Running was the superpower that made us all human--which means it's a superpower all humans possess

" . . . It's yet another feature of human evolution that only makes sense in terms of running."

But the big mystery continued to be food. Judging by the Godzilla-like growth of our heads, Lieberman could pinpoint the exact moment when the caveman menu changed: it had to be two million years ago . . . Only one thing could have sparked such a dramatic makeoever: a diet no primate had ever eaten before, featuring a reliable supply of meat, with its high concentrations of calories, fat, and protein.

"So where the fuck did they get it?" Lieberman asks, with all the gusto of a man who's not squeamish about hacking into goats with a rock. "The bow and arrow is twenty thousand years old. The spearhead is two hundred thousand years old. But Homo erectus is around two million years old. That means that for most of our existence--for nearly two million years!--hominids were getting meat with their bare hands." . . .

So how long would it take to actually run an animal to death? . . . A jogger in decent shape averages about three to four meters a second. A deer trots at almost the identical pace. But here's the kicker: when a deer wants to accelerate to four meters a second, it has to break into a heavy-breathing gallop, while a human can go just as fast and still be in his jogging zone. A deer is way faster at a sprint, but we're faster at a jog; so when Bambi is already edging into oxygen debt, we're barely breathing hard.

Lieberman kept looking, and found an even more telling comparison: the top galloping speed for most horses is 7.7 meters a second. They can hold that pace for about ten minutes, then have to slow to 5.8 meters a second. But an elite marathoner can jog for hours at 6 meters a second. The horse will erupt away from the starting line, as Dennis Poolheco had discovered in the Man Against Horse Race, but with enough patience and distance, you can slowly close the gap.

You don't even have to go fast, Lieberman realized. All you have to do is keep the animal in sight, and within ten minutes, you're reeling him in.

Lieberman began calculating temperatures, speed, and body weight. Soon, there it was before him: the solution to the Running Man mystery. To run an antelope to death, Lieberman determined, all you have to do is scare it into a gallop on a hot day. "If you keep just close enough for it to see you, it will keep sprinting away. After about ten or fifteen kilometers' worth of running, it will go into hypothermia and collapse." Translation: if you can run six miles on a summer day, then you, my friend, are a lethal weapon in the animal kingdom. We can dump heat on the run, but animals can't pant while they gallop. . . .

. . . One morning, four of the renegade Bushmen--!Nate, !Nam!kabe, Kayate, and Bor/xao--woke Louis up before dawn to invite him on a special hunt. Don't eat any breakfast, they warned him, and drink all the water you can hold. Louis downed a mug of coffee, grabbed his boots, and fell in behind the hunters as they marched off across the savannah in the dark. The sun rose until it was broiling over their heads, but the hunters pushed on. Finally, after walking nearly twenty miles, they spotted a clutch of kudu, an especially agile form of antelope. That's when the Bushmen started to run. . . .

Later, after !Nate had helped him back to camp, Louis marveled at the ruthless efficiency of the persistence hunt. "It's much more efficient than a bow and arrow," he observed. "It takes a lot of attempts to get a successful hunt by bow. You can hit the animal and still lose it, or scavengers can smell blood and get to it before you do, or it can take all night for the poison on the arrow tips to work. Only a small percentage of arrow shots are successful, so for the number of days hunting, the meat yield of a persistence hunt is much higher."

Louis found out only in his second, third, and fourth persistence hunts how lucky he'd gotten in the first; that debut kudu dropped after only two hours, but every one after that kept the Bushmen on the run for three to five hours (neatly corresponding, one might note, to how long it takes most people to run our latter-day version of prehistoric hunting, the marathon. Recreation has its reasons).

To succeed as a hunter, Louis had to reinvent himself as a runner. . . .

After a while, Louis began to look at running the way other people look at walking; he learned to settle back and let his legs spin in a quick, easy trot, a sort of baseline motion that could last all day and leave him enough reserves to accelerate when necessary. . . .

The Kalahari summer cooled into winter, but the hunts continued. The Utah-Harvard docs would turn out to be wrong about one part of their Running Man theory: persistence hunting doesn't depend upon killer heat, because the ingenious Bushmen had devised ways to run down game in every weather. . . .

"Then why do so many people hate it?" I asked Dr. Bramble as he came to the end of the story of Louis and the Bushmen. "If we're all born to run, shouldn't all of us enjoy it?"

Dr. Bramble began his answer with a riddle. "This is fascinating stuff," he said. "We monitored the results of the 2004 New York City Marathon and compared finishing times by age. What we found is that starting at age nineteen, runners get faster every year until they hit their peak at twenty-seven. After twenty-seven, they start to decline. So here's the question--how old are you when you're back to running the same speed you did at nineteen?" . . .

" . . . It's sixty-four."

"Are you serious? That's a--" I scribbled out the math. "That's a forty-five-year difference. You're saying teenagers can't beat guys three times their age?"

"Isn't it amazing?" Bramble agreed. "Name any other field of athletic endeavor where sixty-four-year-olds are competing with nineteen-year-olds. Swimming? Boxing? Not even close. There's something really weird about us humans; we're not only really good at endurance running, we're really good at it for a remarkably long time. We're a machine built to run--and the machine never wears out."

You don't stop running because you get old, the Dipsea Demon always said. You get old because you stop running. . . .

"But there's a problem," Dr. Bramble said. He tapped his forehead. "And it's right up here." Our greatest talent, he explained, also created the monster that could destroy us. "Unlike any other organism in history, humans have a mind-body conflict: we have a body built for performance, but a brain that's always looking for efficiency." We live or die by our endurance, but remember: endurance is all about conserving energy, and that's the brain's department. "The reason some people use their genetic gift for running and others don't is because the brain is a bargain shopper." . . .

"We live in a culture that sees extreme exercise as crazy," Dr. Bramble says, "because that's what our brain tells us: why fire up the machine if you don't have to?" . . .

By the time the astronauts returned to earth, they'd aged decades in a matter of days. Their bones were weaker and their muscles had atrophied; they had insomnia, depression, acute fatigue, and listlessness. Even their taste buds had decayed. If you've ever spent a long weekend watching TV on the sofa, you know the feeling, because down here on earth, we've created our own zero-gravity bubble; we've taken away the jobs our bodies were meant to do, and we're paying for it. Nearly every top killer in the Western world--heart disease, stroke, diabetes, depression, hypertension, and a dozen forms of cancer--was unknow to our ancestors. They didn't have medicine, but they did have a magic bullet . . .

"You could literally halt epidemics in their tracks with this one remedy. . . . So simple. Just move your legs. Because if you don't think you were born to run, you're not only denying history. You're denying who you are."

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From Born to Run