If biography really is properly considered a discipline unto itself, then, it follows, you could explain on biography exactly why it deserves to be so considered. Does it have its own journals (like?)? Its own scholarly standards (such as?)? Its experts (who?)? --LMS
I don't know if it is a "discipline" or a "subdiscipline" of history or a "literary genre", but the work being invested into writing biographies is different from other work that the same people do. What does it take to be qualified as a "discipline"? Is there a wikipedia entry that explains what a discipline is?
Links to biography should be found from History and Literature.