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SANTA CLARA -- One theory about the origin of the handshake is that it was born to demonstrate neither party was carrying a weapon.

What may have been true as early as 5th century B.C. remains worth remembering Sunday at Candlestick Park, where two coaches will attempt to clasp hands without doing each other bodily harm.

Jim Harbaugh of the 49ers and Jim Schwartz of the Detroit Lions had to be separated during their last meeting when the ritual display of sportsmanship nearly ended in a fistfight.

Now, almost a year later, Harbaugh and Schwartz are having a hard time shaking it. NBC used the coaches gone wild (and not, say, Alex Smith's winning touchdown pass) as the featured clip in promoting its Sunday night broadcast. The network's promotional material bills it as the "Rematch of the Handshake Game."

49ers CEO Jed York closed a fan rally Wednesday by playfully warning fans, "By all means, when you're shaking somebody's hand at the end of the game, don't do it too hard."

Gamblers can even wager on whether the coaches will exchange pleasantries. Betting website lists "No Handshake or Hug" as a heavy underdog.

Who cares about the controversy?

Well, some former Super Bowl coaches do. There's an unwritten protocol to the midfield meeting. And when coaches engage in hand-to-handshake combat -- whether it's Harbaugh vs. Schwartz, Jerry Glanville vs. Chuck Noll, Bill Belichick vs. Eric Mangini or any other memorable dust-up -- they betray one of the game's long traditions.

"Show the other guy respect and somewhat put honor in the game," said Marv Levy, 87, the Hall of Fame coach who guided the Buffalo Bills to four AFC titles. "I could see why Jim Schwartz was upset. He had just lost a game. He's going to congratulate the other guy. The guy runs up to him, hardly looks him in the eye, then slaps him on the back. I can see where he would be offended.

"I think (Harbaugh) was too involved in the elation of it to realize that the other guy was feeling pain. I think he overstepped a bit. And my guess is -- and this is only a guess -- that he felt bad about it afterward, whether he said so or not."

After the 49ers' taut 25-19 victory in Detroit last Oct. 16, Harbaugh was in full celebration mode as he delivered a handshake and a roundhouse of a backslap to Schwartz. A scrum ensued, with Schwartz trying to chase down the 49ers coach as several players began pushing and shoving.

Tony Dungy, an analyst for the NBC "Football Night in America" broadcast Sunday, recalled sensing the tremors before the shake. "There's so much focus on what happened afterward, but that game was very emotionally and physically intense," he said. "It was high-energy right down to the wire."

The boiling emotions included Schwartz appearing to shout "Know the rules!" toward Harbaugh after the 49ers coach asked for a replay challenge on an unreviewable play.

Dungy called the fracas that followed: "A teaching moment, definitely."

"As a coach, you're trying to set the example for your players," said Dungy, who won Super Bowl XLI with the Indianapolis Colts. "Yes, you want to be emotional and intense. But you've got to find that line. There still comes a time when self-control needs to win out, even when the script doesn't play out as you imagined."

Harbaugh and Schwartz remained unrepentant in the aftermath. ("Apologies always seem to me like excuses," the 49ers coach said.) And far from a black mark, several 49ers players this week pointed to the incident as a pivotal moment in Harbaugh's early leadership.

"It definitely made me fired up for the next game," tight end Vernon Davis said. "It was like, 'We got Harbaugh going crazy like this? Oh, yeah, I'm all for him.' "

Now, both the 49ers and Lions lament that the fight distracts from a game worth watching for football reasons -- not the boxing undercard. Both teams are Super Bowl hopefuls coming off dramatic season-opening victories.

John Madden, the Hall of Fame football coach, ventured that there would be zero revisiting of the infamous handshake on the practice fields or in the meeting rooms.

"If you list 100 things to get ready for, that wouldn't be on the list. It would be like 112th on a list of 100," said Madden, who led the Raiders in Super Bowl XI. "It's something to talk about and for show and storylines. But I know both these coaches, and unless someone is making a joke about it, I guarantee neither one is thinking about it."

The incident continues to generate buzz elsewhere in part because the scene was so rare. Dungy noted the thousands of handshakes that have gone by without incident, so when something goes awry it causes a frenzy. After a "Monday Night Football" game in 1985, Noll of the Pittsburgh Steelers refused to extend his hand to the victorious Cincinnati Bengals coach Sam Wyche as cameras rolled.

Dungy joked now that "It was like the world had come to an end."

Wyche, now 67 and living in South Carolina, is eager to clear up the controversy. "Let me explain that because that got out of hand," he said.

Wyche recalled that the Bengals' 37-24 upset victory included a late score that miffed Noll, who wasn't a fan of shaking hands under any circumstance. As the two approached each other at midfield, Noll kept his hands shoved firmly in his pockets. But he saluted Wyche in another way. "Chuck was disappointed. He wasn't going to do it (shake hands), but he did acknowledge me (with a look)," he said.

"The postscript is: That next offseason the league meetings were in Hawaii. Chuck and I went for a walk on the beach and laughed about it," he said.

Some coaches, including Mack Brown of Texas, have wondered whether the postgame handshake is a tradition worth keeping. But Wyche said even if it can look hollow, it's never an empty gesture.

"It's always meaningful for those who are watching," he said. "There's nothing like a father watching with his son and being able to say: 'This game can be fierce, it can be unpredictable, but when the competition is over you shake hands and wish the other guy well.'

"What you want to do is set an example. You've got a pulpit with 80,000 seats."

Levy agreed.

"I'd like to see it continue," he said. "You tell the other guy, 'Congratulations, see you down the road, maybe in the playoffs.' Maybe you wish him luck beating other teams in your division.

"Then you trot off the field, get somewhere private and celebrate if you win or mourn if you lost."

The Bay Area News Group's Cam Inman and Bud Geracie contributed to this story. Contact Daniel Brown at