Steve, on top of his house, has learned when to back off.

"I almost killed him in Wyoming."

Steve Pete and his brother, Chris, were just outside the mining town of Gillette, in the north-eastern corner of the state. They were at the tail end of a road trip to the Sturgis Motorcycle Rally in South Dakota. They'd just rolled out of a strip bar called Bryan's Place. Steve had been nursing a coffee since midnight, chatting to the owner. But Chris kept drinking.

You might ask: what could make a man so angry he'd want to kill his younger brother? "He punched me in the face while I was driving!" says Steve, the old familiar exasperation flaring up all these years later.

There will always be something special about fights between brothers, a certain intimacy and conviction to the violence. But the fights of Steve and Chris Pete were the stuff of legend. "We had fights in the back of a truck driving down a logging road," Steve says, "hitting each other with metal bars. I almost killed him that night, too, because I grabbed a chain and I wrapped it around his neck and I threw him off the back of the truck."

Yep, that's extreme, even for brothers. But Steve and Chris were no ordinary brothers. They were both born with a rare mutation in their SCN9A gene, leaving them incapable of feeling physical pain. Once a fight got going, their bodies never gave them a reason to stop. A punch in the face was just a way of getting someone's attention.

Their condition is called congenital insensitivity to pain, or CIP. The mutation that causes it was discovered relatively recently, and a study was published in 2006 in Nature, after a story surfaced about a 10-year-old in Pakistan who performed street theatre by sticking knives through his arms and walking on hot coals. By the time researchers arrived to investigate, the kid had died; he'd jumped off a roof. They identified the gene mutations in the child's extended family.

Steve Pete didn't attract attention until 2012, after someone from a science museum in England invited him to participate in a pain-themed exhibit. In medical circles, cases of such rarity or exoticism are referred to as fascinomas. Often they're just an occasion for gawking. But in Steve's case, says Dr Stephen Waxman, the attention might well be warranted.

Unusual medical cases and genetic abnormalities can lead to pharmaceutical breakthroughs. Statin drugs, for example, "have their origins in studies of very rare families where everyone was having heart attacks in their 20s," says Waxman, a professor of neurology at Yale School of Medicine.

Guys like the Pete brothers could be the key to unlocking a new generation of pain blockers that have all the potency of opioids but none of the undesirable side effects, says Waxman. He adds: "That's the Holy Grail of pain research."

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For Steve, life as a fascinoma has had much to recommend it. When he was growing up, kids admired him because he would do the things they only dreamed of doing. Leap from a tree with a tattered umbrella, for instance. When he went mountain biking, no one but his brother Chris could keep up with him. Sometimes they’d cover 120 kilometres a day. And when a couple of toughs were foolish enough to challenge him to a game of cigarette chicken, going forearm to forearm with a lit cigarette between, Steve won both times.

Hearing the stories, you can't help but be fascinated. Maybe because in Steve, the love we feel for loud explosions and sharp knives and high places is so gloriously uncomplicated. Or maybe because, in being impervious to life's greatest source of misery, he is halfway to being that which we all wish we could be – indestructible.

We attune ourselves to him. As much as there is to be learned about pain from studying someone who has never felt it, there may be more to be learned about human nature from someone who is missing one of its more human components.

This is also why the story reads a bit like a Greek tragedy. Because by the time Steve Pete came to understand his own nature, it was too late. By then the damage had been done. By then headlights had already swept across the body in the barn.

There are downsides to a life without pain. When a new kid moved to town, someone would tell Steve, "Go fight that guy." Some fights were broken up, but he never lost. Because he never hesitated and never stopped. "You just don't care if you get hit," he says. "So if someone throws a punch at you, you don't have to pull away."

With fear removed, you see what a head game pain can be

Feeling no pain, he felt no fear. Once, when he sliced his forearm open while working with wood, he saved himself a doctor's visit by stitching the wound himself. When he broke two bones in his foot after drunkenly vaulting a couch at a party, the remedy was duct tape and a stiff boot. ("I had to work that day.")

Doctors, naturally, were fascinated – and sometimes disbelieving, especially when he declined anesthesia. "I had one dentist who was shaking because he thought he was gonna hurt me."

With fear removed, you see what a head game pain can be. "If pain didn't have an emotional component to it," says Dr Allan Basbaum, a professor of anatomy at University of California, San Francisco, "it wouldn't be pain; it would just be sensation."

