Actually, sitcoms, like nearly everything else on TV, originated in radio. Something like The Jack Benny Program was one, with the added features of a song interlude and some banter amongst the stars - much like It's Garry Shandling's Show, in which they broke the "fourth wall" that (allegedly) enables you to suspend disbelief. Nearly every sitcom on television has a radio antecedent, or at least one from the early days of TV. This is one case where recycling is ungood.