Despite what the chubby owner of Vegas’ Moonlite Bunnyranch might tell those HBO cameras, violence is the world’s oldest profession. And if our war-mongering culture is any indication, business is booming. The real question is why? Why do we fight? What drives men to become warriors?

After studying environmental issues and oil painting at Harvard, Sam Sheridan, a former Merchant Marine and boxing enthusiast, decided he needed to satisfy a deep-seated adventure jones. In the summer of 1998, he started doing what any adrenaline-junkie (okay, maybe just Sebastian Junger) might do: he crewed yachts from the Bahamas to Australia, worked for Raytheon building the new South Pole Station in Antarctica, and fought fires in New Mexico with the Gila Hot Shots. He also traveled to Thailand, where he managed to track down Apidej Sit-Hirun (the “Muhammad Ali of Thai kickboxing”) to train him at Bangkok’s legendary Fairtex gym. Within months he got his first Muay Thai fight—and won.

Far from scratching an itch, that fight only fueled a bloodlust he’d been carrying around with him since childhood. He had already pushed himself to the limits of the globe and physical endurance but he still needed to know one thing: what drove him to fight? So Sheridan kept traveling—to Bettendorf, Iowa, where a posse of UFC champions introduced him to “car-wreck-itis”; and Rio where he hit the mats with the jiu-jitsu masters of Brazilian Top Team; he even got in the ring with Olympic boxer Andre Ward at his Oakland gym—so he might connect the dots and see where he fit in this worldwide warrior culture. The result is A Fighter’s Heart, Sheridan’s fast-paced, in-the-ring, scholar-turned-gladiator’s view of violence—from the streets of Tokyo to the film lots of Hollywood—and the men who are made (and broken) by pursuing it as a career. On the eve of his book tour we caught up with the gentleman brawler for a behind-the-scenes look at his world tour of toe-to-toe carnage.

Read an excerpt from A Fighter’s Heart.

The book begins with the bullfighting poem JFK carried around with him and you write, “The man in the ring knows, and not just about that particular bullfight and whether he did a good job. He knows.” What do you know now having fought your way around the world?
I guess I know a lot more about myself, and about the nature of striving, pain, aggression, dominance and endurance. I understand those things much more completely. I might have learned them in some other way, or just with age—but fighting in particular teaches you a lot about yourself. It changes you, for the better.

Was there any one thing you experienced that made you want to fight other than a fascination with fighters as a teenager?
My fascination with fighting began much, much earlier—pre-school maybe. My mom read me aloud The Hobbit, The Lord of the Rings, and I read fantasy all the time in grammar school and junior high. I grew up without a TV, so when I wanted to be Conan, it wasn’t Arnold but Robert E. Howard’s version. I loved the athleticism and ballet of a good kung-fu movie. I thought boxing was boring—so few clean punches, not like the movies. I can’t think of any one event, but I do remember getting to college and meeting guys who DIDN’T like kung-fu movies and just being shocked. How can you be male and not like kung-fu movies?

Your physical training was grueling. Was there any mental or emotional preparation you went through to write about your battles in the ring?
I just get up early and drink tons and tons of coffee. I’m an easy writer—I write a lot and most of it’s bad. I had excellent editors.

As a teenager you described yourself as a D&D playing nerd. How did you steel yourself to first step into the ring? And when did you first write about the experience?
Getting into the ring for the first time was about just setting it up, setting a trap for myself—“yeah, I’ll do it in three months” and then the days roll by and suddenly you’re fighting next weekend. I never thought it would be something I’d write about, but people kept telling me about how good the story was, and that I should really write it down. So eventually I did, and things started snowballing. With a few false starts.

Did you ever think of writing a fictional account of your fighting days? Why the Gonzo approach?
I actually did try and fictionalize things first—I wrote a murder-mystery that had the hero as a young retired Muay Thai fighter leaving Thailand. But I couldn’t sell it. So I went to Antarctica, got into fire. Then the non-fiction stuff sort of came to me, and I just wanted to make money as a writer. The Gonzo approach is more about my personal style than anything—that’s how I roll. It actually isn’t Gonzo, but it looks a little crazy from the outside.

In the book you write, “My idea of a war hero is Hawkeye on MASH: If you have to go to war, then you go; but if you don’t, then you don’t. Did you find that most ring warriors feel the same way?
Yeah, I’d say most fighters love what they do, but they don’t want to kill anybody. They don’t have the need to prove their manhood that others might have.

Do you have any regrets about not testing yourself on the battlefield?
Some. I regret almost anything I didn’t do. I know, intellectually, that war and the “test of the battlefield” is propaganda, a mirage, and so on—but I still feel it. I doubt you can come out of this culture and not. I’m old enough now to see that particular illusion pretty clearly.