The emotional correlates of pain are threaded through our lives. And they aren't always negative. Think of the deep satisfaction you feel on completing an agonising workout. Or the esprit de corps that shared pain can produce among teammates. Pain can sharpen our attention, facilitate empathy, even heighten our capacity for pleasure in certain instances.
Stripped of pain, Steve's injuries never gave rise to the associated emotions that usually imbue pain with meaning. Which may explain why he has such a hard time remembering the injuries. "My memory is shot," he says. "I can hardly recall anything."

Occasionally his wife will run into someone who knew him growing up and who is haunted by some traumatic event that Steve can't recall. Like that time he jumped off a swing in grade school. "His bone was just kind of, like, hanging out of his leg," the woman told his wife, "and he's just standing there laughing."

Why Steve doesn't feel pain

A mutated gene jams electrical charges that normally send pain signals.

Pain is not simply an exaggeration of touch; it has its own pathway to the brain, a specific sodium channel sub-type in nerve cells called NaV1.7. When you cut your finger, for instance, nerve endings open the channels so positively charged sodium ions can flow through. These ions set off an electrical charge that signals pain to your brain, says Dr Allan Basbaum, chairman of the department of anatomy at University of California, San Francisco, School of Medicine.

Nerve cells have several subtypes of sodium channels serving different purposes. Steve Pete has a flaw in the gene that controls NaV1.7, keeping the channel closed so the signal never occurs.
A local anesthetic blocks all channels, so you feel no pain, no heat, no cold – nothing. Researchers hope to develop drugs that can target specific channels.

Laughter, actually, is something you hear often from Steve. And why not? Take the pain away, and the world becomes a much funnier place. A world without pain is basically slapstick.

"I do enjoy slapstick," Steve says. "Like the Three Stooges – not the new one, of course; the new one sucks." In early photos, actually, Steve bears a resemblance to Moe – same blocky features, same bowl haircut. Now, with short hair, he has more of a dented look, like a veteran hockey enforcer. There's a stump where a tooth has gone missing. ("I guess it just rotted and fell out.")

The Stooges, of course, were human cartoons. We all loved them. But you have to wonder whether Steve's ignorance of pain has made it harder for him to relate to others. His wife, for instance, suffers from migraines. "He's getting better," she says. "He doesn't laugh at me anymore. But with other people, sometimes he'll laugh."

When he was a kid, Steve would go coyote hunting with a .22. Each pair of ears was worth a $20 bounty, and on a good night a guy could make real money, popping the animals one by one as the lantern picked their glowing eyes out of the dark.
The trick was the bait – a rabbit with a foot chopped off. "It squeals in pain, and when the coyotes hear that, it attracts them," Steve says. "Then you just start shooting."

"To have great pain is to have certainty; to hear that another person has pain is to have doubt."

Philosophers have long wrestled with the question of whether you need to feel pain in order to understand the pain of others. Several years ago, researchers from France and Canada teamed up to try to settle the question. Rounding up 12 people who were, like the Pete brothers, unable to feel pain since birth, they showed a series of clips from stupidvideos.com – everything from a dog biting a man's face to a missed jump from a diving board – in which the people's pain-related behaviors, like facial expressions, were omitted. The study, published in the journal Brain, found the 12 people significantly underestimated the pain of the people in the video. Bear in mind, even those with a normal sense of pain tend to underestimate the pain of others. (Doctors and other health care professionals, of all people, are prone to this, research shows.)

Pain is private. As one scholar wrote: "To have great pain is to have certainty; to hear that another person has pain is to have doubt."

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Growing up with Chris, Steve never had to worry that he might be missing something, that Chris might somehow be suffering in a way he couldn't understand. Then again, Chris never seemed to have a problem with empathy. "He was a lot more empathic," Janette Pete says.

That's Chris and Steve's mum talking. We're back at the farm, a 23-acre spread in the timbered Pacific Northwest hills where the brothers grew up and where their parents still live today. The front porch overlooks a steep grade that the boys used to roll down inside a 55-gallon metal drum. Alongside that runs a driveway, where they took turns lying on the gravel, using each other's heads for a ramp.

Chris was always the quiet one. He could lose himself for hours inscribing Salish tribal emblems on the head of a handmade drum, his mother says. And he would then give it to you without a second thought. "Chris was always fishing and hunting," she says. When they took Steve fishing, he'd lie at the bottom of the boat, pull a tarp over himself, and go to sleep.

Steve was reckless, headlong, the kind of kid who stuck keys in electric outlets because he liked the tingle that shot up his arm. ("I like electricity," he says. "I still like it. Like electrical fences, it's cool if you grab it because you can feel the pulse.")

