Originally Posted by: dlwalke. . . is there something unique to the guitar that lends itself to having it's practioners focus, or have the possibility of focusing on those different possible roles.[/quote]There are two factors that led to the distinction of lead vs. rhythm playing.
1. The guitar is capable of playing melodically & harmonically. You can play more than one note at a time which isn't possible on many other instruments.
2. Traditionally in popular music those roles have been separated as a matter of orchestrating or arranging.
Relatively few other instruments can play more than one note at a time. Among those that can are the piano & it's associated percussion family instruments (glockenspiel, xylophone, vibes, marimba, etc.) & violin family (viola, cello, bass).
And while it's possible to play harmonies & full chords on those other instruments they are typically used in an orchestral or ensemble setting in which there is no traditional need to conceptually distinguish the parts. The piano might take a solo or featured melodic part in a concerto or a jazz band. But it's just regarded as one aspect of what is possible on the piano. But you already do that with the right hand of the piano. So it's more a matter of arrangment in the tune or song.
[quote=dlwalke]Or maybe my premise is incorrect and there are indeed lead vs rhythm violinists or violin parts (e.g., in an orchestra), for example.
The violin or xylophone might take a solo, but again it's just regarded as featuing the instrument in the arrangement. There's no need for the player to fundamentally change the technique or approach to the instrument.
When the other orchestral instruments play harmonic parts they are usually just part of a chord. The entire string, horn or wind section plays a chord, each player getting one note of the chord. Either because it's not possible to play more than one note at a time (horns, winds), or not desirable sonically (strings), traditionally the harmony has been split one note to an instrument for a more precise result.
Historically & culturally those instruments have very clearly designated roles & structured paths to learning.
Conversely the guitar has a much more do-it-yourself cultural history. And that means you can play as much or a little as you want. And since many people used it as accompaniment (chords to support a melody, either sung or played on another instrument) that's the origin of rhythm guitar.
Also, prior to electric guitar it was difficult to hear the guitar playing single note melodies in an ensemble. Especially compared to the other orchestral instruments!
But once pickups & amps were available jazz players (Charlie Christian being notable) jumped at the chance to play solo lines! And lead guitar was born. It's also worth noting that lead playing requires a significant different physical playing technique from rhythm chord strumming and sometimes a different set of timbre parameters through the use of effects.
Once popular music (jazz, blues, rock, etc.) started featuring guitars as the primary harmonic & melodic instruments it helped to conceptually designate the division of labor in the band based on what any given player was doing.
Also worth noting is that while Tarrega (1800s) & Segovia (1900s) both developed a repertoire for classical guitar, their approach was much more holistic in the sense that "rhythm & lead" were combined or integrated into one whole. The guitarst simply played all the music of a piece at the same time with no need to distinguish parts of the music; very much like piano playing.
Hope that helps!
