought bebop sounded like a lot of chromatic scales.
reed