CHICAGO — There's something primal here, something elemental. Something theatrically sinister too.

Before each bout begins, the throbbing bass of the piped-in music vibrates inside legs and chests and brainpans. If you were forced to guess — if, say, an Ultimate Fighting Championship competitor threatened to separate your face from the front of your head — you'd hazard that it's the kind of music the Mayans played before ritual sacrifices.

And you'd be fairly sure this answer would allow you to live another day.

Except for the glowing octagon, where the fights are taking place, it's all darkness. And from that darkness comes the oohing and aahing of people who have come to Allstate Arena on a Saturday night to get a taste of blood that isn't theirs.

It's closed in, loud, an assault on the senses, and we're not even the ones fighting. Trying to imagine what it's like to be the fighters, to be the ones who are putting brain cells and tracheas on the line, is like trying to imagine what it was like to be a crash-test dummy for the Ford Pinto.

But the people who take part in the sport say we all have this inside us, this need to punch and kick and generally beat the ever-living crud out of one another. Maybe. But it says a lot that, on the outside, most of us don't have cauliflower ears and scar tissue masquerading as eyebrows.

East Chicago's Miguel Torres, who is the World Extreme Cagefighting bantamweight champion, started competing in organized bar fights in northwest Indiana. He said there were no scales, which would explain why he, as a 135-pounder, was allowed to fight (and beat) a 205-pound man. The gloves weren't padded around the knuckles, which would explain the two broken hands he suffered. Torres said he took on all comers, "bikers, Marines, boxers," which doesn't really explain why he fought for free back then.

"This is the oldest sport in the world — combat," said Torres, who didn't fight Saturday. "If you look back in time, not just wars, the Romans and stuff like that, it's always been that natural man vs. man, that fighting spirit everywhere.

"I've loved it since I was a kid. I don't know what it's been that's drawn me to this, but I followed it and I'm here. I think every male, female, every child have it in them."

This might have been have been my favorite paragraph in the Tribune last week, and although it might seem to have to do with presidential politics, it actually dealt with illegal UFC moves and tactics:

"Head butting; eye gouging; biting; hair pulling; fish hooking; groin attacks; small-joint manipulation; spitting; throat strikes; striking the spine/back of the head; throwing out of the ring; grabbing the clavicle; kicking/kneeing the head of a grounded opponent; stomping a grounded opponent; heel to the kidney."

Everything else: OK.

Saturday night didn't change the impression here: Mixed martial arts has too much inert ground fighting and not enough boxing. A main-card event featuring lightweights Gray Maynard and Rich Clementi looked like a frozen game of Twister. Fans, some of whom paid upward of $600 for a ticket, booed lustily.

And it didn't help when, in the third round of the main event, Patrick Cote went down with an unforced leg injury against champion Anderson Silva.

"Patrick should not be booed," Silva told the crowd, which didn't listen.

In an earlier fight, Spencer Fisher dropped Shannon Gugerty with a punch, opening a gash above Gugerty's left eye in the process, and all was right in a world predicated on the survival of the fittest and a good cut man.

And Tyson Griffin vs. Sean Sherk in another main-card lightweight bout was a straight-up slugfest. More. Give us more of that.

There indeed is something to this sport that resonates, and you can count on all sorts of academic dissertations in the coming years to explain what MMA says about us as a society. This will save a lot of time and trees: It says we like to watch people hit each other. Same as it ever was.

This is the first time the UFC has been in Chicago, and it likely will be back, given the popularity of the sport and the fact that most of the seats at Allstate Arena were filled.

The sport is extinguishing boxing, the way a heel grinds a cigarette butt, and that's too bad. But it's also life, and MMA answers a call that boxing hasn't or can't. In a very short amount of time, MMA has gone from being considered a despicable bloodsport to being Main Street America.

Before the start of the main card, organizers absolutely blasted the Who's "Baba O'Reilly," and it was impossible to miss one verse: "I don't need to fight to prove I'm right."

Here, they argue that they do need to fight.

And some of us need to watch.