Why must NFL coaches shake hands?

Baseball managers don't do it. NHL coaches wouldn't even consider it. And in the NBA, when it does occur, it's half-heated at best.

I'm talking about the postgame handshake. And wondering why -- in the NFL of all sports -- it is expected for two coaches who just spent the last three hours trying to destroy each other to navigate a sea of players, meet midfield and shake hands at the end of the game.

Apparently Jim Harbaugh doesn't think much of the tradition. At least that's what I get out of watching the video of the dismissive handshake and get-out-of-my-way pat on the back he gave Lions coach Jim Schwartz on Sunday. Though Harbaugh definitely comes off as odd for the way he acted on the field, in another sport his antics wouldn't have caused anyone to bat an eye, let alone cause the temper tantrum Schwartz displayed in running after him.

I know that as a parent, I'm supposed to preach sportsmanship on all levels and encourage civilized behavior on the athletic field. Yet, while I want my kids to shake hands with the opposition after a soccer or baseball game, it just seems so hypocritical to expect it from two professional coaches whose teams have just violently clashed on the football field to do the same. Afterall, this is multimillion-dollar sports, not youth recreational sports.

In fact, if we are talking about not setting a bad example for kids, maybe it's better not to tempt fate and expect coaches to meet at all on a field after an emotional and physical game. Because it's not just on the professional level that there were some problems last week. Though it didn't grab as many headlines, a tussle between Vanderbilt coach James Franklin and Georgia defensive coordinator Todd Grantham resulted in the two having to be separated by their players on the field after Georgia's 32-28 win.

The odd thing is that the postgame handshake between NFL coaches is a relatively new phenomenon. Some of the games greatest coaches -- George Halas, Vince Lombardi, Tom Landry, George Allen, Paul Brown -- never shook an opponent's hand after a game. They never would have considered it. But in the 1980s, an entertainment mentality began to take over the NFL, one in which television cameras loved to focus on the postgame handshake between coaches.

Suddenly, if you didn't shake an opponent's hand, it became something worth noting. That, of course, didn't stop Don Shula from refusing to shake hands with Buddy Ryan, Mike Ditka and even Tom Coughlin after various games. Fast forward to this century, however, and suddenly it was something that had to happen, even between coaches who clearly didn't like each other. In fact, the buildup to the postgame handshake between Bill Belichick and Eric Mangini after "Spygate" in 2007 was arguably bigger than the buildup to the game itself.

Of course, it won't be the last time we see a big buildup to a handshake: Imagine if the 49ers and Lions meet again in the playoffs?