There's a Pete family rule: don't follow Steve. Eventually, even Chris learned to stand back and watch. Like that time it snowed 10 centimetres, and they climbed with a sled to the roof of the barn. "I just dropped and landed on my back with the sled right on top of me," Steve says. "And the ground I hit was as solid as rock." He didn't go to the hospital but had a hard time breathing for a couple of weeks after that. He suspects he cracked some ribs.

Today Steve's body carries the toll of this punishment. He has severe arthritis, for instance. He can't feel it, but sometimes his fingers lock up and he has to physically wrench them open.

"I found out Friday I have two fractured vertebrae," he says. "My T8 and my T9. The doctor said it happened 12 months ago. I have no idea how. He asked me if I did any bungee jumping or was in a car wreck." Steve's not too concerned about the fractures. "That can be repaired," he says.

His biggest problem now is his knee, which is giving out – perhaps from all the times he jumped from trees and roofs and landed straight-legged. You can see it in the way he walks, with his knee canted inward, as if it's about to buckle. Which it is.

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As Dr Frank Vertosick Jr, points out in his book, Why We Hurt: The Natural History of Pain, there's no structural reason our joints can't bend in both directions. "As we take each step, subtle pain sensations provide our muscles the information they need to keep the joints in the correct alignment," he writes.

So pain does more than just warn us away from hot stoves. It also transmits a steady whisper of data to help us use our bodies. This may explain why retired NFL players, who are often encouraged to ignore pain, are more than three times as likely as the rest of us to develop early-onset osteoarthritis. And it's also why, in a 2011 study, six per cent of retired NFL footballers surveyed (average age: 48) require the use of a cane, walker, or wheelchair.

The very existence of pain speaks volumes about our place in evolution's hierarchy, Dr. Vertosick argues. Unlike a centipede, for instance, we have almost no physical redundancy – just as many limbs as we require, and no more. This makes our bodies highly efficient but also highly perishable. And that perishability is not offset by the knack for mass reproduction. The amount of pain we feel, in other words, and the intelligence we use to interpret that pain, directly reflects our value to the species. The Pete brothers grew up like centipedes, behaving as if they had an infinite supply of limbs. Part of Janette's job was to teach them that they didn't. Spanking clearly wouldn't work. Instead, she'd squirt them with a water bottle, as if they were squabbling cats.

Sitting on her front porch, Janette taps a cigarette and cackles, her talk still full of vitriol at the legions of skeptical doctors, dimwitted schoolteachers and sanctimonious child-protection agents that she's had to deal with. But somewhere behind this complacent facade you can sense the anguish of a mother who can't be sure she struck the right balance between protecting her boys and letting them run free.
Even though Steve was more reckless, it always seemed like Chris was the one who paid the dearer price, which he brought on himself. "Chris did body contortions," Janette says. "He'd throw his legs up over his head backward. It gave me the chills."

"I used to love to watch him do that," Steve chuckles. "He would egg him on!" Janette says.

Janette was the only one who could come between the brothers when they started fighting. It was the usual stuff. Steve, the older brother, was always bossing Chris around. And Chris usually rolled with it. But every now and then he'd rebel, and all hell would break loose. After they'd fight, Janette would make them sit with their arms around each other until they made up. "I said, 'I tell you what, if you guys are ever fighting, and I come home and find one of you dead, the other one might as well kiss their butt goodbye because you're gonna be dead too.'"

There's always a moment when the warring we are born to moves on to new battlefields, when shared history outweighs the aggravation, and brothers actually become valuable to each other. For Steve and Chris Pete, the moment came a few miles outside Gillette. By that point, Chris had never needed his big brother more. He'd started drinking when he was about 19, around the time Steve started spending more time with his girlfriend. By his mid-twenties, Chris had already been through several detox programs.

The drinking may have been his way of coping as his body began to break down. Years of slouching in school had deformed his spine, and as his vertebrae chewed into his spinal cord, he was losing the use of one arm. Semi paralysed, he couldn't work. Nor, says Janette, was he allowed to receive disability, since, by the reasoning of one judge anyway, he wasn't actually in pain.

Steve struggled too, with his arthritis and buckled knee. But even if the leg had to come off, it wouldn't mean the loss of what he most valued in life – his wife and kids. And video games. Both brothers had played video games as kids. It was one of the few ways they kept sane during their many long hospital stays. Steve had gone on to become a serious gamer – the mayhem of first-person shooters suited him. The violence could not be desensitising to one who already felt nothing. And no matter how many times you got shot, blown up or stabbed in the neck with a combat knife, the biggest impact was only on your fingertips.

