Those interested in studying identity as a historical, and thus changeable, creation, should watch the recent documentary “When Jews Were Funny,” paying particular attention to the relationship between the off-camera interviewer and filmmaker, Alan Zweig, and his interviewees — especially the older comedians, such as Shelly Berman, pictured above (b. 1925; known more recently to some as Larry David’s father on “Curb Your Enthusiasm”), whose appearances frame the film. […]