You reference everything from Barbara Ehrenreich’s Blood Rites and Mailer to A.J. Liebling’s essays on boxing. Was there one book that really sparked your initial interest in the currency of violence?
It was the lack of any one book that sparked my interest in writing something. Kind of. I couldn’t find a good book on MMA [mixed-martial arts] that answered the questions I had about fighting.

You traded a lot of blows in this book. Is it tricky to write about an experience that to a layman seems utterly disorienting? Did you ever worry about scrubbing the details in this post-James Frey world?
It kind of goes by in a blur, so I just wrote that. I have footage of my fights, which make it easy to refer to, and I am a bizarrely honest person. The only things I obscure or don’t deal with are things that would get friends or acquaintances in trouble.

Seriously, if anyone wants to dispute one of my fights, I can show him the tapes. Pretty easy. There’s a National Geographic documentary that features the first one, called A Fighting Chance. Right after the fights I would write down my impressions, and that’s what I would go with, although I’d watch the tapes several times just to clarify things. For instance, in my Muay Thai fight I never saw the punch that knocked me down—I thought it was a kick at the time.

You got your SAG card working fighting scenes on a Paul Walker movie for “sitting around drinking coffee all day and doing fifteen minutes of kicks” and most fight movies are trending toward CGI effects and rope work. Having worked on a movie, what do you think needs to change for cinematic fights to actually tell stories again?
I’m not really sure. I think there are still good fights and good fight scenes being done, it just has to be done with love and care—like any art. I love some “effects” fights—the end of Blade 2 has a great “superpowered” fight, and the Spiderman films do a cool job, and exhilarate with the CGI. I love Jet Li and Tony Jaa—but I don’t really buy it. They’re great athletes, but they’re also about 5’5 and 130 pounds.

You’re seeing more and more MMA in movies though—armbars and RNC’s (rear-naked choke—Angelina Jolie slips a loose one on Brad in Mr. and Mrs. Smith) are popping up everywhere. Movie fights need a narrative. I think in part of what drives the John Woo action sequences is a deeply ingrained sense of story, you know who everyone is and there is a complicated, plot-driven story that runs through the action. That the action carries out. When I think about it, probably what needs to happen is actors and stunt men need more time to train and rehearse and get sequences right, and looking good. Nothing worse than seeing an actor who can’t punch beat the shit out of 10 stuntmen who all can do back-flips and spinning reverse crescent kicks. Actors need to learn how to fight.

You mentioned feeling star-struck around fighters like Andre Ward, but yet you got in the ring with him, and lived to tell the tale. Was there ever a hesitation on your part to write about men who could beat the hell out of you? If so, which ones?
For the most part, there were a few B-level guys I avoided, because they would try and fuck me up, as opposed to teaching me something. Guys at the top have nothing to prove, they’re not threatened by me. But still, there are good guys who if you catch a few times, get pissed and look to drop you.

Do you find that there’s a reluctance on the part of storytellers to get in the ring, so to speak, as writers like Hemingway or Plimpton once did?
No, not really—though writers have to believe it’s possible to write, which takes time and a certain amount of introspection. And for the record, I’m not sure Hemingway was a very good boxer . He tried to get an old, washed-up Jack Dempsey to fight in a bar and Dempsey didn’t; because Dempsey didn’t want to kill him. Plimpton at least went four rounds with Archie Moore. An editor at Men’s Journal once asked me if I’d do three rounds with Tyson. I declined, and it showed me that the editor in question didn’t really get what he was asking—three rounds with Tyson isn’t like three rounds with Archie Moore. Moore was trustworthy, a lifelong journeyman boxer who’d won the title late—he “got it” and didn’t kill Plimpton. Tyson…might not think it was funny. He might not get it, and come out throwing bombs. See, I’m not really Gonzo. I don’t do things just to be crazy. I countered that editor with the idea that I’d get Mike Tyson to train me for a fight—which sounds much more interesting to me. Really pick Mike’s brain, spend some time with him.

You end the book by writing, “Learning to fight, trying to embody the virtue of the hunter and warrior—these things are useful and important, even essential. But don’t be content with being a warrior, be a builder as well. Make something. The true calling of man, real manhood, is about creation, not destruction, and everyone secretly knows it.” If this is true then why do we focus so much attention in the media, literature, and pop culture on the warrior culture?
Wow, what a great question. I think the short answer is because of how sexy war and warrior-dom is. Part of it is endemic and biological, little boys and girls will always look up to whoever’s the toughest, and father’s strength seems so legendary to a young boy. Another part is cultural, or one could even say “cultural evolution”—the societies with the most martial cultures have eradicated those without. Western society has thousands of years of building on the marvel of warrior culture, something Keegan touched on in History of Warfare, the warrior elite has been a critical mainstay.

So have you finally tamed your inner beast?
The short answer is yes and no. I don’t need to fight, but I can’t stop training.

Read an excerpt from A Fighter’s Heart.