It’s a guy thing.

The headbutt reared its ugly head over the weekend when Zinedine Zidane, captain of the French soccer team, headbutted the chest of Italian defender Marco Materazzi during the World Cup finals. The aggression, seen by a billion viewers around the world, caused Zidane to get ejected and left Materazzi writhing on the ground before Italy won the championship in a shootout.

“Most animals that fight that way have skulls built to take it. We don’t appear to be built that way,” says Katherine Ralls, senior scientist at the Smithsonian’s National Zoo in Washington. “But I guess when you get so much adrenaline and testosterone going, it’s butt first and think later.”

Before we harshly judge Zidane (still voted best player of the tournament), let’s explore the anthropological and cultural origins of the headbutt.

As old as the dinosaur, the headbutt is the universal male symbol for territorial aggression when hands and words just aren’t enough. The message it sends, in so many words is: I’m angry and don’t feel like punching you or beating you fairly, so I’m going to launch my head at your nose, cheekbone, hinge of your jaw, temple or eye socket. And the idea, roughly speaking, is to establish dominance and win the girl, or the soccer match, whichever comes first.

Zidane joins a Who’s Who of other male creatures who, in striking moments of desperation, frustration, lust, passion and even silliness, resorted to the primordial act.

French soccer player Zinedine Zidane, left, headbutts Italy's Marco Materazzi. Zidane was ejected from the World Cup final Sunday in Berlin.

The list includes just about any professional wrestler, the cartoon dad Homer Simpson and Star Wars bounty hunter Jango Fett, who headbutted Obi-Wan in “Episode 2: Attack of the Clones.” In one of the most celebrated such incidents, the writer Norman Mailer headbutted literary opponent Gore Vidal – for suggesting that Mailer was a violent man. There’s a move in the children’s card game Pokemon called a headbutt and, not surprisingly, a punk rock band named Headbutt.

In the beginning, the Bible makes no mention of Adam attempting the first headbutt, but a thick-headed lizard called Pachycephalosaurus, who lived 65 million years ago, was a skillful headbutter. His cranium consisted of a very thick bone (not unlike many modern-day professional wrestlers).

“Within a species, it’s mostly the males that will headbutt for territory and social dominance,” says Stephen Zawistowski, chairman of New York-based Board of Certified Animal Behaviorists. “They will do this to gain access to a harem of females.”

Rams, mountain goats and antler-locking deer come to mind in the animal kingdom, but hippopotami are also notorious headbangers. They evolved into butting at an angle so not to damage their frontal lobes. Pigs developed dermal protrusions (not covered by any known HMO) for their head-to-head attacks. Cetaceans such as whales and porpoises are also natural headbangers but stick to headbutting sharks.

Which brings us to the Alaskan muskox. During breeding season, the males achieve dominance by headbutting rivals. The muskoxen throw in grunting and bellowing for full machismo effect.

Oh, and cats headbutt too.

In sports, pro wrestling has long featured the move. Old-timer Harley Race innovated the “diving headbutt,” delivered from the top rope or turnbuckle. As other styles emerged such as the “swan dive” headbutt, spinal injuries arose. With the exception of pro wrestling and something called Burmese boxing, headbutting is generally illegal in sports. But some martial arts and self-defense programs include headbutting, if done properly.

“Effective headbutting revolves around striking a sensitive area with a less sensitive area,” according to Wikepedia. The on-line encyclopedia devotes an entire page to headbutting and its mechanics. “A misplaced headbutt can cause more damage to the headbutter than the headbuttee.” Lacerations, concussions, that sort of thing, it points out.

In boxing, Roberto Duran practically headbutted Davey Moore into submission in their junior middleweight fight in 1983. Mike Tyson was also known to headbutt when not chewing off an opponent’s ear. During the NBA playoffs in 1993, the New York Knicks’ John Starks headbutted Reggie Miller of the Indiana Pacers. And former pro basketball and MTV star Dennis Rodman was suspended six games for headbutting an NBA referee in 1996.

The headbutting bar, however, was set highest by Curly Howard of the Three Stooges when he knocked a bull out with his head in one episode.

As an animal behaviorist and soccer coach himself, how does the behaviorist Zawistowski explain players resorting to headbutting?

“It’s an expression of anger,” he says. “If you can’t use your hands, there isn’t much left.”