All Saturday morning and afternoon it goes on, bulls torquing in the air, riders snapping back and forth with terrible speed. Brown is coming up fast with a score of 89.5 on a bull named Tuscarora, leaving him in the top few by the end of the day.

In the evening, the bulls return to their pens, stomping out of the metal trailers with an air of lumbering superiority. Riders do the same, only they go back to a high-rise hotel for a dance party. There, lasers strobe through an acrid, smoke-machine haze full of cowboy hats and petite feminine shoulders. Young women parade in and out; tight jeans and halter tops, pretty mouths, hands clasping and unclasping. Some dance, and some remain wrapped around beer bottles.

I've never been especially good at parties, and the music is so loud it makes my ears hurt. Working my way out takes a while, and involves navigating past an overbearing publicity agent in a black leather jacket who is shouting the names of his clients at me. He has some Brazilian riders on his roster and he wants to make sure they get mentioned in the article I am writing, for who is it? New York Times, Newsweek, what magazine?

"High Country News," I say and slip out from under him and catch the elevator.

I am staying in a room on the same floor as the bull riders. The hallway is brilliantly lit and mostly quiet but for the muffled giggles and drunken laughter coming through closed doors.

Around midnight, the sex begins.

My bed feels like a plank as I lie on it, listening to intermittent copulation from various locations. This sport cannot be considered properly without the sex. It is one of the raw elements of bull riding, as if PBR were a straight shot to the bottom of Maslow's hierarchy of needs, a direct connection to vulgar desires.

At 3:00 a.m., I lay awake wondering how they manage to keep up with so little sleep. Maybe they have been cycling from room to room, pausing for rest in between. Maybe I'm the only one who feels like I've been tumbling around in a washing machine all night.

At 6 in the morning, it starts up again.

I come slowly awake facedown on a pillow, reminding myself why I asked for this room. I'd wanted to get as close to this sport as possible, to spend as much time with the bull riders as I could. I sure as hell was not going to actually get on a bull. But this morning I feel as if I've been in the arena all night.

I roll out of bed groggy and swipe a hotel writing pad off the nightstand. With pen in hand and my forehead against the wall, I listen through to the other side and start writing. It sounds like fish slapping on pavement. 

My daily sunrise meeting with bull handlers is going to be hell.

The finish line comes on Sunday afternoon. Zack Brown has been coming out on top of every ride, his points pushing him to the final round. The top two Brazilians have made it this far, along with a gutsy rider named Mike Lee from Decatur, Texas. For Brown, a win here would be a thunderous victory, since it was in this same arena that the bull stomped him back in 2006.

In the earlier rounds, the bulls are randomly drawn. But in these final rounds, riders are allowed to choose their animals. Lee makes the bold move of picking a bull named White Magic, who has never been successfully ridden and has an average buck-off time of 3.2 seconds. Nobody behind the chutes is surprised at his decision. Lee is known for his snappy, jolting judgments, and this time it works for him. Lee manages to hang on through the kick-storm for the full eight seconds. He dismounts and runs, but before he reaches safety, the mass of White Magic comes down on him, and drives him to the ground just as a bullfighter gets his body between the two. The bull grinds its head into them as another bullfighter slaps the bull's head, whirling it around. Somehow, everyone gets out without injury, and Lee comes off with a satisfying 88.75 points.

Brown is last to go. He picks Soulja Boy, a bull successfully ridden four out of nine times with a 5.48-second average buck-off. A smaller bull at 1,200 pounds and freshly bought for the circuit, Soulja Boy is one Cody Lambert told me to keep an eye on. He said the bull is a born champion.

Wearing a protective black Kevlar vest, Brown knuckles down inside the chute. He gets himself in position, sitting on his hand, and calls for the gate. Soulja Boy launches. The chocolate-colored bull looks like he's bound tight in rubber bands, his kicks and recoils spring-loaded.

It's as if the bull knows it's the final round. He gives more vertical flex than usual, switching abruptly out of his routine until Brown's leg-lock comes loose and he's suddenly floating in mid-air.