But Chris still preferred the stillness of the woods to the mania of video games. It was only there that he could actually hear himself. As his body gave out, though, the woods were becoming ever more inaccessible to him. It was only a matter of time, doctors said, before he'd be in a wheelchair. So he kept drinking and turned inward, like he always did. It had to come to a head eventually. And when it did, his brother was there.

"I picked him up from somewhere when he was drunk," Steve says. "I told him, 'If you don't change the way you live, you're not going to be there to teach my kids all the things I can't teach them. I'm not into hunting or fishing or anything like that. And you are. So I expect you to be the one to teach my kids that stuff.'"

It was his best shot, and Steve let him have it. It was also exactly the kind of bossy big-brother move Chris used to hate. In the past, he might have reached across and socked him. And Steve might've pulled over, wrapped the seatbelt around Chris's neck, and commenced punching his lights out. But Steve and Chris Pete's fighting days were over. In a way, they'd been replaced by something even more terrible. Because if there's one thing worse than a fight between brothers, it's the fight a man wages against himself.

The shattered hulk of mount St Helens broods beneath an overcast sky near Castle Rock, Washington, the small town north of Portland where Steve and Chris Pete grew up. When the volcano erupted in 1980, one year before Steve was born, it dropped a couple of feet of ash on his parents' house. Today, as the magma gradually recharges, volcanoes remain one of the few things (along with appendicitis and, of course, sharks) that Steve actually fears.

Now rain tickles the windshield as we wind slowly through the stands of cedar and Douglas fir, hoping for a view of the dire landmark. As kids, Steve and Chris used to come up here all the time. It was the kind of place Chris loved – all wind and distance and silence. Sometimes you could catch a glimpse of an elk herd.
"Part of me wishes my brother could have stuck with it for a while and fought through," Steve says. "It's kind of a selfish thing to ask, though, because I know he was going through his own little hell inside his own head."

Steve got the call from his father, who came home from work one Thursday and found Chris hanging in the barn. "After that it was just kind of like autopilot," Steve recalls. He remembers talking to the chaplain, and the coroner's van disappearing down the driveway. "I was thinking, 'Damn, this is the last time he's gonna be . . . the last time he's leaving the house,' you know?" Steve says. "After that, even days after that, it was just kind of foggy. Just kind of like living in disbelief."

That was nearly six years ago. Steve hasn't jumped off any roofs since. "Once Chris passed, I really started to slow things down a lot more," he says.

None of Steve's three children inherited his inability to feel pain, since his wife doesn't carry the mutated gene. His job keeps him out of trouble. And every now and then he flies to London to help a leading pain researcher sort out the science that may one day give relief to others who suffer.

The research on people like Steve – and on certain animals with pain-related superpowers – may someday lead to drugs that target the specific nerve pathways, or sodium channels, that send pain signals to the brain. Some centipedes and spiders produce venom that may block that pain channel in humans. There's also the southwestern grasshopper mouse, which can stop the transmission of pain signals caused by the venom of bark scorpions.

The hope is for calibrated pharmaceuticals that relieve chronic pain but allow acute pain to be felt. Because if Steve's story tells us anything, it's that pain does serve a purpose. We wish we didn't have to feel it; we wish we could leap from a tree with an umbrella and keep right on going.

It's either man meets limit and overcomes, or man meets limit and takes a left. Some of our ambitions are by nature lethal. To leap, soar, scale great heights. It's up to us to figure out how much caution to use, and when recklessness is still warranted. To distinguish between good pain and bad pain. And to endlessly recalibrate to make the absolute most of our mortal limits.

For Steve, painlessness is itself the limit. Not that he would ever want to be free of it, even if technology could somehow magically make that possible.

Call him a slow learner, but Steve still hopes to bungee jump one day. Closer to earth, he's pursuing the interest he's always had in electronics, scouring the Internet for damaged iPhones, tablets, laptops and TVs that he can repair in his workshop. His most recent acquisition is a router that will help him integrate electronics into woodwork. As for that busted leg of his, if the time does come to amputate, he looks forward to equipping his prosthesis with a custom iPod dock.

Now, as the road winds ever higher toward the mountain lookout, the rain thickens into snow that wools the windows and whitens the tiered eaves of the evergreens. When they were young, Steve and Chris used to come up here and have snowball fights, packing the snow tight with their bare hands until the skin dried and cracked and stained the snow red.

Steve was rewatching footage from those days recently. He can see Chris, who was about 12 at the time, writing in the snow with a stick. "It said 'Chris was here,'" Steve says.

The snow comes down in a white whisper. Suddenly all color is gone and he's fighting again, fighting the pain of his lost brother. Which is odd. Because he's really not supposed to feel pain. Technically, he shouldn't be able to feel pain at all.

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