From what I recall wasn't MASH a little more light hearted in the early seasons, but still touched on series issues to becoming more serious in the later seasons? Especially when Alan Alda got more control over the show. I also recall the use of a laugh track that I think most fans agree was a bad idea and the show is better when the laugh track wasn't used. Also I think the way it was is most of humor would come from them hanging out, but in the surgery area, where even when the characters would sometimes make puns they always made sure that stuff was taken serious. Even with the laugh track they never used the laugh track during the surgery scenes.