Brown's only contact with the bull is his fist, still anchored to the rope. The bull yanks him back down and gives him a full-body slam, then hurls him up, then snaps him back down. As I watch, I will him to let go, to forfeit the round to save himself. This is why I am watching safely through a pipe-rail gate, and Brown is out there getting pummeled.

It is not a pretty ride, not one of those where the rider gracefully matches the intractable rhythm of the bull. Brown is nothing but fist and body. But he hangs on for the full eight seconds.

The buzzer sounds. Brown lets go and flies right over Soulja Boy's head so that for an instant they are face-to-face in mid-air. He hits the ground running the other way. The bull is still going full-tilt, probably aware that he's been bested, finishing out with a fury. The bullfighters take over.

Twisted around half-backwards, Brown checks the bull over his shoulder, then looks for his score. He is surprised to see one of the judges stopped his clock at 7.5 seconds, saying Brown touched the bull with his free hand and is disqualified. The crowd gasps and boos, not a sound often heard on the PBR circuit.

Brown reaches the chutes and slams his hand on the challenge button. Few riders ever hit the button. Here are the rules: You have 30 seconds to challenge after being disqualified, and if you turn out wrong you get a $500 fine.

Thousands of agitated murmurs fill the dome, a tension that reaches through the throngs at floor-level around the chutes. Even the lightly clad women in chaps look concerned, peering up at the huge video monitors hanging throughout the arena, showing again and again the image of Brown flying over the horns.

After two minutes, a voice wakes the arena, announcing the judge has reversed his decision: The ride is legal at 89.25 points. Added to his day's number, this means the championship in Billings goes to Brown, giving him a season's total of more than half a million dollars. His PBR comeback is sealed.

The roar eventually dies down. Autograph-seekers fill the halls, and then trickle out. Long-haired roadies in T-shirts move in, coiling up heavy lengths of electrical cord. TV crews pack up their production trucks and depart for the next gig. Riders start the cycle all over, leaving for home or wherever before being sucked into yet another spectacle the following weekend. Empty except for folding chairs and rolls of sports tape, the prep room still smells of chew and rope.

Bull hooves clatter into truck-trailers, last to leave.

The next morning, I am sitting with Brown at a Cracker Barrel just off the interstate. Pulled up to a cornucopia of hash browns and gravy, he wears a faded leather jacket, his expression unflappable. He looks like any guy, not particularly like a champion. The only way you might know is from the other breakfasters who stop by to congratulate him.

Brown is telling me about his hiatus from bull riding after the injury. He got into spear-fishing, swimming in the ocean with a line, buoy and a barbed weapon. Spearing and taking down a big fish, he says, can be a hair-raising experience. "You gotta swim down to it with a knife and stab it in the brain."

I jump on that comment, trying to get him to admit he is in bull riding for the animals, in order to have a raw experience with them. Brown sees where I'm going, but says the bulls might just as well be surfboards. You ride them, that's all.

Stymied, I blurt, "You could take this sport to the next level, enter the arena wearing nothing but a loincloth and jump the bull, try and ride it for eight seconds. That'd be something, eh?"

Brown slowly comes up from his plate and eyes me. I see that I am mistaken. It would not be something.

Still, from my perspective, the PBR circuit looks a lot like a bull-money-sex cult. It scratches a savage, animalistic itch we seem to have, and it is rapidly edging into the mainstream market. While still too visceral and callous a sport for many, it is also organic and utterly primal. There are no mechanical parts, no rumbling engines.

Rumor has it that the first bull-riding match happened in 1869 in Deer Trail, Colo., when ranch hands from two local outfits tried to outride each other. The competition must have been a terrifying and disorderly spectacle.

But long before that, Minoans on the island of Crete vaulted over the backs of sharp-horned bulls. You can see them still, in frescoes and pottery dating from around 1800 B.C. The strength and even approachability of bulls have long drawn us close to them, tempting us to put as little distance as possible between ourselves and this formidable beast.

Eventually, when we have all become good and civilized, bull riding will become a thing of the past. We will look back on it as a brutish and bygone sport, and we will look back with longing.

Craig Childs is the author of several books on nature, science and wilderness. He has never ridden a bull, nor does he ever intend to.